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Mercury risk assessment combining internal and external exposure methods for a population living near a municipal solid waste incinerator
2016
Deng, Chunyan | Xie, Han | Ye, Xuejie | Zhang, Haoran | Liu, Maodian | Tong, Yindong | Ou, Langbo | Yuan, Wen | Zhang, Wei | Wang, Xuejun
Risk assessments for human health have been conducted for municipal solid waste incinerators (MSWIs) in many western countries, whereas only a few risk assessments have been performed for MSWIs in developing countries such as China where the use of waste incineration is increasing rapidly. To assess the mercury exposure risks of a population living near the largest MSWI in South China, we combined internal exposure and external exposure assessment with an individual–specific questionnaire. The mercury concentrations in air, soil, and locally collected food around the MSWI were assessed. The total mercury (T-Hg) and methylmercury (MeHg) of 447 blood samples from a control group, residential exposure group, and MSWI workers were measured. The internal and external exposures of the subject population were analyzed. Significant difference in MeHg concentrations was observed between the control group and the exposed group, between the control group and the MSWI workers, and between the exposed group and the MSWI workers (median levels: 0.70 μg/L, 0.81 μg/L, and 1.02 μg/L for the control group, exposed group, and MSWI workers, respectively). The MeHg/T-Hg ratio was 0.51 ± 0.19, 0.59 ± 0.17 and 0.58 ± 0.25, respectively. Multiple linear regression analysis indicated that MeHg concentrations were positively correlated with the gaseous mercury in the air. Combining internal and external exposure assessment showed that the direct contribution of MSWI emissions was minor compared with the dietary contribution. The external and internal exposures were well matched with each other. This study also suggested that an integrated method combining internal and external exposure assessment with an individual–specific questionnaire is feasible to assess the risks for a population living near a MSWI.
Mostrar más [+] Menos [-]Colloidal aggregation and structural assembly of aspect ratio variant goethite (α-FeOOH) with nC60 fullerene in environmental media
2016
Ghosh, Saikat | Pradhan, Nihar R. | Mashayekhi, Hamid | Zhang, Qiu | Pan, Bo | Xing, Baoshan
Environmental mobility of C60 fullerene can be significantly affected in the presence of naturally abundant α-FeOOH. However, α-FeOOH vary significantly in sizes, shapes and associated properties that can greatly influence the fate and transport of C60 fullerene in environmental media. Therefore, colloidal hetero-association between well crystallized low aspect (LAsp) α-FeOOH and nC60 fullerene may differ substantially to weakly crystallized high-aspect (HAsp) counterpart. In contrast to LAsp α-FeOOH, inherent crystal defects and surface charge generation in HAsp α-FeOOH facilitated strong Coulombic attraction and aggregation with fullerene in acidic pH. However, LAsp α-FeOOH demonstrated subtle entropic depletion mediated interaction with fullerene prevalent in hard rods. Humic acid (HA) encapsulation of HAsp α-FeOOH substantially blocked fullerene attachment. Minute enhancement in colloidal stability was detected for HA-coated HAsp α-FeOOH and fullerene mixture to HA-coated HAsp α-FeOOH alone. To investigate the interfacial assembly of α-FeOOH with fullerene “in situ” differential interference contrast (DIC) microscopic investigations were employed. This study showed significantly different interface behavior of the binary mixtures of fullerene and HAsp α-FeOOH NPs, and LAsp particles. On air-water interface, bare HAsp α-FeOOH displayed liquid crystalline packing. However, addition of fullerene to HAsp α-FeOOH suspension at pH5 produced closed-loop polygonal and circular ring structures. Head-to-tail alignment of magnetic dipoles as well as fullerene hydrophobicity facilitated such assembly formation. “Ex situ” AFM investigation revealed further the presence of magnetically derived ring structure which asserts that the formed “in situ” ensembles were not transient, hence, may abate fullerene transport through environmental interfaces. Barring hydrophobicity assisted attachment of fullerene to LAsp α-FeOOHs, the absence of any close-packed structures may unlikely abate fullerene transport as envisaged in case of HAsp α-FeOOH. Thus, aspect ratio variation and associated material properties of naturally abundant α-FeOOH may significantly impact fullerene transport through environmental media.
