Research | Children’s Health Risk of Childhood Cancers Associated with Residence in Agriculturally Intense Areas in the United States Susan E. Carozza,1 Bo Li,2 Kai Elgethun,3 and Ryan Whitworth 4 1Department of Epidemiology and Biostatistics, School of Rural Public Health, Texas A&M Health Science Center, College Station, Texas, USA; 2National Center for Atmospheric Research, Boulder, Colorado, USA; 3Department of Community and Environmental Health, Boise State University, Boise, Idaho, USA; 4Centers for Health Promotion and Prevention Research, School of Public Health, University of Texas Health Science Center at Houston, Houston, Texas, USA BACKGROUND: The potential for widespread exposure to agricultural pesticides through drift during application raises concerns about possible health effects to exposed children living in areas of high agricultural activity. OBJECTIVES: We evaluated whether residence in a county with greater agricultural activity was associated with risk of developing cancer in children < 15 years of age. METHODS: Incidence data for U.S. children 0–14 years of age diagnosed with cancer between 1995 and 2001 were provided by member registries of the North American Association of Central Cancer Registries. We determined percent cropland for each county using agricultural census data, and used the overall study distribution to classify agriculturally intense counties. We estimated odds ratios and 95% conﬁdence intervals for all ages and 5-year age groups for total cancers and selected cancer sites using logistic regression. RESULTS: Our study results showed statistically signiﬁcant increased risk estimates for many types of childhood cancers associated with residence at diagnosis in counties having a moderate to high level of agricultural activity, with a remarkably consistent dose–response effect seen for counties having ≥ 60% of the total county acreage devoted to farming. Risk for different cancers varied by type of crop. CONCLUSIONS: Although interpretation is limited by the ecologic design, in this study we were able to evaluate rarer childhood cancers across a diverse agricultural topography. The ﬁndings of this exploratory study support a continued interest in the possible impact of long-term, low-level pesticide exposure in communities located in agriculturally intense areas. KEY WORDS: agricultural pesticides, childhood cancers, farming, pediatric cancers. Environ Health Perspect 116:559–565 (2008). doi:10.1289/ehp.9967 available via http://dx.doi.org/ [Online 10 January 2008] Increased incidence of certain cancers among farmers and workers employed in agricultural settings has been reported in a variety of epi- demiologic studies, raising concerns about exposure to agricultural chemicals in general and agricultural pesticides in particular (Blair and Zahm 1991, 1995; Blair et al. 1993; De Roos et al. 2003). Agricultural pesticides rou- tinely spread beyond the intended agricultural target area, with drift possible for miles depending on wind conditions and particle size (Tiefenbacher 1998; van den Berg et al. 1999). Because measurable amounts of agri- cultural pesticides have been reported in non- farming households and communities [Baker et al. 1996; Centers for Disease Control and Prevention (CDC) 2005; Koch et al. 2002; Shalat et al. 2003], it is probable that pesticide drift provides a mechanism by which exposure can occur not only to agricultural workers but also to their families and neighbors. This potential for widespread exposure raises concerns about possible health effects in the offspring of women who are exposed to these pesticides during pregnancy and in very young children, a population whose age- related behaviors put them at particularly high risk of exposure. Children living in areas of high agricultural activity may be exposed to higher levels of pesticides than other children, through playing in nearby fields, increased opportunities for pesticides to be tracked into the home by various household members, and breast milk from exposed mothers (Eskenazi et al. 1999). In addition to having more opportunities for exposure, young children may prove to be particularly vulnerable to lower-dose exposures of pesticides with terato- genic and carcinogenic potential (Faustman et al. 2000; Tilson 1998). Given that the most direct effect of agri- cultural practices is likely to be among farm- ers, agricultural workers, and their families, there is clearly potential as well for an impact on the surrounding communities, particularly among the children of those communities. To investigate that potential, we evaluated whether residence in a county with greater agricultural activity, as determined by percent of total land devoted to crop production, was associated with an increased risk of developing childhood cancers. Materials and Methods Cancer incidence and population data. Incidence data for U.S. children 0–14 years of age diagnosed with cancer between 1995 and 2001 were provided by member registries of the North American Association of Central Cancer Registries (NAACCR). To be eligible Environmental Health Perspectives • VOLUME 116 | NUMBER 4 | April 2008 for the study, U.S. member registries had to agree to participate and had to have met at least NAACCR Silver certification require- ments (NAACCR 2007). Given these crite- ria, 30 U.S. population-based state registries were initially eligible to be included in the analyses. County-level sex- and age-specific rates for the entire time period were obtained for all International Classification for Childhood Cancer (ICCC) site codes using the Surveillance Research Program, National Cancer Institute SEER*Stat software (SEER 2007) version 5.3.0. The National Cancer Institute receives population estimates from the U.S. Census Bureau’s Population Estimates Program through an interagency agreement. Accurate population data for Hawaii at the county level were not available, and Hawaiian counties were consequently excluded from the study population, leaving 29 eligible registries. County acreage, percent cropland, and percent acres in speciﬁc crops data. Data on the total land area by county in 2000 came from the database of county information maintained by the National Association of Counties (NACo), an organization that provides an extensive line of services including legislative, research, technical, and public affairs assistance to all U.S. counties (NACo 2005). Data from the 1997 U.S. Department of Agriculture (USDA) National Agricultural Statistics Service (NASS) Census of Agriculture were used to obtain information on both the acres of cropland and acres of land planted in six leading U.S. crops (barley, corn, cotton, oats, soybean, and wheat) in each of the counties in the study population (USDA 1997). This peri- odic census is the most thorough source of U.S. agricultural data from the county, state, and national level. We chose the 1997 census because it was conducted at the approximate Address correspondence to S.E. Carozza, Department of Epidemiology and Biostatistics, School of Rural Public Health, 1266 Texas A&M University, College Station, TX 77843-1266 USA. Telephone: (979) 845-2387. Fax: (979) 862-8371. E-mail: scarozza@ srph.tamhsc.edu This project has been funded by the National Cancer Institute, National Institutes of Health, and the Department of Health and Human Services, under contract N02-PC-44401. The authors declare they have no competing ﬁnancial interests. Received 8 December 2006; accepted 10 January 2008. 559