Tissue-specific distributions of organic ultraviolet absorbents in free-range chickens and domestic pigeons from Guangzhou, China.

The ecological risks of organic ultraviolet absorbents (UVAs) have been of increasing concern. Studies have found that these chemicals could be accumulated in terrestrial animals and pose toxicities. However, tissue distribution of UVAs in terrestrial species was far from well understood. In this study, free-range chickens and domestic pigeons were selected to investigate the occurrence and tissue distribution of UVAs. Total concentrations of eleven UVAs in muscles ranged from 778 to 2874 (mean 1413 ± 666) ng/g lipid weight, which were higher than those in aquatic species worldwide. Since low UVA concentrations in local environment were previously reported, the results implied the strong accumulation of UVAs in studied species. Brain, stomach and kidney were main target organs for studied UVAs, differentiating from the strong liver sequestration in aquatic species. The mean tissue-to-muscle ratios of 1.02-4.23 further indicated the preferential accumulation of target UVAs in these tissues. The tissue-to-blood ratios of benzophenone (BP), 2-ethylhexyl salicylate (EHS) and homosalate (HMS) in brain were 370, 1207 and 52.0, respectively, implying their preferential accumulation in brain. More research is needed to characterize the toxicokinetics and tissue distribution of UVAs in terrestrial wild species, in order to further understand their potential risks.

Uptake and elimination of methylsiloxanes in hens after oral exposure: Implication for risk estimation.

Methylsiloxanes are accumulated easily in aquatic organisms and may pose potential risks. However, available information on their uptake and accumulation in terrestrial species remains scarce. This study investigated the uptake, elimination and accumulation of eight typical methylsiloxanes in hens after a single oral exposure. At 1440 min after oral exposure, methylsiloxanes were mainly accumulated in kidney, liver and ovary, representing for 29.5 %, 20.4 % and 17.4 % of the summed methylsiloxanes in all tissues, respectively; all investigated chemicals were also detected in brains and unformed yolks. We found much higher mass uptake fractions (MUFs) of cyclic (27.5-66.5 %) than linear chemicals (9.9-17.3 %) by hens via this exposure, and the observed MUFs of individual cyclic congeners were comparable to the higher values of those reported for rats or fish previously. However, the metabolic half-life (t1/2) of these chemicals in hen tissues were in the range of 1.04-57.5 h based on kinetic analyses, indicating higher clearances in comparison with those reported for fish and rats. More research is needed on the metabolic mechanism of these chemicals in hens. Our findings provide important information for further understanding of transportation and transformation of these chemicals in terrestrial organisms and the associated potential risks.

Recent progress of covalent organic frameworks membranes: Design, synthesis, and application in water treatment.

To date, significant efforts have been devoted to eliminating hazardous components to purify wastewater through the development of various nanomaterials. Covalent organic frameworks (COFs), an important branch of the porous crystalline family, possess the peculiarity of ultrahigh surface area, adjustable pore size, and facile functionality. Exciting studies from design fabrication to potential applications in water treatment by COF-based membranes (COMs) have emerged. This review summarizes various preparation strategies and synthesis mechanisms for COMs, including layer-by-layer stacking, in situ growth, interfacial polymerization, and electrochemical synthesis, and briefly describes the advanced characterization techniques for COMs. Moreover, the application of COMs in heavy metal removal, dye separation, purification of radionuclides, pollutant detection, sea water desalination, and so on, is described and discussed. Finally, the perspectives on future opportunities for designing COMs in water purification have been proposed.

Occurrence and potential release of heavy metals in female underwear manufactured in China: Implication for women's health.