Mostrar más [+] Menos [-]Metal exposure in cows grazing pasture contaminated by iron industry: Insights from magnetic particles used as tracers
2016
Ayrault, Sophie | Catinon, Mickaël | Boudouma, Omar | Bordier, Louise | Agnello, Gregory | Reynaud, Stéphane | Tissut, Michel
Magnetic particles (MP) emitted by an iron smelter were used to investigate the exposure of cows grazing on a grassland polluted by these MP and by large amounts of potentially toxic elements (PTE). The morphology as well as the chemical composition of the MP separated from cow dung were studied. Large amounts of typical MP were found (1.1 g kg−1 dry weight) in the cow dung sampled from the exposed site, whereas these particles were absent from the reference unpolluted site. The ingested MP were mainly technogenic magnetic particles (TMP) emitted by the smelter. Considering the MP concentration in the grazed grass on the exposed site, it was concluded that cows absorb the MP not only from the grass but also from the soil surface. The results of a mild acidic leaching of the MP suggested that the particles were possibly submitted to a superficial dissolution in the abomasum, pointing at a potential route of transfer of the PTE originating from the TMP and leading into food chains. TMP were only a small part of the anthropogenic contamination having affected the soil and the dung. However, due to their unequivocal signature, TMP are a powerful tracer of the distribution of PTE in the different compartments constituting the food chains and the ecosystems. Furthermore, the measurement of the particle sizes gave evidence that a noticeable proportion of the MP could enter the respiratory tract.
Mostrar más [+] Menos [-]Are styrene oligomers in coastal sediments of an industrial area aryl hydrocarbon-receptor agonists?
2016
Hong, Seongjin | Lee, Junghyun | Lee, Changkeun | Yoon, Seo Joon | Jeon, Seungyeon | Kwon, Bong-Oh | Lee, Jong Hyeon | Giesy, John P. | Khim, Jong Seong
Effect-directed analysis (EDA) was performed to identify the major aryl hydrocarbon receptor (AhR) agonists in sediments collected from a highly industrialized area (Lake Shihwa, Korea). Great AhR-mediated potencies were found in fractions containing aromatic compounds with log Kow values of 5–8, and relatively great concentrations of styrene oligomers (SOs) and polycyclic aromatic hydrocarbons (PAHs) were detected in those fractions. Until now, there was little information on occurrences and toxic relative potencies (RePs) of SOs in coastal environments. In the present study; i) distributions and compositions, ii) AhR binding affinities, and iii) contributions of SOs to total AhR-mediated potencies were determined in coastal sediments. Elevated concentrations of 10 SOs were detected in sediments of inland creeks ranging from 61 to 740 ng g−1 dry mass (dm), while lesser concentrations were found in inner (mean = 33 ng g−1 dm) and outer regions (mean = 25 ng g−1 dm) of the lake. Concentrations of PAHs in sediments were comparable to those of SOs. 2,4-diphenyl-1-butene (SD3) was the predominant SO analogue in sediments. SOs and PAHs were accumulated in sediments near sources, and could not be transported to remote regions due to their hydrophobicity. RePs of 3 SOs could be derived, which were 1000- to 10,000-fold less than that of one representative potent AhR active PAH, benzo[a]pyrene. Although concentrations of SOs in sediments were comparable to those of PAHs, the collective contribution of SOs to total AhR-mediated potencies were rather small (<1%), primarily due to their smaller RePs. Overall, the present study provides information on distributions and AhR binding affinities for SOs as baseline data for degradation products of polystyrene plastic in the coastal environment.
