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Contact allergy to woods
Contact Allergy to Woods
9 Bjorn M. Hausen, PhD
From the Department of Dermatology, University Hospital, University of Hamburg, Hamburg, West Germany
Among the various natural resources, wood plays an important role for construction, furniture, boat-building, plywood, veneer, and other purposes. It also is absolutely necessary for the production of pulp and paper. In addition, half of the world demands wood for use as fuel. The principal areas from which the major timbers come are tropical and subtropical regions such as South Asia, West and Central Africa, and South America (Amazon basin). Wood for pulp and paper production is provided from the temperate zone and from the tropics of Brazil and Malaysia. Inhalation of wood particles, especially fine wood dust, as well as direct contact with solid wood, may cause a series of different changes in the human organism among which severe poisoning and wood dermatitis are the most striking. Another occupational hazard is adenocarcinoma of the nose and nasal cavities in workers heavily exposed for decades to fine wood dust.’ This currently is the subject of much discussion in Europe. Carpenters, cabinet makers, joiners, and others who saw, sand, turn, and plane wood are at high risk to develop allergic contact dermatitis, allergic rhinitis, asthma, and, sometimes, extrinsic allergic aveolitis. Irritant dermatitis may arise from the sap or latex of species belonging to the plant families Anacardiaceae, Apocynaceae, Euphorbiaceae, and Moraceae. Among these, some timbers contain compounds with blistering properties due to histamine-liberating alkaloids like cryptopleurine in poison walnut and chloroxylonine in East Indian satinwood. Others contain strong sensitizers, such as (R)-3,4-dimethoxy-dalbergione in Machaerium scleroxylum Tul., which may elicit irritant reactions when applied to the skin in high concentrations. Contact urticaria is produced by species such as obeche (Triplochiton scleroxylon K. Schum.),2 limba (Terminalia superba Engl. & Diels),3 ramin (Gonystylus bancanus Bai11.),3p4teak (Tectona grandis L.),5 and larch (Larix decidua Mi11.),4y6 but rarely is seen. Certain wood species of the families Rutaceae and Flindersiaceae are known for their phototoxic properties,7 but most of them are not of great commercial value. 65
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Clinical Aspects While irritant dermatitis is produced mainly by compounds like alkaloids, glycosides, saponines, anthraquinones, and certain phenols, allergic sensitization from woods arises in most cases from benzo- and naphthoquinones. Sometimes, the sensitizing agents occur as a precursor in the timber and are oxidized to the effective quinone in air or enzymically in the skin. As in many types of plant allergy, most of the allergenic wood constituents have not been identified until now. As allergic contact dermatitis comes from the fine wood dust created during the different woodworking processes, the clinical picture is mostly that of an airborne contact dermatitis. Commonly, those affected have worked occupationally with the woods for a long time. Under occupational conditions, great amounts of fine wood dust reach the skin, are trapped in clothing, especially at the neck and sleeves, and also enter the trousers from the bottom. Sometimes the dust particles are carried manually to the genitals, hairs, shoes, boots; clothes, in general, become impregnated with the dust, even when effective exhaust systems are present.
Symptoms The first symptoms appear at the exposed areas of the skin-hands, forearms, eyelids, face, and neck (Figs. 1 and 2)-accompanied by itching. Later, the axillae, groins, ankles, waist, and dorsa of the feet are also involved. The acid conditions of sweaty regions and the enzymatic properties of the skin may help to oxidize precursors to efficient contact allergens. Preliminary damage of the skin by acids, alkali, detergents, disinfectants, hand cleansers, generally wet work, fat solvents, and other factors facilitate the penetration of toxic and allergenic substances from the wood particles into the skin. At first, preliminary symptoms are ignored, as they usually disappear quickly during weekends. Continued exposure worsens
the dermatitis; attacks become more frequent, lesions increase in severity, larger areas are involved; finally, symptom-free intervals become increasingly shorter. In severe cases, dermatitis will spread over the whole integument, and work must stop. All symptoms will subside within a short time when the woodworker is removed from his working place. Nonoccupational dermatitis, resulting from direct contact with finished wood products, is more rare but sometimes of remarkable importance for the individual. Allergy may arise from wooden gun handles (Fig. 3), cutlery hafts, tools, and other utensils; mouth pieces of woodwind instruments, chin rests of violins and violas (Fig. 4); wooden jewelrylike bracelets, necklaces, wooden crosses, and wooden footwear. Allergic perioral dermatitis with swelling of the lips, sometimes involving the cheeks or even the whole face, will be seen in persons playing recorders and flutes manufactured from cocobolo, Brazilian rosewood, and pao ferro.
Diagnosis A detailed anamnesis (case history) and an exact botanic identification of the offending wood species is absolutely necessary; otherwise, any patch testing and description of the case is meaningless as it gives no information to the patient or anyone else. Trade names, especially those of tropical species, often are misleading, insufficient, and confusing. On one hand, a single name may be used for a large number of different timbers, while on the other hand, one species may have ten or more different trade names. Few of the people working with wood occupationally really know what species they are handling. Thus, in cases of allergic contact dermatitis a wood anatomist should be consulted who will be capable of identifying the species by means of a solid sample. As it is generally known that the amount of an allergenic or toxic compound in plants and woods may vary considerably, diagnosis is performed preferably after correct identification of the species by epicutaneous tests with the wood constituent itself. Patch test-
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FIG. 1 (left). Severe contact dermatitis of a cabinetmaker’s arms caused by pao ferro (Machaerium scleroxylum). FIG. 2 (above). Allergic contact dermatitis of a cabinetmaker’s face and neck from teak wood (Teckma grandis). FIG.
3 (left). Revolver grip manufactured
from cocobolo (Dalber-
gia retusa). (Courtesy of Fuzzy Farrant, West Covina, CA.)
FIG. 4 (below). “Fiddler’s neck” in a violinist due to persistent contact with a chin rest of Brazilian rosewood (Dalbergia nigra).
ing with the wood dust should be avoided. Irritant reactions may occur, especially when the wood or the concentration of its constituents is unknown. Certain timbers like teak, pao ferro, and mansonia usually contain so high a concentration of their allergens that irritant reactions are obligatory. Even a single test may risk active sensitization. As most of the hitherto known allergenic wood constituents are not commercially available, patch testing with the sawdust or shavings should be done with caution.
A simple method to obtain sub-irritative extracts is the following: l-10 g of wood dust or shavings are stirred overnight at room temperature with 50 ml ethanol. After filtration, the ethanolic solution is poured onto a flat glass container of which the weight has been previously determined. From here, the organic solvent is allowed to evaporate under exhaustion equipment or on a windowsill until dry. After renewed determination of the weight, the residue is dissolved again by 1:lO. This 10% ethanolic wood extract or
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further dilutions of it are used for patch testing. In case of an irritant reaction, the next dilution should be tested, and controls are necessary, A list of the essential wood contact allergens and their recommended test concentrations are given in Table 1. These are, in the event of an interesting case, available from the author on request. Protection Prevention of irritant and allergic contact dermatitis from woods sometimes is difficult. Although efficient exhaust ventilation for molders, sanders, polishers, circular saws, and other machines has to be installed by law at the working places, some wood species create such a fine and noxious dust that these precautionary measures will not help. Only protective clothing, personal cleanliness, and sometimes moistening of the air with oil or water near the place where the dust is generated may be successful. Barrier creams and adequate washing facilities, including showers, will be partly effective. Knowledge of the dangerous properties of certain woods is of great importance. Everyone who works with a wood should know the risk it bears. Only in very rare cases can a strongly sensitizing species be replaced satisfactorily by a less sensitizing one with equal or similar physical properties and appearance. Replacement sometimes means substitution of a whole consignment of an offending timber by the same species from another locality. Finally, there is no way to protect against the accidental appearance of an irritant timber as an errant sample in a normal shipment. In case a woodworker has to change jobs and be retrained, occupations dealing with plants or plant extracts (eg, gardener, florist, pharmacist) should not be considered as exposure to chemically related compounds of the quinonoid type may occur in the new work place. Certain quinones, known sensitizers in woods, also occur in plants or are chemically related so that cross-reactions can occur. Experimentally, such cross-reactions have been produced in guinea pigs.x
Sensitizing Species The following review comprises those species that may cause allergic contact dermatitis and are of commercial value. As the field is very broad, space permits only a few of the many examples. For further details, several booksg-I2 are recommended. Afrormosia Afrormosia (Pericopsis elata van Meuven, Fabaceae) is a West African timber of good strength properties used for exterior and interior work, joinery, furniture, flooring, framing, boat building, and marine construction. Woods and Calnan,’ Wilkinson and coworkers,‘3 and Schleicher14 reported several persons with positive patch tests. Chemical investigation revealed three alkaloids and an isoflavone. Sensitization experiments in guinea pigs were successful.'0 A patient allergic to afrormosia, which he had used for the framework of his house, reacted to two isolated compounds, which are still unidentified, but not to 2,6-dimethoxyquinone,‘O which also has been found in the wood (unpublished observation). Afxelia Afzelia (Afzelia africana Sm., Caesalpiniaceae) is a heavy West and Central African timber of outstanding stability and durability. It is in great demand for staircases, loadbearing floors and railway wagons, and wooden floors built for a heavy load. Dermatitis has been reported several times15j16 and observed by me in one case. The patient reacted to an ethanolic extract of the heartwood, but failed to react to any of the fractions isolated by thin-layer chromatography. Open epicutaneous sensitization in guinea pigs was successful.1° A uodirS Avodire (Turreanthus africanus Pellgr., Meliaceae) is an African timber commonly used in veneer production. Dermatitis, irritation, and nosebleeding has been report-
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TABLE 1. Contact Allergens In Wood Specks and Their Recommended Test Concentrations Allergen Name
Formula
Concentration (%)
Acamelin
1.0
Anthothecol
1.0
Wood Species Botanic Name
Trade Name(s)
Acacia melanoxylon R.Br.
Australian blackwood
Khaya anthotheca
African mahogany
C.DC. Chlorophorin
10.0
Chlorophora
excelsa Benth. and Hook.
Iroko, Kambala
Cordia and Patagonula species
Cordia, Frejo, Canalet
Cordiachromes
0.1
Deoxylapachol
0.01
Tectona grandis Tabebuia sp.
