Diazinon carcinogenicity

Estimates of exposure levels posing minimal risk to humans (Minimal Risk Levels or MRLs) have been made for diazinon. An MRL is defined as an estimate of daily human exposure to a substance that is likely to be without an appreciable risk of adverse effects (noncarcinogenic) over a specified duration of exposure. MRLs are derived when reliable and sufficient data exist to identify the target organ(s) of effect or the most sensitive health effect(s) for a specific duration within a given route of exposure. MRLs are based on noncancerous health effects only and do not consider carcinogenic effects. MRLs can be derived for acute-, intermediate-, and chronic-duration exposures for inhalation and oral routes. Appropriate methodology does not exist to develop MRLs for dermal exposure. 

The National Cancer Institute (NCI) concluded that diazinon was not carcinogenic in either rats or mice following chronic bioassays in Fischer 344 rats and B6C3Fj mice (NCI 1979). 

NCI. 1979. Bioassay of diazinon for possible carcinogenicity. National Cancer Institute Technical Report Series No. 137, National Institutes of Health, Public Health Service, U.S. Department of Health, Education, and Welfare, Bethesda, MD. NCI-CG-TR-137 DHEW/PUB/NIH-79-1392. 

U.S. National Cancer Institute. Bioassay of Diazinon for Possible Carcinogenicity. NCI Carcinogenesis Technical Report Series... 

Studies of the carcinogenicity of PG in a human leukemia cell line have suggested that gallic acid plays an important role in this effect since it is more easily oxidized than PG [11]. However, when rat hepatocytes were incubated with the esterase inhibitor diazinon, the cytotoxic effects of PG were enhanced. These results suggest that the hepatotoxicity of PG was not mediated by its metabolites [3]. 

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