Xiaolan Zhang

Synthetic musks in the aquatic environment and personal care products in Shanghai, China

The concentrations and distributions of six polycyclic musks and two nitro musks in Suzhou Creek, influent/effluent of a sewage treatment plant (STP), and household commodities were investigated and discussed in this study. The levels of 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexa-methylcyclopenta(g)-2-benzopyran (HHCB) and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (AHTN) in Suzhou Creek were 3-78 ng g(-1) (dry weight) and 2-31 ng g(-1) (dry weight) in sediments, while 20-93 ng l(-1) and 8-20 ng l(-1) in surface waters. The results indicated a low proportion of wastewater burden in this river. The concentrations of HHCB and AHTN in the effluent of the STP were 5- to 6-fold higher than those in Suzhou Creek. The amounts discharged into the aquatic environment from sewage in Shanghai are 1.26 t (HHCB) and 0.38 t (AHTN) in 2007, and the input into the STPs is estimated to be HHCB 0.2 g y(-1) and AHTN 0.06 g y(-1) per inhabitant, respectively. A broad concentration range of HHCB and AHTN could be observed in household commodities. The distributions are in accordance with the profiles of musks in aquatic environment, with HHCB and AHTN being the major components.

Trace elements in fish from Taihu Lake, China: Levels, associated risks, and trophic transfer

Concentrations of eight trace elements [iron (Fe), manganese (Mn), zinc (Zn), chromium (Cr), mercury (Hg), cadmium (Cd), lead (Pb), and arsenic (As)] were measured in a total of 198 samples covering 24 fish species collected from Taihu Lake, China, in September 2009. The trace elements were detected in all samples, and the total mean concentrations ranged from 18.2 to 215.8 μg/g dw (dry weight). The concentrations of the trace elements followed the sequence of Zn>Fe>Mn>Cr>As>Hg>Pb>Cd. The measured trace element concentrations in fish from Taihu Lake were similar to or lower than the reported values in fish around the world. The metal pollution index was used to compare the total trace element accumulation levels among various species. Toxabramis swinhonis (1.606) accumulated the highest level of the total trace elements, and Saurogobio dabryi (0.315) contained the lowest. The concentrations of human non-essential trace elements (Hg, Cd, Pb, and As) were lower than the allowable maximum levels in fish in China and the European Union. The relationships between the trace element concentrations and the δ(15)N values of fish species were used to investigate the trophic transfer potential of the trace elements. Of the trace elements, Hg might be biomagnified through the food chain in Taihu Lake if the significant level of p-value was set at 0.1. No biomagnification and biodilution were observed for other trace elements.

Route-specific daily uptake of organochlorine pesticides in food, dust, and air by Shanghai residents, China

Dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexanes (HCHs) are widely detected in the environment, although they have been banned in China since 1980s. To better understand the route-specific daily uptake of the pesticides by humans, a total of 322 food, dust, and air samples were collected in Shanghai, China, during 2008-2011. The median concentrations were 0.2-126.6 and 0.03-1.6 ng/g wet weight for DDTs (DDT and its metabolites) and HCHs, respectively, in different types of foods. The values in dust (indoors and outdoors) were 5.7-29.8 and 1.3-5.4 ng/g, and 13.9×10(-3) and 2.6×10(-3)ng/m(3) in air (gas+particle) for DDTs and HCHs, respectively. The daily uptake of a pesticide by humans was calculated via the pesticide intake multiplied by its uptake efficiency. The uptake efficiencies of DDTs and HCHs in food through human intestines were estimated using bioaccessibility measured via an in vitro method simulating the human gastrointestinal digestion process. The total daily uptakes of DDTs and HCHs through three routes (i.e., ingestion, inhalation, and dermal contact) were 79.4 and 4.9 ng/day, respectively, for children, and 131.1 and 8.0 ng/day, respectively, for adults. Ingestion via food and dust was the main route of human exposure to the pesticides, and the daily uptake of the pesticides via food consumption accounted for 95.0-99.2% of the total.

Levels and congener profiles of polybrominated diphenyl ethers (PBDEs) in breast milk from Shanghai: Implication for exposure route of higher brominated BDEs

Breast milk has been widely used as a bioindicator to assess the extent of human exposure to PBDEs via various exposure routes. In this study, 48 breast milk samples were collected from primiparous women in Shanghai city, and 14 PBDEs congeners (BDE-28, -47, -99, -100, -153, -154, -183, -196, -197, -203, -206, -207, -208, and -209) were quantified using gas chromatography-electron capture negative ionization-mass spectrometry. The mean concentration of total PBDEs was 8.6 ng/g lipid weight, and ranged from 1.8 to 26.7 ng/g lipid weight. These concentration levels were similar to those reported in Europe and Asia, but one order of magnitude lower than those in North America. The congener profiles in this study exhibited a specific pattern in human milk found worldwide, BDE-153 and BDE-28 accounted for a relatively higher proportion of lower brominated BDEs (from tri- to hepta-BDEs), whereas higher brominated BDEs (from octa- to deca-BDEs) contributed more than 70% of the total PBDEs. The Spearmans correlation coefficient among higher brominated BDEs showed a positive relationship, and concentration levels of higher brominated BDEs were statistically different between office workers and housewives. Due to relatively higher proportion of PBDEs from octa- to deca-BDEs were detected, air inhalation and dust ingestion might be the major exposure routes of higher brominated BDEs. Further research is needed to clarify the major exposure route of higher brominated BDEs to humans.