(R)-3,4-dimethoxyldalbergione
0.01
Machaerium scleroxylum
Dalbergiones P$-Dimethoxybenzoquinone Grevillol
1.0 10.0
0.1
Dalbergia
L.;
Tul.
Pa0 ferro, Caviuna vermelha
species
Rosewoods
Various wood species
eg, Mahogany, Makori
Greviliea robusta
Silky oak, Silver oak
A. Cunn. Lapachenole
0.1
Teak, Bethabara, Ipe
Paratecoma
peroba
Peroba
Kuhlm. Macassar quinone
1.0
oxidation product of macassar II from Diospyros
celebica
Bakh. Mansonone A
0.1
Mansonia
altissima
Mansonia, B&e
A. Chev. Obtusaquinone
1.0
Dalbergia
retusa
Hemsl. Oxyayanin A and B
1.0
Distemonanthus benthamianus Baill.
Tectoquinone
1.0
Tectona grandis
/3-Thujaplicin
0.1
L.
Thuja plicata
Donn ex D.Don Thymoquinone
‘Cordiachrome A. toxyayanin A.
0.1
Calocedrus decurrens Florin
Ayan Teak Western red cedar Incense cedar
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ed.l2~1’-19Positive patch tests were obtained in a cabinetmaker suffering by Calnan from dermatitis of the hands, arms, and neck. The responsible constituent is unknown. A yan
Ayan, also called Movingui (DistemonanBaill., Fabaceae) is a decorative and heavy timber from West Africa mainly used for cab bodies, coffins, and kitchen and laundry equipment. Severe dermatitis was seen by Morgan and Thomson21 in four carpenters who had positive reactions to the flavonoids oxyayanin A and B. Thirteen additional cases were described by Woods and Calnan.12 Guinea pigs were successfully sensitized. At least 12 different flavonoids have been found,220f which four to five seem to be involved as contact allergens. Oxyayanin A and B, however, can only be regarded as minor sensitizers (unpublished observation). thus benthamianus
Blackwood,
Clinics in Dermatology
African
African blackwood (Dalbergia melanoxylon Guill. & Perr.), also termed grenadille, is almost as dark as ebony wood but is the only rosewood (Fabaceae)growing in West Africa. Due to its nearly black color, it occasionally is called African ebony. Grenadille is in high demand for clarinets, chessmen, brush backs, chanters of backpipes, flutes, recorders, oboes, truncheons, and other turnery and ornamental purposes. Dermatitis has been described in several cases, especially after handling knife handles and having contact with the mouthpieces of woodwind instruments.lO-l2 Contact allergy is due to the sensitizing quinones (S)I-methoxy dalbergione and (S)-4’-hydroxy-4methoxy dalbergione .lORecently, a new case of allergic contact dermatitis of the face and cheek was observed in a woodworking amateur who prepared jewelry boxes from leftovers of grenadille. Patch tests revealed (R)and (S)-4-methoxy dalbergione to be the responsible sensitizers.23
Blackwood,
Australian
Blackwood (Acacia melanaxylon R.Br., Mimosaceae) is the most important Australian timber for high quality furniture, panelling, joinery, bench work, boat building, handles, and even musical instruments. Blackwood is mainly used in its native country, but is also exported in small quantities to Europe. Cases of contact dermatitis have been described since 1925.10r24Experimental and chemical studies here showed blackwood to be a moderate sensitizer.25 Two of its contact allergens were identified as acamelin and 2,6-dimethoxybenzoquinone.26Jl A recent case showed that another, nonquinonoid and still unknown constituent must be contained in the wood, which reveals a remarkable sensitizing capacity (unpublished observation). Cedar
The name cedar is used for a variety of woods belonging to different genera and families. In the strict meaning, cedar is the term for the genus Cedrus of the Pinaceae which, however, plays only a minor role as a sensitizer. Cedar belonging to another family (Meliaceae), such as Cedrela odorata L. and C.fissilis (L.) Vell., have been more frequently described as the source of allergic contact dermatitislO The first yielded 2,6-dimethoxybenzoquinone as a weak sensitizingconstituentz7; however, other still unknown constituents also may be responsible. Incense cedar (Calocedrus decurrens [Tori-.] Florin, Cupressaceae), a tree native to California, has been reported to cause contact dermatitis when used as a pencil.28 The responsible allergen was found to be thymoquinone, a relatively strong sensitizerto; but another constituent-p-thujaplicinwhich may comprise up to 3% of the total weight, also may be involved as an allergen. (See also, Western red cedar, below.) Cocobolo
Cocobolo (Dalbergia retusa Hemsl., syn.: D. obtusa Lee., Fabaceae), native to Central
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America (Nicaragua, Costa Rica, Panama), was the most important timber for the manufacture of musical instruments until 1945, especially for recorders. It still holds a supreme position in the cutlery trade. Other uses are chessmen, scientific instruments, butts for billiard cues, wooden jewelry, and revolver stocks (Fig. 3). Cocobolo is strong, hard, compact, resistant and not influenced by moisture, even when left for 90 days in tropical seawater.29 Hundreds of cases of allergic contact dermatitis, mostly of a perioral dermatitis in recorder players, have been described.i0~30+ The responsible allergens belong to the group of dalbergiones. A recent reinvestigation of the wood demonstrated that the main contact allergens are the isomeric compounds (R)-4methoxydalbergione and obtusaquinone. As both possess a high inhibitory activity toward marine microorganisms, such as the marine borer Teredo navalis, it has been intended to incorporate them into ship paint and protective coatings of waste pipes. If this should come to pass, ship and pipe painters will be at high risk to develop allergic contact dermatitis.30 Ebony
African ebony (Diospyros crassiflora Hiern.) and East Indian ebony (D. ebenum Koenig) are members of the family Ebenaceae. They have a black color and metal-like properties. Both are especially prized for tool handles, piano keys, knobs, butt ends of billiard cues, cutlery, brush backs, pocket knives, and tail pieces of musical instruments. Eczematous reactions of the skin have been observed after contact with sawdusts and wearing of bracelets.33 The Diospyros species are known for a wide distribution of various naphthoquinones, of which several have to be considered as contact allergens.lO Patch tests to extracts of another ebony species, called coromandel (D. melanoxylon Roxb.) have been reported by Bleumink and Nater.34 (See also; Macassar, below.) Grevillea A tree native to Australia, called “Austral-
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WGQCJS
ian silky oak,” is also commonly grown in Africa, Sri Lanka, India, and the United States. It is properly called G-revillea robusta A. Cunn of the family Proteaceae (“Silver oak”). The timber is suitable for plywood, furniture, and flooring, giving a somewhat decorative veneer. In Australia and the United States, the tree is used for shade. Trees that have to be cut after heavy storms cause “grevillea poisoning,” as the sap causes bullous reactions.36Recently, three women developed acute vesicular dermatitis on their forearms after wearing wooden bracelets. The bracelets had been purchased in a California department store and were labeled “Silver oak, made in India.” Patch tests with one of the main components-grevi1101(O.Ol%)-gave a ++ reaction in all three beginning at 48 hours.36 Controls remained negative. Grevillol (5-n-tridecylresorcinol) chemically resembles the sensitizing pentadecylcatechols of poison ivy and similarly may oxidize to a p-quinone, which is suggested to be the real sensitizer. Iroko, Kambala
This West African species (Chlorophora excelsa Benth. & Hook.) has been used since the beginning of the 20th century as a substitute for teak as it possesses many of the desirable features of Tectona grandis L. Iroko (Moraceae) has been reported since 1910 on numerous occasions as a cause of allergic contact dermatitis.lO The responsible allergen is the stilbene chlorophorine, which is a moderate sensitizer. In recent years, iroko allergy has slightly decreased as its use in window framing has been replaced by mahogany species. Lauan,
Meranti
Many species of the genus Shorea (Dipterocarpaceae) provide timbers of commercial value that are sold in great quantities as a mahogany-type wood for interior and exterior joinery, boat building, flooring, furniture, and plywood. Its main use is the manufacture of lamella doors which, at present, are very popular in Europe and elsewhere. Although meranti (or lauan) mahogany is
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frequently said to be a sensitizer, dermatitis from it is very uncommon: no convincing case has been described in the literature.17y1* Macassar One of the ebony species that is not completely black but displays characteristically light-colored streaks is the Celebesian macassar ebony (Diospyros celebica Bakh., Ebenaceae). The wood is suitable for special decorative purposes like brush backs, knife handles, small turnery articles, boxes, inlay work, and cutlery hafts. In musical instruments, the fingerboards, saddles, pigs, bow nuts, and tail pieces are preferably made from macassar. For a long time, a special use has been the manufacture of expensive rulers. Buschke and Joseph37 reported dermatitis of the face, hands, and forearms in a cabinetmaker, which became generalized after a time. Eaton38states that, in British factories, macassar caused such frequent problems that its use had to be discontinued. Chemical analysis revealed the presence of different naphthalene derivatives which easily oxidized to the corresponding naphthoquinones. Sensitization experiments with the main macassar quinone were successful.1o Compared with other quinonoid sensitizers, macassar quinone is a moderate contact allergen that positively may be considered as the possible cause of macassar contact allergy (unpublished observations). Mahogany Initially, the term mahogany had only been used for the two South American species Swietenia macrophylla King and S. mahagoni Jacq. of the family Meliaceae. Today, the name refers mostly to the African mahogany species of the genera Khaya and Entandophragma because the American mahogany resources have nearly completely disappeared as a result of exploitation. The African mahogany species of Khaya grandifolia DC., K. anthotheca C. DC., K.ivorensis A. Chev., Ksenegalensis A. Juss., and Entandophragma utile Sprag. (Sipo, Utile) are among the most widely used timbers of the world.
