Malathion, carcinogenicity

National Cancer Institute smdies showed that administration of 4700 or 8150mg/kg for 80 weeks or 2000 or 4000mg/kg for 103 weeks in the diets of rats was not carcinogenic. Subsequent data reevaluation by NTP confirmed these conclusions. Mice fed diets containing 8000 or 16,000 mg/kg for 80 weeks also had no significant increase in mmor incidence. The lARC determined that there is no available evidence to suggest that malathion is likely to present a carcinogenic risk to humans. 

Malathion for Possible Carcinogenicity, TR-24. DHEW (NIH) Pub No 78-824. Washington, DC, US Department of Health, Education and Welfare, 1978... 

National Cancer Institute, Bioassay of Malathion for Possible Carcinogenicity, Technical Reports 192, National Institutes of Health, Bethesda, MD, 1979. 

Chronic toxicity of organophosphates may be discussed under four different areas carcinogenicity, delayed neurotoxicity, experimental myopathy, and, in humans, psychiatric disorders. In 1983, the IARC (International Agency for Research on Cancer) evaluated the carcinogenic potential of, among other pesticides, five organophosphate insecticides/acaricides (malathion, methyl parathion, parathion,... 

Solanine and chaconine (the main natural alkaloids in potatoes) are cholinesterase inhibitors and were widely introduced into the hviman diet about 400 years ago with the dissemination of the potato from the Andes. They can be detected in the blood of all potato eaters. Total alkaloids are present in potatoes at a level of 15,000 Vig per 200-g potato, which is only about a six-fold safety margin from the toxic level for hximans ( .) Neither alkaloid has been tested for carcinogenicity. By contrast, the pesticide malathion, the main synthetic organophosphate cholinesterase inhibitor present in our diet (17 ug/day), has been thoroughly tested and is not a carcinogen in rodents. Plant breeders have produced an insect-resistant potato however, it had to be withdrawn from the market because of its acute toxicity to hvunans, a consequence of higher levels of solanine and chaconine. 

There are no known 5-containing compounds in tobacco or tobacco smoke in Group 1, 2A, or 2B. There are only six compounds that are found in Group 3 (Malathion , ethylenethiourea, Parathion , Parathion-methyl , sulfur dioxide, and ethylene sulfide). The evidence for the carcinogenicity in humans of aU these compounds was classified as inadequate (18A04). 

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