Urinary phthalate metabolites among elementary school children of Korea: sources, risks, and their association with oxidative stress marker.

Phthalates have been used in a variety of consumer products and hence frequently been detected in humans. Children are susceptible to endocrine disrupting chemicals such as phthalates, but only limited information is available on the sources of exposure and potential adverse health effects among children. In this study, elementary school students (n=39, aged 9-12 years) were recruited in Seoul, and first void urine samples were collected twice in three-day intervals. Then six phthalate metabolites were analyzed by high performance liquid chromatography with triple quadrupole tandem mass spectrometry. In addition, malondialdehyde (MDA) as an oxidative stress marker was measured. A questionnaire was conducted and information on food consumption and the use of plastic packaging or storage materials was gathered. The concentrations of phthalate metabolites varied substantially by sampling time even within the same subject, but all target metabolites were detected in 100% of the samples with the highest geometric mean of 107 μg/g-creatinine for mono-n-butyl phthalate (MnBP). Urinary levels of mono-isobutyl phthalate (MiBP), and MnBP among Korean children were 8 and 3 times greater than those reported for US children, but those of monoethyl phthalate (MEP) were about 5 times lower than those of US children. Estimated phthalate intakes were generally in safe range, but in 3-8% of the participating children, the hazard quotients greater than one were noted. Urinary MDA concentrations were significantly associated with several metabolite levels after adjusting covariates in regression model. Consumption of dairy products or meat, and use of a plastic material were significantly associated with the DEHP metabolites or MnBP levels in multivariate model. The results of this study provide evidence of the association between phthalate exposure and oxidative stress especially among the early teenagers, and identified major sources that can be applied to development of management plan for phthalate exposure among children.