Mostrar más [+] Menos [-]Characterizing distributions, composition profiles, sources and potential health risk of polybrominated diphenyl ethers (PBDEs) in the coastal sediments from East China Sea
2016
Wang, Guoguang | Peng, Jialin | Zhang, Dahai | Li, Xianguo
Sediment samples (n = 20) were collected from Yangtze River Estuary (YRE) and the adjacent East China Sea (ECS) inner shelf to explore spatial and temporal distributions, environmental fate, sources and potential health risk of polybrominated diphenyl ethers (PBDEs). Concentrations of BDE-209 and total 7 PBDEs (without BDE-209; ∑7PBDEs) ranged from 62.3 to 1758 pg g−1 and from 36.9 to 233.6 pg g−1 dry weight, respectively; both of the highest values occurred near the city of Wenzhou. Concentrations of BDE-209 and ∑7PBDEs both indicated a decreasing trend from inshore areas toward outer shelf. Significantly positive linear correlations were only observed between logBDE-183 concentrations and TOC/grain size (r2 = 0.6734 and 0.5977 for TOC and grain size, respectively) as well as BDE-209 and TOC/grain size (r2 = 0.4137 and 0.5332 for TOC and grain size, respectively) in the north of 28°N, indicating that YR had significant influence on the distribution of higher brominated congeners only in the north part. Depth profiles of PBDEs in a sediment core P01 (n = 1, m = 11) collected from YRE showed that the input of BDE-209 gradually increased from 1930 to 2010, while the levels of ∑7PBDEs peaked in 1986 and obviously decreased in recent years. Partial Least-Squares Regression (PLSR) revealed that PBDEs in the coastal ECS were mainly from direct discharge of local anthropogenic activities (80.7%), followed by surface runoff of contaminated soils (15.1%), microbial degradation after sedimentation (2.6%) and photodegradation during atmospheric transportation (1.6%). The cancer risk of human exposure to BDE-209 at the 95% confidence level was 3.09 × 10−7, 1.67 × 10−7 and 8.86 × 10−7 for children, teens and adults, respectively, significantly lower than the threshold level (10−6). Hazard index (HI) calculated for non-cancer risk was also far less than 1 for the three groups, suggesting no non-cancer risk.
Mostrar más [+] Menos [-]Evaluation of in situ simulated dredging to reduce internal nitrogen flux across the sediment-water interface in Lake Taihu, China
2016
Yu, Juhua | Fan, Chengxin | Zhong, Jicheng | Zhang, Yinlong | Wang, Changhui | Zhang, Lei
Sediment dredging is considered an effective restoration method to reduce internal loading of nitrogen (N) and phosphorus (P) in eutrophic lakes. However, the effect of dredging on N release from sediments to overlying water is not well understood. In this study, N exchange and regeneration across the sediment-water interface (SWI) were investigated based on a one-year simulated dredging study in Lake Taihu, China. The results showed low concentrations of inorganic N in pore water with low mobilization from the sediments after dredging. The calculated fluxes of NO3−-N from post-dredged sediments to overlying water significantly increased by 58% (p < 0.01), while those of NH4+-N dramatically decreased by 78.2% after dredging (p < 0.01). N fractionation tests demonstrated that the contents and lability of N generally declined in post-dredged sediments. Further high-throughput sequencing analysis indicated that relative abundance of the bacterial communities decreased, notably by 30% (compared with undredged sediments). The estimated abundance of Nitrospira enhanced, although the relative abundance of Thiobacillus, Sterolibacterium, Denitratisoma, Hyphomicrobium, Anaeromyxobacter and Caldithrix generally declined after dredging. Therefore, dredging reduced N mobilization from the sediments, which primarily due to decreases in N mobility, in organic matter (OM) mineralization potential and in the bacterial abundance of post-dredged sediments. Overall, to minimize internal N pollution, dredging is capable of effectively reducing N release from sediments. In addition, the negative side effect of dredging on removal of NO3−-N and NO2−-N from aquatic ecosystems should be paid much more attention in future.
Mostrar más [+] Menos [-]Health benefits from improved outdoor air quality and intervention in China
2016
Li, Shanshan | Williams, Gail | Guo, Yuming
China is at its most critical stage of outdoor air quality management. In order to prevent further deterioration of air quality and to protect human health, the Chinese government has made a series of attempts to reduce ambient air pollution. Unlike previous literature reviews on the widespread hazards of air pollution on health, this review article firstly summarized the existing evidence of human health benefits from intermittently improved outdoor air quality and intervention in China. Contents of this paper provide concrete and direct clue that improvement in outdoor air quality generates various health benefits in China, and confirm from a new perspective that it is worthwhile for China to shift its development strategy from economic growth to environmental economic sustainability. Greater emphasis on sustainable environment design, consistently strict regulatory enforcement, and specific monitoring actions should be regarded in China to decrease the health risks and to avoid long-term environmental threats.
