Daily Archives: January 17, 2015

350+ Articles Documenting Obamacare Failures

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Perchlorate Exposure via Indoor Dust in Fireworks Areas

 Zhang T, Chen X, Wang D, Li R, Ma Y, Mo W, Sun H, Kannan K.  Perchlorate in Indoor Dust and Human Urine in China: Contribution of Indoor Dust to Total Daily Intake. Environmental Science and Technology. 2015 Jan 14.

Perchlorate is used in fireworks and China is the largest fireworks producer and consumer in the world. Information regarding human exposure to perchlorate is scarce in China, and exposure via indoor dust ingestion (EDIindoor dust) has rarely been evaluated. In this study, perchlorate was found in indoor dust (detection rate: 100%, median: 47.4 µg/g), human urine (99%, 26.2 ng/mL), drinking water(100%, 3.99 ng/mL), and dairy milk (100%, 12.3 ng/mL) collected from cities that have fireworks manufacturing areas (Yueyang and Nanchang) and in cities that do not have fireworks manufacturing industries (Tianjin, Shijiazhuang, Yuxi and Guilin) in China. In comparison with perchlorate levels reported for other countries, perchlorate levels in urine samples from fireworks sites and non-fireworks sites in China were higher. Median indoor dust perchlorate concentrations were positively correlated (r = 0.964, p < 0.001) with outdoor dust perchlorate levels reported previously. The total daily intake (EDItoal) of perchlorate, estimated based on urinary levels, ranged from 0.090 to 27.72 µg/kg body weight (bw)/day for all studied participants; the percentage of donors who had EDItotal exceeding the reference dose (RfD) recommended by the United States Environmental Protection Agency (US EPA) was 79%, 48%, and 25% for toddlers (median: 1.829 µg/kg bw/day), adults (0.669 µg/kg bw/day), and children (median: 0.373 µg/kg bw/day), respectively. Toddlers (0.258 µg/kg bw/day) had the highest median EDIindoor dust, which was 2 to 5 times greater than the EDIindoor dust calculated for other age groups (the range of median values: 0.044 to 0.127 µg/kg bw/day). Contribution of indoor dust to EDItotal was 26%, 28%, and 7% for toddlers, children, and adults, respectively. Indoor dust contributed higher percentage to EDItotal than that by dairy milk (0.5-5%).

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Halobenzoquinones (HBQs): A New Class of Disinfection Byproducts

Li J, Wang W, Moe B, Wang H, Li XF. Chemical and Toxicological Characterization of Halobenzoquinones, an Emerging Class of Disinfection Byproducts. Chemical Research in Toxicology. 2015 Jan 14.

Halobenzoquinones (HBQs), a new class of disinfection byproducts (DBPs), occur widely in treated drinking water and recreational waters. The main concerns of human exposure to DBPs stem from epidemiological studies that have consistently linked the consumption of chlorinated drinking water with an increased risk of developing bladder cancer. US Environment Protective Agency and Health Canada have set regulations of DBPs in drinking water to minimize the risk. However, these regulated DBPs do not account for this increased cancer risk, because they have presented different target organs or lower magnitudes of risk based on animal carcinogenic studies. Because of pervasive exposure to DBPs, identification of DBPs of human health relevance has become one of the important research targets to address DBP health concerns. Quantitative structure toxicity relationship (QSTR) analysis has predicted HBQs as potential bladder carcinogens. Therefore, this perspective focuses on the chemical and toxicological characterization of HBQs. In vitro cytotoxicity experiments have shown that HBQs induce greater cytotoxicity and/or greater developmental toxicity than most of the regulated DBPs. Cellular mechanistic studies indicate that HBQs are capable of producing reactive oxygen species (ROS) either within cells or in solution, depleting cellular glutathione levels and influencing cellular antioxidant enzymes that further induces oxidative stress and oxidative damage to cellular proteins and DNA. Oxidative damage to DNA was demonstrated in the form of significant increases in cellular levels of 8-hydroxydeoxyguanosine (8-OHdG), DNA strand breaks, and apurinic/apyrimidinic (AP) sites. HBQs can also form DNA adducts, affect genome-wide DNA methylation, and inhibit DNA repair enzymes. These findings demonstrate that HBQs are highly cytotoxic and potentially genotoxic and carcinogenic, although in vivo data is not available. To fully understand the potential adverse health effects and cancer risk due to HBQ exposure, multidisciplinary research is required on human exposure, health risk assessment, and toxicological mechanisms of HBQs.

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