Occurrence of Phthalates and Association between Phthalates Exposure and Health Effects of Pregnant Women and Newborns in Taiwan

• Main Authors: Po-Chin Huang, 黃柏菁
• Other Authors: Ching-Chang Lee
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/28291328451176165433

博士 === 國立成功大學 === 環境醫學研究所 === 96 === Phthalates are developmental and reproductive toxicants for the fetus in pregnant rodents, and the ability of phthalates to penetrate the placenta have been reported. Scientific evidences showed probable thyroid-like function of some phthalates in vitro and in vivo, and phthalates exposure can begin in utero. Because phthalates are ubiquitous in daily life, the potential consequences of human exposure to phthalates have raised concerns in susceptible subjects, such as pregnant women, and infants. Therefore, the body burden and health effects of phthalates are a matter of concerned in countries all over the world, particularly in those that use a great many plastics, such as Taiwan. The aims of this study are (1) to determine the relationships between phthalate levels in sediment and aquatic factors, and biota-sediment accumulation factor (BSAF) for phthalates; (2) to investigate the association between phthalates exposure, and health effects of pregnant Taiwanese women and newborns. A total number of 128 sediment samples for two seasons, and 23 single fish and 10 pooled fish samples were collected from seventeen selected principal Taiwan’s rivers during 2004 to 2005. Six phthalates, including di-n-butyl phthalate (DBP), butyl benzyl phthalate (BBzP), di(2-ethylhexyl) phthalate (DEHP), were measured in sediment and biota samples by GC/MS. Water quality parameters including dissolvable oxygen, water temperature, chemical oxygen demand (COD), suspended solids, and ammonia-nitrogen, were obtained from the water quality monitoring network of Taiwan’s EPA from the same week as our sampling period. Besides, after signing a consent form, we collected eighty-three, seventy-eight and sixty-one urine, serum and cord blood samples from pregnant Taiwanese women in the first, second and third trimesters, respectively. Sixty-five amniotic fluid samples and the health of newborns were also collected during 2005-2006. Demographic characteristics of our participants were obtained from an administrated questionnaire in the 2nd trimester. Five phthalates monoesters, including mono butyl phthalate (MBP), mono ethyl phthalate (MEP), and mono ethylhexyl phthalate (MEHP), were measured in urine, amniotic fluid, serum and cord blood samples using HPLC-MS/MS. Serum samples were also analyzed for maternal and fetal thyroid hormones, including thyroid stimulating hormone (TSH), triiodothyronine (T3), thyroxine (T4), and free T4 (FT4). Mean concentrations (range) of DEHP, BBzP and DBP in sediment at low-flow season were 4.1 (<0.05–46.5), 0.22 (<0.05–3.1) and 0.14 (<0.05–1.3) mg kg-1 dw; those at high-flow season were 1.2 (<0.05–13.1), 0.13 (<0.05–0.27) and 0.09 (<0.05–0.22) mg kg-1 dw, respectively. Trace levels of dimethyl phthalate (DMP), diethyl phthalate (DEP) and di-n-octyl phthalate (DOP) in sediment were found in both seasons. Concentrations of DEHP in sediments were significantly affected by temperature, suspended solids, ammonia-nitrogen, and COD. Highest concentration of DEHP in fish samples were found in Liza subviridis (253.9 mg kg-1 dw) and Oreochromis niloticus niloticus (129.5 mg kg-1 dw). BSAF of DEHP in Liza subviridis (13.8–40.9) and Oreochromis miloticus niloticus (2.4–28.5) were higher than those in other fish species, indicating that the living patterns of fish and physical-chemical properties of phthalates, like log Kow, may influence the bioavailability of phthalates in fish. Our data suggested that DEHP level in river sediments were influenced by water quality parameters due to their effects on the biodegradation processes, and that the DEHP level in fish was affected by fish habitat and physiochemical properties of polluted contaminants. For pregnant women, MBP, MEP and MEHP, the median levels of which were 81.8, 27.7, and 20.6 ng/mL, respectively, were the predominant substances in the urinary phthalate monoesters from the second trimester. Significantly mild negative correlations were found between T4 and urinary MBP (R = -0.248, p < 0.01), and between FT4 and urinary MBP (R = -0.368, p < 0.05). After adjusting for age, BMI, and gestation, urinary MBP levels showed a negative association with FT4 and T4 . Exposure to DBP might affect thyroid activity in pregnant women, but how DBP affects thyroid function is unclear. Further studies are needed to elucidate the mechanism of action or if other factors related to DBP exposure alter the thyroid function. For newborns, the median levels of three phthalate monoesters in urine and amniotic fluid were 78.4 and 85.2 ng/mL (MBP); 24.9 and 22.8 ng/mL (MEHP); 19.8 and Not Detected (MEP). We found a significant positive correlation only between creatinine adjusted urinary MBP and amniotic fluid MBP (R2 = 0.156, p < 0.05) in all infants and, only in female infants, a significantly negative correlation between amniotic fluid MBP, AGD (R = -0.31, p < 0.05), and the anogenital index adjusted by birth weight (AGI-W) (R = -0.32, p < 0.05). Although the influence of prenatal DBP exposure on the endocrinology and physiology of the fetus is still a puzzle, our data clearly show that in utero exposure to phthalates in general has anti-androgenic effects on the fetus. On the other hand, MBP and MEHP, the median levels of which were 256.0 and 24.7 ng/mL, respectively, were the predominant substances in cord blood phthalate monoesters. We found a negative correlation between TSH×T4 and MBP in cord blood (R = -0.23, p < 0.05). After maternal age, gestational age, and MEHP in cord blood had been adjusted for, MBP levels in cord blood showed a negative association with TSH (TSH: = -0.217, p < 0.05), T4 (T4: �� = -1.71, p < 0.05), and TSH×T4 (TSH×T4: = -42.8, p < 0.05) in cord blood. Prenatal phthalate exposure may decrease thyroid hormones in newborns. Because aggregate exposure to phthalates is unavoidable in pregnant women, we suggest that pregnant women reduce their contact with products containing a high level of phthalates, particularly cosmetics, and have thyroid function test in their newborns measured.