Dibutyl Phthalate Contributes to the Thyroid Receptor Antagonistic Activity in Drinking Water Processes

State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871 Beijing 100085, China.
Environmental Science & Technology (Impact Factor: 5.33). 09/2010; 44(17):6863-8. DOI: 10.1021/es101254c
Source: PubMed

ABSTRACT It has long been recognized that thyroid hormone (TH) is essential for normal brain development in both humans and animals, and there is growing evidence that environmental chemicals can disrupt the thyroid system. In the present work, we used a two-hybrid yeast assay to screen for agonistic or antagonistic thyroid receptor (TR) mediated effects in drinking waters. We found no TR agonistic, but TR antagonistic activities in all samples from the drinking water processes. The TR antagonistic activities in organic extracts of water samples were then calibrated regarding to a known TR-inhibitor, NH3, and were expressed as the NH3 equivalents (TEQbio). The observed TEQbio in waters ranged from 180.8+/-24.8 to 280.2+/-48.2 microg/L NH3. To identify the specific compounds responsible for TR disrupting activities, the concentrations of potentially thyroid-disrupting chemicals including organochlorine pesticides (OCPs), phenols, and phthalates in organic extracts were quantitatively determined and their toxic equivalents with respect to NH3 (TEQcal) were estimated from their concentration-dependent relationships, respectively, using the same set of bioassays. Based on the TEQ approach, it was revealed that dibutyl phthalate (DBP) accounted for 53.7+/-8.2% to 105.5+/-16.7% of TEQbio. There was no effective removal of these potential thyroid disrupting substances throughout drinking water treatment processes.

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Available from: Zijian Wang, May 16, 2014
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    • "For reducing the risk of phthalates contamination in drinking water, some countries and organizations have regulated the guideline values of phthalates in drinking water (in China, 8, 3, and 300 μg/L for DEHP, DBP, and DEP, respectively (NSC 2006); in WHO, 8 μg/L for DEHP (WHO 2011); in the USA, the maximum contaminant level (MCL) value (6 μg/L) for DEHP (US EPA 2006); in Japan, 100, 200, and 500 μg/L for DEHP, DBP, and BBP, respectively (Wakayama 2004)). In eastern and northern China, phthalates have been detected in 13 drinking water samples and 10 drinking water samples, respectively, ranging from no detection to 28.9 μg/L (Hu et al. 2013; Li et al. 2010a, b; Shi et al. 2012). No potential health risks to humans were identified by determining the androgen and thyroid receptor agonistic and antagonistic potencies based on reporter gene assay in eastern China (Hu et al. 2013; Shi et al. 2012). "
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    ABSTRACT: The first nationwide survey of six phthalates (diethyl phthalate (DEP); dimethyl phthalate (DMP); di-n-butyl phthalate (DBP); butyl benzyl phthalate (BBP); bis(2-ethylhexyl) phthalate (DEHP); din-octyl phthalate (DnOP)) in drinking waters from waterworks was conducted across seven geographical zones in China. Of the six target phthalates, DBP and DEHP were the highest abundant phthalates with median (± interquartile range) values of 0.18 ± 0.47 and 0.18 ± 0.97 μg/L, respectively, but did not exceed the limit values in China's Standards for Drinking Water Quality. These phthalates in drinking water were generally higher in the northern regions of China than those in the southern and eastern regions. Based on the investigated concentrations, lifetime exposure risk assessment indicated that phthalates in drinking water did not pose carcinogenic and noncarcinogenic risks to Chinese residents, even under the conservative scenario (with 95th percentile risk). In addition, we found that DEHP contributed the greatest risk to the total exposure risk of all the selected phthalates and oral ingestion was the main exposure route for phthalates in drinking water.
    Environmental Science and Pollution Research 03/2015; 22(14). DOI:10.1007/s11356-015-4253-9 · 2.83 Impact Factor
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    • "Thyroid hormone disrupting effects have been detected in environmental samples including sediment extracts, indoor dust, industrial effluents and even water sources [7], [8]. Normal treatment processes in sewage treatment plants, including filtration, coagulation, aerobic biodegradation and ozonation are not considered to be effective for removal of endocrine disrupting chemicals [7]. "
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    ABSTRACT: Some synthetic chemicals, which have been shown to disrupt thyroid hormone (TH) function, have been detected in surface waters and people have the potential to be exposed through water-drinking. Here, the presence of thyroid-active chemicals and their toxic potential in drinking water sources in Yangtze River Delta were investigated by use of instrumental analysis combined with cell-based reporter gene assay. A novel approach was developed to use Monte Carlo simulation, for evaluation of the potential risks of measured concentrations of TH agonists and antagonists and to determine the major contributors to observed thyroid receptor (TR) antagonist potency. None of the extracts exhibited TR agonist potency, while 12 of 14 water samples exhibited TR antagonistic potency. The most probable observed antagonist equivalents ranged from 1.4 to 5.6 µg di-n-butyl phthalate (DNBP)/L, which posed potential risk in water sources. Based on Monte Carlo simulation related mass balance analysis, DNBP accounted for 64.4% for the entire observed antagonist toxic unit in water sources, while diisobutyl phthalate (DIBP), di-n-octyl phthalate (DNOP) and di-2-ethylhexyl phthalate (DEHP) also contributed. The most probable observed equivalent and most probable relative potency (REP) derived from Monte Carlo simulation is useful for potency comparison and responsible chemicals screening.
    PLoS ONE 10/2013; 8(10):e73883. DOI:10.1371/journal.pone.0073883 · 3.23 Impact Factor
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    • "In humans, BBP increases the severity of endometriosis (Reddy et al., 2006). DBP exhibits antagonistic thyroid receptor activity (Li et al., 2010). Phthalates are not only an endocrine disruptor for animals but also an environmental stressor for plants. "
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    ABSTRACT: Phthalates, also known as phthalate esters, an alkyl aryl esters of 1, 2 benzenedicarboxylic acid. They have a broad range of applications, and are widely used as plasticizer (as vinyl softener). Phthalates act as endocrine disrupters and due to the increased awareness of its adverse effects on environment and health of living organisms, biodegradation of phthalates are now researched at a faster pace. This review highlights the applications of phthalates, their adverse effects on health, regulatory status and biodegradation of phthalates by pure and mixed bacterial cultures and fungi.
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