IARC evaluates three pesticides, classifies lindane as carcinogenic
June 30, 2015 – The CAREX Canada team monitors evaluations by the International Agency for Research on Cancer (IARC) as part of our ongoing surveillance of Canadians’ exposures to known and suspected carcinogens. IARC recently convened a working group of 26 experts from 13 countries to assess the carcinogenicity of three pesticides: lindane, DDT (dichlorodiphenyltrichloroethane), and 2,4-D (2,4-dichlorophenoxyacetic acid).
Based on a review of the latest scientific literature, the classifications are summarized as follows:
Lindane has been used extensively for insect control, and is found in prescription medicines to treat scabies and head lice.[1,2] According to IARC, high exposures have occurred among agricultural workers and pesticide applicators; however, agricultural use of lindane is now banned or restricted in most countries, including Canada. The general public may be exposed to lindane through contaminated food, air, soil, and water. Lindane is persistent in the environment and is deposited throughout the Canadian arctic through atmosphere and ocean currents. It can also bioaccumulate in the fat tissue of organisms, contaminating foods with high fat content, such as meat and dairy products.[3,4] It has also been found in breast milk .
DDT was introduced for the control of insect-borne diseases during the Second World War and was later applied widely to eradicate malaria. Although most uses of DDT were banned from the 1970s, IARC notes that DDT and its breakdown products are highly persistent and can be found in the environment and in animal and human tissues throughout the world. Exposure to DDT still occurs, mainly through diet.
2,4-D is the most widely used herbicide in the world, and the third most widely used in North America. Sales data from the Pest Management Regulatory Agency (PMRA) of Health Canada show that by weight, 2,4-D is the second most widely sold herbicide in the country. According to IARC, it is used in agriculture, forestry, and urban and residential settings. They note that occupational exposures to 2,4-D can occur during manufacturing and application, and the general population can be exposed through food, water, dust, or residential application, and during spraying.
The CAREX team is currently developing a profile for DDT, and investigating exposures to these and other pesticides as a priority for 2015-16. To learn more about exposure to lindane, 2,4-D, and other pesticides, visit our Profiles and Estimates page.
- PMRA database of registered pesticides
- ATSDR Toxicological Profile for Hexachlorocyclohexane (2005)
- NTP 13th Report on Carcinogens for Lindane and Other Hexachlorocyclohexane Isomers (2014)
- Managing Potentially Toxic Substances in Canada – A State of the Debate Report (2001) By the National Round Table on the Environment and the Economy (NRTEE)
- Industry Task Force II on 2,4-D Research Data