Abstract
BACKGROUND: Exposure to polycyclic aromatic hydrocarbons (PAH), generated through incomplete combustion of organic materials such as coal and wood, and through activities, like charbroiling meat and smoking tobacco, negatively impact children's health. This study evaluates early-life PAH exposure in children from Southern India and its association with early childhood caries (ECC). METHODS: We utilized maternal and child urine samples from the Household Air Pollution Intervention Network (HAPIN) cohort to measure PAH metabolites: 2-naphthol (2-NAP) and 1-hydroxypyrene (1-PYR). We evaluated presence of dental caries in children (n = 712) using decayed, missing, and filled surfaces (dmfs) index. Socio-demographic data and dietary recall information were collected through questionnaires. Data analysis was conducted using a negative binomial hurdle model. FINDINGS: Dental caries prevalence was high, with 53.6 % of participants having cavitated lesions, 13.6 % showing non-cavitated lesions, and 32.8 % classified as caries-free. Elevated urinary concentrations of 2-NAP during first and third trimesters were associated with a 1.09-fold increase in caries incidence (95 % CI, 1.03-1.16 and 1.02-1.17, respectively). Postnatal exposure to 1-PYR at six months corresponded to an 8 % increase in ECC risk per log-unit rise (IRR, 1.08; 95 % CI, 1.02-1.16). Average postnatal PAH exposure (mean 96.55 μg/g creatinine) demonstrated a stronger link with each log-unit increase corresponding to an incident rate ratio (IRR) of 1.22 (95 % CI, 1.10-1.36) in the count model and an odds ratio (OR) of 1.36 (95 % CI, 1.06-1.63) in zero model. Categorical analyses revealed monotonic dose-response relationships, with children in the highest quartile of postnatal 2-NAP and 1-PYR exposure exhibiting 39 % and 35 % greater ECC burden, respectively, compared to those in the lowest quartile. INTERPRETATION: Our findings suggest an association between PAH exposure and ECC, particularly during the first and third trimesters with lifestyle factors playing a modifying role. The compounded impact of co-exposure to smoke from secondhand smoke and biomass-based cooking underscores critical need to reduce PAH exposure during early childhood.