PM_2.5-bound organophosphate esters and childhood attention-deficit hyperactivity disorder symptoms: A...

The association between childhood exposure to PM_2.5-bound organophosphate esters (OPEs) and attention deficit hyperactivity disorder (ADHD) remains poorly understood. In this large population-based study of 131,412 children aged 6-18 years attending schools in the Pearl River Delta, China, we collected ambient fine particulate matter (PM_2.5) samples from schools to quantify OPEs levels, and screened for ADHD symptoms using parent-reported ADHD/Diagnostic and Statistical Manual of Mental Disorders (DSM-Ⅳ) Scales. We employed elastic net regression for variable selection, generalized linear mixed models (GLMMs) for association estimates, and weighted quantile sum regression to evaluate mixture effects. Odds ratios (ORs) are expressed as the change in odds of ADHD symptoms per interquartile range (IQR) increase in OPE levels. Elevated PM_2.5-bound OPE exposure was associated with higher odds of ADHD symptoms in children, especially for triphenyl phosphate (TPHP) (OR = 1.75, 95% CI: 1.70-1.79), tris(2-ethylhexyl) phosphate (TEHP) (OR = 1.73, 95% CI: 1.69-1.77), tris(1,3-dichloroisopropyl) phosphate (TDCIPP) (OR = 1.71, 95% CI: 1.67-1.75), and tris(3,4-dimethylphenyl) phosphate (T34DMPP) (OR = 1.45, 95% CI: 1.41-1.49). Similar associations were observed across different ADHD subtypes. Stratified analyses indicated heterogeneous associations across age, sex, and breastfeeding subgroups, with no consistent pattern of effect modification across all OPE exposures. These findings suggest that inhalation of OPE mixtures may be associated with adverse neurodevelopmental outcomes in children, highlighting a potential developmental window of susceptibility and raising public health concerns about airborne contaminants.