Prenatal exposure to p,p'-DDE and p,p'-DDT in relation to lower respiratory tract infections in boys from a highly exposed area of Mexico.

BACKGROUND

Prenatal exposure to 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE), the major breakdown product of DDT, has been associated with recurrent lower respiratory tract infections (LRTIs) in infants. However, epidemiological investigations are limited.

OBJECTIVE

To assess the association of prenatal exposure to p,p'-DDE and p,p'-DDT with the occurrence of LRTI in boys from Chiapas, a highly exposed area of Mexico.

METHODS

We analyzed data from 747 singleton boys whose prenatal exposure to p,p'-DDE and p,p'-DDT was determined in maternal serum drawn at delivery (2002-2003). LRTI (i.e., pneumonia, bronchiolitis, and other illness of the bronchi) experienced by the children were reported by their mothers during in-person interviews. The median age of the children when they were last seen was 21.4 months (quartiles 19.1 and 25.3 months).

RESULTS

Median exposure to p,p'-DDE in this population was higher (2.7 µg/g lipid) than recent U.S. levels (0.20 µg/g). There were 0.19 episodes of LRTI per child-year. After adjusting for potential confounders, children in the highest category of p,p'-DDE (>9.00 µg/g) exposure compared to those in the lowest (≤ 3.00 µg/g) had an adjusted incidence rate ratio (aIRR) of LRTI of 0.77 (95% confidence interval [CI], 0.41-1.46). The corresponding aIRR for p,p'-DDT (≥ 2.00 µg/g compared to ≤ 0.25 µg/g) was 0.65 (95% CI: 0.30-1.39).

CONCLUSION

An association of prenatal exposure to p,p'-DDE and p,p'-DDT with LRTI during childhood was not supported in this population with relatively high levels of exposure.