30 June 2015 14:51

A Lancaster researcher has contributed to a review by the World Health Organisation, which has concluded that a once-common insecticide is carcinogenic. 

Professor Frank Martin, of Lancaster Environment Centre, was one of around 20 experts commissioned by the World Health Organisation, to evaluate the effect of the insecticides lindane and DDT (dichlorodiphenyltrichloroethane) and the herbicide 2,4-D on humans.

After thoroughly reviewing population-based case studies in several countries, the team classified lindane as carcinogenic to humans, and warned that exposure to the insecticide could increase the risk of the rare immune cancer, non-Hodgkin lymphoma.

Although lindane is now banned or restricted in most countries, it was once widely used in agriculture and continues to be found in some treatments for head lice and scabies.

Professor Frank Martin said: “Although mostly banned in Europe and North America, because of its continued usage in emerging regions and consequent movement through the environment, identifying the real-world effects of persistent agents such as lindane is crucial.

“Designating a substance a human carcinogen is fraught with difficulty and rare; although first-hand exposure in the UK is unlikely, exposures via travel to other regions or food consumption remains a possibility.

“Given its persistence, evidence of hormone activity and ability to induce effects at low levels, closer monitoring will be critical.”

The WHO’s International Agency for Research on Cancer (IARC) also concluded that DDT is ‘probably carcinogenic to humans’, having found some links between the insecticide and non-Hodgkin lymphoma, testicular cancer and liver cancer.

There was strong experimental evidence that DDT can suppress the immune system and disrupt sex hormones.

DDT was used for the control of insect-borne diseases during World War 2, and it was later applied to eradicate malaria and in agriculture.

The team also said that there is strong evidence that the herbicide 2,4-D causes an imbalance called oxidative stress, and that there is moderate evidence that it causes immunosuppression.  

Given there was insufficient information overall, the group classified the herbicide as ‘possibly carcinogenic to humans’.

The study was published in The Lancet Oncology.