Urinary Phthalate Metabolites Quantitative Detectionand Their Association With Childhood Obesity

Phthalates, the diesters of phthalic acid, are extensively used asplasticizers and solvents in industrial, medical and consumer products.There is increasing evidences suggesting that some phthalate and theirurinary metabolites are endocrine disrupting chemicals(EDCs). Labstudies have suggested that ubiquitous phthalate exposures are related toobesity, but relevant epidemiological studies are scarce, especially forchildren.We study to establish a method for the determination of severalurinary phthalate metabolites (MEP, monoethyl phthalate; MBP,mono-n-butyl phthalate; MBzP, monobenzyl phthalate; MEHP,mono[2-ethylhexyl]phthalate)in children by SPE-HPLC, then BMI (BodyWeight Index) and Percent Body Fat were measured by InBody bodycomposition tester. Date analysis was perform using SPSS (Version20;SPSS.Inc) to establish association between urinary phthalatemetabolites and childhood obesity; A p value of＜0.05was taken asbeing statistically significant, and we compare our results with several similar studies.Phthalate metabolites, which were extracted from urine samples withWaters OASIS HLB SPE column, were chromatographed with a WatersXBridge Phenyl column. The phthalate metabolites (MEP, MBP, MBzPand MEHP) were quantitated with external standard method. Over therange of20-10000μg/L. The correlation coefficients were R≥0.99. Thelimits of detection were MEP6.50μg/L, MBP9.50μg/L, MBzP10.50μg/L, MEHP12.50μg/L. The average standard recovery rates were80.3%-94.1%and the relative standard deviations were1.2%-3.62%. Thismethod was significant for monitoring urinary phthalate metabolitesamong children accurately and efficiently.Analysis of variance showed that two metabolites(MEP, MEHP)were significantly high in children9-10years than those11-12years old,and MBzP were marginally higher(p＜0.10). No significant sex-relateddifference was observed for all urine phthalate metabolites, and analysisof variance indicated that MEP, MBP and MEHP were significantlydifferent among BMI groups, and MEP, MEHP showed an increasingtrend with BMI.In multiple linear regession analysis, all phthalate metabolites exceptMEP, MBzP were positively associated with increasing BMI afteradjusted for age and sex, So phthalate metabolites are positivelyassociated with childhood obesity. Given the study lack of some important obesity-related covariances, further studies are needed toconfirm the associations.