Workers Health & Safety Centre

WHO cancer agency evaluates and classifies common herbicide, insecticides

Farmer spraying insecticide on crops
The International Agency for Research on Cancer has recently evaluated and classified DDT, lindane and 2,4-D for their ability to cause cancer in humans.
 
IARC, an agency of the World Health Organization, has classified the insecticide lindane as carcinogenic to humans. North American studies have found a 60 per cent increase in non-Hodgkin lymphoma (NHL) among those exposed to lindane. Those most at risk include agricultural workers and pesticide applicators.  Once used in treatment for human lice and scabies, lindane is now banned or restricted in most countries.
 
The insecticide DDT is classified as probably carcinogenic to humans based upon research which links DDT exposure and NHL, testicular cancer and liver cancer. Further evidence suggests DDT suppresses the immune system and disrupts the hormonal system. While its use is greatly restricted, DDT is still relied upon to control malaria in some countries.
 
The herbicide 2,4-D, widely used to control weeds in both commercial and residential settings, is classified as possibly carcinogenic to humans. Exposures can occur during manufacturing and spraying but the public may be exposed through residue in food, water or dust.
 
Many pesticides are deemed persistent organic pollutants (POP)—once released they remain intact in the environment for years and can be widely found in soil, water and air. These toxins can accumulate in the fatty tissue of humans and animals and have been linked to health effects from cancer to reproductive disorders. Canada is a signatory to the United Nations Stockholm Convention on Persistent Organic Pollutants. Countries to the Convention agree to eliminate or reduce the production, use and release of high priority POP’s which include DDT and more recently lindane.
 
Other related resources:
OCRC: Cross-Canada study of pesticides and select cancers: New analyses
CAREX Canada--Pesticides profiles and estimates
WHSC Hazard-Resource Lines--Endocrine-Disruptors
OHCOW - Migrant Farm Worker Project
 
WHSC offers a wide range of training programs and resources to help workplace parties understand their legal duties and responsibilities related to workplace hazards including the prevention of toxic exposures. Many of these resources also offer essential insight into the information and tools needed to eliminate or reduce harmful workplace and environmental exposures.
 
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