Exposure, risk, and potential sources of phthalates, alternative plasticizers, and phenolic compounds in Thai children: A two-region comparison study

Phthalates and phenolic compounds are ubiquitous consumer chemicals, and children are particularly vulnerable to their potential health effects. In Thailand, however, information on children's exposure and regional variation remains limited. We recruited 250 children from two distinct regions of Thailand (Suphan Buri and Chiang Rai) in 2023, measured urinary concentrations of major metabolites of phthalates and alternative plasticizers as well as parent phenolic compounds, and administered questionnaires. The highest median concentrations were observed for the sum of di(2-ethylhexyl) phthalate metabolites (∑DEHP, 73.2 ng/mL), followed by mono-n-butyl phthalate (MnBP, 72.2 ng/mL) and the sum of diisononyl phthalate metabolites (∑DiNP, 22.6 ng/mL). These levels were 1.4–3.4 times higher than those in German children (GerES V, 2014–2017) and 2.5–5.7 times higher than those in U.S. children (NHANES, 2017–2018). Significant regional differences were identified, with 16 of 26 metabolites showing higher concentrations in Chiang Rai children. These included metabolites of diisobutyl phthalate (DiBP), di-n-butyl phthalate (DnBP), DEHP, DiNP, and di(2-ethylhexyl) terephthalate (DEHTP) as well as benzophenone-3 and bisphenol S. Notably, DiNP metabolite levels in Chiang Rai were 1.9–2.6-fold higher than the highest levels reported elsewhere. Risk assessment showed 69.3% of children in Chiang Rai and 16.4% in Suphan Buri exceeded a cumulative hazard index of 1. Regardless of region, DnBP, DEHP, DiBP, and di(2-ethylhexyl) adipate (DEHA) were the primary contributors to risk. Sauce consumption and medication use were associated with higher phthalate levels. These findings highlight the need to develop targeted exposure-reduction strategies and regulatory interventions for Thai children.