Congenital limb reduction defects in the agricultural setting.

To ascertain whether parental involvement in agricultural work and residence in an agricultural setting are associated with the development of congenital limb reduction defects, we carried out a case-control study using California birth records from 1982, 1983, and 1984. Cases with limb reduction defects (N = 237) and randomly selected controls (N = 475) were compared regarding parental occupation and maternal county of residence. After adjustment for potential confounders in a multivariate analysis, the estimated relative risk (RR) of parenting a child with a limb reduction defect among parents involved in agricultural work was 0.9 (95 per cent confidence limits = 0.4, 1.7). The RR among mothers who resided in a county of high agricultural productivity as compared with minimal agricultural productivity was 1.7 (95% CL = 1.1, 2.7), while the RR associated with residence in a county with high pesticide use as compared with minimal pesticide use was 1.9 (95% CL = 1.2, 3.1). When we limited the cases to children with limb reduction defects who had at least one additional anomaly (n = 79) and compared them to the control births, the corresponding RRs were 1.6 (95% CL = 0.7, 3.6), for parental involvement in agricultural work, 2.4 (CL = 1.2, 4.7) for county agricultural productivity, and 3.1 (CL = 1.5, 6.5) for county pesticide use.