[Distribution Characteristics and Potential Risk of CBs in Aquatic Organisms from Typical Epidemic Areas of Schistosomiasis Prevalence].

Eleven mollusca samples and 32 fish samples were collected from typical epidemic areas of schistosomiasis prevalence. The contents of 12 CB congeners in aquatic organism samples were measured using the GC/MS technique. The results indicated that 1,3-DIC, 1,4-DIC, 1,2-DIC and HCB were the most predominant CB congeners in the samples from the studying area. The geometric average of CBs in muscle of mollusca was 11 947 ng x g(-1) lipid weight. The summarized concentration of CBs in fish muscle ranged from 1 851 to 8 159 ng x g(-1) lipid weight. The highest concentration of CBs sum was detected in the catfish, while the lowest one was found in the crucian carp. The concentrations of CBs in fish samples were much higher than those reported in other countries, while in mollusca samples were at the same level. The estimated cumulative cancerigenic risks for the local residents consumed the aquatic organisms from the studying area were 1.49 x 10(-7) and 3.73-21.1 x 10(-7), respectively for mollusca and fish, both of which were acceptable.

[Application of ICP-mS in the health risk assessment of heavy metals for drinking water sources in reservoirs].

The six heavy metal concentrations (Cr, Cr, As, Cd, Cu, Zn and Pb) in water samples collected from five reservoirs of Liao River Basin were studied. The health risk assessment for heavy metals pollution in reservoirs was conducted based on the environmental health risk assessment model recommended by U. S. Environmental Protection Agency. The results showed that the average concentrations of Cr, Cu, Zn, As, Cd and Pb in five reservoirs of Liao River Basin were 3.36, 1.03, 2. 70, 1.23, 0. 02 and 0. 03 microg L-1, respectively. In fact, these heavy metals concentrations were obviously lower than the Standard of National Drinking Water in China (GB 5749-2006). The results also showed that the metal carcinogenic risk was relatively high in this region. The order of the risk level of carcinogenic metals was Cr>As>Cd. The highest carcinogenic risk was from Cr, with the risk for adults ranging from 4. 50 X 10(-5) approximately 7. 53 X 10(-5) a-1' and the risk for children ranging from 6. 29 X 10(-5) to 1. 05 X 10(-4) a-1. The health risk levels caused by non-carcinogenic metals ranging from 10-13 to 10(-10) a-1 were lower than the acceptable range suggested by International Commission on Radiological Protection (ICRP) and the order of the risk level of non-carcinogenic metals was Cu>Zn>Pb. The total health risk of heavy metals for adults ranging from 1. 07X 10(-4) to 1. 72X 10(-4) a-1 and for children ranging from 1. 49 X 10(-4) to 2. 40 X 10(-4) a-1 exceeded the accepted level of 5 X 10(-5) a-1 as suggested by ICRP. The health risk levels of carcinogenic metals were significantly higher than those of non-carcinogenic metals in the reservoirs for Liao River Basin.

Chronic exposure to pentachlorophenol alters thyroid hormones and thyroid hormone pathway mRNAs in zebrafish.

Pentachlorophenol (PCP) is frequently detected in the aquatic environment and has been implicated as an endocrine disruptor in fish. In the present study, 4-month-old zebrafish (Danio rerio) were exposed to 1 of 4 concentrations of PCP (0.1, 1, 9, and 27 µg/L) for 70 d. The effects of PCP exposure on plasma thyroid hormone levels, and the expression levels of selected genes, were measured in the brain and liver. The PCP exposure at 27 µg/L resulted in elevated plasma thyroxine concentrations in male and female zebrafish and depressed 3, 5, 3'-triiodothyronine concentrations in males only. In both sexes, PCP exposure resulted in decreased messenger RNA (mRNA) expression levels of thyroid-stimulating hormone ß-subunit (tshß) and thyroid hormone receptor ß (trß) in the brain, as well as increased liver levels of uridine diphosphoglucuronosyl transferase (ugt1ab) and decreased deiodinase 1 (dio1). The authors also identified several sex-specific effects of PCP exposure, including changes in mRNA levels for deiodinase 2 (dio2), cytosolic sulfotransferase (sult1 st5), and transthyretin (ttr) genes in the liver. Environmental PCP exposure also caused an increased malformation rate in offspring that received maternal exposure to PCP. The present study demonstrates that chronic exposure to environmental levels of PCP alters plasma thyroid hormone levels, as well as the expression of genes associated with thyroid hormone signaling and metabolism in the hypothalamic-pituitary-thyroid (HPT) axis and liver, resulting in abnormal zebrafish development.

[Distribution characteristics of PBDEs in surface sediment from the Three Gorges Reservoir of Yangtze River].

A total of 28 surface sediment samples (at the top 0-5 cm layer) were collected from the Three Gorges Reservoir of Yangtze River. The content of polybrominated diphenyl ethers (PBDEs) in sediments was measured with Varian GC-MS (NCI). The results showed that sigma26 PBDEs and BDE209 both had a low concentration in sediments, with a mass concentration of 35.24 pg x g(-1) and 11.92 pg x g(-1), respectively. Among the 26 PBDEs, BDE28, 47, 77 and 99 were the most predominant sigma26 PBDEs congeners. The highest concentrations of sigma26 PBDEs and BDE209 were detected in the sediment samples collected from Long River, with geometric mean of 146.07 and 502.63 pg x g(-1), respectively. A significant correlation was found between sigma26 PBDEs and BDE209, indicating that they might have the same pollution source. The concentrations of sigma26 PBDEs and BDE209 in the sediment were in the same order of magnitude with those reported on background levels in sediments of remote lakes in other countries, which shows the toxic biological effects on aquatic biota and potential risk due to sigma26 PBDEs and BDE209 contamination in sediments are negligible.

[Distribution characteristics and potential risk of PCBs in surface water from three tributaries of Yangtze River in different periods].

Eighty-one surface water samples were collected from 3 tributaries of the Yangtze River in different periods. Contents of 28 PCB congeners in surface water samples were measured using Varian CP3800/300 GC-MS/MS technique. PCB8, 18, and 28 are the most predominant PCB congeners in the samples from tributaries. The measured level of PCBs in the samples from the Tuo river, downstream of Ouchi River and Songlihongdao tributary were 1.96-2.59 ng x L(-1), 1.84-2.54 ng x L(-1) and 1.52-2.38 ng x L(-1). The average concentrations of PCBs in the samples were lower than USEPA criterion continuous concentration (14 ng x L(-1)), which were also in the same order of magnitude of those reported with lower levels in European and American countries. The estimated cumulative cancer risk for the local residents who drink water from tributaries were 0.15 x 10(-7)-0.26 x 10(-7), which shows that cancer risk are negligible due to PCBs contamination in these samples.