Chemical used to fight head lice can cause cancer: Studies conducted in US and Canada say exposure to lindane can increase risk of cancer by up to 60%.

Cancer can occur due to a variety of factors. While it is true that genetic mutation has a big hand in causing cancer, there has been growing evidence that the exposure to a plethora of chemicals in our environment also has an impact on our lives. Chemicals surround us and most of them are not as harmless as they first seem.

The International Agency for Research on Cancer (IARC) held a session in Lyons, France in which 26 experts from 13 countries reviewed the carcinogenic capabilities of insecticides DDT (dichlorodiphenyltrichloroethane), 2,4-D and lindane.

According to studies conducted in US and Canada, exposure to lindane can increase the risk of cancer by as much as 60%. Both DDT and lindane have been associated with cancers such as liver, testicular and non-Hodgkins lymphoma (NHL).

2,4-D is a common weed killer, introduced in 1945. Exposure to this weedicide can occur through water, dust, food or even residential application.

Although the report did not find a strong increase in cancer risk from exposure to it, there is evidence that it causes oxidative stress. Oxidative stress can damage cells of the body. According to moderate evidence, 2,4-D can also suppress the immune system.

The ones most at risk of such chemicals are agricultural workers who have had contact with these chemicals on a regular basis.

Lindane, was previously used to control insect populations but has been banned for agricultural use in countries such as the US and Canada. It is still in circulation, however, mainly as an agent in anti-lice shampoos and treatments for scabies in countries such as India, China, Canada and US.

Anti-lice shampoos and scabies treatment lotions are products approved by the FDA and have been on the market since 1950s. The report stated that it was not possible to assess the risk through the usage of such products.

Dr Kurt Straif, Head of the IARC said, “The agricultural usage of lindane has been severely restricted but current general population exposure is mainly through the diet or through treatment for scabies or lice. There are currently no epidemiological studies to quantify the lymphoma risk from these exposures.”

Although DDT was introduced during WWII as an agricultural pesticide, and later to combat malaria, it was banned during the 1970s for agricultural use. The IARC has classified it as a “probable carcinogen to humans”.

Exposure to DDT is still possible, as it is used to control disease-carrying vectors. Furthermore, DDT and its breakdown products are highly persistent, lingering in the environment for years.

The report stated that they could be found “in the environment and in animal and human tissues throughout the world. Exposure can mainly occur through diet”. The agency published its findings in the journal Lancet Oncology.