Methylsiloxanes in street dust from Hefei, China: Distribution, sources, and human exposure.

Methylsiloxanes are widely found in the environment and have been of increasing concern because of their strong resistance to degradation and potential toxicity to organisms. However, little is known about the distributions of these chemicals in street dust and the associated human health risks. This study investigated three cyclic (D4-D6) and nine linear methylsiloxanes (L5-L13) in street dust from Hefei, China and found total concentrations in the range of 183-1030 (median, 527) ng/g dry weight. The linear congeners were dominant and represented a median of 85.3% of the total methylsiloxanes. D5 contributed 90.0% of the total concentrations of cyclic methylsiloxanes. In this study, higher concentrations of dust methylsiloxanes were found in the industrial area relative to the other functional areas. A source assessment indicated that the linear and cyclic methylsiloxanes in the street dust were mainly from the industrial and traffic activities, respectively, in addition to important sources of the use of siloxanes-containing products. The estimated median daily intakes of total methylsiloxanes through street dust were 0.037 and 0.476 ng/kg-bw/d for adults and children, respectively, under high-exposure scenarios. More research is needed to characterize the occurrence of methylsiloxane in various exposure sources and the associated adverse effects on human health.

Occurrence and trophic transfer of synthetic musks in the freshwater food web of a large subtropical lake.

Synthetic musks (SMs) have drawn worldwide attention, as they are persistent, bioaccumulative, and toxic to many organisms. There is not enough information on the bioaccumulation and trophodynamic behavior of SMs in freshwater food webs to reliably understand the associated ecological risks. In this study, the concentrations of six SM congeners in fifteen aquatic species from Lake Chaohu, China, was investigated. The total concentrations of the six SMs ranged from 0.29 to 59.7 ng/g dry weight (median, 4.41) in fish muscle tissue and in the whole body tissues of small fish species and shrimps. Galaxolide (HHCB) and tonalide (AHTN) were the predominant congeners, accounting for 65.0% and 28.5% of the total SM concentration, respectively. On the whole, the total concentrations of SMs in livers and gills were 0.18-32.8 and 0.84-254 times higher than those in muscle tissues in fish species, respectively. In the food web of Lake Chaohu, cashmeran (DPMI) and HHCB showed a trend towards trophic magnification, and AHTN tended to show trophic dilution, but these trends were not statistically significant. This suggested that the trophic transfer of these chemicals through the food web was strongly influenced by many factors, including tissue-specific distribution within individuals at higher trophic levels. More investigation into the trophic transfer of SMs in aquatic ecosystems and the factors influencing uptake is needed.

Occurrence, distribution and ecological risk of ultraviolet absorbents in water and sediment from Lake Chaohu and its inflowing rivers, China.

The available information is insufficient to enable a reliable understanding of the global distribution and effect of organic ultraviolet absorbents (UVAs) on ecosystems. Little is known about the pollution of China's lakes by these chemicals. We conducted a survey of UVAs in water and sediment from Lake Chaohu and its inflowing rivers. The UVAs were widely present in this area and the concentrations of total 12 UVAs (Σ12 UVAs) ranged between 162 and 587 ng/L in water and 9.70-178 ng/g in sediment. Benzophenone and benzophenone-3 were dominant in water, and benzophenone and octocrylene dominated in sediment. Higher concentrations of benzophenone were detected in the investigated water samples, although the contamination levels of UVAs in this study were comparable to those investigated in other areas. In addition to the inputs from the UVAs used as filters in cosmetics, the discharge from industries using UVAs as stabilizers also contributed much to the pollution in the study waters. Generally, the risk to aquatic organisms from exposure to UVAs in this area was low, but further research is needed to elucidate the fate of UVAs and to understand bioaccumulation and associated risks.

A new multistep purification method for simultaneously determining organic ultraviolet absorbents in fish tissue.

More information is required to improve our understanding of the presence of organic ultraviolet absorbents (UVAs) in organisms and the risks posed to biota. Effective removal of lipids in the determination of UVAs in biological samples is a sample-processing bottleneck. In this study, we optimized a multistep purification method for fish tissue samples extracted using an ultrasonic-assisted extraction method. The purification method involved performing Florisil column chromatography, redissolving the extract in ethanol, and then performing dispersive solid-phase extraction using primary and secondary amine, Florisil, and C18 silica sorbents. The purified samples were analyzed by gas chromatography-mass spectrometry. The method was effective and reliable, and was used to detect trace concentrations (ng/g) of 12 UVAs in fish tissue samples. The mean recovery range of the UVAs in fish tissue extracts was 65.4-118%, and the method detection limit range was 0.20-2.50 ng/g dw. The validated method was used to analyze 12 UVAs in fish samples from a local supermarket.

