Urinary phthalate metabolites in primary school starters in Pearl River Delta, China: Occurrences, risks and possible sources

Assessment of children's exposure risks of phthalates before puberty is important, as phthalates are ubiquitous and are associated with reproductive development. However, relevant data in Pearl River Delta, China are scarce. Nineteen phthalate metabolites were analyzed in urine samples from 1490 primary school starters (6-8 years old) recruited in 2016-2017 using ultra-performance liquid chromatography and tandem mass spectrometry (UHPLC-MS/MS). Nine phthalate metabolites were detected more than 80% of the urine samples. Monobutyl phthalate (MnBP) was the highest metabolite (median, 212 μg/g creatinine), followed by two short chained phthalate metabolites, four secondary metabolites of di(2-ethylhexyl) phthalate (DEHP), and the primary metabolites of DEHP. The MnBP level was the third highest of those reported worldwide while other metabolites were in the lower range compared with previous studies. Significantly positive associations were found between urinary metabolite levels and family income as well as parent education levels (p < 0.05). Duration since the latest interior decoration was inversely associated with phthalate metabolites (p < 0.05). Significantly positive associations had also been found between the frequency of eating takeaway food and four DEHP metabolites (p < 0.01). The geometric mean of estimated daily intake (EDI) of di-n-butyl phthalate (DnBP), DEHP, di-iso-butyl phthalate (DiBP), dimethyl phthalate, diethyl phthalate and butylbenzyl phthalate (BBzP) were 6.24, 2.67, 1.06, 0.64, 0.44, and 0.01 μg/kg bw/day, respectively. Hazard quotient (HQ) was defined as the ratio of EDI and the tolerable daily intake (TDI). Approximately 38% children had HQ _DnBP >1 indicating potential reproductive risks caused by DnBP. To evaluate cumulative exposure risks, hazard index (HI) was calculated as the sum of the HQs of DnBP, DiBP, DEHP, and BBzP. Nearly 48% children had HI > 1 suggesting extremely high cumulative risks in children in Pearl River Delta, China. To our best knowledge, this was the largest study on evaluating phthalate exposure among children in China.