Household insecticides may increase the risk of acute childhood leukaemia, a French study suggests.
Garden insecticides and fungicides more than double the risk of leukaemia
The research, in the Occupational and Environmental Medicine journal, focused on data from 568 children - half of whom had acute leukaemia.
The team from the Inserm medical research institute also found exposure to insecticidal shampoos doubled the risk of developing the disease.
But UK cancer experts said the report did not prove there was a link.
Researchers carried out face-to-face interviews with the mothers of 280 children with acute leukaemia and a further 288, matched for sex and age, but free of the disease.
They asked them about employment history of both parents, and the use of insecticides in the home and garden.
They found use of home insecticides during pregnancy and childhood increased the risk of leukaemia by nearly twice. A similar risk was also seen for the use of insecticidal shampoo to treat head lice.
Use of garden insecticides was linked to a 2.4-fold increase in risk and fungicide to a 2.5-fold increase.
Report author Dr Florence Menegaux said it was still not possible to say for definite that insecticide use caused the leukaemia and it was unclear what agent in it was potentially dangerous.
But she added: "The findings of the study reinforce the hypothesis already suggested by the literature that household pesticide exposure may play a role in childhood acute leukaemia.
"The consistency of our results and the results from previous studies suggests that it may be opportune to consider preventative action."
But Ken Campbell, of the Leukaemia Research Fund, said the link between insecticide use and leukaemia was "contentious".
"There are mixed reports and the problem is that the ones that make the link get the publicity.
"There are two problems with this study, first, it is small, and, second, it depends on parental recall which is notoriously inaccurate.
"I do not think this proves a link."