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2139. Don't throw those bras away yet
452
THE CHEMICAL ENVIRONMENT
early as 12 hr after the addition of silica to the culture medium, while diamond dust of the same particle size caused no apparent damage even after 30 hr, the discrete cytoplasmic granules seen being comparable to those found in untreated macrophages. These results support the earlier proposals that the lysosome was the target organelle of the silica particles and that enzyme leakage was the cause of necrosis. 2138. A breathalyser for trichloroethylene Stewart, R. D., Dodd, H. C., Gay, H. H. & Erley, D. S. (1970). Experimental human exposure to trichloroethylene. Archs envir. Hlth 20, 64. Trichloroethylene (TCE) continues to be extensively used as an industrial solvent for fats and oils and has proved particularly useful as a vapour degreasing agent. Previous reports have shown that TCE is neurotoxic (Cited in F.C.T. 1964, 2, 225; ibm 1969, 7, 547; ibid 1970, 8, 232) and also hepatotoxic (ibid 1966, 4, 618). In the present study volunteers were subjected to TCE at 200 ppm for periods varying from I hr to a 5-day working week and intensive biochemical and neurological tests were carried out both during and for 12 days after the experiments. Previous experiments had indicated little likelihood of adverse effects at levels below 200 ppm, a concentration that normal subjects could tolerate for several hours without untoward physiological effect. The responses elicited during the exposures were mild and, except for complaints of fatigue or sleepiness, were inconsistent. Some 50% of the volunteers reported that greater mental effort was required in performing a modified Romberg test (balancing on one foot with eyes closed and both arms at the side) but the actual results of all performance and neurological tests were normal. Similarly, the results of clinical laboratory tests (haematology, serum biochemistry and urinalysis) were all normal, including the urinary urobilinogen level, which is a sensitive index of hepatic malfunction following overexposure to chlorinated aliphatic hydrocarbon solvents. The assessment of TCE exposure by urinary excretion of its metabolites, particularly trichloroacetic acid, has been criticized by previous authors (ibid 1966, 4, 618). In this study there were wide individual variations in metabolite excretion following exposures even of similar severity and duration, and an alternative method of assessment was proposed. The alveolar-breath concentration of TCE was found to be a sensitive measure of post-exposure solvent levels. Breath-excretion curves showed that the concentration in expired air decreased exponentially after exposure, most of the amount absorbed being excreted within 24 hr. However, a small residual proportion remained, probably on account of TCE's great affinity for fatty tissue. The authors claim that the alveolar-breath concentration will become widely used in determining TCE exposure. The analytical methods are rapid, inexpensive and more acceptable to workmen than monitoring methods requiring 24-hr urine collection or venipuncture. The procedure is particularly accurate when used shortly after a vapour exposure and should prove a valuable measure in cases of suspected overexposure when urinalysis would be impossible. 2139. Don't throw those bras away yet Bleehen, S. S. & Hall-Smith, P. (1970). Brassiere depigmentation: Light and electron microscope studies. Br. J. Derm. 83, 157. Contact dermatitis from the wearing of undergarments containing polyurethane elastomers (e.g. spandex) has previously been reported (Citedin F.C.T. 1969, 7, 698). Compounds
NATURAL PRODUCTS
453
held responsible for such dermatitis include antioxidants such as mercaptobenzthiazole (MBT), dipentamethylenethiuram disulphide (PTD) and tetramethylthiuram disulphide (MTD). The present paper reports a case of depigrnentation in an area of skin in contact with an elasticated brassiere containing spandex yarn. Depigmentation of the skin at sites of friction and pressure is common in subjects with vitiligo. In such patients temporary loss of pigmentation may follow the stroking of normally pigmented skin with a sharp instrument, a feature that often distinguishes vitiligo from other disorders in which there is localized hypomelanosis. The patient in the present case, a 50-year-old woman with no history of skin disease or familial vitiligo, was examined in connexion with the depigmentation of areas of skin covered by her brassiere. At no time had there been irritation or inflammation of the skin. Examination of the affected skin with a Woods lamp showed that depigmentation was complete, the skin being milky-white in colour. Patch-tests to MBT, MTD, rubber thread and 1 ~o hydroquinone monobenzyl ether were all negative. Histological examination of skin sections confirmed that melanocytes were absent from the depigmented areas and presented a picture compatible with that seen in vitiligo. Certain antioxidants such as hydroquinone monobenzyl ether, which is known to be a depigmenting agent, could not be ruled out entirely as a possible cause of this lesion. The histological picture produced by such compounds is again virtually indistinguishable from that of vitiligo and in some cases is not reversed by discontinuation of the skin contact. However, the authors suggest that, although other possibilities exist, the patient described had latent vitiligo and that the skin depigmentation developed under a tight, elasticated brassiere as a result of pressure and friction on the skin.