Evaluation of human health risks posed by carcinogenic and non-carcinogenic multiple contaminants associated with consumption of fish from Taihu Lake, China

The present study estimated the human daily intake and uptake of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), and toxic trace elements [mercury (Hg), chromium (Cr), cadmium (Cd), and arsenic (As)] due to consumption of fish from Taihu Lake, China, and the associated potential health risks posed by these contaminants. The health risks posed by the contaminants were assessed using a risk quotient of the fish consumption rate to the maximum allowable fish consumption rate considering the contaminants for carcinogenic and non-carcinogenic effect endpoints. The results showed that fish consumption would not pose non-cancer risks. However, some species would cause a cancer risk. Relative risks of the contaminants were calculated to investigate the contaminant which posed the highest risk to humans. As a result, in view of the contaminants for carcinogenic effects, As was the contaminant which posed the highest risk to humans. However, when non-carcinogenic effects of the contaminants were considered, Hg posed the highest risk. The risk caused by PBDEs was negligible. The results demonstrated that traditional contaminants, such as As, Hg, DDTs (dichlorodiphenyltrichloroethane and its metabolites), and PCBs, require more attention in Taihu Lake than the other target contaminants.

Levels of synthetic musk fragrances in human milk from three cities in the Yangtze River Delta in Eastern China

Synthetic musks are used as additives in many household products. After absorption into the human body, they accumulate and their concentrations in human milk reflect both the mother and her infants exposure level. Concentrations of four synthetic musks, musk xylene (1-tert-butyl-2,6-dimethyl-2,4,6-trinitrobenzene, MX), musk ketone (4-tert-butyl-2,6-dimethyl-3,5-dinitroacetophenone, MK), 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[gamma]-2-benzopyran (HHCB) and 7-acetyl-1,1,3,4,4,6-hexamethyl- 1,2,3,4-tetrahydronaphthalene (AHTN), were determined in human milk samples collected from Shanghai, Wuxi, and Shaoxing in Eastern China. The four synthetic musks were found in most samples analyzed, with HHCB the dominant component followed by MX. The median (mean) values for HHCB, AHTN, MX and MK concentrations were 63 (82), 5 (12), 17 (24) and 4 (9) ng/g lipid weight, respectively. These data suggested the total synthetic musk contamination was low, and the distribution percentage was HHCB > MX > AHTN approximately MK. The relative high ratio of nitro to polycylic musk indicated that nitro musks were still widely used. The musk concentrations in these cities were not significantly different from each other (p > 0.05). Principal components score plots were obtained, which showed similar exposure sources. The amount of total synthetic musks in human milk were not associated with mothers age, although HHCB was significantly correlated with AHTN (p < 0.05). Daily ingestion of HHCB, AHTN, MX and MK for infants from human milk were estimated as (2526 +/- 2926), (370 +/- 524), (7391 +/- 832), and (277 +/- 462) ng/day, respectively. Those doses were 1-2 orders of magnitude below the provisional tolerable daily intakes.

Polybrominated biphenyl ethers in breast milk and infant formula from Shanghai, China: temporal trends, daily intake, and risk assessment.

To investigate the temporal trend of polybrominated diphenyl ethers (PBDEs) in breast milk and assess the risks to breast- and formula-fed infants, breast milk and infant formula samples were collected from Shanghai, China. The PBDE concentrations decreased from 14.8 to 4.85 pmol/g lipid weight during 2006-2012, with a rate of decrease by half approximately every four years. Although there were no significant correlations between the total PBDEs in breast milk and age, parity, and pre-pregnant BMI of mothers, there were significant differences between primiparous and multiparous mothers for tri- to hepta-BDEs. PBDEs in breast milk were much higher than those in infant formula (equivalent to 91.9 vs. 5.25 pg/mL). Among the different brand infant formulas, there were no significant differences in their PBDE concentrations. The estimated daily intake of PBDEs by breast- and formula-fed infants suggested that breast-fed infants are exposed to much more PBDEs than formula-fed ones (12.9 vs. 0.72 ng/kg-bw/day). However, the hazard quotient values were much smaller than one, indicating that the ingested PBDEs did not exert obvious adverse effects on both breast- and formula-fed infants considering non-carcinogenic effect endpoint. This is the first report on temporal trend of PBDEs in breast milk from China.

Occurrence and transport of synthetic musks in paired maternal blood, umbilical cord blood, and breast milk.

