Kori B. Flower, Jane A. Hoppin, Charles F. Lynch, Aaron Blair, Charles Knott, David L. Shore, and Dale P. Sandler
Parental exposure to pesticides may contribute to childhood cancer risk. Through the Agricultural Health Study (AHS), a prospective study of pesticide applicators in Iowa and North Carolina, we examined childhood cancer risk and associations with parental pesticide application. Identifying information for 17,357 children of Iowa pesticide applicators was provided by parents via questionnaires (1993-1997) and matched against the Iowa Cancer Registry. Fifty incident childhood cancers were identified (1975-1998). Risk of all childhood cancers combined was increased (standardized incidence ratio (SIR)=1.36; 95% CI=1.03, 1.79). Risk of all lymphomas combined was also increased (SIR=2.18; 95% CI=113, 4.19), as was risk of Hodgkin’s lymphoma (SIR=2.56; 95% CI=1.06, 6.14). Logistic regression was used to explore associations between self-reported parental pesticide application practices and childhood cancer risk. No association was detected between frequency of parental pesticide application and childhood cancer risk. An increased risk of cancer was detected among children whose fathers did not use chemically resistant gloves (OR=1.98; 95% CI=1.05, 3.76) compared with children whose fathers used gloves. Of sixteen specific pesticides used by fathers prenatally, ORs were increased for aldrin (OR=2.66), DDVP (OR= 2.06), and ETPC (OR=1.91). However, these results were based on small numbers and not supported by prior biologic evidence. Identification of excess lymphoma risk suggests that farm exposures including pesticides may play a role in the etiology of childhood lymphoma.