N A T U R A L PRODUCTS 2140. Grazing on bracken
Schacham, P., Philp, R. B. & Gowdey, C. W. (1970). Antihematopoietic and carcinogenic effects of bracken fern (Pteridium aquilinum) in rats. Am. J. vet. Res. 31, 191. Barnett, K. C. & Watson, W. A. (1970). Bright blindness in sheep. A primary retinopathy due to feeding bracken (Pteris aquilina). Res. vet. Sei. 11, 289. When grazed extensively by livestock, bracken fern has a radiomimetic effect and gives rise to intestinal haemorrhages and intestinal and bladder tumours (Cited in F.C.T. 1970, 8, 85). Further details of its toxic effects are revealed in the two papers cited above. In the first study cited, rats were given a feed containing 50 ~o bracken that had been airdried at 40°C to one-third of its fresh weight. Half of these rats (group A) were given drinking water containing I0 mg thiamine hydrochloride/litre, while the rest (group B) had normal drinking water. A control group (C) received a standard feed and untreated drinking water. A blood sample was taken from each group twice weekly, the rats being sampled in rotation, for red and white blood cell and platelet counts and other estimations. After 60 days the rats were killed and a total bone-marrow cell count was carried out for each animal. Total white cell counts in groups A and B did not differ significantly from one another, but over the 60 days the mean value for each group was lower than that of controls given a standard feed. In group A, platelet counts fell significantly, while in group B neutrophil counts were raised. Counts of bone-marrow cells in the two treatment groups were
THE CHEMICAL ENVIRONMENT
early as 12 hr after the addition of silica to the culture medium, while diamond dust of the same particle size caused no apparent damage even after 30 hr, the discrete cytoplasmic granules seen being comparable to those found in untreated macrophages. These results support the earlier proposals that the lysosome was the target organelle of the silica particles and that enzyme leakage was the cause of necrosis. 2138. A breathalyser for trichloroethylene Stewart, R. D., Dodd, H. C., Gay, H. H. & Erley, D. S. (1970). Experimental human exposure to trichloroethylene. Archs envir. Hlth 20, 64. Trichloroethylene (TCE) continues to be extensively used as an industrial solvent for fats and oils and has proved particularly useful as a vapour degreasing agent. Previous reports have shown that TCE is neurotoxic (Cited in F.C.T. 1964, 2, 225; ibm 1969, 7, 547; ibid 1970, 8, 232) and also hepatotoxic (ibid 1966, 4, 618). In the present study volunteers were subjected to TCE at 200 ppm for periods varying from I hr to a 5-day working week and intensive biochemical and neurological tests were carried out both during and for 12 days after the experiments. Previous experiments had indicated little likelihood of adverse effects at levels below 200 ppm, a concentration that normal subjects could tolerate for several hours without untoward physiological effect. The responses elicited during the exposures were mild and, except for complaints of fatigue or sleepiness, were inconsistent. Some 50% of the volunteers reported that greater mental effort was required in performing a modified Romberg test (balancing on one foot with eyes closed and both arms at the side) but the actual results of all performance and neurological tests were normal. Similarly, the results of clinical laboratory tests (haematology, serum biochemistry and urinalysis) were all normal, including the urinary urobilinogen level, which is a sensitive index of hepatic malfunction following overexposure to chlorinated aliphatic hydrocarbon solvents. The assessment of TCE exposure by urinary excretion of its metabolites, particularly trichloroacetic acid, has been criticized by previous authors (ibid 1966, 4, 618). In this study there were wide individual variations in metabolite excretion following exposures even of similar severity and duration, and an alternative method of assessment was proposed. The alveolar-breath concentration of TCE was found to be a sensitive measure of post-exposure solvent levels. Breath-excretion curves showed that the concentration in expired air decreased exponentially after exposure, most of the amount absorbed being excreted within 24 hr. However, a small residual proportion remained, probably on account of TCE's great affinity for fatty tissue. The authors claim that the alveolar-breath concentration will become widely used in determining TCE exposure. The analytical methods are rapid, inexpensive and more acceptable to workmen than monitoring methods requiring 24-hr urine collection or venipuncture. The procedure is particularly accurate when used shortly after a vapour exposure and should prove a valuable measure in cases of suspected overexposure when urinalysis would be impossible. 