Effects of ambient levels of air pollution generated by traffic on birth and placental weights in mice.

OBJECTIVE: To examine whether there is an association between fetal and/or placental weight and exposure to ambient levels of air pollution in mice.
DESIGN: Chronic experiments on mice that were exposed to polluted vs. clean air.
SETTING: Environmental exposure to atmospheric pollution. ANIMAL(S): Female Swiss mice (n = 70) were maintained at different stages of gestation in an exposure chamber located at an intersection with heavy traffic in a major city in Brazil. Control mice were maintained in a similar chamber, located adjacent to the exposure chamber but equipped with filters for particles and reactive gases. INTERVENTION(S): Animals were divided into six groups as follows: no exposure, exposure to a polluted chamber throughout gestation, exposure to a polluted chamber during the 1st week of pregnancy, exposure to a polluted chamber during the 2nd and 3rd weeks, exposure to a polluted chamber during the 1st and 2nd week, and exposure to a polluted chamber during the 3rd week. MAIN OUTCOME MEASURE(S): At the end of the gestational period, the determination of fetal and placental weight was performed after cesarean section. RESULT(S): Exposure to air pollution during the 1st week of pregnancy promoted a significant reduction in fetal weight. Mice exposed to polluted air, in any phase of gestation, presented with lower placental weight in comparison to mice maintained in clean chambers. CONCLUSION(S): Exposure to ambient levels of traffic pollution at early phases of gestation is a determinant for decreased final fetal weight. Placental weight is reduced with exposure to air pollution at any phase of gestation.