Air pollution and limb defects: A matched-pairs case-control study in Taiwan

Background: Air pollution influences the development of limb defects in animals. There is little epidemiologic evidence on the effect of prenatal air pollution exposure on the risk of limb defects. Objective: To assess the relations between exposure to ambient air pollutants and the risk of limb defects. Methods: We conducted a matched-pairs case-control study in Taiwan from 2001 through 2007. The case group consisted of 1687 limb defects and the control group was density-sampling matched one to ten based on the month and year of conception from 1510,064 live singleton newborns in 2001-2007. Adjusted conditional logistic regression models were used to estimate odds ratios per 10 ppb change for O-3, NO2, 1 ppb change for SO2, 10 mu/m(3) change for PM10, and 100 ppb change for CO during the first trimester and first three gestational months. Results: Of the specific limb defects, reduction deformities of limbs (adjusted OR=1.024, 95% CI: 1.000, 1.048) was associated with a 1 ppb increase in SO2 during weeks of 9-12 of gestation as well as the first trimester. Reduction deformities of limbs was also associated with a 10 ppb increase in O-3 during weeks of 1-4 of gestation (adjusted OR=1.391, 95% CI: 1.064, 1.818) among preterm births. Conclusion: The present study provides evidence that exposure to outdoor air SO2 during the first trimester of pregnancy may increase the risk of limb defects. Exposure to O-3 was associated with reduction deformities of limbs among preterm births. Similar levels of SO2 and O-3 are encountered globally by large numbers of pregnant women. (C) 2014 Elsevier Inc. All rights reserved.