Although several outbreaks of contact dermatitis have been observed,l+l4,44 only one species has been found to contain a compound that could be shown to be a sensitizer: anthothecol.39 As it does not occur in the other Khaya species, it does not explain the observed reactions; thus, there must be other still-unknown constituents responsible. Mansonia A valuable substitute for walnut is the decorative and resistant African timber Mansonia altissima A.Chev. (Sterculiaceae). BetC, as it also is called, is a troublesome species that not only causes irritant and allergic contact dermatitis, but also severe side effects, eg., nosebleeds, cardiac disturbances, and other systemic symptoms. Reports of allergic contact dermatitis have been described in numerous papers.lO In Switzerland, 400 guinea pigs died because mansonia wood shavings had been used as bedding.4’J Sensitization experiments demonstrated that the main quinonoid constituent of mansonia-mansonone A-possesses a strong allergenic power.8 Other minor allergenic mansonones might elicit cross-reactions, thus contributing to its allergenic properties. Fungitoxic mansonones are produced in certain wood species like Ulmus spp. (elm) when infected by the fungus Ceratocystis ulmi, which possibly may explain their resistance toward the generally known Dutch elm disease.lO Recently, a severe outbreak of dermatitis and general health disturbance, especially nosebleeds was reported from a small workshop in West Germany, where half of the workers became ill because of bad ventilation systems (unpublished observations). Pa0 ferro
From an allergologic point of view, pao ferro wood (ikfachaerium scleroxylum Tul., Fabaceae) is presently the most hazardous timber. Caviuna vermelha, as it is called in South America, resembles Brazilian rosewood (Dalbergia nigra All.) so much in its physical and decorative properties that it has nearly replaced the latter completely in re-
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cent years. Bearing the same fate as American mahogany, Brazilian rosewood has been exploited so persistently that it had to be replaced by another species, Muchaerium scleroxylum, of the same family. Pao ferro, however, is considerably more irritant and sensitizing than Brazilian rosewood itself. Outbreaks of contact dermatitis are not only reported from its native country, Brazi1,41but more frequently from those countries to which the wood or semifinished pao ferro products have been exported.42-47 In Europe, where pao ferro is used for television sets, recorders, and scientific instruments, outbreaks of contact dermatitis are known from Italy, Czechoslovakia, Spain, Denmark, and especially West Germany, where more than 140 cases have been reported in less than 2 year+(Fig. 1). Perioral dermatitis in a 12-year-old girl playing a recorder manufactured from pao ferro was described by Hausen.10 Patch test by tying the whole instrument with a plaster to her upper arm for 24 hours demonstrated the acquired contact allergy by positive results. In another case, a woman developed severe eczema of both hands due to extensive contact with the wooden handle of her pastry knife.49 The sensitizer is the quinone (R)-3,4-dimethoxydalbergionem-(R)-3,4-DMD-which occurs in the wood as its precursor (R)-3,4dimethoxydalbergiquinole at a level of about 75%. Easy oxidation to the dalbergione may occur early during extraction and machining or later in the skin. Chemical screening for (R)-3,4-DMD in pao ferro samples from different countries, where outbreaks of dermatitis have been registered yielded varying amounts, the highest of which-4.9%-was found in a consignment aelivered to a Danish television factory.51 As (R)-3,4-DMD is a primary irritant when exceeding a concentration of O.l%, the safe dilution for patch testing should be 0.01% in petrolatum. Direct testing of the wood dust or shavings should be avoided as irritant reactions as well as active sensitization may occur. The latter was observed when two nurses who had been tested with the sawdust as controls developed a flare-up at the test
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73
site after a fortnight (unpublished observation). Subsequent patch testing with (R)-3,4DMD in 0.01% and less demonstrated that they had been actively sensitized by the control procedure. The timber industry is evidently aware of the hazardous effects of pao ferro, but continues to market the wood, even under misleading names. Thus, attention should be paid to other trade names, like “Santos” or “Peru rosewood,” as well as “moradillo,” as they all cover the wood of pao ferro. Pine
Numerous timbers of the genus Pinus are important commercial woods that are used for interior and exterior construction, paper and pulp manufacture, and other purposes. Dermatitis is rare. This may be explained by the fact that most of the compounds of the essential oils that occur widely in the coniferous trees are only effective in their oxidative form, which is reached when the terpenes cY-pinene, /3-pinene, and A3-carene, have acquired the state of a hydroperoxide. Usually, this is not the case when fresh wood or shavings are touched. Pine balsams are the main sources of rosin (colophony) and turpentine. Thus, it is seen that a pine-sensitive patient reacts to rosin or turpentine. More often, however, it is observed that a rosin-sensitive patient will react to pine; rosin products are extremely widespread in our daily environment and allergic contact dermatitis, therefore, is slightly acquired to it. Patients with a positive patch-test response to pine should always be tested with colophony and turpentine. In the last 10 years, rosin products have become an important commercial factor in the printing, paper, electrical, and plastic industries. An increasing number of genuine rosins have been replaced by rosin derivatives, which are used for their sticky, adhesive, and plasticizing properties in printing inks, coatings, solders, adhesive tapes, road asphalt, textile sizing, varnishes, floor polishes, chewing gum, plasters, foundry core binders; for impregnating papers; wrapping electrical cables; and hundreds of other pur-
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poses. Chemical and experimental studies have shown that the native rosin acids, like abietic acid and laevopimaric acid, are only moderate sensitizers. But products of their chemical modification-pentaerythritolester, lime and zinc salts, tetra-, di- and dehydro alcohols, maleic and fumaric derivatives, and others-are stronger sensitizers than the native compounds. Cross-reactions rarely are seen (unpublished observations). Thus, the derivatives of the pine rosin will play a more important role in the near future.
“Fiddler’s neck,” skin lesions under the angle of the left side of the jaw (Fig. 4), is due to a specific hypersensitivity in only 10% of all observed cases. In all other cases, the skin reactions are a combination of different factors such as friction, pressure, stress, occlusion, rubbing, squeezing, poor hygiene, and sweating. When an allergic reaction is produced by a chin rest, it usually is due to one of the dalbergiones found in the different rosewoods.
Teak Redwood,
Californian
One of the most durable and valuable woods is the East Indian Tectona grandis L. (Verbenaceae). Like the Lebanon cedar, it is one of the oldest trade timbers of the world and was in use 4000 years ago. Teak is most suitable for boat building, especially for decking, rails, hatches, storm doors, and bulwarks. Other uses include fittings, moldings, furniture, veneer, flooring, and framing. Teak is extremely resistant to water and termites. It has existed in old temples, ships, and palaces in Egypt and India for more than Rosewoods 1000 years. Cases of allergic contact dermatitis have These highly decorative and hard timbers been mentioned as early as 189657; since then, from South America, Africa, and East Asia numerous papers on teak allergy have been belong to the most important woods in the published.lO-12 Patch testing formerly was production of high quality furniture, veneer, always done with the quinone lapachol, a and musical instruments. East Indian (Dalbergia latifolia Roxb.) as well as Brazilian teak constituent known since the beginning of the century as a yellow dye: however, epirosewood (Dalbergia nigra All., Fabaceae) cutaneous tests with pure lapachol were have been reported in numerous cases to be always as strong as with the sawdust itself. sensitizers.lO-12 The responsible allergens The primary sensitizer (inductor) was were identified some 20 years ago as benzofound in the early 1960s by Sandermann and quinones comprising a new class of neoflaSimatupang.58159 Deoxylapachol, which difvanoids named dalbergiones.h4 In animal fers from lapachol only by the absence of a experiments, the dalbergiones showed mehydroxy group, is the true sensitizer in teak, dium to strong sensitizing properties, the giving 100 to 200 times stronger patch test strongest being (R)-3,4_dimethoxydalbergreactions in teak-sensitive individuals than ione.s lapachol.60 Its strong capacity was corroboCharacteristically, rosewoods cause trourated by guinea pig sensitization experible not only during sawing, sanding, and ments.61 As deoxylapachol may produce falseturning, but also when used as a finished positive, eg, irritant reactions in concentraproduct. Allergic contact dermatitis develtions exceeding O.Ol%, direct testing of the oped after direct contact with rosewood clarteak wood dust or shavings should be avoided. inets, recorders, wooden crosses, bracelets, may vary wideknife handles, and wooden chin rests.10~*2~55~56 The content of deoxylapachol The wood of Sequioa sempertirens Endl. (Taxodiaceae) primarily causes respiratory symptoms of the immediate type and probably also an extrinsic allergic alveolitis. Occasionally, cases of contact dermatitis have been described,52753 especially when the redwood is incompletely dried. The observed dermatitis may be severe. The responsible substances are unknown.
