Prenatal and early life exposure to fine particulate matter and telomere length in early childhood

Background

Telomere length is a biomarker of molecular aging that may be impacted by air pollution exposure starting in utero. We aimed to examine the association between prenatal and early life exposure to fine particulate matter (PM_2.5) and leukocyte telomere length (LTL) in children and explore sex differences.

Methods

Analyses included 384 mother–child pairs enrolled in the Programming Research in Obesity, Growth, and Environmental Stressors (PROGRESS) birth cohort in Mexico City. Exposure to PM_2.5 was estimated at the residential level using a satellite based spatio-temporally resolved prediction model. Average relative LTL was measured in DNA isolated from blood collected at age 4–6 years using quantitative real-time polymerase chain reaction. Linear regression models were used to examine the association between average PM_2.5 across pregnancy, individual trimesters, first postnatal year, and LTL. Models were adjusted for maternal age and education at enrollment, prenatal environmental tobacco smoke exposure, child sex, age, and body mass index z-score at LTL measurement. Effect modification by sex was investigated with interaction terms and stratification.

Results

In trimester specific models, we found an association between 2nd trimester PM_2.5 and elongated LTL (β: 4.34, 95%CI [0.42, 8.42], per 5 μg/m³ increase). There was suggestive effect modification by sex on average 2nd trimester PM_2.5 with stronger associations seen in females compared to males (β: 7.12, [95%CI: 0.98, 13.6] and β: 1.43 [95%CI: −3.46, 6.57]) per 5 μg/m³ increase respectively.

Conclusion

Second trimester PM_2.5 levels were associated with changes in LTL in early childhood. Understanding temporal and sex differences in PM_2.5 exposure may provide insights into telomere dynamics over early life.