Mostrar más [+] Menos [-]Palaeo-pollution from mining activities in the Vosges Mountains: 1000 years and still bioavailable
2016
Mariet, Anne-Lise | de Vaufleury, Annette | Bégeot, Carole | Walter-Simonnet, Anne-Véronique | Gimbert, Frédéric
Mining and smelting activities have contaminated the environment with trace metals (TMs) at a worldwide scale for at least two millennia. A combination of chemical approaches and active biomonitoring was performed to analyse the environmental availability and bioavailability of TM palaeo-pollution in a former PbAg mining district in the Vosges Mountains, France. Along a soil TM contamination gradient that covered eight stations, including two archaeological mining sites, the toxicokinetics of six TMs (Pb, Cd, As, Ag, Co, Sb) in the snail Cantareus aspersus revealed that palaeo-pollution from the studied sites remains bioavailable. This study provides the first data on the accumulation kinetics of Ag and Co for C. aspersus. The environmental availability of the TMs was estimated with three chemical extraction methods (aqua regia, EDTA 50 mM, CaCl2 10 mM). Univariate regression analyses showed that EDTA extraction is the best method for estimating the bioavailability of Pb, As, Ag, Co and Sb to snails. None of the three extractants was efficient for Cd. A multivariate analysis of bioaccumulation data revealed that TM bioavailability and transfer were modulated by exposure sources (soil, humus and vegetation) rather than by soil physico-chemical characteristics. Hence, although the deposition of mining wastes dates back several centuries, these wastes still represent a source of contamination that must be considered to develop relevant site management and environmental risk assessment.
Mostrar más [+] Menos [-]An evaluation of the toxicity and bioaccumulation of bismuth in the coastal environment using three species of macroalga
2016
Kearns, James | Turner, Andrew
Bismuth is a heavy metal whose biogeochemical behaviour in the marine environment is poorly defined. In this study, we exposed three different species of macroalga (the chlorophyte, Ulva lactuca, the phaeophyte, Fucus vesiculosus, and the rhodophyte, Chondrus crispus) to different concentrations of Bi (up to 50 μg L⁻¹) under controlled, laboratory conditions. After a period of 48-h, the phytotoxicity of Bi was measured in terms of chlorophyll fluorescence quenching, and adsorption and internalisation of Bi determined by ICP after EDTA extraction and acid digestion, respectively. For all algae, both the internalisation and total accumulation of Bi were proportional to the concentration of aqueous metal. Total accumulation followed the order: F. vesiculosus > C. crispus > U. lactuca; with respective accumulation factors of about 4200, 1700 and 600 L kg⁻¹. Greatest internalisation (about 33% of total accumulated Bi) was exhibited by C. crispus, the only macroalga to display a phytotoxic response in the exposures. A comparison of the present results with those reported in the literature suggests that Bi accumulation by macroalgae is significantly lower than its accumulation by marine plankton (volume concentration factors of 10⁵ to 10⁷), and that the phytotoxicity of Bi is low relative to other heavy metals like Ag and Tl.
Mostrar más [+] Menos [-]Exposure to pyrethroid pesticides and the risk of childhood brain tumors in East China
2016
Chen, Sheng | Gu, Shuo | Wang, Yue | Yao, Yongliang | Wang, Guoquan | Jin, Yue | Wu, Yeming
Pesticide exposure is hypothesized as one of the risk factors for the development of childhood brain tumors (CBT). This hospital-based case–control study evaluated the association of pyrethroid pesticide exposure with the risk for CBT in a children population in East China. In total, 161 CBT cases and 170 controls were recruited from 2 children's medical centers in Shanghai (Xinhua Hospital and Shanghai Children's Medical Center) between September 2012 and June 2015. The cases and controls were matched for age, sex, and province of residence. Pyrethroid pesticide exposure was evaluated by urinalysis of 3 nonspecific metabolites of pyrethroids (cis-DCCA, trans-DCCA, and 3-PBA) using gas chromatography-mass spectrometry (GC-MS) detection and by administering a questionnaire. Unconditional logistic regression showed that trans-DCCA, 3-PBA, and total metabolites (sum of the 3 metabolites) were positively associated with the increased risk of CBT. Children in the highest quartile had a nearly 3-fold increased risk of CBT compared with those in the lowest quartile after adjusting for confounding factors (trans-DCCA, odds ratio (OR) = 2.58, 95% confidence interval (CI), 1.38–4.80, p = 0.003; 3-PBA, OR = 3.26, 95% CI, 1.73–6.14, p < 0.0001; total metabolites, OR = 3.60, 95% CI, 1.87–6.93, p < 0.0001). We also found that exposure to both mosquitocide and cockroach killer was related to the increased risk of CBT (mosquitocide, OR = 1.68, 95% CI, 1.06–2.67, p = 0.027; cockroach killer, OR = 1.83, 95% CI, 1.13–2.95, p = 0.013). These findings indicate that exposure to pyrethroid pesticides might be associated with increased risk of CBT. Prospective cohort studies with larger sample sizes are required to confirm this conclusion.
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