Underwear is a potential source of women's exposure to heavy metals owing to its direct contact with the skin, especially the skin of the vagina and vulva, which has a strong absorptive capacity. However, information regarding the prevalence of metals in female underwear, and its potential hazards, remains scarce. In the present study, we examined the concentrations and potential release of Cr, Co, Ni, Cu, As, Cd, Sb, and Pb in brassieres and briefs manufactured in China. We detected higher levels of Pb and moderate levels of other metals, relative to the metal levels reported for other textiles in the literature. Cu, As, Ni and Cd, had higher migration rates (MRs) from the underwear, with medians of 100%, 100%, 30.1%, and 20.7%, respectively. The median MRs of the other metals were in the range 1.07%-15.7%. On the whole, the total and extractable concentrations of these metals differed by item and fabric type. The pollution of raw materials and the use of chemical additives containing metals commonly contributed to the metals in the underwear. On the basis of the exposure estimation, the non-carcinogenic risks posed by the underwear metals were acceptable, but the carcinogenic risks from the metals in 5.18% of brassiere samples exceeded the acceptable level.

Organic ultraviolet absorbents in soils and typical plants from an industrial metropolis in China: Concentrations, profiles and environmental implications.

There is accumulating evidence of the toxicity of organic ultraviolet absorbers (OUVAs); however, limited information is available regarding the presence of OUVAs in terrestrial environments and organisms. Therefore, this study was conducted to investigate the occurrence of 11 OUVAs in soils and typical plant species from an industrial metropolis in China. Total OUVA concentrations in soils ranged from 1.30 to 80.3 ng g-1 DW. Based on comparison with previously reported data, OUVA contamination in soil was not severe. Benzophenone and octocrylene were the dominant OUVAs in soils, with median contributions to total concentrations of 25% and 15%, respectively. Source assessment revealed that the observed OUVA contamination primarily originated from industrial activities and the use of personal care products. The concentration of 11 OUVAs in plants ranged from 159 to 4470 ng g-1 DW, at high levels. Our findings imply that great attention should be given to the presence of these chemicals in plants because of the risk they could pose as well as the potential for biomagnification as plants are eaten by insects and birds. Our results also indicate the necessity to further study the geochemical behavior of these chemicals in urban ecosystems in order to better manage the harmfulness to terrestrial ecological health caused by their exposure through the food chains.

Occurrence of methylsiloxanes in indoor store dust in China and potential human exposure.

Methylsiloxanes are synthetic molecules with versatile and extensive applications. Because of their volatile properties, they are easily released from manufactured products and contaminate indoor environments, causing high human exposure. However, available information on their presence in specific microenvironments, and on the related potential risks for human health, is limited. We conducted a survey of sixteen methylsiloxanes species, including three cyclic (D4-D6) and thirteen linear (L4-L16) chemicals, in indoor dust samples from twenty-eight stores representative of six store categories in Beijing, China. Total methylsiloxane concentrations in store dust were 176-54,825 ng/g, depending on the store, with a median of 2196 ng/g. Linear chemicals represented a median proportion of 90.8% of total methylsiloxanes. The measured methylsiloxane concentrations in this study were marginally higher than those reported previously for standard living and working environments. The highest linear and total methylsiloxane concentrations were measured in electronic stores, while the highest cyclic methylsiloxane concentrations were measured in department stores. The presence of methylsiloxanes in the store dust samples was attributed mainly to their release from chemical additives in marketed products. Estimated median total exposure doses under normal and worst-case exposure scenarios were 0.237 and 0.888 ng/kg bw/d, respectively. Further investigation is needed to characterize methylsiloxane distribution in other microenvironments and to evaluate the associated health risks.

Occurrence and health implications of heavy metals in preschool children's clothing manufactured in four Asian regions.

