Prop 65 List: 3 New Cancer-Causing Chemicals Listed by OEHHA Effective Nov 17, 2023

Coal-Tar Pitch, Fluoro-Edenite, and Silicon Carbide Whiskers added to Proposition 65 Cancer-Causing Chemicals List

In a recent development, the Office of Environmental Health Hazard Assessment (OEHHA) has taken a significant step in public health protection by adding three substances to the list of chemicals known to the State of California to cause cancer. This decision, effective November 17, 2023, comes under the purview of the Safe Drinking Water and Toxic Enforcement Act of 1986, more commonly known as Proposition 65.

The three chemicals in question are

1. Coal-tar Pitch,
2. Fluoro-Edenite Fibrous Amphibole, and
3. Silicon Carbide Whiskers.

The inclusion of these substances is based on the "Labor Code" listing mechanism, as outlined in the Health and Safety Code, section 25249.8(a), and further detailed in Cal. Code of Regs., title 27, section 25904.

The OEHHA's decision follows a thorough examination of the scientific evidence and public input. The basis for these listings was detailed in a public notice published on September 22, 2023, in the California Regulatory Notice Register. This initiated a public comment period from September 22, 2023, to October 23, 2023, during which no comments were received.

Learn more about CA Proposition 65 Warning Label Requirement!

Background on Proposition 65 Listing by the Labor Code Mechanism

The decision to include substances in Proposition 65 is guided by Health and Safety Code section 25249.8(a), which incorporates California Labor Code section 6382(b)(1) into the Proposition. This mandates the listing of substances identified by the International Agency for Research on Cancer (IARC) as known to cause cancer. The IARC classifications are based on substances identified as human or animal carcinogens.

OEHHA, as the lead agency for the implementation of Proposition 65, evaluates whether a chemical listing is warranted under these criteria. In this case, coal-tar pitch, fluoro-edenite fibrous amphibole, and silicon carbide whiskers have met the requirements for listing as known to the state to cause cancer, as per CCR, title 27, section 25904(b)(3).

OEHHA’s Determination

The International Agency for Research on Cancer (IARC) played a crucial role in determining the carcinogenicity of the three substances. According to IARC's classifications in "IARC Monographs on the Evaluation of Carcinogenic Risks to Humans," Volume 100F (2012) and Volume 111 (2017), coal-tar pitch and fluoro-edenite fibrous amphibole fall into Group 1 ("carcinogenic to humans"). Silicon carbide whiskers are classified in Group 2A ("probably carcinogenic to humans"). The evidence cited by IARC includes sufficient data on carcinogenicity in both humans and animals for coal-tar pitch and fluoro-edenite fibrous amphibole. For silicon carbide whiskers, there is sufficient evidence of carcinogenicity in animals.

This determination underscores the importance of ongoing efforts to identify and regulate substances that pose potential health risks. The OEHHA's decision to list these chemicals aims to provide consumers and the public with essential information to make informed choices regarding exposure to potentially harmful substances. It also emphasizes the ongoing commitment to safeguard public health and the environment.

Learn about previous updates.

• California Proposition 65 List April 21, 2023
• California Proposition 65 List August 11, 2023