The California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment (OEHHA) has announced that it intends to list vinylidene chloride as a carcinogen under Proposition 65 based on the Labor Code listing mechanism. Also known as the Safe Drinking Water and Toxic Enforcement Act of 1986, Proposition 65 prohibits knowingly exposing any individual to a listed chemical without first providing a “clear and reasonable warning” to such individual. 

OEHHA cited the International Agency for Research on Cancer’s (IARC) classification of vinylidene chloride as a Group 2B substance “possibly carcinogenic to humans” as the basis for the listing under the Labor Code. IARC determined that there is sufficient evidence of carcinogenicity in animals for vinylidene chloride. (See “Agents Classified by the International Agency for Research on Cancer (IARC) Monographs, Volumes 1 - 119" (IARC, 2017).) Notice of the intent to list can be found on OEHHA’s website.

OEHHA also proposed a No Significant Risk Level (NSRL) for vinylidene chloride of 0.88 micrograms per day. A warning would not be required for products causing an exposure less than the NSRL, which defined as the level of exposure that would result in not more than one excess case of cancer in 100,000 individuals exposed to the chemical over a 70-year lifetime.

Written comments on the listing and the proposed NSRL are due by November 6, 2017. OEHHA specified that the comments on the listing “should be limited to whether IARC has identified the specific chemical or substance as a known or potential human or animal carcinogen.” The agency added that under the Labor Code listing mechanism, it “cannot consider scientific arguments concerning the weight or quality of the evidence considered by IARC when it identified this chemical and will not respond to such comments if they are submitted.”