2139. Don't throw those bras away yet Bleehen, S. S. & Hall-Smith, P. (1970). Brassiere depigmentation: Light and electron microscope studies. Br. J. Derm. 83, 157. Contact dermatitis from the wearing of undergarments containing polyurethane elastomers (e.g. spandex) has previously been reported (Citedin F.C.T. 1969, 7, 698). Compounds
NATURAL PRODUCTS
453
held responsible for such dermatitis include antioxidants such as mercaptobenzthiazole (MBT), dipentamethylenethiuram disulphide (PTD) and tetramethylthiuram disulphide (MTD). The present paper reports a case of depigrnentation in an area of skin in contact with an elasticated brassiere containing spandex yarn. Depigmentation of the skin at sites of friction and pressure is common in subjects with vitiligo. In such patients temporary loss of pigmentation may follow the stroking of normally pigmented skin with a sharp instrument, a feature that often distinguishes vitiligo from other disorders in which there is localized hypomelanosis. The patient in the present case, a 50-year-old woman with no history of skin disease or familial vitiligo, was examined in connexion with the depigmentation of areas of skin covered by her brassiere. At no time had there been irritation or inflammation of the skin. Examination of the affected skin with a Woods lamp showed that depigmentation was complete, the skin being milky-white in colour. Patch-tests to MBT, MTD, rubber thread and 1 ~o hydroquinone monobenzyl ether were all negative. Histological examination of skin sections confirmed that melanocytes were absent from the depigmented areas and presented a picture compatible with that seen in vitiligo. Certain antioxidants such as hydroquinone monobenzyl ether, which is known to be a depigmenting agent, could not be ruled out entirely as a possible cause of this lesion. The histological picture produced by such compounds is again virtually indistinguishable from that of vitiligo and in some cases is not reversed by discontinuation of the skin contact. However, the authors suggest that, although other possibilities exist, the patient described had latent vitiligo and that the skin depigmentation developed under a tight, elasticated brassiere as a result of pressure and friction on the skin.
N A T U R A L PRODUCTS 2140. Grazing on bracken
Schacham, P., Philp, R. B. & Gowdey, C. W. (1970). Antihematopoietic and carcinogenic effects of bracken fern (Pteridium aquilinum) in rats. Am. J. vet. Res. 31, 191. Barnett, K. C. & Watson, W. A. (1970). Bright blindness in sheep. A primary retinopathy due to feeding bracken (Pteris aquilina). Res. vet. Sei. 11, 289. When grazed extensively by livestock, bracken fern has a radiomimetic effect and gives rise to intestinal haemorrhages and intestinal and bladder tumours (Cited in F.C.T. 1970, 8, 85). Further details of its toxic effects are revealed in the two papers cited above. In the first study cited, rats were given a feed containing 50 ~o bracken that had been airdried at 40°C to one-third of its fresh weight. Half of these rats (group A) were given drinking water containing I0 mg thiamine hydrochloride/litre, while the rest (group B) had normal drinking water. A control group (C) received a standard feed and untreated drinking water. A blood sample was taken from each group twice weekly, the rats being sampled in rotation, for red and white blood cell and platelet counts and other estimations. After 60 days the rats were killed and a total bone-marrow cell count was carried out for each animal. Total white cell counts in groups A and B did not differ significantly from one another, but over the 60 days the mean value for each group was lower than that of controls given a standard feed. In group A, platelet counts fell significantly, while in group B neutrophil counts were raised. Counts of bone-marrow cells in the two treatment groups were