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The persistence of diethylstilboestrol residues
Feed additives. The chemical environment When rats were fed MCPA or MCPP for 90 days at dietary levels of 50, 400 or 32OOppm, the highest level of either compound depressed food consumption and body-weight gain. Rats fed 3200 ppm MCPA had enlarged erythrocytes with an increased haemoglobin content, while rats fed 3200ppm MCPP had decreased haemoglobin and erythrocyte counts, accompanied in the males by a decreased haematocrit and leucocyte count and in the females by a decrease in neutrophils. This level of MCPP also increased alka-
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line-phosphatase activity, indicating possible liver damage. and decreased relative ovary and prostate weights. Erythrocyte levels were depressed in males fed MCPP even at 400 ppm, and each compound produced a significant increase in relative kidney weight at 400 and 32OOppm, but no histological changes were detected in any organ. At 50 ppm there was only an insignificant increase in kidney weight, tuniccornpanied by other signs of adverse effect.
FEED ADDITIVES labelled compounds were characterized by thin-layer chromatography and isotope-dilution procedures Aschbacher, P. W., Thacker, E. J. & Rumsey, T. S. after extraction and hydrolysis (to free any conjugated (1975). Metabolic fate of diethylstilbestrol implanted DES present). In addition, some faecal extracts were in the ear of steers. J. Anirn. Sci. 40, 530. subjected to gas-liquid chromatography (GLC). Radioactivity persisted in the plasma throughout The use of diethylstilboestrol (DES) implants for the 120 days, the levels at the end of this period being about one-third of the early values. Urinary and faefattening cattle and sheep was banned by the FDA in 1973, after residues of this compound and/or its cal excretion rates conformed to a similar pattern. conjugates had been detected in the livers of steers The total excreted had accounted for 24.7, 56.8, 52.5 slaughtered up to 60 days after implantation. The and 84.9% of the implanted radioactivity after 30, 60, residues were detected by radioactive-tracer studies 90 and 120 days, respectively, activity in the faeces being some 2-3 times greater than that in the urine. and confirmed by isotope-dilution and recrystallizaIn four animals, total recovery of radioactivity from tion techniques and by thin-layer chromatography, rather than by the less sensitive official method in- excreta and tissues ranged from 82.7 to 90.9% of that implanted. The proportion remaining in the ears fell volving mouse uterine assay. The FDA subsequently from 65.9% after 30 days to 4.2% after 120, but that proposed to revoke the official method but substitution of an alternative method awaits agreement on detected in the carcass and internal organs remained relatively constant at O.O>0~05o/, of that implanted. the necessary level of sensitivity. Meanwhile, a court Highest tissue concentrations were found in the bile order for a public hearing had the effect of voiding the FDA ban and there has followed a sharp increase and gall bladder (homogenized together), salivary in the number of illegal DES residues detected. The gland, lungs, liver and kidney, but there was considerregulation governing ear implants for beef cattle (Sec. able variation between animals and no evidence of a decline with time. In the liver, 9-34% of the label 135b.6) specifies only a 2l-day withdrawal period before slaughter, but the study now under review was identified by isotope dilution as DES or a conjushows that low residues can persist far beyond this gate, equivalent to 0.07-0.13 ppb (b = IO’) DES, and omission of the hydrolysis step from one sample inditime. Four steers were implanted in the ear with pellets cated that about 7% (0.04ppb DES) was in unconjucontaining about 28 mg [‘4C]DES and were slaugh- gated form. The major part of the urinary radioactivity appeared to be present as either DES or a conjutered after 30, 60, 90 and 120 days. Levels of radioacgate, but in the faeces less than half was in these tivity in tissues and excreta were determined by liquid forms, and GLC data suggested the presence of a scintillation, allowance being made for background levels as determined in control animals. and the much smaller molecule than DES. 2999. The persistence of diethylstilboestrol
residues
THE CHEMICAL 3000. Chromates as lung carcinogens Langard, S. & Norseth, T. (1975). A cohort study of bronchial carcinomas in workers producing chromate pigments. Br. J. irzd. Med. 32, 62. Chromates have come under fire chiefly for their sensitizing properties, but there is also some evidence that calcium chromate, formed during the processing of crude chrome ores, has some carcinogenic potential (Cited in F.C.T 1969, 7, 690).
