Intellectual evaluation of children exposed to phthalate-tainted products after the 2011 Taiwan phthalate episode

Abstract

Introduction: Phthalate exposure may reduce intellectual development in young children. In 2011, numerous Taiwanese children had been reported to have consumed phthalate-tainted products. We investigated the effects of phthalate exposure on the intellectual development of these children after the 2011 Taiwan di-2-ethylhexyl phthalate (DEHP) episode.

Methods: We recruited 204 children, aged 3-12 y, from 3 hospitals in Taiwan between 2012 and 2013. First-morning urine samples were collected for analyzing 5 phthalate metabolites. We applied a Bayesian model to estimate the past DEHP exposure (_estDEHP_ADD) of each participant before the 2011 DEHP episode. Demographic information, consumption of phthalate-tainted products, and maternal education, of each participant were obtained using a questionnaire. We used the Wechsler intelligence evaluation tools for assessing the children's and maternal intelligence quotient.

Results and discussion: The median levels of mono-2-ethylhexyl phthalate, mono(2-ethyl-5-hydroxyhexyl) phthalate, mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono-n-butyl phthalate, and mono-iso-butyl phthalate in the children were 9.97, 45.8, 32.2, 46.2, and 24.3μg/g creatinine, respectively. Using the aforementioned urinary phthalate metabolites, we found that the children's verbal comprehension index (N =98) was significantly negatively associated with urinary log₁₀ MEOHP (β, -11.92; SE, 5.33; 95%CI, -22.52~ -1.33; P=0.028) and log₁₀ ΣDBP metabolites (β, -10.95; SE, 4.93; 95%CI, -20.74~ -1.16; P=0.029) after adjustment for age, gender, maternal IQ and education, passive smoking, _estDEHP_ADD, active and passive smoking during pregnancy. Through a tolerable daily intake-based approach, we only found a significant negative association between past estimate DEHP_ADD and VIQ_≥3-<6 in preschool children whereas no correlation was observed between current DEHP exposure and IQ_≥3-<6 score with/ without estimate DEHP_ADD adjustment. It revealed that the effect of past high-DEHP exposure on verbal-related neurodevelopment of younger child are more sensitive.

Conclusion: Our results are consistent with the hypothesis that exposure to DEHP and DnBP affects intellectual development in preschool and school-aged children, particularly their language learning or expression ability.

Keywords: Children; Episode; Intellectual development; Phthalates.