April-June 1986 Volume 4 Number 2
ly, so that some teak samples contain none, and thus are harmless, but others contain large amounts. Cultivation of teak in South Africa has led to trees with a reduced deoxylapachol content.lO Western Red Cedar Western red cedar (Thuja plicata Donn ex D. Don, Cupressaceae) is one of the most interesting timbers concerning its side effects, which comprise three different types of allergic diseases: allergic asthma and rhinitis, extrinsic allergic alveolitis, and allergic contact dermatitis. The tree is native to the west coast of the United States, but is exported all over the world, especially to Australia, Europe, and Japan. The wood is durable and useful for interior and exterior construction, boat building, planking, shingles, paneling, and framing. While one of the wood constituents-plicatic acid-has been found to be responsible for the numerous cases of extrinsic allergic alveolitis,@ several uncommon tropolones have been reported to be the source of allergic contact dermatitis. Bleumink et al.‘jsobtained positive test results with the thujaplicins, thymoquinone, 2-methyl-1,4-benzoquinone (toluquinone), and 7-hydroxy-4-isopropyltropolone. Suskind64 succeeded in sensitizing guinea pigs with extracts of western red cedar. Our experiments showed that thymoquinone seems to play a role as a sensitizer in patients sensitive to this species. Although thymoquinone does not occur in the wood,65it seems to be an oxidation product of one of the minor wood constituents, probably carvacrol methyl ether (unpublished results). Thus, it is not misguided to test thymoquinone in the recommended concentration of O.l%, particularly because this is one of the few wood constituents that is commercially available. The main constituent of the steam-volatile oil-fi-thujaplicin-is made responsible for the natural decay resistance of western red cedar.65 In Japan, p-thujaplicin (hinokitiol, in Japanese) is used in hair liquids and cosmetics because of its stimulating effects on hair growth; however, allergic contact dermatitis has been observed to hinokitiol.66
Woods
75
References 1. Wills JH. Nasal cancer in woodworkers: a review. J
Occup Med. 198224526-530. 2. Nava C. Patologia da polveri di legno. Med Lav. 1974;65:1-7. 3. Nava C. Briatico Vangoea G, Brambilla G, et al. La immunoterapia specifica contra essenze di legno. Med Lav. 1978;(suppl)3:463-470. 4. Beck MH. A case of ramin wood sensitivity. Contact Dermatitis. 1982874. 5. Schmidt H. Contact urticaria to teak with systemic effects. Contact Dermatitis. 19784176-177. 6. Hanslian L, Kadlec K. Alergickeonemocneni pomodrinovem dreve (allergy caused by larch wood). Pracov Lekarst. 196481362-366. 7. Ritchie E. Chemistry of the Flindersia species. Rev Pure Appl Chem. X%4:14:47-56. 8. Schulz KH. Garbe I, Hausen BM, et al. The sensitizing capacity of naturally occurring quinones: II. Benzoquinones. Arch Dermatol Res. 19’79;264:275-286. 9. Cronin E. Contact dermatitis. Edinburgh: Churchill Livingstone, 1980548-574. 10. Hausen BM. Woods injurious to human health. New York: de Gruyter, 1981:1-189. 11. Mitchell JC, Rook A. Botanical dermatology. Vancouver: Greengrass, 19791-956. 12. Woods B, Calnan CD. Toxic woods. Br J Dermatol. 1976;(Suppl 13)95:1-97. 13. Wilkinson DS, Budden MG, Hambly EM. A lo-year review of an industrial dermatitis clinic. Contact Dermatitis. 1980$X1-17. 14. Schleicher H. L&r phytogene allergische Kontaktekzeme. Derm Monatsschr. 1974;160:433-444. 15. Dantin-Gallego J, Armayor AF, Riesco J. Some new toxic woods. Industr Med Surg. 195221:41-46. 16. Raymond V. Dermatoses professionnelles dans le batiment. Rev Prat. 1959;9:2638-2690. 17. Hublet P, Sporcq J, Oleffe J, et al. Etude sur les accidents cutanes et muqueux provoques par les bois tropicaux. Arch Belg Med Sot Hyg. 1972;38:314-337. 18. Oleffe J, Sporcq J, Hublet P. et al. Troubles cutan& et muqueux provoques par le travail des bois tropicaux en Belgique. Rev Franc Allergol. 19731365-68. 19. Wagenfuhr R. Gibt es giftige Holzer? Mabel Wohnraum. 1961;4:120-121. 20. Calnan CD. Avodire wood sensitivity. Contact Dermatitis Newsletter. 1970;8:190. 21. Morgan JWW, Thomson J. Ayan dermatitis. Br J Industr Med. 1967;24:156-158. 22. Malan E, Roux DG. Flavonoids from D;stsmorucnthua benthamianus Baillon. J Chem Sot Perkin I. 1977; 2696-2703. 23. Hausen BM, Kuhlwein A, Schmalle HW. Kontaktallergie auf ein “afrikanisches Ebenholz,” Grenadill (Dalbergia mdanosyh Guill. & Perr.). Akt Dermatol.
1984:10X221-223. 24. Nott H. Diseases communicated by plants. Med J Aust. 1925;2:464-466.
76
Clinics in Dermatology
Hausen
25. Hausen BM, Schmalle HW. Quinonoid constituents as contact sensitizers in Australian blackwood Acacia melanoxylon R.Br. Br J Industr Med. 1981:38:105-109.
46 Sak M, Uhrik J, Fabian J, et al. Dermatozy vyvolane drevinoo Macherium sclerozylon (Dermatoses due to Ms.) Csl Dermatol. 1983;58:89-91.
26. Schmalle HW. Hausen BM. Acamelin. a new sensitizing furanoquinone from Acacia mlanos$m R.Br. Tetrahedron L&t. 1980;21:149-152.
L, Garcia-Diez A. Rafeensperger F, et 47 Conde-Salazar al. New cases of contact allergy to Brazilian rosewood substitute Machaerium sclerozylum Tul. (Pao ferro). Contact Dermatitis. 1980:6:246-250.
27. Hausen BM. The sensitizing capacity of naturally occurringquinones. V. 2,6-dimethoxybenzoquinone. Contact Dermatitis. 1978;4:204-213. 28. Calnan CD. Dermatitis from cedar wood pencil. Tram St. John’s Hosp Dermatol Soe. 1972;58:43-47. 29. Southwell CR, Bultman JD. Marine borer resistance of untreated woodsover longperiodsof immersion in tropical waters. Biotropica. 1971;3:81-107. 30. Hausen BM, Munster G. Cocobolo-Holz, ein vergessenes Ekzematogen? Derm Beruf Umwelt. 1983:31: 110-117. 31. Schulz KH, DietrichsHH. Chinonealssensibilisierende Beatandteile von Rio Palisander und Cocobolo. Allergic Asthma. 1962;8:125-131. 32. Herxheimer K. Uber die gewerblichen Erkrankungen der Haut. Dtsch Med Wochenschr. 1912;1:18-22. 33. Nicholas J, Petourand C. Dermite eczematiforme du bras ‘a la suite du port d’un bracelet d’6bsne. Bull Sot Franc Derm. 1935;42:27-28. 34. Bleumink E, Nater JP. Allergic reactions to tropical woods. Contact Dermatitis Newsletter. 1974:16:436. 35. May SB. Dermatitis due to Grevillea Dermatol. 1960;82:1C@6.
robusta.
Arch
36. Hoffman TE, Hausen BM, Adams RM. Allergic contact dermatitis to “silver oak” wooden arm bracelets. J Am Acad Dermatol. 1985;13:‘778-779. 37. Buschke A, Joseph A. Uber Hautentzundung hervorgerufen durch Makassarholz. Dtsch Med Wochenschr. 1927;53:1641-1642, 38. Eaton KK. Respiratoryallergytoexotic All. 1973;3:307-310.
wood dust. Clin
39. Morgan JWW, Orsler RJ. A simple test to distinguish Khaya anthotheca from Khaya ivorensti and Khaya grandqolia. J Inst Wood Sci. 1967;18:61-64. 40. Bertschinger HU, I&t-Stolz S. Erkrankungen bei Schweinen durch Holzabfalle von Mansonia altissima. Schweiz Arch Tierheilk. 1970;112:641-651. 41. Miranda Bastes A de, Mates Filho A de. “Jacaranda” timber causing dermatitis. Proc 5th Forest Congr. 1962;3:1414-1416. 42. Hjorth N. Occupational dermatitis from Pao ferro. Contact Dermatitis Newsletter. 1974:16:473. 43. Maibach HI. Active sensitization to wood extracts. tact Dermatitis Newsletter. 1970;7:149.
Con-
44. Morgan JWW, Orsler RJ. Wilkinson DS. Dermatitis due to the wood dusts of Khaya anthotheea and Machwr-km sclerosylm. Br J Industr Med. 1968;25:119-125. 45. Beck MH, Hausen BM, Dave VK. Allergic contact dermatitis from Machaerium scleroxylum (Pao ferro) in a joinery shop, Clin Exp Dermatol. 1984;9:159-166.
48 Hausen BM. Haufigkeit und Bedeutung toxischer und allergischer Kontaktdermatitiden durch Machaerium sclerozylum (Pao ferro) einem Ersatzholz fur Palisander(Da&rgiun@ra All.) Hautarzt. 1982;33:321-328. Kontaktsensibilisierung 49 Hausen BM. Ungwdhnliche im Konditorgewerbe. Akt Derm. 1984;10:13-16. 50 Schmalle HW, Jarchow OH, Hausen BM. et al. Structure of (R)-3,4-dimethoxydalbergione. Act Cryst. 1984: c40:1090-1092. 51 Hausen BM. Aktuelle Kontaktallergene. 1983;6:194-197.
Allergologie.
52. McCord CP. The toxic properties of some timber woods. Industr Med Surg. 1958;27:202-204. skin disease. 53. Adams MR. Occupational Grune & Stratton, 19831-477.
New York:
54. Donnellv DMX. Neoflavanoids. In: Harborne JB. Mabrv TJ, eds: The flavonoids. New York: Academic Press. 1975:800-865. durch einen 55. Hausen BM, Mau HH. Kontaktallergie Geigenkinnhalter aus Palisander. Derm Beruf Umwelt. 1979;27:18-21. 56 Haustein UF. Violin chin rest eczema due to Eastindian rosewood (Dalbergia latifolia Roxb.). Contact Dermatitis. 1982:8:77-78. 57. Anonymous. A skin affection produced by working in teak. Lancet. 1896:1113, 1193. W, Simatupang MH. Ein toxisches Chi58. Sandermann non aus Teakholz. Angew Chem. 1962;74:782-783. W, Simatupang MH. Uber Inhaltsstoffe 59. Sandermann aus Teak (Z’ectona grand& L.). Chem Ber. 1963;96: 2182-2185. 60. Schulz KH. Berufsdermatosen. Ztschr Haut Geschlechtskrkh. 1967;42:499-509. 61. Schulz KH, Garbe I, Hausen BM, et al. The sensitizing capaeityofnaturallyoccurringquinones:I. Naphtoquinones. Arch Dermatol Res. 1977;258:41-52. 62. Chan-Yeung M. Barton GM, MacLean L, et al. Occupational asthma and rhinitis due to Western red cedar (Thujaplicata). Am Rev P,espir Dis. 1973;108:1094-1102. 63. Bleumink E. Mitchell JC, Nater JP. Allergic contact dermatitis from cedar wood Thuja plicata. Br J Dermatol. 1973;88:499-504. 64. Suskind RR. Dermatitis in the forest product industries. Arch Environ Health. 1967:15:322-326. 65. Barton GM, MacDonald BF. Thechemistryand utilization of Western red cedar. Department of Fisheries and Forestry, Canadian Forestry Service Public No 1023. 1971:1-28. 66 Fujita M, Aoki T. Allergic contact dermatitis to pyridoxine ester and hinokitiol. Contact Dermatitis. 1983:9: 61-65.
Address for correspondence: B. M. Hausen, PhD, Department of Dermatology, Hospital, Martinistrasse 52, D-2000 Hamburg 20, West Germany.