Bioaccumulation and trophic transfer of organic ultraviolet absorbents in the food web of a freshwater lake: Implications for risk estimation.

Organic ultraviolet absorbents (UVAs) are increasingly reported in environmental matrices and organisms. However, available information on the bioaccumulation of UVAs in freshwater species is insufficient and their trophodynamics in lake food webs remain unknown. We measured the concentrations of twelve UVAs in the wild species from Lake Chaohu. Except for UV-320 not detected, the other UVAs were prevalent in the study species and their total concentrations were in the range of 5.44-131 ng/g dry weight, which were comparable to the concentrations reported in other waters. Compound and species-specific accumulations of UVAs in the organisms were observed. In the lake, the log-transformed concentrations of 4-methyl benzylidene camphor, octyl p-dimethylaminobenzoate, UV-326, and UV-327 related significantly to the trophic levels of species separately. The calculated trophic magnification factors (TMFs) of the four UVAs were 3.79, implying trophic magnification, and 0.18, 0.40 and 0.58, suggesting trophic dilution, respectively. These suggested that the magnification potential and the associated risks of individual UVAs in freshwater lake differed. To our knowledge, this is the first report of these TMFs in lake food webs. However, more investigation is needed to characterize their trophodynamic behaviors in lakes because food web characteristics likely affect trophic transfer of these chemicals.

Synthetic musk fragrances in sediments from a subtropical river-lake system in eastern China: occurrences, profiles, and ecological risks.

Synthetic musk fragrances (SMFs) in aquatic environments have been of increasing concern because of their potential characteristic of persistent, bioaccumulated, and ecological harm. However, little is known about the distribution of SMFs in river-lake systems. In this study, the occurrence and risks of six SMFs measured in sediments from Lake Chaohu (eastern China) and the rivers flowing into it were investigated. The total sedimentary SMF concentrations ranged from 2.43 to 15.5 ng/g in Lake Chaohu (median = 5.17 ng/g), and 2.34-104 ng/g in the rivers (median = 10.6 ng/g). Overall, moderate levels of SMFs were found in comparison with previous results from other areas. Galaxolide and tonalide dominated in the rivers whereas cashmeran was dominant in Lake Chaohu. A source assessment indicated that the discharge from industries contributed importantly to the pollution of SMFs in the studied waters, in addition to the inputs from domestic sewage. Our estimates suggested that the current sedimentary SMF concentrations were likely to pose extremely low ecological risk to aquatic organisms. However, more studies are needed to focus on the spatial and temporal trends in distribution as well as the ecotoxicological implications of SMFs in the Lake Chaohu area because there is a general lack of relevant information.

Concentrations and tissue-specific distributions of organic ultraviolet absorbents in wild fish from a large subtropical lake in China.

Organic ultraviolet absorbents (UVAs) have been detected in various materials and biota, but little is known about the distributions of UVAs in the tissues of biota. In this study, tissue-specific UVA accumulation in six fish species from Lake Chaohu, China, was investigated. The sums of 12 UVA concentrations in muscles, gills, and livers were 7.65-120, 10.1-281, and 26.4-359 ng/g dry weight, respectively. Ethylhexyl methoxycinnamate, 4-methylbenzylidene-camphor, and 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole were the dominant UVAs. Ethylhexyl salicylate and homosalate have been found in the aquatic species firstly. UVAs were taken up to different degrees by different fish species. The UVA muscle bioconcentration factors were lower than predicted by the Estimation Programs Interface Suite model, suggesting that such models may overestimate UVA accumulation in fish. The tissue distribution patterns indicated that UVAs are easily transferred to the muscles after being absorbed through the gills. The liver was found to preferentially accumulate UVAs and have a high UVA accumulation capacity, implying liver damage may be caused by UVAs. This is the first time the partitioning of UVAs between the liver, muscle, and gills of freshwater fish has been studied. The data acquired will improve our understanding of the pharmacokinetics and toxicities of UVAs in aquatic organisms.