Clothing may be a potential contributor to body metal burden in children. However, available information on heavy metals in children's clothing is extremely limited and the associated health risks remain poorly understood. This study investigated the concentrations of Pb, Cd, Co, Zn, Cr, As, Cu and Ni in new preschool children's clothing manufactured in four Asian regions. The children's clothing had higher levels of Ni and Cr but lower levels of Pb and Cd in comparison to the concentrations reported in other textile products. The concentrations of Cd were higher in the black clothing than those in the white and color samples. The non-cotton samples contained higher Co concentrations. The Pb concentrations in the samples manufactured in China were significantly higher than those in the other three regions. We estimated the dermal exposure doses for these metals and calculated the associated risks. The results indicated that the health risks from exposure to these metals in the children's clothing were acceptable. However, more research is required to investigate heavy metals and the associated risks in child clothing due to the increasing complexity of their materials and manufacturing processes.

Occurrence and distribution of organic ultraviolet absorbents in soils and plants from a typical industrial area in South China.

Organic ultraviolet absorbents (UVAs) have attracted increasing concern due to their ubiquity, bioaccumulation, and potential toxicity. However, available information on their occurrence and transfer in terrestrial environment is still extremely insufficient. In this study, we investigated twelve UVAs in the soils and five terrestrial plant species from a typical industrial area in South China, and found their total concentrations were 5.87-76.1 (median 13.1) and 17.9-269 (median 82.9) ng/g dry weight, respectively. Homosalate was dominant in soils while benzophenone and octrizole were predominant in plants, likely due to their complex sources and bioaccumulation preferences. The bioaccumulation factors (BAFs) were further evaluated based on the ratios of UVA concentrations in plants and soils. The observed BAFs of UVAs were compound and species-specific, and most of them were much >1.0, indicating the chemicals could be transferred from soils to plants. To the best of our knowledge, this is the first report of organic UVAs in field soil-plant systems, providing information that may improve our understanding of the bioaccumulability of these chemicals in terrestrial environment and the associated risks. More studies are needed to investigate the transfer and bioaccumulation of such chemicals in soils and terrestrial biota.

Occurrence and distribution of organic ultraviolet absorbents in sediments from small urban rivers, Tianjin, China: Implications for risk management.

Organic ultraviolet absorbents (OUVAs) in the environment have been of increasing concern because of their potential hazards. However, the OUVAs in waters is far from being well studied and little is known about their occurrence in small urban rivers. This study investigated the concentrations and distribution of eleven OUVAs in the sediments from five small urban rivers of Tianjin, China, and found total concentrations in the range of 11.6-189 ng/g dry weight. Relative to other rivers and lakes, no high concentrations of sediment OUVAs were observed in the small rivers. Benzophenone, homosalate and octocrylene were the dominant OUVAs, representing medians of 13.3%, 12.4% and 12.3% of the total concentrations, respectively. Our observed composition profiles of these chemicals were different from those found in most of other waters. The sediment OUVAs may originate more from industrial activities than the use of cosmetics and personal care products in this area. The risk to aquatic organisms from exposure to the sediment OUVAs in these small urban rivers was considered low, except for benzophenone. However, more researches are needed to investigate the pollution and associated risks of these chemicals in urban rivers due to the complexity of their toxicity to aquatic organisms.

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.

Concentrations, distribution and potential health risks of organic ultraviolet absorbents in street dust from Tianjin, a megacity in northern China.

The distribution of organic ultraviolet absorbers (OUVAs) in outdoor dust remains poorly understood, especially in megacities. We measured the concentrations of 11 OUVAs in street dust from Tianjin, China, by a gas chromatography-mass spectrometry, and found total concentrations in the range of 10.3-129 ng/g. These OUVAs were prevalent in the study street dust, but their concentrations were much lower than those in indoor dust reported in other areas previously. Benzophenone and octocrylene were the dominant OUVAs, representing medians of 15.5% and 13.1% of total OUVA concentrations, respectively. Total concentrations of dust OUVAs in the industrial area were higher than the residential, cultural and new urban areas. Source assessment indicated that the OUVAs likely originated mainly from the manufacture and consumption of cosmetics and personal care products, and some may have been from the production and use of OUVA-containing consumer products. The calculated non-carcinogenic risks of OUVAs in street dust were low. Our results further confirmed that the OUVAs were prevalent in the environment, provide useful information for understanding potential risks of these chemicals and developing risk management strategies. Further studies are needed to investigate the occurrence, environmental behaviors and potential risks of these emerging contaminants in outdoor environment.

