Early-life exposure to ambient air pollutants and kidney function in adolescents: a cohort study based on the 'Children of 1997' Hong Kong birth cohort.

Objectives: Air pollution is increasingly linked to impaired kidney function in adults. However, little is known about how early-life exposure to air pollutants affects kidney function in adolescents.

Study Design: Cohort study.

Methods: We leveraged data from the 'Children of 1997' Hong Kong population-representative birth cohort (N = 8327). Residential exposure to average ambient levels of four air pollutants, including inhalable particle (PM), sulfur dioxide (SO), nitrogen dioxide (NO), and nitrogen monoxide (NO), during in utero, infancy, and childhood periods was estimated using the inverse distance weighting. Kidney function was assessed using estimated glomerular filtration rate (eGFR) calculated from age-adjusted equations for adolescents. Generalized linear regression was used to examine the association of air pollutant exposure in each period with kidney function at 17.6 years. Two-pollutant models tested the robustness of the association.

Results: Of the 3350 participants included, 51.4% were boys. Exposure to PM was associated with poorer kidney function. Each interquartile range increment in PM was inversely associated with eGFR (β: -2.933, 95% confidence interval -4.677 to -1.189) in utero, -2.362 (-3.992 to -0.732) infancy, -2.708 (-4.370 to -1.047) childhood, and -2.828 (-4.409 to -1.247) overall. Exposure to PM and SOin utero had a stronger inverse association with kidney function in males. The associations were robust to PM exposure in two-pollutant models.

Conclusions: Our findings suggest that early-life exposure to ambient PM and SO is associated with reduced kidney function in adolescents, especially exposure in utero.