Exposure to moderate air pollution during late pregnancy and cord blood cytokine secretion in healthy neonates.

Ambient air pollution can alter cytokine concentrations as shown in
vitro and following short-term exposure to high air pollution
levels in vivo. Exposure to pollution during late pregnancy has
been shown to affect fetal lymphocytic immunophenotypes. However,
effects of prenatal exposure to moderate levels of air pollutants
on cytokine regulation in cord blood of healthy infants are
unknown. In a birth cohort of 265 healthy term-born neonates, we
assessed maternal exposure to particles with an aerodynamic
diameter of 10 µm or less (PM₁₀), as well as to indoor air
pollution during the last trimester, specifically the last 21, 14,
7, 3 and 1 days of pregnancy. As a proxy for traffic-related air
pollution, we determined the distance of mothers' homes to major
roads. We measured cytokine and chemokine levels (MCP-1, IL-6,
IL-10, IL-1ß, TNF-α and GM-CSF) in cord blood serum using LUMINEX
technology. Their association with pollution levels was assessed
using regression analysis, adjusted for possible confounders. Mean
(95%-CI) PM₁₀ exposure for the last 7 days of pregnancy was 18.3
(10.3-38.4 µg/m³). PM₁₀ exposure during the last 3 days of
pregnancy was significantly associated with reduced IL-10 and
during the last 3 months of pregnancy with increased IL-1ß levels
in cord blood after adjustment for relevant confounders. Maternal
smoking was associated with reduced IL-6 levels. For the other
cytokines no association was found. Our results suggest that even
naturally occurring prenatal exposure to moderate amounts of indoor
and outdoor air pollution may lead to changes in cord blood
cytokine levels in a population based cohort.