In a report which will be of concern to parents, French researchers say that household insecticides may increase the risk of childhood leukaemia.
Leukaemia affects 43 children in every million in France each year and is the most common childhood cancer there.
The study by Inserm, France’s national institute for medical research, supports concerns raised in recent years about the use of toxic insecticides around the home and garden, including plant sprays, medication shampoos and mosquito repellents, and a possible correlation with increased rates of acute leukaemia in children.
The findings are based on 280 children newly diagnosed with acute leukaemia and a further 288 children matched for sex and age, but free of the disease.
Comprehensive and detailed face to face interviews were carried out with each of their mothers, and included questions about the employment history of both parents, the use of insecticides in the home and garden, and the use of insecticidal shampoos to eradicate head lice.
The researchers found that the risk of developing acute leukaemia was almost twice as likely in children whose mothers said that they had used insecticides in the home while pregnant and long after the birth.
It was found that exposure to garden insecticides and fungicides as a child was associated with a more than doubling of the risk of acute childhood leukaemia, while the use of insecticidal shampoos to eradicate head lice, based on what the mothers had said, was associated with almost double the risk.
A group of pesticides known as carbamates, which are present in plant treatments, lice shampoos and insect sprays, are most commonly linked to cases of leukaemia.
According to Florence Menegaux, the lead researcher, and her fellow authors, no one agent can be singled out and a causal relation between insecticides and the development of acute childhood leukaemia remains.
Many scientists believe that the cancer starts in the womb, with a second event triggering the disease’s development in childhood.
Meanwhile studies are continuing to determine whether this trigger is genetic, environmental, dietary or related to other factors.
The three main carbamates used in the UK are carbaryl, carbofuran and carbosulfan.
Head lice products containing carbaryl are now restricted to prescription after a report by a government committee that gave warning of potential carcinogenic properties.
The study is published in the journal Occupational and Environmental Medicine.