Although early exposure to environmental pollutants may have important toxicological consequences, the mechanisms of transplacental transfer of synthetic musks are still not well understood. The objective of the present study was to learn the musk contaminations in three matrices, including maternal blood, umbilical cord blood, and breast milk; and investigate their placental transfer mechanisms. The concentrations of eight commonly used synthetic musks were measured in 42 paired samples (126 individual samples in total) of maternal serum, umbilical cord serum, and breast milk from Chinese women living in Shanghai. Musks were ubiquitously detected, especially galaxolide (HHCB) and musk xylene (MX). The total lipid-based concentrations were higher in umbilical cord sera (87.3ng/g), but lower in breast milk (35.2ng/g), compared with maternal serum concentrations (71.2ng/g). There were significant correlations between maternal serum concentrations of HHCBs (HHCB and HHCB-lactone) and umbilical cord serum concentrations, and between maternal serum concentrations and breast milk concentrations (Spearmans rho=0.338-0.597, p<0.05), when outliers are excluded. The average transfer ratios of HHCB and HHCB-lactone between maternal sera and umbilical cord sera were >1. And the HHCB-lactone/HHCB ratio in maternal sera was higher compared with umbilical cord sera. Contamination levels were low compared with other regions and HHCBs were found to be the predominant constituents. No regional differences or age-related accumulations were observed. Our study suggests that prenatal exposure to HHCBs occurs and that transplacental transfer is the main route of exposure. Preferential accumulation in umbilical cord blood was observed. The results showed that transplacental transfer of HHCB did not correspond to passive diffusion since the transfer ratios were significantly different from 1. The transfer ratio for HHCB was also larger than that of HHCB-lactone, although HHCB has higher lipid solubility. Low fetal metabolism of HHCB was suggested by the HHCB-lactone/HHCB ratio in maternal and umbilical cord blood.

Estimation of intake and uptake of bisphenols and triclosan from personal care products by dermal contact

Increasing concern has been raised in respect of exposure to bisphenols and triclosan (TCS) due to their widespread use. However, little is known about their occurrence in personal care products (PCPs) or, particularly, their dermal uptake following daily application. It is therefore necessary to evaluate the human health risk of bisphenols and TCS via dermal absorption. In this study, 150 PCPs, covering 11 different categories, were collected in China. The concentrations of seven bisphenol analogues and TCS were measured, and the associated human health risks by dermal contact were estimated. High detection frequencies of TCS (46.7%) and bisphenol AF (38.7%) were found in the PCPs. The highest mean concentration of Σ7BPs (sum concentration of all seven bisphenols) was 77.8ngg-1 found in masks, and the highest mean concentration of TCS was 86.7ngg-1 in hand sanitizers. The bisphenol composition profiles varied among different categories. Bisphenol A and bisphenol F generally showed higher concentrations. Combining the concentrations of the target substances with the daily usage quantities of PCPs and other parameters, the total estimated dermal intakes and uptakes of Σ7BPs and TCS were calculated. The results showed that the former (12.1 and 1.06ng·kg-1bwday-1) were markedly higher than the latter (1.21 and 9.58×10-2ng·kg-1bwday-1), which included dermal absorption rates of the chemicals in the estimation. Although diet is the main source, and oral ingestion is the main route, for human BPA exposure, the results of the estimated dermal uptakes of BPA in the present study combined with those from a European study show that dermal contact is the main route with thermal paper being the main contributor when both unconjugated and conjugated BPA in the human body are considered. The present study also showed that exposure to BPA in PCPs following dermal contact should not be ignored.

Low-concentration BPF induced cell biological responses by the ERα and GPER1-mediated signaling pathways in MCF-7 breast cancer cells

Bisphenol F (BPF), one of the alternatives to bisphenol A (BPA), can induce proliferation through the nuclear estrogen receptor ERα (estrogen receptor alpha) pathway in human breast cancer MCF-7 cells. However, the roles of membrane estrogen receptor GPER1 (G-protein-coupled receptor 1)-mediated signaling pathways in MCF-7 cell proliferation caused by BPF are unclear. The influence of BPF on MCF-7 cells was evaluated in terms of cell proliferation, intracellular calcium (Ca2+) fluctuations, and reactive oxygen species (ROS) generation. The molecular mechanisms of the cellular responses to low doses of BPF were studied through detecting the activations of ERα and GPER1-regulated PI3K/PKB or AKT (phosphatidylinotidol 3-kinase/protein kinase B) and ERK1/2 (extracellular-signa1-regulated kinase 1/2) signals. At 0.01-1 μM, BPF significantly promoted cell proliferation and elevated the levels of intracellular ROS and Ca2+. At these concentrations, BPF also significantly upregulated protein expressions of ERα, GPER1, c-myc, and cyclin D and phosphorylations of PKB and ERK1/2. Specific signal inhibitors decreased PKB and ERK1/2 phosphorylations and attenuated the effects of BPF. Silencing of GPER1 also significantly decreased BPF-induced cell proliferation. These results indicate that activating the GPER1-PI3K/PKB and ERK1/2 signals by low doses of BPF can regulate the response of MCF-7 cells and that ERα also influences the effects of exposure to BPF on the cells. The present study suggests a new mechanism by which BPF exerts relevant estrogenic action in cancer cells and also highlights the potential risks in using BPF as an alternative to BPA.