Occurrence, potential release and health risks of heavy metals in popular take-out food containers from China.

Global consumption of take-out food increased rapidly and the chemicals in their containers become a potential source of human exposure. However, available information on heavy metals in the containers is extremely limited and the associated health risks remain poorly understood. We investigated Cd, Cr, Pb, Sb, Mn, Ni and Co in the popular take-out food containers from China and found the concentrations of these metals were moderate in comparison to the concentrations reported in other food contact materials. The metal concentrations in sampled containers by material type differed significantly, and higher concentrations of Cd, Pb, Sb, Mn and Co were observed in expanded polystyrene samples. The metals in the containers likely originated from intentional addition and/or contamination of materials. The potential release of the metals from containers was simulated and found the median leaching rates of Cd, Pb, Sb, Ni and Co in the range of 0.36-4.80% under typical conditions, which depended largely on the material types. Based on the observed leaching rates, we estimated that the summed carcinogenic risks of Cd, Pb, Ni and Co were unacceptable under specific exposure frequency, although the total non-carcinogenic risks from metal intake were low.

Occurrence of methylsiloxanes in sediments from a subtropical river-lake system in eastern China and its implication for ecological risks.

Distribution of methylsiloxanes in environment is still far from being well studied. Little is known about the concentrations and associated risks of these chemicals in river-lake systems. This study investigated the occurrence of twelve methylsiloxanes (D4-D6, L5-L13) in the sediments from Lake Chaohu and its inflowing rivers, China, and found the total concentrations (ng/g dry weight) were in the range of 47.1-496 and 239-3593, respectively. Linear congeners were dominant, representing a median of 62.8% and 58.7% of the total concentrations found in the lake and its inflowing rivers, respectively. In general, the concentrations of sediment methylsiloxanes in the investigated river-lake system were low to moderate, compared with the results reported previously in other waters. Source assessment indicated that the emissions from industrial activities and the use of silicone-containing products were the main contributors of sediment methylsiloxanes in the investigated waters. D4 and D5 in 18.5% and 11.1% of river sediment samples might pose ecological risks to fish. The risks from the linear congeners in sediments in the area were not estimated due to no related benchmarks available. More studies are needed to investigate the occurrence of these chemicals and associated risks in aquatic environment.

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.

Polybrominated Diphenyl Ethers and Heavy Metals in a Regulated E-Waste Recycling Site, Eastern China: Implications for Risk Management.

Serious pollution of multiple chemicals in irregulated e-waste recycling sites (IR-sites) were extensively investigated. However, little is known about the pollution in regulated sites. This study investigated the occurrence of 21 polybrominated diphenyl ethers (PBDEs) and 10 metals in a regulated site, in Eastern China. The concentrations of PBDEs and Cd, Cu, Pb, Sb, and Zn in soils and sediments were 1-4 and 1-3 orders of magnitude lower than those reported in the IR-sites, respectively. However, these were generally comparable to those in the urban and industrial areas. In general, a moderate pollution of PBDEs and metals was present in the vegetables in this area. A health risk assessment model was used to calculate human exposure to metals in soils. The summed non-carcinogenic risks of metals and PBDEs in the investigated soils were 1.59-3.27 and 0.25-0.51 for children and adults, respectively. Arsenic contributed to 47% of the total risks and As risks in 71.4% of the total soil samples exceeded the acceptable level. These results suggested that the pollution from e-waste recycling could be substantially decreased by the regulated activities, relative to poorly controlled operations, but arsenic pollution from the regulated cycling should be further controlled.

Methyl siloxanes in soils from a large silicone-manufacturing site, China: concentrations, distributions and potential human exposure.