ENVIRONMENT The study by Langird & Norseth (cited above) involved 133 workers employed in making chromate pigments between 1948 and 1972: Of the 24 workers employed for more than 3yr, there were three with bronchial carcinoma. Compared with an incidence rate of 0.079 for a corresponding group of the general population of Norway, the risk ratio for chrome workers was about 38. The average age of these workers when they were found to have bronchial carcinoma was 50 yr. The workers in this company were exposed mainly to zinc chromate, and those develop-
215
line-phosphatase activity, indicating possible liver damage. and decreased relative ovary and prostate weights. Erythrocyte levels were depressed in males fed MCPP even at 400 ppm, and each compound produced a significant increase in relative kidney weight at 400 and 32OOppm, but no histological changes were detected in any organ. At 50 ppm there was only an insignificant increase in kidney weight, tuniccornpanied by other signs of adverse effect.
FEED ADDITIVES labelled compounds were characterized by thin-layer chromatography and isotope-dilution procedures Aschbacher, P. W., Thacker, E. J. & Rumsey, T. S. after extraction and hydrolysis (to free any conjugated (1975). Metabolic fate of diethylstilbestrol implanted DES present). In addition, some faecal extracts were in the ear of steers. J. Anirn. Sci. 40, 530. subjected to gas-liquid chromatography (GLC). Radioactivity persisted in the plasma throughout The use of diethylstilboestrol (DES) implants for the 120 days, the levels at the end of this period being about one-third of the early values. Urinary and faefattening cattle and sheep was banned by the FDA in 1973, after residues of this compound and/or its cal excretion rates conformed to a similar pattern. conjugates had been detected in the livers of steers The total excreted had accounted for 24.7, 56.8, 52.5 slaughtered up to 60 days after implantation. The and 84.9% of the implanted radioactivity after 30, 60, residues were detected by radioactive-tracer studies 90 and 120 days, respectively, activity in the faeces being some 2-3 times greater than that in the urine. and confirmed by isotope-dilution and recrystallizaIn four animals, total recovery of radioactivity from tion techniques and by thin-layer chromatography, rather than by the less sensitive official method in- excreta and tissues ranged from 82.7 to 90.9% of that implanted. The proportion remaining in the ears fell volving mouse uterine assay. The FDA subsequently from 65.9% after 30 days to 4.2% after 120, but that proposed to revoke the official method but substitution of an alternative method awaits agreement on detected in the carcass and internal organs remained relatively constant at O.O>0~05o/, of that implanted. the necessary level of sensitivity. Meanwhile, a court Highest tissue concentrations were found in the bile order for a public hearing had the effect of voiding the FDA ban and there has followed a sharp increase and gall bladder (homogenized together), salivary in the number of illegal DES residues detected. The gland, lungs, liver and kidney, but there was considerregulation governing ear implants for beef cattle (Sec. able variation between animals and no evidence of a decline with time. In the liver, 9-34% of the label 135b.6) specifies only a 2l-day withdrawal period before slaughter, but the study now under review was identified by isotope dilution as DES or a conjushows that low residues can persist far beyond this gate, equivalent to 0.07-0.13 ppb (b = IO’) DES, and omission of the hydrolysis step from one sample inditime. Four steers were implanted in the ear with pellets cated that about 7% (0.04ppb DES) was in unconjucontaining about 28 mg [‘4C]DES and were slaugh- gated form. The major part of the urinary radioactivity appeared to be present as either DES or a conjutered after 30, 60, 90 and 120 days. Levels of radioacgate, but in the faeces less than half was in these tivity in tissues and excreta were determined by liquid forms, and GLC data suggested the presence of a scintillation, allowance being made for background levels as determined in control animals. and the much smaller molecule than DES. 2999. The persistence of diethylstilboestrol
residues
THE CHEMICAL 3000. Chromates as lung carcinogens Langard, S. & Norseth, T. (1975). A cohort study of bronchial carcinomas in workers producing chromate pigments. Br. J. irzd. Med. 32, 62. Chromates have come under fire chiefly for their sensitizing properties, but there is also some evidence that calcium chromate, formed during the processing of crude chrome ores, has some carcinogenic potential (Cited in F.C.T 1969, 7, 690).
ENVIRONMENT The study by Langird & Norseth (cited above) involved 133 workers employed in making chromate pigments between 1948 and 1972: Of the 24 workers employed for more than 3yr, there were three with bronchial carcinoma. Compared with an incidence rate of 0.079 for a corresponding group of the general population of Norway, the risk ratio for chrome workers was about 38. The average age of these workers when they were found to have bronchial carcinoma was 50 yr. The workers in this company were exposed mainly to zinc chromate, and those develop-