Prenatal exposure to PM2.5 components and fetal growth: identifying critical gestational weeks and key toxic...

Current evidence remains inconclusive regarding the developmental toxicity of specific fine particulate matter (PM2.5) components during critical fetal growth periods, particularly concerning key toxic components and exposure windows.

This prospective birth cohort included 2680 mother-newborn pairs with 9339 growth ultrasound measurements [abdominal circumference, head circumference (HC), femur length (FL), estimated fetal weight (EFW)] in Guangzhou, China, from 2017 to 2020. Weekly exposures to PM2.5 components-black carbon (BC), organic matter (OM), nitrate (NO3-), sulfate (SO42-), and ammonium (NH4+)-were quantified by using the Tracking Air Pollution in China database (TAP) real-time air-pollutant-exposure model. Distributed lag models with generalized estimating equations were employed to identify critical exposure windows and machine-learning approaches were used to assess constituent mixture effects and identify dominant toxic components.

FL, HC, and EFW demonstrated component-specific vulnerability. FL reduction at gestational Weeks 12-15 was most strongly associated with BC exposure, followed by OM and SO42-; HC deficits in Weeks 5-12 and 22-24 were predominantly linked to NO3- exposure; EFW reductions during Weeks 6-8 were most sensitive to NO3- exposure. BC and NO3- were identified as the most impactful constituents.

Our findings identify gestational Weeks 12-15 for BC exposure and Weeks 5-12 and 22-24 for NO3- exposure as critical vulnerable windows for adverse fetal development associated with PM2.5 components. These results support the need for further research into component-specific air-quality guidelines targeting sensitive gestational periods.