University
9 Bjorn M. Hausen, PhD
From the Department of Dermatology, University Hospital, University of Hamburg, Hamburg, West Germany
Among the various natural resources, wood plays an important role for construction, furniture, boat-building, plywood, veneer, and other purposes. It also is absolutely necessary for the production of pulp and paper. In addition, half of the world demands wood for use as fuel. The principal areas from which the major timbers come are tropical and subtropical regions such as South Asia, West and Central Africa, and South America (Amazon basin). Wood for pulp and paper production is provided from the temperate zone and from the tropics of Brazil and Malaysia. Inhalation of wood particles, especially fine wood dust, as well as direct contact with solid wood, may cause a series of different changes in the human organism among which severe poisoning and wood dermatitis are the most striking. Another occupational hazard is adenocarcinoma of the nose and nasal cavities in workers heavily exposed for decades to fine wood dust.’ This currently is the subject of much discussion in Europe. Carpenters, cabinet makers, joiners, and others who saw, sand, turn, and plane wood are at high risk to develop allergic contact dermatitis, allergic rhinitis, asthma, and, sometimes, extrinsic allergic aveolitis. Irritant dermatitis may arise from the sap or latex of species belonging to the plant families Anacardiaceae, Apocynaceae, Euphorbiaceae, and Moraceae. Among these, some timbers contain compounds with blistering properties due to histamine-liberating alkaloids like cryptopleurine in poison walnut and chloroxylonine in East Indian satinwood. Others contain strong sensitizers, such as (R)-3,4-dimethoxy-dalbergione in Machaerium scleroxylum Tul., which may elicit irritant reactions when applied to the skin in high concentrations. Contact urticaria is produced by species such as obeche (Triplochiton scleroxylon K. Schum.),2 limba (Terminalia superba Engl. & Diels),3 ramin (Gonystylus bancanus Bai11.),3p4teak (Tectona grandis L.),5 and larch (Larix decidua Mi11.),4y6 but rarely is seen. Certain wood species of the families Rutaceae and Flindersiaceae are known for their phototoxic properties,7 but most of them are not of great commercial value. 65
66
Clinics in Dermatology
Heusen
Clinical Aspects While irritant dermatitis is produced mainly by compounds like alkaloids, glycosides, saponines, anthraquinones, and certain phenols, allergic sensitization from woods arises in most cases from benzo- and naphthoquinones. Sometimes, the sensitizing agents occur as a precursor in the timber and are oxidized to the effective quinone in air or enzymically in the skin. As in many types of plant allergy, most of the allergenic wood constituents have not been identified until now. As allergic contact dermatitis comes from the fine wood dust created during the different woodworking processes, the clinical picture is mostly that of an airborne contact dermatitis. Commonly, those affected have worked occupationally with the woods for a long time. Under occupational conditions, great amounts of fine wood dust reach the skin, are trapped in clothing, especially at the neck and sleeves, and also enter the trousers from the bottom. Sometimes the dust particles are carried manually to the genitals, hairs, shoes, boots; clothes, in general, become impregnated with the dust, even when effective exhaust systems are present.
Symptoms The first symptoms appear at the exposed areas of the skin-hands, forearms, eyelids, face, and neck (Figs. 1 and 2)-accompanied by itching. Later, the axillae, groins, ankles, waist, and dorsa of the feet are also involved. The acid conditions of sweaty regions and the enzymatic properties of the skin may help to oxidize precursors to efficient contact allergens. Preliminary damage of the skin by acids, alkali, detergents, disinfectants, hand cleansers, generally wet work, fat solvents, and other factors facilitate the penetration of toxic and allergenic substances from the wood particles into the skin. At first, preliminary symptoms are ignored, as they usually disappear quickly during weekends. Continued exposure worsens
the dermatitis; attacks become more frequent, lesions increase in severity, larger areas are involved; finally, symptom-free intervals become increasingly shorter. In severe cases, dermatitis will spread over the whole integument, and work must stop. All symptoms will subside within a short time when the woodworker is removed from his working place. Nonoccupational dermatitis, resulting from direct contact with finished wood products, is more rare but sometimes of remarkable importance for the individual. Allergy may arise from wooden gun handles (Fig. 3), cutlery hafts, tools, and other utensils; mouth pieces of woodwind instruments, chin rests of violins and violas (Fig. 4); wooden jewelrylike bracelets, necklaces, wooden crosses, and wooden footwear. Allergic perioral dermatitis with swelling of the lips, sometimes involving the cheeks or even the whole face, will be seen in persons playing recorders and flutes manufactured from cocobolo, Brazilian rosewood, and pao ferro.
Diagnosis A detailed anamnesis (case history) and an exact botanic identification of the offending wood species is absolutely necessary; otherwise, any patch testing and description of the case is meaningless as it gives no information to the patient or anyone else. Trade names, especially those of tropical species, often are misleading, insufficient, and confusing. On one hand, a single name may be used for a large number of different timbers, while on the other hand, one species may have ten or more different trade names. Few of the people working with wood occupationally really know what species they are handling. Thus, in cases of allergic contact dermatitis a wood anatomist should be consulted who will be capable of identifying the species by means of a solid sample. As it is generally known that the amount of an allergenic or toxic compound in plants and woods may vary considerably, diagnosis is performed preferably after correct identification of the species by epicutaneous tests with the wood constituent itself. Patch test-
April-June1986 Volume 4 Number 2
FIG. 1 (left). Severe contact dermatitis of a cabinetmaker’s arms caused by pao ferro (Machaerium scleroxylum). FIG. 2 (above). Allergic contact dermatitis of a cabinetmaker’s face and neck from teak wood (Teckma grandis). FIG.
3 (left). Revolver grip manufactured
from cocobolo (Dalber-
gia retusa). (Courtesy of Fuzzy Farrant, West Covina, CA.)
FIG. 4 (below). “Fiddler’s neck” in a violinist due to persistent contact with a chin rest of Brazilian rosewood (Dalbergia nigra).
ing with the wood dust should be avoided. Irritant reactions may occur, especially when the wood or the concentration of its constituents is unknown. Certain timbers like teak, pao ferro, and mansonia usually contain so high a concentration of their allergens that irritant reactions are obligatory. Even a single test may risk active sensitization. As most of the hitherto known allergenic wood constituents are not commercially available, patch testing with the sawdust or shavings should be done with caution.
A simple method to obtain sub-irritative extracts is the following: l-10 g of wood dust or shavings are stirred overnight at room temperature with 50 ml ethanol. After filtration, the ethanolic solution is poured onto a flat glass container of which the weight has been previously determined. From here, the organic solvent is allowed to evaporate under exhaustion equipment or on a windowsill until dry. After renewed determination of the weight, the residue is dissolved again by 1:lO. This 10% ethanolic wood extract or
Clinics in Dermatology
Hausen
60
further dilutions of it are used for patch testing. In case of an irritant reaction, the next dilution should be tested, and controls are necessary, A list of the essential wood contact allergens and their recommended test concentrations are given in Table 1. These are, in the event of an interesting case, available from the author on request. Protection Prevention of irritant and allergic contact dermatitis from woods sometimes is difficult. Although efficient exhaust ventilation for molders, sanders, polishers, circular saws, and other machines has to be installed by law at the working places, some wood species create such a fine and noxious dust that these precautionary measures will not help. Only protective clothing, personal cleanliness, and sometimes moistening of the air with oil or water near the place where the dust is generated may be successful. Barrier creams and adequate washing facilities, including showers, will be partly effective. Knowledge of the dangerous properties of certain woods is of great importance. Everyone who works with a wood should know the risk it bears. Only in very rare cases can a strongly sensitizing species be replaced satisfactorily by a less sensitizing one with equal or similar physical properties and appearance. Replacement sometimes means substitution of a whole consignment of an offending timber by the same species from another locality. Finally, there is no way to protect against the accidental appearance of an irritant timber as an errant sample in a normal shipment. In case a woodworker has to change jobs and be retrained, occupations dealing with plants or plant extracts (eg, gardener, florist, pharmacist) should not be considered as exposure to chemically related compounds of the quinonoid type may occur in the new work place. Certain quinones, known sensitizers in woods, also occur in plants or are chemically related so that cross-reactions can occur. Experimentally, such cross-reactions have been produced in guinea pigs.x
Sensitizing Species The following review comprises those species that may cause allergic contact dermatitis and are of commercial value. As the field is very broad, space permits only a few of the many examples. For further details, several booksg-I2 are recommended. Afrormosia Afrormosia (Pericopsis elata van Meuven, Fabaceae) is a West African timber of good strength properties used for exterior and interior work, joinery, furniture, flooring, framing, boat building, and marine construction. Woods and Calnan,’ Wilkinson and coworkers,‘3 and Schleicher14 reported several persons with positive patch tests. Chemical investigation revealed three alkaloids and an isoflavone. Sensitization experiments in guinea pigs were successful.'0 A patient allergic to afrormosia, which he had used for the framework of his house, reacted to two isolated compounds, which are still unidentified, but not to 2,6-dimethoxyquinone,‘O which also has been found in the wood (unpublished observation). Afxelia Afzelia (Afzelia africana Sm., Caesalpiniaceae) is a heavy West and Central African timber of outstanding stability and durability. It is in great demand for staircases, loadbearing floors and railway wagons, and wooden floors built for a heavy load. Dermatitis has been reported several times15j16 and observed by me in one case. The patient reacted to an ethanolic extract of the heartwood, but failed to react to any of the fractions isolated by thin-layer chromatography. Open epicutaneous sensitization in guinea pigs was successful.1° A uodirS Avodire (Turreanthus africanus Pellgr., Meliaceae) is an African timber commonly used in veneer production. Dermatitis, irritation, and nosebleeding has been report-
April-June 1986 Volume 4 Number 2
WOOdS
69
TABLE 1. Contact Allergens In Wood Specks and Their Recommended Test Concentrations Allergen Name
Formula
Concentration (%)
Acamelin
1.0
Anthothecol
1.0
Wood Species Botanic Name
Trade Name(s)
Acacia melanoxylon R.Br.
Australian blackwood
Khaya anthotheca
African mahogany
C.DC. Chlorophorin
10.0
Chlorophora
excelsa Benth. and Hook.
