Modification of the Listing of Glasswool Fibers (Airborne Particles of Respirable Size) to Glass Wool Fibers (Inhalable and Biopersistent)

The Office of Environmental Health Hazard Assessment (OEHHA), within the California Environmental Protection Agency, is the lead agency for the implementation of Proposition 65¹.  OEHHA listed² “glasswool fibers (airborne particles of respirable size)” as known to the State to cause cancer via the authoritative bodies listing mechanism, effective July 1, 1990.  The basis for the listing was a formal identification by the International Agency for Research on Cancer (IARC) in its publication, Man-made Mineral Fibres and Radon, IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 43, 1988.

In 1994, the National Toxicology Program (NTP), another authoritative body under Proposition 65, formally identified “glass wool (respirable size)” as causing cancer in the Seventh Annual Report on Carcinogens, concluding that “glass wool (respirable size)” was reasonably anticipated to be a human carcinogen. In 2011, the NTP reviewed the carcinogenicity of glass wool fibers in its 12th Edition of the Report on Carcinogens and revised the scope of the listing, formally identifying “certain glass wool fibers (inhalable)” as reasonably anticipated to be carcinogenic to humans.  This classification was based on (1) sufficient evidence of carcinogenicity from studies in experimental animals of inhalable glass wool fibers as a class … and (2) evidence from studies of fiber properties which indicates that only certain fibers within this class — specifically, fibers that are biopersistent in the lung or tracheobronchial region — are reasonably anticipated to be human carcinogens.” 

Based on this 2011 NTP finding, OEHHA is modifying the listing as described in the table below:

Chemical Reference

• Glass wool fibers (inhalable and biopersistent)

Footnotes and References

International Agency for Research on Cancer (IARC, 1988).  IARC Monographs on the Evaluation of Carcinogenic Risks to Humans.  Man-made Mineral Fibres and Radon.  Volume 43, World Health Organization, Lyon, France, 1988.

National Toxicology Program (NTP, 1994).  Seventh Annual Report on Carcinogens, 7th Edition, U.S. Department of Health and Human Services. Research Triangle Park, NC.

National Toxicology Program (NTP, 2011).  Report on Carcinogens, 12th Edition, U.S. Department of Health and Human Services. Research Triangle Park, NC.

¹ The Safe Drinking Water and Toxic Enforcement Act of 1986, codified at Health and Safety Code section 25249.5 et seq. commonly known as Proposition 65.

²Proposition 65 provides mechanisms for administratively listing chemicals that are known to the State to cause cancer or reproductive toxicity (Health and Safety Code section 25249.8(b)).  A chemical may be listed under Proposition 65 when a body considered to be authoritative has formally identified the chemical as causing cancer or reproductive toxicity.  The criteria for listing chemicals through the authoritative bodies mechanism are set forth in Title 27, California Code of Regulations, section 25306.