Methyl siloxanes are widely found in the environment, but little is known about the distributions of these chemicals in soils especially in areas where they are manufactured. We determined the concentrations of four cyclic (D3-D6) and 13 linear methyl siloxanes (L4-L16) in the soils from a siloxane-manufacturing site in China; the total concentrations of these 17 siloxanes (TSi) in the soils were 17.1-3,191 (median, 134) ng/g. We did not find extremely high concentrations of siloxanes in the soils. The median concentrations of total cyclic siloxanes (TCSi) were approximately sevenfold higher than those of total linear congeners. Hexamethylcyclotrisiloxane and octamethylcyclotetrasiloxane contributed a median of 59.7% and 20.3% of the TSi concentrations, respectively. Higher concentrations of soil TCSi were found in the silicone-manufacturing area relative to the other study areas. Source analysis indicated that industrial activities contributed substantially to soil siloxanes, in addition to the contribution of the siloxane emissions from specific consumer products. We calculated that the median values of daily TSi intakes through soil ingestion were 0.021 and 0.138 ng/kg-body weight/day for adults and children, respectively, under high exposure scenarios. Although our estimated daily intakes of the chemicals from soils were low, more research is required to improve our understanding of the health risks posed to humans exposed to siloxanes through other pathways.

Methylsiloxane occurrence and distribution in free-range poultry eggs near a rural industrial park: Indicators of potential risks to birds.

The ecological harm from methylsiloxanes has drawn worldwide attention. This study investigated three cyclic (D4-D6) and four linear siloxanes (L7-L10) in the eggs of free-range poultry collected near a rural industrial park in China and found total concentrations in the range of 19.2-1204 (median, 268) ng/g dry weight. Higher concentrations of methylsiloxanes were observed in chicken eggs than duck eggs. Cyclic siloxanes represented a median of 62.2% of the total methylsiloxane concentrations. A source assessment indicated that local soils and outdoor dust were more important sources of egg methylsiloxanes than poultry food. The partitioning of methylsiloxanes between egg yolk and egg albumen was investigated, and preferential distributions of the chemicals in the yolk were observed. This study confirmed that methylsiloxanes were highly prevalent in the study poultry eggs. The results suggested that the potential risks to some wild birds inhabiting this area should be of concern, as their physiologies and feeding ecologies are similar to those of the studied poultry, although available ecotoxicological data of the chemicals to birds remains scarce. Additional research is needed to characterize the accumulation of methylsiloxanes in different bird species and its associated adverse effects on their offspring.

Bioaccumulation and trophodynamics of cyclic methylsiloxanes in the food web of a large subtropical lake in China.

Available information on the bioaccumulation and trophodynamics of cyclic methylsiloxanes in aquatic food webs is insufficient for a reliable understanding of their toxicity and potential ecological harm. The concentrations of four cyclic methylsiloxanes in aquatic species collected from Lake Chaohu (China) were measured and the total concentration was in range of 2.01-36.1 ng/g dry weight. Dodecamethylcyclohexasiloxane (D6) represented 57.7% of the total measured methylsiloxane concentration. The distribution of these methylsiloxanes constitute the first tissue-specific record. The hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) tended to accumulate preferentially in fish muscles, while D6 was preferentially accumulated in fish liver and gills. In Lake Chaohu, significant trophic magnification of D3 (p < 0.01) and dilution of D6 (p < 0.05) were observed, and the trophic magnification factors (TMFs) were estimated at 4.94 and 0.68, respectively. No significant trends in D4 and D5 (p > 0.05) were observed within the food web. This study further confirmed the complexity of trophic transfer of the methylsiloxanes in the aquatic food web. The findings suggest that tissue-specific methylsiloxane distribution in aquatic species might also affect the observed TMFs. More research is required to investigate methylsiloxanes in additional species and their trophodynamics in different food webs.

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.