Iroko, Kambala
Cordia and Patagonula species
Cordia, Frejo, Canalet
Cordiachromes
0.1
Deoxylapachol
0.01
Tectona grandis Tabebuia sp.
(R)-3,4-dimethoxyldalbergione
0.01
Machaerium scleroxylum
Dalbergiones P$-Dimethoxybenzoquinone Grevillol
1.0 10.0
0.1
Dalbergia
L.;
Tul.
Pa0 ferro, Caviuna vermelha
species
Rosewoods
Various wood species
eg, Mahogany, Makori
Greviliea robusta
Silky oak, Silver oak
A. Cunn. Lapachenole
0.1
Teak, Bethabara, Ipe
Paratecoma
peroba
Peroba
Kuhlm. Macassar quinone
1.0
oxidation product of macassar II from Diospyros
celebica
Bakh. Mansonone A
0.1
Mansonia
altissima
Mansonia, B&e
A. Chev. Obtusaquinone
1.0
Dalbergia
retusa
Hemsl. Oxyayanin A and B
1.0
Distemonanthus benthamianus Baill.
Tectoquinone
1.0
Tectona grandis
/3-Thujaplicin
0.1
L.
Thuja plicata
Donn ex D.Don Thymoquinone
‘Cordiachrome A. toxyayanin A.
0.1
Calocedrus decurrens Florin
Ayan Teak Western red cedar Incense cedar
Hausen
70
ed.l2~1’-19Positive patch tests were obtained in a cabinetmaker suffering by Calnan from dermatitis of the hands, arms, and neck. The responsible constituent is unknown. A yan
Ayan, also called Movingui (DistemonanBaill., Fabaceae) is a decorative and heavy timber from West Africa mainly used for cab bodies, coffins, and kitchen and laundry equipment. Severe dermatitis was seen by Morgan and Thomson21 in four carpenters who had positive reactions to the flavonoids oxyayanin A and B. Thirteen additional cases were described by Woods and Calnan.12 Guinea pigs were successfully sensitized. At least 12 different flavonoids have been found,220f which four to five seem to be involved as contact allergens. Oxyayanin A and B, however, can only be regarded as minor sensitizers (unpublished observation). thus benthamianus
Blackwood,
Clinics in Dermatology
African
African blackwood (Dalbergia melanoxylon Guill. & Perr.), also termed grenadille, is almost as dark as ebony wood but is the only rosewood (Fabaceae)growing in West Africa. Due to its nearly black color, it occasionally is called African ebony. Grenadille is in high demand for clarinets, chessmen, brush backs, chanters of backpipes, flutes, recorders, oboes, truncheons, and other turnery and ornamental purposes. Dermatitis has been described in several cases, especially after handling knife handles and having contact with the mouthpieces of woodwind instruments.lO-l2 Contact allergy is due to the sensitizing quinones (S)I-methoxy dalbergione and (S)-4’-hydroxy-4methoxy dalbergione .lORecently, a new case of allergic contact dermatitis of the face and cheek was observed in a woodworking amateur who prepared jewelry boxes from leftovers of grenadille. Patch tests revealed (R)and (S)-4-methoxy dalbergione to be the responsible sensitizers.23
Blackwood,
Australian
Blackwood (Acacia melanaxylon R.Br., Mimosaceae) is the most important Australian timber for high quality furniture, panelling, joinery, bench work, boat building, handles, and even musical instruments. Blackwood is mainly used in its native country, but is also exported in small quantities to Europe. Cases of contact dermatitis have been described since 1925.10r24Experimental and chemical studies here showed blackwood to be a moderate sensitizer.25 Two of its contact allergens were identified as acamelin and 2,6-dimethoxybenzoquinone.26Jl A recent case showed that another, nonquinonoid and still unknown constituent must be contained in the wood, which reveals a remarkable sensitizing capacity (unpublished observation). Cedar
The name cedar is used for a variety of woods belonging to different genera and families. In the strict meaning, cedar is the term for the genus Cedrus of the Pinaceae which, however, plays only a minor role as a sensitizer. Cedar belonging to another family (Meliaceae), such as Cedrela odorata L. and C.fissilis (L.) Vell., have been more frequently described as the source of allergic contact dermatitislO The first yielded 2,6-dimethoxybenzoquinone as a weak sensitizingconstituentz7; however, other still unknown constituents also may be responsible. Incense cedar (Calocedrus decurrens [Tori-.] Florin, Cupressaceae), a tree native to California, has been reported to cause contact dermatitis when used as a pencil.28 The responsible allergen was found to be thymoquinone, a relatively strong sensitizerto; but another constituent-p-thujaplicinwhich may comprise up to 3% of the total weight, also may be involved as an allergen. (See also, Western red cedar, below.) Cocobolo
Cocobolo (Dalbergia retusa Hemsl., syn.: D. obtusa Lee., Fabaceae), native to Central
April-June 1986 Volume 4 Number 2
America (Nicaragua, Costa Rica, Panama), was the most important timber for the manufacture of musical instruments until 1945, especially for recorders. It still holds a supreme position in the cutlery trade. Other uses are chessmen, scientific instruments, butts for billiard cues, wooden jewelry, and revolver stocks (Fig. 3). Cocobolo is strong, hard, compact, resistant and not influenced by moisture, even when left for 90 days in tropical seawater.29 Hundreds of cases of allergic contact dermatitis, mostly of a perioral dermatitis in recorder players, have been described.i0~30+ The responsible allergens belong to the group of dalbergiones. A recent reinvestigation of the wood demonstrated that the main contact allergens are the isomeric compounds (R)-4methoxydalbergione and obtusaquinone. As both possess a high inhibitory activity toward marine microorganisms, such as the marine borer Teredo navalis, it has been intended to incorporate them into ship paint and protective coatings of waste pipes. If this should come to pass, ship and pipe painters will be at high risk to develop allergic contact dermatitis.30 Ebony
African ebony (Diospyros crassiflora Hiern.) and East Indian ebony (D. ebenum Koenig) are members of the family Ebenaceae. They have a black color and metal-like properties. Both are especially prized for tool handles, piano keys, knobs, butt ends of billiard cues, cutlery, brush backs, pocket knives, and tail pieces of musical instruments. Eczematous reactions of the skin have been observed after contact with sawdusts and wearing of bracelets.33 The Diospyros species are known for a wide distribution of various naphthoquinones, of which several have to be considered as contact allergens.lO Patch tests to extracts of another ebony species, called coromandel (D. melanoxylon Roxb.) have been reported by Bleumink and Nater.34 (See also; Macassar, below.) Grevillea A tree native to Australia, called “Austral-
71
WGQCJS
ian silky oak,” is also commonly grown in Africa, Sri Lanka, India, and the United States. It is properly called G-revillea robusta A. Cunn of the family Proteaceae (“Silver oak”). The timber is suitable for plywood, furniture, and flooring, giving a somewhat decorative veneer. In Australia and the United States, the tree is used for shade. Trees that have to be cut after heavy storms cause “grevillea poisoning,” as the sap causes bullous reactions.36Recently, three women developed acute vesicular dermatitis on their forearms after wearing wooden bracelets. The bracelets had been purchased in a California department store and were labeled “Silver oak, made in India.” Patch tests with one of the main components-grevi1101(O.Ol%)-gave a ++ reaction in all three beginning at 48 hours.36 Controls remained negative. Grevillol (5-n-tridecylresorcinol) chemically resembles the sensitizing pentadecylcatechols of poison ivy and similarly may oxidize to a p-quinone, which is suggested to be the real sensitizer. Iroko, Kambala
This West African species (Chlorophora excelsa Benth. & Hook.) has been used since the beginning of the 20th century as a substitute for teak as it possesses many of the desirable features of Tectona grandis L. Iroko (Moraceae) has been reported since 1910 on numerous occasions as a cause of allergic contact dermatitis.lO The responsible allergen is the stilbene chlorophorine, which is a moderate sensitizer. In recent years, iroko allergy has slightly decreased as its use in window framing has been replaced by mahogany species. Lauan,
Meranti
Many species of the genus Shorea (Dipterocarpaceae) provide timbers of commercial value that are sold in great quantities as a mahogany-type wood for interior and exterior joinery, boat building, flooring, furniture, and plywood. Its main use is the manufacture of lamella doors which, at present, are very popular in Europe and elsewhere. Although meranti (or lauan) mahogany is
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frequently said to be a sensitizer, dermatitis from it is very uncommon: no convincing case has been described in the literature.17y1* Macassar One of the ebony species that is not completely black but displays characteristically light-colored streaks is the Celebesian macassar ebony (Diospyros celebica Bakh., Ebenaceae). The wood is suitable for special decorative purposes like brush backs, knife handles, small turnery articles, boxes, inlay work, and cutlery hafts. In musical instruments, the fingerboards, saddles, pigs, bow nuts, and tail pieces are preferably made from macassar. For a long time, a special use has been the manufacture of expensive rulers. Buschke and Joseph37 reported dermatitis of the face, hands, and forearms in a cabinetmaker, which became generalized after a time. Eaton38states that, in British factories, macassar caused such frequent problems that its use had to be discontinued. Chemical analysis revealed the presence of different naphthalene derivatives which easily oxidized to the corresponding naphthoquinones. Sensitization experiments with the main macassar quinone were successful.1o Compared with other quinonoid sensitizers, macassar quinone is a moderate contact allergen that positively may be considered as the possible cause of macassar contact allergy (unpublished observations). Mahogany Initially, the term mahogany had only been used for the two South American species Swietenia macrophylla King and S. mahagoni Jacq. of the family Meliaceae. Today, the name refers mostly to the African mahogany species of the genera Khaya and Entandophragma because the American mahogany resources have nearly completely disappeared as a result of exploitation. The African mahogany species of Khaya grandifolia DC., K. anthotheca C. DC., K.ivorensis A. Chev., Ksenegalensis A. Juss., and Entandophragma utile Sprag. (Sipo, Utile) are among the most widely used timbers of the world.
