Toxicity of Chloroprene, 1,3-Dichlorobutene-2, and 1,4-Dichlorobutene-2

Clary, J. J.

doi:10.2307/3428532

Cited by 3 publications

(2 citation statements)

References 4 publications

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“…Of the 11 pre‐2010 studies identified (Ambartsumyan, Khapkina, & Agoyan, ; Avakian, Gasparian, Avetisian, & Kondakova, ; Clary, ; Lewis, Ioannides, & Parke, ; Lloyd, ; Melnick & Khon, ; Morgan, ; Rannug & Ostman, ; Valentine & Himmelstein, ; Zaridze, Bulbulyan, Changuina, Margaryan, & Boffetta, ; Zhang, Sussman, Macina, Rosenkranz, & Klopman, ), we excluded two studies (Ambartsumyan et al., ; Avakian et al., ) because they were in Russian and the screening of the available titles indicated that they did not fit the inclusion criteria. Only the abstract for Morgan () was available and it indicated that the study was a summary of the results of a six‐month NTP inhalation study conducted in two strains of transgenic mice; however, no technical report for the study was available from the NTP website.…”

Section: Literature Search and Reviewmentioning

confidence: 99%

“…The available information is discussed in Section 3.1. Three of the studies identified (Clary, ; Lloyd, ; Valentine & Himmelstein, ) were excluded because they were presentations, reviews, or commentaries and did not provide any new information not already considered in the 2010 Review or for this assessment. The studies by Lewis et al.…”

Section: Literature Search and Reviewmentioning

confidence: 99%

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Extended Analysis and Evidence Integration of Chloroprene as a Human Carcinogen

et al. 2019

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β‐Chloroprene is used in the production of polychloroprene, a synthetic rubber. In 2010, Environmental Protection Agency (EPA) published the Integrated Risk Information System “Toxicological Review of Chloroprene,” concluding that chloroprene was “likely to be carcinogenic to humans.” This was based on findings from a 1998 National Toxicology Program (NTP) study showing multiple tumors within and across animal species; results from occupational epidemiological studies; a proposed mutagenic mode of action; and structural similarities with 1,3‐butadiene and vinyl chloride. Using mouse data from the NTP study and assuming a mutagenic mode of action, EPA calculated an inhalation unit risk (IUR) for chloroprene of 5 × 10−4 per µg/m3. This is among the highest IURs for chemicals classified by IARC or EPA as known or probable human carcinogens and orders of magnitude higher than the IURs for carcinogens such as vinyl chloride, benzene, and 1,3‐butadiene. Due to differences in pharmacokinetics, mice appear to be uniquely responsive to chloroprene exposure compared to other animals, including humans, which is consistent with the lack of evidence of carcinogenicity in robust occupational epidemiological studies. We evaluated and integrated all lines of evidence for chloroprene carcinogenicity to assess whether the 2010 EPA IUR could be scientifically substantiated. Due to clear interspecies differences in carcinogenic response to chloroprene, we applied a physiologically based pharmacokinetic model for chloroprene to calculate a species‐specific internal dose (amount metabolized/gram of lung tissue) and derived an IUR that is over 100‐fold lower than the 2010 EPA IUR. Therefore, we recommend that EPA's IUR be updated.

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Section: Literature Search and Reviewmentioning

confidence: 99%

Section: Literature Search and Reviewmentioning

confidence: 99%

Extended Analysis and Evidence Integration of Chloroprene as a Human Carcinogen

et al. 2019

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Degradation of chlorinated butenes and butadienes in granular iron columns

Hughes

Gui

Gillham

2009

Journal of Environmental Science and Health, Part A

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Manufacturing facilities for production of chlorobutyl rubber have the potential to release a mixture of at least 5 chlorinated butenes and butadienes including trans-1,4-dichlorobutene-2 (1,4-DCB-2), 3,4-dichlorobutene-1 (3,4-DCB-1), 2,3,4-trichlorobutene-1 (TCB), 2-chlorobutadiene-1,3 (chloroprene) and 2,3-dichlorobutadiene-1,3 (DCBD) into groundwater environment. To evaluate the potential of using granular iron in the remediation of the above contaminants, a series of column experiments were conducted. Degradation of all 5 compounds followed pseudo-first-order kinetics. The three chlorinated butenes degraded much faster (surface area normalized half-lives, t(1/2)', ranged from 1.6 to 5.2 min m2/mL) than the 2 chlorinated butadienes (t(1/2)' ranged from 102 to 197 min m2/mL). All contaminants fully dechlorinated by granular iron to 1,3-butadiene as a common reaction intermediate that then degraded to a mixture of relatively non-harmful end products consisting of 1-butene, cis-2-butene, trans-2-butene and n-butane. Based on the kinetic data, product distributions, and chlorine mass balances, reaction pathways for these compounds are proposed. For the chlorinated butenes, 3,4-DCB-1 and TCB, undergo reductive beta-elimination reactions resulting in 1,3-butadiene and chloroprene intermediates. Dechlorination of 1,4-DCB-2 to 1,3-butadiene occurs through a reductive elimination similar to reductive beta-elimination. For dechlorination of the two chlorinated butadienes, chloroprene and DCBD, dechlorination occurs through a hydrogenolysis pathway. The common non-chlorinated intermediate, 1,3-butadiene, undergoes catalytic hydrogenation resulting in a mixture of butane isomers and n-butane. The results suggest that granular iron is an effective material for treatment of groundwater contaminated with these compounds.

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References

2007

Groundwater Chemicals Desk Reference, Fourth Edition

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Toxicity of Chloroprene, 1,3-Dichlorobutene-2, and 1,4-Dichlorobutene-2

Cited by 3 publications

References 4 publications

Extended Analysis and Evidence Integration of Chloroprene as a Human Carcinogen

Extended Analysis and Evidence Integration of Chloroprene as a Human Carcinogen

Degradation of chlorinated butenes and butadienes in granular iron columns

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