Diet, transplacental carcinogenesis, and risk to children

With an estimated worldwide annual incidence of 175 000 and a rate below 200 cases per million, cancer in children is rare. Although survival rates have steadily improved, especially for leukaemia, the prognosis for other cancers remains poor, with brain tumours now the major cause of death from cancer in childhood. The aetiology of individual childhood cancers remains largely unknown, but interest continues in the possible role of environmental and lifestyle factors, especially given that incidence seems to be increasing.1 The rarity of childhood cancer, however, creates severe challenges for epidemiology in that even national studies often lack statistical power to investigate possible environmental causes.

Childhood leukaemia is the most investigated in terms of potential causes. Ionising radiation is an established cause. Estimates from the Japanese atomic bomb survivors, supported by epidemiological evidence, suggest that 15-20% of incidence could be due to largely unavoidable exposure to natural background radiation.2 Other environmental exposures linked to increased risk include magnetic fields from the electricity supply,3 pollution from motor vehicle exhausts,4 5 and pesticides.6 Infections seem to be associated …