Although several outbreaks of contact dermatitis have been observed,l+l4,44 only one species has been found to contain a compound that could be shown to be a sensitizer: anthothecol.39 As it does not occur in the other Khaya species, it does not explain the observed reactions; thus, there must be other still-unknown constituents responsible. Mansonia A valuable substitute for walnut is the decorative and resistant African timber Mansonia altissima A.Chev. (Sterculiaceae). BetC, as it also is called, is a troublesome species that not only causes irritant and allergic contact dermatitis, but also severe side effects, eg., nosebleeds, cardiac disturbances, and other systemic symptoms. Reports of allergic contact dermatitis have been described in numerous papers.lO In Switzerland, 400 guinea pigs died because mansonia wood shavings had been used as bedding.4’J Sensitization experiments demonstrated that the main quinonoid constituent of mansonia-mansonone A-possesses a strong allergenic power.8 Other minor allergenic mansonones might elicit cross-reactions, thus contributing to its allergenic properties. Fungitoxic mansonones are produced in certain wood species like Ulmus spp. (elm) when infected by the fungus Ceratocystis ulmi, which possibly may explain their resistance toward the generally known Dutch elm disease.lO Recently, a severe outbreak of dermatitis and general health disturbance, especially nosebleeds was reported from a small workshop in West Germany, where half of the workers became ill because of bad ventilation systems (unpublished observations). Pa0 ferro
From an allergologic point of view, pao ferro wood (ikfachaerium scleroxylum Tul., Fabaceae) is presently the most hazardous timber. Caviuna vermelha, as it is called in South America, resembles Brazilian rosewood (Dalbergia nigra All.) so much in its physical and decorative properties that it has nearly replaced the latter completely in re-
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cent years. Bearing the same fate as American mahogany, Brazilian rosewood has been exploited so persistently that it had to be replaced by another species, Muchaerium scleroxylum, of the same family. Pao ferro, however, is considerably more irritant and sensitizing than Brazilian rosewood itself. Outbreaks of contact dermatitis are not only reported from its native country, Brazi1,41but more frequently from those countries to which the wood or semifinished pao ferro products have been exported.42-47 In Europe, where pao ferro is used for television sets, recorders, and scientific instruments, outbreaks of contact dermatitis are known from Italy, Czechoslovakia, Spain, Denmark, and especially West Germany, where more than 140 cases have been reported in less than 2 year+(Fig. 1). Perioral dermatitis in a 12-year-old girl playing a recorder manufactured from pao ferro was described by Hausen.10 Patch test by tying the whole instrument with a plaster to her upper arm for 24 hours demonstrated the acquired contact allergy by positive results. In another case, a woman developed severe eczema of both hands due to extensive contact with the wooden handle of her pastry knife.49 The sensitizer is the quinone (R)-3,4-dimethoxydalbergionem-(R)-3,4-DMD-which occurs in the wood as its precursor (R)-3,4dimethoxydalbergiquinole at a level of about 75%. Easy oxidation to the dalbergione may occur early during extraction and machining or later in the skin. Chemical screening for (R)-3,4-DMD in pao ferro samples from different countries, where outbreaks of dermatitis have been registered yielded varying amounts, the highest of which-4.9%-was found in a consignment aelivered to a Danish television factory.51 As (R)-3,4-DMD is a primary irritant when exceeding a concentration of O.l%, the safe dilution for patch testing should be 0.01% in petrolatum. Direct testing of the wood dust or shavings should be avoided as irritant reactions as well as active sensitization may occur. The latter was observed when two nurses who had been tested with the sawdust as controls developed a flare-up at the test
woods
73
site after a fortnight (unpublished observation). Subsequent patch testing with (R)-3,4DMD in 0.01% and less demonstrated that they had been actively sensitized by the control procedure. The timber industry is evidently aware of the hazardous effects of pao ferro, but continues to market the wood, even under misleading names. Thus, attention should be paid to other trade names, like “Santos” or “Peru rosewood,” as well as “moradillo,” as they all cover the wood of pao ferro. Pine
Numerous timbers of the genus Pinus are important commercial woods that are used for interior and exterior construction, paper and pulp manufacture, and other purposes. Dermatitis is rare. This may be explained by the fact that most of the compounds of the essential oils that occur widely in the coniferous trees are only effective in their oxidative form, which is reached when the terpenes cY-pinene, /3-pinene, and A3-carene, have acquired the state of a hydroperoxide. Usually, this is not the case when fresh wood or shavings are touched. Pine balsams are the main sources of rosin (colophony) and turpentine. Thus, it is seen that a pine-sensitive patient reacts to rosin or turpentine. More often, however, it is observed that a rosin-sensitive patient will react to pine; rosin products are extremely widespread in our daily environment and allergic contact dermatitis, therefore, is slightly acquired to it. Patients with a positive patch-test response to pine should always be tested with colophony and turpentine. In the last 10 years, rosin products have become an important commercial factor in the printing, paper, electrical, and plastic industries. An increasing number of genuine rosins have been replaced by rosin derivatives, which are used for their sticky, adhesive, and plasticizing properties in printing inks, coatings, solders, adhesive tapes, road asphalt, textile sizing, varnishes, floor polishes, chewing gum, plasters, foundry core binders; for impregnating papers; wrapping electrical cables; and hundreds of other pur-
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poses. Chemical and experimental studies have shown that the native rosin acids, like abietic acid and laevopimaric acid, are only moderate sensitizers. But products of their chemical modification-pentaerythritolester, lime and zinc salts, tetra-, di- and dehydro alcohols, maleic and fumaric derivatives, and others-are stronger sensitizers than the native compounds. Cross-reactions rarely are seen (unpublished observations). Thus, the derivatives of the pine rosin will play a more important role in the near future.
“Fiddler’s neck,” skin lesions under the angle of the left side of the jaw (Fig. 4), is due to a specific hypersensitivity in only 10% of all observed cases. In all other cases, the skin reactions are a combination of different factors such as friction, pressure, stress, occlusion, rubbing, squeezing, poor hygiene, and sweating. When an allergic reaction is produced by a chin rest, it usually is due to one of the dalbergiones found in the different rosewoods.
Teak Redwood,
Californian
One of the most durable and valuable woods is the East Indian Tectona grandis L. (Verbenaceae). Like the Lebanon cedar, it is one of the oldest trade timbers of the world and was in use 4000 years ago. Teak is most suitable for boat building, especially for decking, rails, hatches, storm doors, and bulwarks. Other uses include fittings, moldings, furniture, veneer, flooring, and framing. Teak is extremely resistant to water and termites. It has existed in old temples, ships, and palaces in Egypt and India for more than Rosewoods 1000 years. Cases of allergic contact dermatitis have These highly decorative and hard timbers been mentioned as early as 189657; since then, from South America, Africa, and East Asia numerous papers on teak allergy have been belong to the most important woods in the published.lO-12 Patch testing formerly was production of high quality furniture, veneer, always done with the quinone lapachol, a and musical instruments. East Indian (Dalbergia latifolia Roxb.) as well as Brazilian teak constituent known since the beginning of the century as a yellow dye: however, epirosewood (Dalbergia nigra All., Fabaceae) cutaneous tests with pure lapachol were have been reported in numerous cases to be always as strong as with the sawdust itself. sensitizers.lO-12 The responsible allergens The primary sensitizer (inductor) was were identified some 20 years ago as benzofound in the early 1960s by Sandermann and quinones comprising a new class of neoflaSimatupang.58159 Deoxylapachol, which difvanoids named dalbergiones.h4 In animal fers from lapachol only by the absence of a experiments, the dalbergiones showed mehydroxy group, is the true sensitizer in teak, dium to strong sensitizing properties, the giving 100 to 200 times stronger patch test strongest being (R)-3,4_dimethoxydalbergreactions in teak-sensitive individuals than ione.s lapachol.60 Its strong capacity was corroboCharacteristically, rosewoods cause trourated by guinea pig sensitization experible not only during sawing, sanding, and ments.61 As deoxylapachol may produce falseturning, but also when used as a finished positive, eg, irritant reactions in concentraproduct. Allergic contact dermatitis develtions exceeding O.Ol%, direct testing of the oped after direct contact with rosewood clarteak wood dust or shavings should be avoided. inets, recorders, wooden crosses, bracelets, may vary wideknife handles, and wooden chin rests.10~*2~55~56 The content of deoxylapachol The wood of Sequioa sempertirens Endl. (Taxodiaceae) primarily causes respiratory symptoms of the immediate type and probably also an extrinsic allergic alveolitis. Occasionally, cases of contact dermatitis have been described,52753 especially when the redwood is incompletely dried. The observed dermatitis may be severe. The responsible substances are unknown.
