Association Between Ambient Air Pollution and Birth Weight in Novocheboksarsk, Russia

Abstract

SM4-PD-04 Introduction: We have evaluated the relationship between ambient air pollution and the occurrence of low birth weight using routinely collected data in Novocheboksarsk, Chuvash Republic, Russia. Methods: We used an epidemiologic case-control study design to examine whether exposure of ambient air pollutants to influenced the occurrence of low birth weight (LBW). The study comprised 120 term LBW infants and 240 term infants weighing 2500 g or more; date of mother's last menstrual period was used to define gestational age. Matching variables were parity, mother's height, age, education, and ethnic, infant's gender. Birth data and information on maternal characteristics were obtained from the medical documentations (“history of delivery,” “history of newborn”). To estimate trimester exposures, we used measurements of ambient nitrogen dioxide (NO2), phenol, sulfur dioxide (SO2), ammonia (NH3), chlorine (Cl), which were collected at 3 monitoring posts (the mean distance between study subject’ home and monitoring post was approximately 2.5 km, and although 90% of subjects lived within 3 km, the maximum distance was 4.5 km). The exposure variables were categorized into percentiles of the exposure distribution: <25th, 25 to <75th, ≥75th. For the categorical analysis, the group of infants with exposures under the 25th was used as the reference category. We calculated OR across trimester exposure categories for each pollutant. Results: Our results suggest that exposures to ambient phenol, chlorine, and ammonia increase the risk for term LBW. Infants with phenol second trimester exposure falling within the 25th (0.005 mg/m3) and <75th (0.008 mg/m3) (OR, 1.85; CI, 1.16–2.98), ≥75th (OR, 3.26; CI, 1.59–6.60) percentiles were at increased risk for term LBW when compared with those in the reference category (<25th percentile). Exposures to atmospheric chlorine above the 75th percentile (0.06 mg/m3; 25th, 0.03 mg/m3) at second trimester yielded an odds ratio of 1.98 (CI, 0.99–3.8). Third trimester exposures to NH3 were associated with an increased risk for LBW among infants with exposures greater than or equal to the 75th percentile of the exposure distribution (0.042 mg/m3; 25th, 0.021 mg/m3) (OR, 2.36; CI, 1.1–4.06). Discussion and Conclusions: Although the effects of unmeasured risk factors (smoking of mother, occupational exposure) could not be excluded with certainty, our findings suggest that in Novocheboksarsk there may be a relationship between maternal exposure to ambient phenol, chlorine, and ammonia and the risk of LBW.