Maternal Exposures to Hazardous Waste Sites and Industrial Facilities and Risk of Neural Tube Defects in Offspring LUCINA SUAREZ, PHD, JEAN D. BRENDER, PHD, PETER H. LANGLOIS, PHD, F. BENJAMIN ZHAN, PHD, AND KAREN MOODY, MS PURPOSE: We examined the relationship between maternal proximity to hazardous waste sites and industrial facilities and neural tube defect (NTD) risk. METHODS: Texas Birth Defects Registry cases were linked with their birth or fetal death certificates; controls (without defects) were randomly selected from birth certificates. Distances from maternal addresses at delivery to National Priority List (NPL) and state superfund sites and Toxic Release Inventory (TRI) facilities were determined for 655 cases and 4368 controls. RESULTS: Living within 1 mile of an NPL or state superfund site was not related to NTD risk (adjusted odds ratio [OR] Z 1.0; 95% confidence intervals [CI] Z 0.6, 1.7). Living within 1 mile of a TRI facility carried a slight risk (adjusted OR Z 1.2; 95% CI Z 1.0, 1.5). The effect was highest among mothers 35 years and older (OR Z 2.7; 95% CI Z 1.4, 5.0) and among non-Hispanic white mothers (OR Z 1.8; 95% CI Z 1.1, 2.8). CONCLUSIONS: Hazardous waste sites posed little risk for NTDs in offspring. Close proximity to indus- trial facilities with chemical air emissions was associated with NTD risk in some subgroups. Further inves- tigation is needed to determine if the effects are real or due to unresolved confounding or bias. Ann Epidemiol 2007;17:772–777. Ó 2007 Elsevier Inc. All rights reserved. KEY WORDS: Neural Tube Defects, Hazardous Waste, Polycyclic Aromatic Hydrocarbons, Heavy Metals, Solvents, Geographic Information Systems. INTRODUCTION There is continuing public and scientific concern that envi- ronmental contaminants dispersed in air, soil, and water are a cause of birth defects. Along the Texas–Mexico border, where there is a high occurrence of neural tube defects (NTDs), community concern about the role of environmen- tal contaminants overrides awareness of well-established NTD risk factors such as folic acid deficiency (1),B 12 defi- ciency (2), obesity (3, 4), or diabetes (3). Studies of the ef- fect of environmental contaminants on NTD risk are few because of the difficulty in assessing exposure at the time the neural tube closes (approximately 1 month postconcep- tion). At hand are occupational studies that suggest a link between presumed parental exposures to specific chemicals and NTD risk in offspring (5–18). Other studies assess the risks associated with living near hazardous waste sites, which more often than not involve exposures to chemical mix- tures. These studies have been inconsistent: some showing no relation between maternal proximity to hazardous waste sites and NTD risk in offspring (19, 20), a modest risk (21–24), or a doubling of risk (25). We present a case–control study of the relationship be- tween maternal exposures to hazardous waste sites and in- dustrial facilities, as measured by residential proximity, and risk of NTDs in offspring. Cases of NTDs were identified from the Texas Birth Defects Registry and linked to their birth or fetal death certificate information. Controls were live births without congenital malformations identified from birth certificates. Potential exposures to hazardous waste sites and chemicals emanating from these sites were assessed using geographic information systems and the ex- tensive databases from the Agency for Toxic Substances and Disease Registry (ATSDR) and the state agency Texas Commission on Environmental Quality (TCEQ). We specifically evaluated exposures to heavy metals, polycyclic aromatic hydrocarbons (PAHs), and solvents. MATERIALS AND METHODS Data on Cases and Controls Cases of NTDs occurring during 1996 to 2000 were identi- fied from the Texas Birth Defects Registry at the Texas From the Epidemiology and Disease Surveillance Unit, Texas Depart- ment of State Health Services, Austin (L.S., P.H.L.); Department of Epide- miology and Biostatistics, Texas A&M School of Rural Public Health, College Station (J.D.B.); Texas Center for Geographic Information Sci- ence, Department of Geography, Texas State University, San Marcos (F.B.Z.); and Infectious Disease Control Unit, Texas Department of State Health Services, Austin (K.M.). Address correspondence to: Lucina Suarez, PhD, Epidemiology and Dis- ease Surveillance Unit, Texas Department of State Health Services, 1100 West 49th S, Austin, TX 78756. Tel.: (512) 458-7381; fax: (512) 458-7689. E-mail: lucina.suarez@dshs.state.tx.us. Received March 1, 2007; accepted May 18, 2007. Ó 2007 Elsevier Inc. All rights reserved. 1047-2797/07/$–see front matter 360 Park Avenue South, New York, NY 10010 doi:10.1016/j.annepidem.2007.05.005