IARC Monograph 117: Carcinogenicity of pentachlorophenol and some related compounds

The International Agency for Research on Cancer (IARC), a specialized agency of the World Health Organization, held a Working Group meeting in October to assess the carcinogenicity of pentachlorophenol, 2,4,6-tricholorphenol, aldrin, dieldrin, and 3,3′,4,4′-tetrachloroazobenzene.

The Working Group determined that the insecticide and wood preservative pentachlorophenol is carcinogenic to humans (Group 1), and causes non-Hodgkin lymphoma. Pentachlorophenol is a persistent organic pollutant and its use has been restricted since the 1990s.

Aldrin and dieldrin are organochlorine pesticides. Their use has been widely¬†restricted since the 1970s, but they are persistent in the environment.¬†3,3′,4,4′-Tetrachloroazobenzene is a contaminant formed in the production of some herbicides. All three compounds were classified as probably carcinogenic to humans (Group 2A).

2,4,6-Trichlorophenol was classified as possibly carcinogenic to humans (Group 2B). It is a pesticide used for wood preservation and for treating animal pelts and leather.

For more information, see the IARC news release and the Monograph summary in the Lancet Oncology.