At a public meeting on December 12 and 13, 2013 a panel of experts reviewed the U.S. National Toxicology Panel (NTP) most recent draft Reports of Carcinogens (RoC) and lowered the listing of the food contact material (FCM) substance pentachlorophenol (PCP, CAS 87-86-5) and by-products of its synthesis from “known human carcinogens” to “reasonably anticipated to be human carcinogens”. In 1991, PCP was declared “possibly carcinogenic to humans” (Group 2B) by the International Association for Research on Cancer (IARC). PCP is usually used as a wood preservative and biocide, but also listed by the U.S. Food and Drug Administration (FDA) as an adhesive for food contact materials (CFR 175-105). The NTP considered that the scientific evidence for PCP’s carcinogenicity is limited and affirmed non-Hodgkin’s lymphoma to be the primary carcinogenic endpoint of PCP. By-products of iPCP’s synthesis are dioxin-like compounds thought to contribute to the carcinogenicity of technical-grade PCP. The RTP also modified the listing of ortho-toluidine, a substance used in dyes, rubber chemicals, herbicides, and the local anesthetic prilocaine, which is now considered a "known human carcinogen".
Ernie Hood (January 2014). “NTP panel peer reviews substances for potential listing as carcinogens.” Inside EPA.