Friday, May 30, 2008

Household exposure to pesticides

Posted by Neill Abayon

Pregnant women exposed to household pesticides may increase the risk of their children developing leukemia, according to a recent study conducted in France. These findings add more weight to the idea that pesticides play a role in childhood blood cancers and may shed light on the actual causes of the diseases.

In the study, parents of leukemia patients were more likely to have used pesticides and insecticides either at home or at work. Exposure to these chemicals is a risk factor for blood cancers, particularly if children are exposed in the womb, the authors' conclude.

What did they do? This study looked at mothers' exposure to household pesticides during pregnancy and the child's risk of developing leukemia or lymphoma. Using the French National Registry of Childhood Blood Malignancies, the authors identified 1,316 cases of childhood leukemia. Of these, only French speaking parents whose children survived and are currently healthy were contacted for the study. This left a study population of 764 volunteers who were surveyed by telephone about pesticide exposure and use for both mother and father during the pregnancy.

Controls were selected randomly from the French population using a quota sampling method of phone numbers equally distributed within 22 geographic regions in France. Of 60,000 phone numbers dialed, 1,682 mothers were interviewed for the study.

Identical surveys were given by the same trained staff to both control and study subjects. Mothers classified their exposure to pesticides during pregnancy as “ever used,” “never used” or “do not know.” They also reported the type of pesticide exposure (insecticide, herbicide, fungicide), if it was household or occupational exposure and whether the father was exposed during the pregnancy.

Other personal and family history, such as socioeconomic status, degree of urbanization, housing type (flat or house) and a child’s contact with pets, were also determined by the survey and controlled for during analysis.

Using these data, the authors' performed a statistical analysis to determine if there was a higher exposure to pesticides during pregnancy among the mothers whose children had cancer. They also asked if the exposures could implicate pesticides as a contributing environmental risk factor for developing leukemia.

What did they find? The use of household pesticides by mothers during their pregnancies was higher in the leukemia group than the randomly chosen controls. More than half of the mothers whose children had acute leukemia or non Hodgkins lymphoma used pesticides at lease once during their pregnancy compared with a little more than a third of the control group mothers.

There were significant associations between maternal pesticide use and acute leukemia (AL) and non-Hodgkin’s lymphoma (NHL), but not with Hodgkin’s lymphoma (HL). Paternal use of household pesticides was significantly associated with AL and NHL, but the associations were slightly weaker.

The authors further broke down their analysis based on the type of pesticides used (insecticide, herbicide, or fungicide). When breaking down the analysis by pesticide type, the strongest association found was between insecticide use and AL and NHL, with weaker associations with herbicides and no association with fungicides.

What does it mean? Children exposed to household pesticides before birth may have an increased risk of developing certain types of leukemia. The results reinforce findings from other studies that also identified associations between pesticide exposure before birth and the risk of developing a blood cancer. The authors' conclude that "the consistency of the findings with those of previous studies on AL raises the question of the advisability of preventing pesticide use by pregnant women."


No comments: