A Working Group of 17 experts from 11 countries met at the International Agency for Research on Cancer (IARC), the specialized cancer agency of the World Health Organization on 3–10 March 2015 to review the available published scientific evidence and evaluate the carcinogenicity of five organophosphate insecticides and herbicides: diazinon, glyphosate, malathion, parathion, and tetrachlorvinphos. A summary of the final evaluations together with a short rationale have now been published online in The Lancet Oncology, and the detailed assessments will be published as Volume 112 of the IARC Monographs.
The pesticides tetrachlorvinphos and parathion were classified as possibly carcinogenic to humans (Group 2B); for the insecticide malathion, there is limited evidence of carcinogenicity in humans for non-Hodgkin lymphoma and prostate cancer; for the insecticide diazinon, there was limited evidence of carcinogenicity in humans for non-Hodgkin lymphoma and lung cancer; for the herbicide glyphosate, there was limited evidence of carcinogenicity in humans for non-Hodgkin lymphoma.
Tetrachlorvinphos is banned in the European Union. In the USA, it continues to be used on livestock and companion animals, including in pet flea collars. Parathion use has been severely restricted since the 1980s. All authorized uses were cancelled in the EU and the USA by 2003. Malathion is currently used in agriculture, public health, and residential insect control. It continues to be produced in substantial volumes throughout the world. Workers may be exposed during the use and production of malathion. Diazinon has been applied in agriculture and for control of home and garden insects. Production volumes have been relatively low and decreased further after 2006 due to restrictions in the USA and the EU. Glyphosate currently has the highest global production volume of all herbicides. The largest use worldwide is in agriculture. The agricultural use of glyphosate has increased sharply since the development of crops that have been genetically modified to make them resistant to glyphosate. Glyphosate is also used in forestry, urban, and home applications.