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ly, so that some teak samples contain none, and thus are harmless, but others contain large amounts. Cultivation of teak in South Africa has led to trees with a reduced deoxylapachol content.lO Western Red Cedar Western red cedar (Thuja plicata Donn ex D. Don, Cupressaceae) is one of the most interesting timbers concerning its side effects, which comprise three different types of allergic diseases: allergic asthma and rhinitis, extrinsic allergic alveolitis, and allergic contact dermatitis. The tree is native to the west coast of the United States, but is exported all over the world, especially to Australia, Europe, and Japan. The wood is durable and useful for interior and exterior construction, boat building, planking, shingles, paneling, and framing. While one of the wood constituents-plicatic acid-has been found to be responsible for the numerous cases of extrinsic allergic alveolitis,@ several uncommon tropolones have been reported to be the source of allergic contact dermatitis. Bleumink et al.‘jsobtained positive test results with the thujaplicins, thymoquinone, 2-methyl-1,4-benzoquinone (toluquinone), and 7-hydroxy-4-isopropyltropolone. Suskind64 succeeded in sensitizing guinea pigs with extracts of western red cedar. Our experiments showed that thymoquinone seems to play a role as a sensitizer in patients sensitive to this species. Although thymoquinone does not occur in the wood,65it seems to be an oxidation product of one of the minor wood constituents, probably carvacrol methyl ether (unpublished results). Thus, it is not misguided to test thymoquinone in the recommended concentration of O.l%, particularly because this is one of the few wood constituents that is commercially available. The main constituent of the steam-volatile oil-fi-thujaplicin-is made responsible for the natural decay resistance of western red cedar.65 In Japan, p-thujaplicin (hinokitiol, in Japanese) is used in hair liquids and cosmetics because of its stimulating effects on hair growth; however, allergic contact dermatitis has been observed to hinokitiol.66
Woods
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References 1. Wills JH. Nasal cancer in woodworkers: a review. J
Occup Med. 198224526-530. 2. Nava C. Patologia da polveri di legno. Med Lav. 1974;65:1-7. 3. Nava C. Briatico Vangoea G, Brambilla G, et al. La immunoterapia specifica contra essenze di legno. Med Lav. 1978;(suppl)3:463-470. 4. Beck MH. A case of ramin wood sensitivity. Contact Dermatitis. 1982874. 5. Schmidt H. Contact urticaria to teak with systemic effects. Contact Dermatitis. 19784176-177. 6. Hanslian L, Kadlec K. Alergickeonemocneni pomodrinovem dreve (allergy caused by larch wood). Pracov Lekarst. 196481362-366. 7. Ritchie E. Chemistry of the Flindersia species. Rev Pure Appl Chem. X%4:14:47-56. 8. Schulz KH. Garbe I, Hausen BM, et al. The sensitizing capacity of naturally occurring quinones: II. Benzoquinones. Arch Dermatol Res. 19’79;264:275-286. 9. Cronin E. Contact dermatitis. Edinburgh: Churchill Livingstone, 1980548-574. 10. Hausen BM. Woods injurious to human health. New York: de Gruyter, 1981:1-189. 11. Mitchell JC, Rook A. Botanical dermatology. Vancouver: Greengrass, 19791-956. 12. Woods B, Calnan CD. Toxic woods. Br J Dermatol. 1976;(Suppl 13)95:1-97. 13. Wilkinson DS, Budden MG, Hambly EM. A lo-year review of an industrial dermatitis clinic. Contact Dermatitis. 1980$X1-17. 14. Schleicher H. L&r phytogene allergische Kontaktekzeme. Derm Monatsschr. 1974;160:433-444. 15. Dantin-Gallego J, Armayor AF, Riesco J. Some new toxic woods. Industr Med Surg. 195221:41-46. 16. Raymond V. Dermatoses professionnelles dans le batiment. Rev Prat. 1959;9:2638-2690. 17. Hublet P, Sporcq J, Oleffe J, et al. Etude sur les accidents cutanes et muqueux provoques par les bois tropicaux. Arch Belg Med Sot Hyg. 1972;38:314-337. 18. Oleffe J, Sporcq J, Hublet P. et al. Troubles cutan& et muqueux provoques par le travail des bois tropicaux en Belgique. Rev Franc Allergol. 19731365-68. 19. Wagenfuhr R. Gibt es giftige Holzer? Mabel Wohnraum. 1961;4:120-121. 20. Calnan CD. Avodire wood sensitivity. Contact Dermatitis Newsletter. 1970;8:190. 21. Morgan JWW, Thomson J. Ayan dermatitis. Br J Industr Med. 1967;24:156-158. 22. Malan E, Roux DG. Flavonoids from D;stsmorucnthua benthamianus Baillon. J Chem Sot Perkin I. 1977; 2696-2703. 23. Hausen BM, Kuhlwein A, Schmalle HW. Kontaktallergie auf ein “afrikanisches Ebenholz,” Grenadill (Dalbergia mdanosyh Guill. & Perr.). Akt Dermatol.
1984:10X221-223. 24. Nott H. Diseases communicated by plants. Med J Aust. 1925;2:464-466.
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25. Hausen BM, Schmalle HW. Quinonoid constituents as contact sensitizers in Australian blackwood Acacia melanoxylon R.Br. Br J Industr Med. 1981:38:105-109.
46 Sak M, Uhrik J, Fabian J, et al. Dermatozy vyvolane drevinoo Macherium sclerozylon (Dermatoses due to Ms.) Csl Dermatol. 1983;58:89-91.
26. Schmalle HW. Hausen BM. Acamelin. a new sensitizing furanoquinone from Acacia mlanos$m R.Br. Tetrahedron L&t. 1980;21:149-152.
L, Garcia-Diez A. Rafeensperger F, et 47 Conde-Salazar al. New cases of contact allergy to Brazilian rosewood substitute Machaerium sclerozylum Tul. (Pao ferro). Contact Dermatitis. 1980:6:246-250.
27. Hausen BM. The sensitizing capacity of naturally occurringquinones. V. 2,6-dimethoxybenzoquinone. Contact Dermatitis. 1978;4:204-213. 28. Calnan CD. Dermatitis from cedar wood pencil. Tram St. John’s Hosp Dermatol Soe. 1972;58:43-47. 29. Southwell CR, Bultman JD. Marine borer resistance of untreated woodsover longperiodsof immersion in tropical waters. Biotropica. 1971;3:81-107. 30. Hausen BM, Munster G. Cocobolo-Holz, ein vergessenes Ekzematogen? Derm Beruf Umwelt. 1983:31: 110-117. 31. Schulz KH, DietrichsHH. Chinonealssensibilisierende Beatandteile von Rio Palisander und Cocobolo. Allergic Asthma. 1962;8:125-131. 32. Herxheimer K. Uber die gewerblichen Erkrankungen der Haut. Dtsch Med Wochenschr. 1912;1:18-22. 33. Nicholas J, Petourand C. Dermite eczematiforme du bras ‘a la suite du port d’un bracelet d’6bsne. Bull Sot Franc Derm. 1935;42:27-28. 34. Bleumink E, Nater JP. Allergic reactions to tropical woods. Contact Dermatitis Newsletter. 1974:16:436. 35. May SB. Dermatitis due to Grevillea Dermatol. 1960;82:1C@6.
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36. Hoffman TE, Hausen BM, Adams RM. Allergic contact dermatitis to “silver oak” wooden arm bracelets. J Am Acad Dermatol. 1985;13:‘778-779. 37. Buschke A, Joseph A. Uber Hautentzundung hervorgerufen durch Makassarholz. Dtsch Med Wochenschr. 1927;53:1641-1642, 38. Eaton KK. Respiratoryallergytoexotic All. 1973;3:307-310.
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39. Morgan JWW, Orsler RJ. A simple test to distinguish Khaya anthotheca from Khaya ivorensti and Khaya grandqolia. J Inst Wood Sci. 1967;18:61-64. 40. Bertschinger HU, I&t-Stolz S. Erkrankungen bei Schweinen durch Holzabfalle von Mansonia altissima. Schweiz Arch Tierheilk. 1970;112:641-651. 41. Miranda Bastes A de, Mates Filho A de. “Jacaranda” timber causing dermatitis. Proc 5th Forest Congr. 1962;3:1414-1416. 42. Hjorth N. Occupational dermatitis from Pao ferro. Contact Dermatitis Newsletter. 1974:16:473. 43. Maibach HI. Active sensitization to wood extracts. tact Dermatitis Newsletter. 1970;7:149.
Con-
44. Morgan JWW, Orsler RJ. Wilkinson DS. Dermatitis due to the wood dusts of Khaya anthotheea and Machwr-km sclerosylm. Br J Industr Med. 1968;25:119-125. 45. Beck MH, Hausen BM, Dave VK. Allergic contact dermatitis from Machaerium scleroxylum (Pao ferro) in a joinery shop, Clin Exp Dermatol. 1984;9:159-166.
48 Hausen BM. Haufigkeit und Bedeutung toxischer und allergischer Kontaktdermatitiden durch Machaerium sclerozylum (Pao ferro) einem Ersatzholz fur Palisander(Da&rgiun@ra All.) Hautarzt. 1982;33:321-328. Kontaktsensibilisierung 49 Hausen BM. Ungwdhnliche im Konditorgewerbe. Akt Derm. 1984;10:13-16. 50 Schmalle HW, Jarchow OH, Hausen BM. et al. Structure of (R)-3,4-dimethoxydalbergione. Act Cryst. 1984: c40:1090-1092. 51 Hausen BM. Aktuelle Kontaktallergene. 1983;6:194-197.
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52. McCord CP. The toxic properties of some timber woods. Industr Med Surg. 1958;27:202-204. skin disease. 53. Adams MR. Occupational Grune & Stratton, 19831-477.
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54. Donnellv DMX. Neoflavanoids. In: Harborne JB. Mabrv TJ, eds: The flavonoids. New York: Academic Press. 1975:800-865. durch einen 55. Hausen BM, Mau HH. Kontaktallergie Geigenkinnhalter aus Palisander. Derm Beruf Umwelt. 1979;27:18-21. 56 Haustein UF. Violin chin rest eczema due to Eastindian rosewood (Dalbergia latifolia Roxb.). Contact Dermatitis. 1982:8:77-78. 57. Anonymous. A skin affection produced by working in teak. Lancet. 1896:1113, 1193. W, Simatupang MH. Ein toxisches Chi58. Sandermann non aus Teakholz. Angew Chem. 1962;74:782-783. W, Simatupang MH. Uber Inhaltsstoffe 59. Sandermann aus Teak (Z’ectona grand& L.). Chem Ber. 1963;96: 2182-2185. 60. Schulz KH. Berufsdermatosen. Ztschr Haut Geschlechtskrkh. 1967;42:499-509. 61. Schulz KH, Garbe I, Hausen BM, et al. The sensitizing capaeityofnaturallyoccurringquinones:I. Naphtoquinones. Arch Dermatol Res. 1977;258:41-52. 62. Chan-Yeung M. Barton GM, MacLean L, et al. Occupational asthma and rhinitis due to Western red cedar (Thujaplicata). Am Rev P,espir Dis. 1973;108:1094-1102. 63. Bleumink E. Mitchell JC, Nater JP. Allergic contact dermatitis from cedar wood Thuja plicata. Br J Dermatol. 1973;88:499-504. 64. Suskind RR. Dermatitis in the forest product industries. Arch Environ Health. 1967:15:322-326. 65. Barton GM, MacDonald BF. Thechemistryand utilization of Western red cedar. Department of Fisheries and Forestry, Canadian Forestry Service Public No 1023. 1971:1-28. 66 Fujita M, Aoki T. Allergic contact dermatitis to pyridoxine ester and hinokitiol. Contact Dermatitis. 1983:9: 61-65.
Address for correspondence: B. M. Hausen, PhD, Department of Dermatology, Hospital, Martinistrasse 52, D-2000 Hamburg 20, West Germany.
University