Child exposure to N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD) and its derived quinone (6PPDQ) in e-waste areas: Urinary concentrations, sources, and health effect assessment

N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine quinone (6PPDQ) and its parent 6PPD are ubiquitous in the environment and may induce multi-endpoint toxicity. Electronic waste (e-waste) dismantling is an under-recognized source of 6PPD and 6PPDQ emissions, and there is a lack of epidemiological investigations into their presence and health effects in local populations. This study aimed to determine the urinary concentrations of 6PPD and 6PPDQ in children aged 2–7 years from e-waste dismantling areas and evaluate their potential risk to physical growth. We found that children from the e-waste area had significantly elevated urinary concentrations of 6PPD and 6PPDQ (median: 0.073 and 2.34 ng/mL) compared to those in the reference area (0.020 and 0.24 ng/mL, respectively). The estimated urinary excretions of 6PPDQ in the e-waste exposure group were considerably higher than that in the reference group (p < 0.001). Furthermore, a borderline significant association of co-exposure to high levels of 6PPD and 6PPDQ with lower BMI z-score (OR = 1.99, 95 % Cl: 1.04, 3.82) was observed in the crude model and the model adjusted for age and gender. In conclusion, our study first reported the urinary 6PPD and 6PPDQ concentrations in children from e-waste dismantling areas. The result indicated that e-waste recycling activities contribute to significantly elevated body burdens of 6PPD and 6PPDQ in children, which may be a potential risk factor for physical growth. Further epidemiological and toxicological studies are needed to investigate the exposure and health risks, especially in vulnerable populations.