Re-evaluation of some organic chemicals, hydrazine and hydrogen peroxide
A Working Group of 31 experts from 12 countries met to update and re-evaluate 121 organic compounds and groups of compounds, most of them industrial chemicals, that had previously been reviewed at least once within the IARC Monographs Programme. Four of these compounds were evaluated as full Monogra...
| Institution: | ETUI-European Trade Union Institute |
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| Format: | TEXT |
| Language: | English |
| Published: |
Lyon
1999
IARC |
| Subjects: | |
| Online Access: | https://www.labourline.org/KENTIKA-19202743124910209259-Re-evaluation-of-some-organic-.htm |
| Summary: | A Working Group of 31 experts from 12 countries met to update and re-evaluate 121 organic compounds and groups of compounds, most of them industrial chemicals, that had previously been reviewed at least once within the IARC Monographs Programme. Four of these compounds were evaluated as full Monographs in which all published literature on the compound in question was reviewed: acrylonitrile, 1,3-butadiene, chloroprene, and dichloromethane. The remaining compounds for which there was generally less literature to review were updated and re-evaluated on the basis of data published since their most recent previous evaluations.
Acrylonitrile is a high-volume production monomer used principally in the manufacture of acrylic fibres, resins and some rubbers. It is a potent multi-site carcinogen in rats, and epidemiological studies had earlier suggested an increased risk of lung cancer in exposed workers. Larger, better, and more recent studies, based in most cases on the cohorts previously assembled, have not confirmed this risk, and acrylonitrile was re-evaluated as possibly carcinogenic to humans (Group 2B), rather than Group 2A in which it had previously been placed. 1,3-Butadiene is also a high-volume production monomer used in the manufacture of a wide range of polymers, including rubbers, resins and latexes, and is also a potent multi-site carcinogen in rats and mice. Epidemiological evidence for increased risk of leukaemia or lymphoma in exposed workers strongly suggests a hazard, but the published evidence does not allow consistency of findings to be evaluated among two or more studies of adequate statistical power, and the epidemiological evidence was thus evaluated as limited. After intense discussion it was concluded that other relevant published data do not compel reclassification of this compound, and butadiene remained classified as probably carcinogenic to humans (Group 2A). Chloroprene, a monomer used almost exclusively for production of polychloroprene elastomers and latexes, was re-evaluated as Group 2B, possibly carcinogenic to humans, in contrast to Group 3 in which it had previously been placed, on the basis of new bioassays that provide sufficient evidence of carcinogenicity in rats and mice. Risk of cancer associated with occupational exposure to chloroprene has been examined in two well-conducted studies, one in the USA and one in Russia, that do not indicate a consistent excess of cancer at any site; epidemiological evidence was thus considered inadequate. Dichloromethane, used principally as a solvent in paint removers and degreasers, in aerosol products, and in the manufacture of foam polymers, remained classified as before in Group 2B, possibly carcinogenic to humans. While seven cohort studies and three case-control studies have examined the risk of cancer associated with exposure to dichloromethane, for no type of cancer was there a consistent elevation of risk across these studies to make a causal interpretation credible, and epidemiological evidence for carcinogenicity in humans was thus judged inadequate. In contrast, bioassays for carcinogenicity by inhalation exposure in both mice and rats provided sufficient evidence for carcinogenicity to experimental animals. Interspecies differences in dichloromethane metabolism and toxicokinetics suggest explanations for organ-site differences in carcinogenic effects between mice and rats, but these considerations were not extrapolated to other species. |
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| Physical Description: | 3 v. Paper |