Childhood cancer risk linked to pesticide exposure
MedWire News: The incidence of childhood cancers, including brain tumors, leukemia and lymphoma is significantly associated with exposure to pesticides during development, results of a meta-analysis show.
The prenatal period was a "critical window of exposure" with both the mother's and father's exposure linked to cancer incidence at different sites in their children, report Laurence Gamet-Payrastre (French National Institute for Agricultural Research [INRA], Toulouse) and colleagues.
Childhood cancer is the second leading cause of death among children aged 5-14 years in Europe and the USA, after accidental causes.
There is concern that in these countries particularly, overall rates of childhood cancer have been increasing since 1970.
Conditions such as Down's syndrome, other specific chromosomal and genetic abnormalities, and exposure to ionizing radiation are known risk factors, but they explain only a small percentage of cases.
Early-life exposure to environmental contaminants is suspected to be responsible for initial anomalies occurring in utero and leading to cancer.
Pesticides are among the suspected factors, as they may promote chromosomal aberrations, oxidative stress, cell signalling disturbances or mutations, that could be linked to increased cancer risk.
Noting a steadily growing body of evidence to support this theory the researchers performed a meta-analysis of case-control studies that gathered data on the site of the cancer and the period and duration of exposure to pesticides.
Of the 40 studies that reported odds ratios (ORs), the risk for lymphoma and leukemia was significantly increased in children when their mother was exposed during the prenatal period with ORs of 1.53 and 1.48, respectively.
The risk for brain cancer was correlated with paternal exposure either before or after birth with ORs of 1.49 and 1.66, respectively.
The ORs for leukemia and lymphoma were highest when the mother was exposed to pesticides through household use or professional exposure. Conversely, the incidence of brain cancer was influenced by the father's exposure from occupational activity or use of household or garden pesticides.
"When assessing environmental health impacts, children, fetuses, and neonates need to be distinguished from adults, as they are believed to be more vulnerable to the effects of environmental pollutants, and many routes of exposure are possible," Gamet-Payrastre et al comment.
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By Andrew Czyzewski