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2692. The villain in the wood dust?
Natural products
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2692. The villain in the wood dust?
Schoental, g. & Gibbard, S. (1972). Nasal and other tumours in rats given 3,4,5-irimethoxycinnamaldehyde, a derivative of sinapaldehyde and of other ~,fl-unsaturated aldehydic wood lignin constituents. Br. J. Cancer 26, 504. It has been suggested that ~,fl-unsaturated aldehydes present in wood lignins may be responsible for the high incidence of nasal adenocarcinomas found in woodworkers in the European furniture industry (Cited in F.C.T. 1971, 9, 899). Some support for this theory has been provided by a small study in which six male rats were injected With 3,4,5-trimethoxycinnamaldehyde (TMCA) in an ip dose of 150 mg/kg in aqueous ethanol, followed 1 wk later by a dose of 100 mg/kg given sc in dimethylformamide. Four rats which survived for more than 17 months after this treatment developed tumours. These consisted of two nasal squamous carcinomas (found in two rats killed after 20 and 24 months, respectively), a sarcoma in the peritoneal cavity with metastatic nodules on the omentum, and a mesothelioma of the tunica albuginea of both testes. In view of the rarity of nasal tumours in rats, these findings were regarded as significant. It is not known whether TMCA as such is present in wood lignins, but it could be formed metabolically in vivo from its phenolic congeners by O-methyl-transferase, and]or be p-O-demethylated to sinapaldehyde and other products. Epoxides, formed by metabolic oxidation of the side-chain double bond, could well provide the proximate carcinogen, as in the case of several other known carcinogens. 2693. Contact dermatitis from cedar wood dust Bleumink, E., Mitchell, J. C. & Nater, J. P. (1973). Allergic contact dermatitis from cedar wood (Thuja plicata). Br. J. Derm. 88, 499.
Cases of contact dermatitis have been reported from time to time among people whose work entails the handling of certain types of wood. One such incident involved men engaged in the processing of African mahogany (Cited in F,C.T. 1966, 4, 553) and the more recent report cited above relates the case of a workman who reacted to the heart-wood of western red cedar (Thuia plic~ua). After exposure to various types of wood in a saw mill for about 2 yr, this workman developed an itching, vesicular dermatitis on his face and forearms and the back of his hands. The dermatitis cleared when he avoided contact with wood but appeared again within a few days of his return to the factory. Patch tests with extracts of 19 different species of wood revealed a strong delayed cutaneous reaction to the extract of western red cedar and a weaker allergy to deal (Picea abies) extract. The man's work brought him into regular contact with the fine sawdust of both of these woods. A further series of patch tests was conducted on a range of compounds known to be present in the woods of various species of Thuja, 0"10-0" ! 5 mg of these compounds being applied on each patch in a 1% solution in ethanol. Positive reactions occurred with 7-hydroxy-4-isopropyltropolone and ~-thujaplicin, both of which are present in western red cedar, and also with thymoquinone, which occurs in various other woods. The first two compounds, both tropolones, are closely related chemically. Thymoquinone is a strong skin irritant, but additional testing in two other patients indicated that it is a potent allergen. Carvacrol, which is present in western red cedar as well as various other species of wood, has also been shown to be an active allergen, although the saw-mill worker discussed in this paper did not react positively .to it.
289
2692. The villain in the wood dust?
Schoental, g. & Gibbard, S. (1972). Nasal and other tumours in rats given 3,4,5-irimethoxycinnamaldehyde, a derivative of sinapaldehyde and of other ~,fl-unsaturated aldehydic wood lignin constituents. Br. J. Cancer 26, 504. It has been suggested that ~,fl-unsaturated aldehydes present in wood lignins may be responsible for the high incidence of nasal adenocarcinomas found in woodworkers in the European furniture industry (Cited in F.C.T. 1971, 9, 899). Some support for this theory has been provided by a small study in which six male rats were injected With 3,4,5-trimethoxycinnamaldehyde (TMCA) in an ip dose of 150 mg/kg in aqueous ethanol, followed 1 wk later by a dose of 100 mg/kg given sc in dimethylformamide. Four rats which survived for more than 17 months after this treatment developed tumours. These consisted of two nasal squamous carcinomas (found in two rats killed after 20 and 24 months, respectively), a sarcoma in the peritoneal cavity with metastatic nodules on the omentum, and a mesothelioma of the tunica albuginea of both testes. In view of the rarity of nasal tumours in rats, these findings were regarded as significant. It is not known whether TMCA as such is present in wood lignins, but it could be formed metabolically in vivo from its phenolic congeners by O-methyl-transferase, and]or be p-O-demethylated to sinapaldehyde and other products. Epoxides, formed by metabolic oxidation of the side-chain double bond, could well provide the proximate carcinogen, as in the case of several other known carcinogens. 2693. Contact dermatitis from cedar wood dust Bleumink, E., Mitchell, J. C. & Nater, J. P. (1973). Allergic contact dermatitis from cedar wood (Thuja plicata). Br. J. Derm. 88, 499.
Cases of contact dermatitis have been reported from time to time among people whose work entails the handling of certain types of wood. One such incident involved men engaged in the processing of African mahogany (Cited in F,C.T. 1966, 4, 553) and the more recent report cited above relates the case of a workman who reacted to the heart-wood of western red cedar (Thuia plic~ua). After exposure to various types of wood in a saw mill for about 2 yr, this workman developed an itching, vesicular dermatitis on his face and forearms and the back of his hands. The dermatitis cleared when he avoided contact with wood but appeared again within a few days of his return to the factory. Patch tests with extracts of 19 different species of wood revealed a strong delayed cutaneous reaction to the extract of western red cedar and a weaker allergy to deal (Picea abies) extract. The man's work brought him into regular contact with the fine sawdust of both of these woods. A further series of patch tests was conducted on a range of compounds known to be present in the woods of various species of Thuja, 0"10-0" ! 5 mg of these compounds being applied on each patch in a 1% solution in ethanol. Positive reactions occurred with 7-hydroxy-4-isopropyltropolone and ~-thujaplicin, both of which are present in western red cedar, and also with thymoquinone, which occurs in various other woods. The first two compounds, both tropolones, are closely related chemically. Thymoquinone is a strong skin irritant, but additional testing in two other patients indicated that it is a potent allergen. Carvacrol, which is present in western red cedar as well as various other species of wood, has also been shown to be an active allergen, although the saw-mill worker discussed in this paper did not react positively .to it.