| Summary: | 碩士 === 國立臺灣大學 === 環境衛生研究所 === 102 === Phthalate esters, bisphenol A, and perfluoroalkyl chemicals (PFACs) are emerging contaminants, and are often used in consumer materials such as plastics, food containers, and personal care products. Polycyclic aromatic hydrocarbons (PAHs) are pollutants generated from incomplete combustion. These contaminants possess developmental and reproductive toxicity, induce allergic symptoms and affect excretion of female hormones. Therefore, our study investigated the associations between the exposure to phthalate esters, bisphenol A, PFACs, and PAHs and on the indices of female hormones, birth outcomes, and allergy.
This study determined urinary concentrations of four phthalate metabolites (monoethyl phthalate, mono-n-butyl phthalate, monobenzyl phthalate, and mono-(2-ethyl-hydroxyhexyl) phthalate), bisphenol A glucuronide (BPA-G), nine perfluoroalkyl chemicals (perfluorobutanoic acid, perfluorohexanoic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, perfluorododecanoic acid, perfluorooctane sulfonate, and perfluorohexane sulfonate), leukotriene E4 (LTE4) and 1-hydroxypyrene glucuronide (1-OHP-G) with ultra-high performance liquid chromatography/tandem mass spectrometry, then associated the concentrations with the female hormones levels of female workers who were employed in a LCD factory. Birth outcomes of newborns and the incidence of allergy among children at age of 2 and 5 from the subjects of the Taiwan Birth Panel Study (TBPS) were also examined with the urinary concentrations of the above analytes in the subjects. There were 60 female worker samples, 138 maternal urine samples, 196 and 74 samples of 2 and 5 years old children, respectively, were included in our study. The data of birth outcomes, demography, diet and living surroundings, and allergy diagnoses were collected by a structured questionnaire. Multiple linear regression analysis was conducted between urinary analyte concentrations and female hormones (follicle-stimulating hormone, FSH; E1C, a metabolite of estradiol; and pregnanediol glucuronide, PdG) or birth outcomes (birth weight, birth length, head circumference, and gestational age). Logistic regression analysis was applied to evaluate the associations between urinary analyte concentrations and incidence of allergy.
Phthalate metabolites have higher positive rates among the 16 analytes (approximately 30-73%); MEP (GM = 15.2-25.5 μg/g creatinine) had relatively higher levels among the four phthalate metabolites, followed by MnBP (4.16-15.1 μg/g creatinine), 5OH-MEHP (3.74-8.01 μg/g creatinine) and MBzP (0.38-0.64 μg/g creatinine). PFACs were not detected in most urine samples. The concentrations of MEP (range = < LOD-8,995 μg/g creatinine), MBP (< LOD-3,213 μg/g creatinine), BPA-G (< LOD-24,416 μg/g creatinine), and 1-OHP-G (< LOD-1,124 μg/g creatinine) varied larger than those of other analytes, and some subjects would have been exposed to higher amount of these chemicals. Regarding the effects on female hormones, urinary concentrations of MBzP and BPA-G showed inverse trends to levels of FSH, that of BPA-G showed positive trend to E1C, and those of MEP and BPA-G showed positive and negative trends to levels of PdG in follicular phase, ovulation phase and luteal phase, respectively; however, the above relationships did not reach statistical significance and were not dose-dependent. The associations between urinary analyte concentrations and birth outcomes varied among the analytes. MnBP and 1-OHP-G were negatively associated with birth weight but 5OH-MEHP were positively; MEP and MBzP showed negative and dose-dependent associations with birth length; compared to the subjects with urine levels below the LODs, the subjects at upper 10% of MEP levels showed significantly negative association with birth length; 5OH-MEHP had positive but not dose-dependent relationships to birth length. The existing data suggested that prenatal exposure to phthalate esters, BPA and pyrene does not affect head circumference and gestation age of newborns. No significant differences in urinary concentrations of most analytes between children with and without allergy; nevertheless, there was a trend on higher urinary levels of MBzP toward increased incidence of allergy and the 5-year-old subjects with upper 25% of MnBP levels showed significantly higher risk of allergy than those below the LOD (β= 1.84, OR = 6.29, p < 0.05); exposure to DEHP, DEP, BPA and pyrene were not associated with allergic symptoms. Urinary levels of phthalate metabolites showed no significant difference in consuming probiotics, but the levels of BPA-G were higher in the subjects consumed probiotics than those who never use them.
The subjects from the TBPS were recruited from Taipei and adjacent areas; consequently, it is able to well illustrate the exposure to phthalate esters, BPA and PAHs in Northern Taiwan, while the subjects of previous similar studies were from Southern Taiwan. There were differences in the background levels and exposure profiles between the two different regions; exposure to DBP was higher than that to DEP in Southern Taiwan, but the profile was opposite in Northern Taiwan.
The urinary concentrations of MEP, MBzP and BPA-G associated with female hormone levels, although not in statistical differences; prenatal exposure to DEP, DBP, BBzP and pyrene resulted in adverse effects on birth weight and birth length. Exposure to DBP and BBzP may be risk factors of allergy in children; the rest analytes did not show significant associations with adverse health outcomes that were concerned in this study. For further studies, more considerations on potential confounders and greater statistical power are desired to better evaluate the associations. In terms of the female hormone study, pressure, work shift and other chemical exposure (such as VOCs) may affect hormone levels. Previous studies showed that prenatal exposure to PCBs or PBDEs affects birth outcomes. Risk factors of allergy such as mite and pollen also need to be considered when investigating the associations between the analytes and the incidence of allergy. An additional strategy is to enhance statistical power by increasing sample sizes and increasing positive rates of analyte detection in samples.
This study provided potential risk compounds to three categories of health outcomes and discussed crucial issues that could improve further studies in a large scale.
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