Assessment of urinary thiodiglycolic acid exposure in school-aged children in the vicinity of a petrochemical complex in central Taiwan.

BACKGROUND: School-aged children living in the vicinity of vinyl chloride (VCM)/polyvinyl chloride (PVC) factories may have an increased risk of exposure to hazardous air pollutants. OBJECTIVES: We aimed to evaluate the urinary thiodiglycolic acid (TDGA) level, as TDGA is a major metabolite of VCM, for students at elementary schools near a petrochemical complex in central Taiwan. METHODS: We recruited 343 students from 5 elementary schools based on distance to the VCM/PVC factory. First-morning urine and blood samples were obtained from our subjects from October 2013 to September 2014. Urine samples were analyzed for urinary creatinine and TDGA using LC/MS-MS. Hepatitis virus infection were assessed using blood samples. We determined their vitamin consumption, resident location, parent's employment, and other demographic or lifestyle characteristics using a questionnaire. RESULTS: Median urinary TDGA levels for 316 students at 5 elementary schools from the closest (<.9km) to the farthest (∼8.6km) with respect to the petrochemical complex were 147.6, 95.5, 115.5, 86.8, and 17.3µg/g creatinine, respectively. After adjusting for age, gender, hepatitis virus infection, vitamin B consumption, passive smoking, and home to source distance, we found that urinary TDGA levels for the closest students was significantly higher than those at other schools. Further, median urinary TDGA levels for students during school time were 4.1-fold higher than those during summer vacation. CONCLUSIONS: After adjusting for confounders, urinary TDGA levels for the school-aged children decreased with increasing distances between the elementary schools and the petrochemical complex.

Early Phthalates Exposure in Pregnant Women Is Associated with Alteration of Thyroid Hormones.

INTRODUCTION: Previous studies revealed that phthalate exposure could alter thyroid hormones during the last trimester of pregnancy. However, thyroid hormones are crucial for fetal development during the first trimester. We aimed to clarify the effect of phthalate exposure on thyroid hormones during early pregnancy. METHOD: We recruited 97 pregnant women who were offered an amniocentesis during the early trimester from an obstetrics clinic in southern Taiwan from 2013 to 2014. After signing an informed consent form, we collected amniotic fluid and urine samples from pregnant women to analyze 11 metabolites, including mono-ethyl phthalate (MEP), mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP), mono-(2-ethylhexyl) phthalate (MEHP), mono-butyl phthalate (MnBP), of 9 phthalates using liquid chromatography/ tandem mass spectrometry. We collected blood samples from each subject to analyze serum thyroid hormones including thyroxine (T4), free T4, and thyroid-binding globulin (TBG). RESULTS: Three phthalate metabolites were discovered to be >80% in the urine samples of the pregnant women: MEP (88%), MnBP (81%) and MECPP (86%). Median MnBP and MECPP levels in pregnant Taiwanese women were 21.5 and 17.6 µg/g-creatinine, respectively, that decreased after the 2011 Taiwan DEHP scandal. Results of principal component analysis suggested two major sources (DEHP and other phthalates) of phthalates exposure in pregnant women. After adjusting for age, gestational age, TBG, urinary creatinine, and other phthalate metabolites, we found a significantly negative association between urinary MnBP levels and serum T4 (ß = -5.41; p-value = 0.012; n = 97) in pregnant women using Bonferroni correction. CONCLUSION: We observed a potential change in the thyroid hormones of pregnant women during early pregnancy after DnBP exposure. Additional study is necessitated to clarify these associations.

Age and Gender Differences in Urinary Levels of Eleven Phthalate Metabolites in General Taiwanese Population after a DEHP Episode.

INTRODUCTION: In 2011, the Taiwan FDA disclosed illegal di(2-ethylhexyl phthalate) (DEHP) and dibutyl phthalate (DBP) use in beverage and nutrition supplements. We aim to determine phthalate exposure and other relevant factors in a sample of the general Taiwanese population in order to evaluate actual phthalate exposure levels after this disclosure of DEHP use. METHOD: We selected subjects aged 7 years old and older in 2013 from the general Taiwanese population. First morning urine samples from each participant were collected to analyze 11 phthalate metabolites representing 7 parent phthalates using on-line liquid chromatography/ tandem mass spectrometry. An interview questionnaire was applied to obtain participant demographic characteristics, lifestyle, and other relevant factors. RESULTS: The median levels of metabolites of DEHP, including mono-ethylhexyl phthalate (MEHP), mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP), DBP (DnBP and DiBP), including mono-n-butyl phthalate (MnBP) and mono-iso-butyl phthalate (MiBP), and mono-ethyl phthalate (MEP) in urine samples of 290 adults/ 97 minors (<18 years) were 7.9/ 6.1, 12.6/ 17.8, 22.0/ 25.8, 25.4/ 30.8, 18.1/ 23.6, 9.4/ 13.6 and 14.5/ 12.4 µg/g creatinine, respectively. Women (≧18 years) were exposed to significantly higher levels of MEHHP (P=0.011), MECPP (P=0.01), MnBP (P=0.001) and MEP (P<0.001) than men (≧18 years), whereas no gender difference was observed in minors. We found significant higher level of MEP (creatinine-unadjusted) in subject aged between 18 to 40 years old (P<0.001), especially for women. Exposure levels of MEOHP (P<0.001), MECPP (P=0.002) and MnBP (P=0.044) in minors were significantly higher than those of adults. High frequency usage of food preservation film and bags, and personal care products are potential sources of phthalates exposure in general Taiwanese. CONCLUSION: Our findings indicated that DEHP and DBP exposure in a sample of the general Taiwanese population varied by age and gender, possibly affected by different lifestyles, and continuing bio-monitoring surveillance is warranted.