MEASURING THE EFFECTS OF DDT AND DDE ON PRETERM DELIVERY, SMALL-FOR-GESTATIONAL AGE BIRTH AND LOW BIRTHWEIGHT BIRTH

Abstract

ISEE-473 Objective: Though banned in the United States since 1972, the pesticide 1,1,1-trichloro-2,2’-bis(p-chlorophenyl)ethane (DDT) is used elsewhere for mosquito control. Its human health costs and benefits thus remain a current concern. DDT, and its persistent metabolite DDE, have been associated with negative reproductive outcomes in birds, rabbits and sea lions. However, there are inconsistencies regarding exposure to DDT and effects on human health. This study was designed to evaluate the effects of serum levels of DDT and its major metabolite DDE on three adverse human birth outcomes - preterm delivery, small-for-gestational-age birth and low birthweight. Methods: Nested case-control study. We studied a sample of male live births from a longitudinal cohort study of 20,754 pregnancies that occurred between 1959 and 1967 (a period of high domestic DDT usage in the United States). The 283 male subjects included in this analysis were randomly selected controls from another study of the effects of organochlorine pesticides on male genital anomalies. Birth outcome data and maternal demographic/behavioral data were collected through maternal interviews and abstracted medical records. Maternal serum samples were taken during pregnancy and post-partum. Serum DDT and DDE were determined by gas chromatography/electron capture detection (GC/ECD). Data were analyzed using multivariate logistic regression for preterm delivery and small-for-gestational age birth and linear regression for birthweight. Results: Mean serum levels for DDT and DDE were 1.6 and 5.9 μg/g lipid, respectively. Variables identified as significant in bivariate analysis against each outcome variable were included as covariates in multivariate analysis. Preliminary findings indicate that maternal DDT and DDE levels, controlling for a range of demographic and behavioral variables associated with birth outcomes (i.e., age, race, education, marital status, income, occupation, place of birth, parity, BMI, and smoking and alcohol use) do not predict preterm delivery (n=23); small-for-gestational age birth (n=28), or low birthweight (n=13). Final results of regression analyses, including odds ratios and confidence intervals, will be presented. Discussion: The effect of DDT and DDE on human birth outcomes in this study appears null. However, we were limited by the small size of the study and the fact that we were only able to examine live births. Considering the persistence of DDT in the environment and its role in malaria control, further studies using more robust data should continue to assess this relationship.