Volume 130: 1,1,1-Trichloroethane and Four Other Industrial Chemicals

We are pleased to announce that the results of the recent IARC Monographs evaluation of the carcinogenicity of 1,1,1-trichloroethane, 1,2-diphenylhydrazine, diphenylamine, N-methylolacrylamide, and isophorone have now been published in The Lancet Oncology.

Three of these agents (1,2-diphenylhydrazine, diphenylamine, and isophorone) were evaluated by the Working Group for the first time.

1,1,1-Trichloroethane is a chlorinated hydrocarbon that was used widely before the implementation of the Montreal Protocol on Substances that Deplete the Ozone Layer, but that since the 1990s has been used mostly as a chemical feedstock in closed systems and for essential purposes, e.g. medical devices and aviation safety. Diphenylamine, N-methylolacrylamide, and isophorone are chemicals with a high production volume that have diverse uses in industry, including as intermediates. 1,2-Diphenylhydrazine was primarily used as an intermediate in the manufacture of benzidine dyes, which has ceased in the USA and European Union, although such use may continue elsewhere. For all agents, data were sparse regarding exposure levels, but indicated that exposures are higher in occupational situations than in the general population.

The Working Group evaluated 1,2-diphenylhydrazine, diphenylamine, N-methylolacrylamide, and isophorone as possibly carcinogenic to humans (Group 2B) mainly on the basis of sufficient evidence of carcinogenicity in experimental animals. 1,1,1-Trichloroethane was evaluated as probably carcinogenic to humans (Group 2A) on the basis of sufficient evidence of carcinogenicity in experimental animals and limited evidence of carcinogenicity in humans (positive associations were seen for multiple myeloma). For all agents, there was limited mechanistic evidence.

Read the article; pdf
Read the Q&A
View the infographic