Insecticide lindane found to cause cancer

http://www.theguardian.com/environment/2015/jun/24/insecticide-lindane-found-to-cause-cancer

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A common insecticide has been found to cause cancer in humans, according to a World Health Organization review. The product, lindane, was once widely used in agriculture and continues to be found in some treatments for head lice and scabies. The WHO concluded today that the substance is carcinogenic and specifically said that exposure to the chemical could increase the risk of the rare immune cancer, non-Hodgkin lymphoma, by 60%.

Although agricultural use of the chemical is heavily restricted in Britain, consumers may still be exposed through foods imported from some developing countries, where it continues to be used in agriculture.

The WHO’s International Agency for Research on Cancer (IARC) also said that the insecticide DDT, dichlorodiphenyltrichloroethane, “probably causes cancer”, after finding evidence that it could increase the risk of non-Hodgkin lymphoma (NHL), testicular cancer and liver cancer.

Lindane has been banned or restricted in most countries since 2009 under the Stockholm Convention on Persistent Organic Pollutants. It was previously used extensively for insect control in agriculture and continues to be used in some developing countries. DDT is also banned in the UK and US.

The findings, published in the Lancet Oncology, showed that there is strong evidence that a third chemical, the herbicide 2,4-D, causes an imbalance in the body called oxidative stress. However, the panel stopped short of concluding there was a definite link to cancer, saying there was insufficient information.

The IARC said high exposures to lindane have previously been reported among agricultural workers and pesticide applicators. “Large epidemiological studies of agricultural exposures in the United States and Canada showed a 60% increased risk of non-Hodgkin lymphoma in those exposed to lindane,” it said. Lower risks were observed for those who had been less heavily exposed to the chemical.

“This agricultural usage of lindane has been severely restricted starting in the 1970s and current general population exposure is mainly through the diet or when treated for scabies or lice,” said Dr Kurt Straif, Head of the IARC. “There are currently no epidemiological studies to quantify the lymphoma risk from these exposures.”

DDT was introduced for the control of insect-borne diseases during the second world war and was later applied widely to eradicate malaria and in agriculture. Although most uses of it were banned from the 1970s, IARC cautioned 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,” it said, adding that DDT is still used, mainly for malaria control in parts of Africa, although under very strict conditions.

A study published last year also found that those with higher levels of DDT metabolites in their system were more likely to develop Alzheimer’s disease – although the research did not prove that the pesticide had caused the dementia.

Since it was introduced in 1945, 2,4-D has been widely used to control weeds in agriculture, forestry and urban and residential settings. IARC said occupational exposure to 2,4-D can occur during manufacturing and application, and people in the general population can be exposed through food, water, dust, or residential application, and during spraying.