Living near to a petrol station or garage may increase the risk of acute childhood leukaemia by 400%.
These new findings are based on 280 cases of acute childhood leukaemia and a comparison group of 285 children matched for sex. The children were drawn from four hospitals in France (Nancy, Lille, Lyon, and Paris), and almost two thirds (60%) of the children with leukaemia were aged between 2 and 6.
Acute childhood leukaemia or acute myeloid leukaemia is a form of cancer that affects the cells producing myeloid blood cells in the bone marrow. Myeloid cells are red blood cells, platelets and all white cells except lymphocytes.
The researchers interviewed the mothers of all the children about their employment and residential histories.
There was no clear association between the mother's occupation during pregnancy or levels of residential traffic and the risk of her child developing leukaemia.
But a child whose home was in the vicinity of a petrol station or a commercial garage that carried out repairs was four times as likely to develop leukaemia as a child whose home was not close to these outlets (17 cases compared with 7).
The risk appeared to be even greater for acute non-lymphoblastic leukaemia. This was seven times more common among the children living close to a petrol station or commercial garage.
The longer a child had lived close to a petrol station or commercial garage, the higher his/her risk of leukaemia seemed to be. The findings held true even after adjusting for other factors likely to influence the degree of risk.
The prevalence of childhood leukaemia is 4 in every 100,000 children, but it is the most common type of childhood cancer in developed countries. Few concrete risk factors have been identified for the childhood variant.
But occupational exposure to benzene has been identified as a possible risk factor for leukaemia in adults, say the authors, and petrol stations and commercial garages are a source of benzene emissions.
Further research will be needed to confirm these findings, say the authors. But they add: "These findings, as far as we know, have never been described before, and could be due to chance. However, the strength of the association and the duration trend are arguments for a causal association."
The research is reported in research in Occupational and Environmental Medicine.