# Announcement of Availability of the Report on Carcinogens, Twelfth Edition
**AGENCY:**
National Toxicology Program (NTP), National Institute of Environmental Health Sciences (NIEHS); National Institutes of Health (NIH).
**ACTION:**
Availability of the Report on Carcinogens, Twelfth Edition (12th RoC).
**SUMMARY:**
The Department of Health and Human Services released the 12th RoC to the public on June 10, 2011. The report is available on the RoC Web site at: *http://ntp.niehs.nih.gov/go/roc12* or in printed text or electronically from the Office of the RoC ( *see**ADDRESSES* below).
**DATES:**
The 12th RoC will be available to the public on June 10, 2011.
**ADDRESSES:**
Dr. Ruth Lunn, Director, Office of the RoC, NTP, NIEHS, P.O. Box 12233, MD K2-14, Research Triangle Park, NC 27709; *telephone:* (919) 316-4637; FAX: (919) 541-0144; *[email protected].*
**FOR FURTHER INFORMATION CONTACT:**
Questions or comments concerning the 12th RoC should be directed to Dr. Ruth Lunn ( *telephone:* (919) 361-4637 or *[email protected]* ).
**SUPPLEMENTARY INFORMATION:**
**Background Information on the RoC**
The RoC is a Congressionally mandated document that identifies and discusses agents, substances, mixtures, or exposure circumstances (collectively referred to as “substances”) that may pose a hazard to human health by virtue of their carcinogenicity. Substances are listed in the report as either *known* or *reasonably anticipated to be human carcinogens.* The listing of a substance in the RoC indicates a potential hazard, but does not establish the exposure conditions that would pose cancer risks to individuals in their daily lives. For each listed substance, the RoC provides information from cancer studies that support the listing as well as information about potential sources of exposure and current Federal regulations to limit exposures. Each edition of the RoC is cumulative, that is, it lists newly reviewed substances in addition to substances listed in the previous edition. Information about the RoC is available on the RoC Web site ( *http://ntp.niehs.nih.gov/go/roc12* ) or by contacting Dr. Lunn ( *see**ADDRESSES* above).
The NTP prepares the RoC on behalf of the Secretary of Health and Human Services. For the 12th RoC, the NTP followed an established, multi-step process with multiple opportunities for public input, and used established criteria to evaluate the scientific evidence on each candidate substance under review ( *http://ntp.niehs.nih.gov/go/15208* ).
**New Listings to the 12th RoC**
The 12th RoC contains 240 listings, some of which consist of a class of structurally related chemicals or agents. There are six new listings and two revised listings in this edition. The revised listings include (1) Formaldehyde, which was previously listed as *reasonably anticipated to be a human carcinogen* and is now listed as *known to be a human carcinogen,* and (2) certain glass wool fibers (inhalable). Glass wool (respirable) was first listed in the 7th RoC as *reasonably anticipated to be a human carcinogen,* but the scope of the listing changed and now certain glass wool fibers (inhalable) are listed as *reasonably anticipated to be human carcinogens.* The six new listings to the 12th RoC include one substance, aristolochic acids, listed as *known to be human carcinogens,* and five substances—captafol, cobalt-tungsten carbide: powders and hard metals, o-nitrotoluene, riddelliine, and styrene—listed as *reasonably anticipated to be a human carcinogen.*
Dated: June 14, 2011.
Linda S. Birnbaum,
Director, National Institute of Environmental Health Sciences and National Toxicology Program.