http://netedu.xauat.edu.cn/jpkc/netedu/jpkc2009/szylyybh/content/wlzy/1/Review%20of%20Arsenic%20in%20natural%20water%20-%20Smedly.pdf

A review of the source, behaviour and distribution of arsenic in natural waters

The contamination of groundwater by arsenic in Bangladesh is the largest poisoning of a population in history, with millions of people exposed. This paper describes the history of the discovery of arsenic in drinking-water in Bangladesh and recommends intervention strategies. Tube-wells were installed to provide ‘‘pure water’’ to prevent morbidity and mortality from gastrointestinal disease. The water from the millions of tube-wells that were installed was not tested for arsenic contamination. Studies in other countries where the population has had long-term exposure to arsenic in groundwater indicate that 1 in 10 people who drink water containing 500mg of arsenic per litre may ultimately die from cancers caused by arsenic, including lung, bladder and skin cancers. The rapid allocation of funding and prompt expansion of current interventions to address this contamination should be facilitated. The fundamental intervention is the identification and provision of arsenic-free drinking water. Arsenic is rapidly excreted in urine, and for early or mild cases, no specific treatment is required. Community education and participation are essential to ensure that interventions are successful; these should be coupled with follow-up monitoring to confirm that exposure has ended. Taken together with the discovery of arsenic in groundwater in other countries, the experience in Bangladesh shows that groundwater sources throughout the world that are used for drinking-water should be tested for arsenic.

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Contamination of drinking-water by arsenic in Bangladesh: a public health emergency

Essentiality Toxicity Carcinogenicity Lead(Pb) Exposure Toxicokinetics Toxicity Neurologic, Neurobehavioral, and Developmental Effects in Children Mechanisms of Effects on the Developing Nervous System Peripheral Neuropathy Hematologic Effects Renal Toxicity Lead and Gout Effects on Cardiovascular System Immunotoxicity Bone Effects Reproductive Effects Birth Outcomes Carcinogenicity Other Effects Dose Response Treatment Organic Lead Compounds Mercury (Hg) Exposure Disposition and Toxicokinetics Metabolic Transformation Cellular Metabolism Toxicology Biological Indicators Treatment Nickel (Ni) Exposure Toxicokinetics Essentiality Toxicity Nickel Carbonyl Poisoning Dermatitis Indicators of Nickel Toxicity

/pdf/toxic-effects-of-metals-2t2btb1i7f.pdf

Toxic effects of metals

We propose a two-class classification model for grouping. Human segmented natural images are used as positive examples. Negative examples of grouping are constructed by randomly matching human segmentations and images. In a preprocessing stage an image is over-segmented into super-pixels. We define a variety of features derived from the classical Gestalt cues, including contour, texture, brightness and good continuation. Information-theoretic analysis is applied to evaluate the power of these grouping cues. We train a linear classifier to combine these features. To demonstrate the power of the classification model, a simple algorithm is used to randomly search for good segmentations. Results are shown on a wide range of images.

/pdf/learning-a-classification-model-for-segmentation-16re2jogiw.pdf

Learning a classification model for segmentation

Arsenic toxicity and potential mechanisms of action

Ingestion of arsenic, both from water supplies and medicinal preparations, is known to cause skin cancer. The evidence assessed here indicates that arsenic can also cause liver, lung, kidney, and bladder cancer and that the population cancer risks due to arsenic in U.S. water supplies may be comparable to those from environmental tobacco smoke and radon in homes. Large population studies in an area of Taiwan with high arsenic levels in well water (170-800 micrograms/L) were used to establish dose-response relationships between cancer risks and the concentration of inorganic arsenic naturally present in water supplies. It was estimated that at the current EPA standard of 50 micrograms/L, the lifetime risk of dying from cancer of the liver, lung, kidney, or bladder from drinking 1 L/day of water could be as high as 13 per 1000 persons. It has been estimated that more than 350,000 people in the United States may be supplied with water containing more than 50 micrograms/L arsenic, and more than 2.5 million people may be supplied with water with levels above 25 micrograms/L. For average arsenic levels and water consumption patterns in the United States, the risk estimate was around 1/1000. Although further research is needed to validate these findings, measures to reduce arsenic levels in water supplies should be considered.

/pdf/cancer-risks-from-arsenic-in-drinking-water-27l7ggsxqj.pdf

Cancer risks from arsenic in drinking water.

Background: Despite 20 y of biomonitoring studies of per- and polyfluoroalkyl substances (PFAS) in both serum and urine, we have an extremely limited understanding of PFAS concentrations in breast milk of women from the United States and Canada. The lack of robust information on PFAS concentrations in breast milk and implications for breastfed infants and their families were brought to the forefront by communities impacted by PFAS contamination. Objectives: The objectives of this work are to: a) document published PFAS breast milk concentrations in the United States and Canada; b) estimate breast milk PFAS levels from maternal serum concentrations in national surveys and communities impacted by PFAS; and c) compare measured/estimated milk PFAS concentrations to screening values. Methods: We used three studies reporting breast milk concentrations in the United States and Canada We also estimated breast milk PFAS concentrations by multiplying publicly available serum concentrations by milk:serum partitioning ratios for perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), and perfluorononanoic acid (PFNA). Measured and estimated breast milk concentrations were compared to children’s drinking water screening values. Discussion: Geometric means of estimated breast milk concentrations ranged over approximately two orders of magnitude for the different surveys/communities. All geometric mean and mean estimated and measured breast milk PFOA and PFOS concentrations exceeded drinking water screening values for children, sometimes by more than two orders of magnitude. For PFHxS and PFNA, all measured breast milk levels were below the drinking water screening values for children; the geometric mean estimated breast milk concentrations were close to—or exceeded—the children’s drinking water screening values for certain communities. Exceeding a children’s drinking water screening value does not indicate that adverse health effects will occur and should not be interpreted as a reason to not breastfeed; it indicates that the situation should be further evaluated. It is past time to have a better understanding of environmental chemical transfer to—and concentrations in—an exceptional source of infant nutrition. https://doi.org/10.1289/EHP10359

Current Breast Milk PFAS Levels in the United States and Canada: After All This Time, Why Don’t We Know More?

Background: High oral exposure and biological vulnerabilities may put formula-fed infants at risk for manganese-induced neurotoxicity. Objectives: We sought to characterize manganese concentrations...

Erratum: "Potential for Manganese-Induced Neurologic Harm to Formula-Fed Infants: A Risk Assessment of Total Oral Exposure".

Combustion of hazardous and municipal waste produces a wide variety of emissions which need to be considered when assessing potential human health risks. A major focus in recent years has been excess cancer risks. The main emissions which rodent studies indicate may be carcinogenic to humans include organic chemicals such as dioxins, furans and polychlorinated biphenyls, which are highly persistent in the environment. Certain metals known to be carcinogenic to humans, such as arsenic, cadmium, chromium and nickel, are also emitted. Priorities for consideration among non-carcinogenic emissions include lead and mercury. Methods for health risk assessment of air emissions are presented in this paper, and illustrated with data from a risk assessment of emissions from a municipal waste incinerator. The most significant potential exposure pathways were fish, meat, and milk consumption, which are dependent on the siting of facilities in relation to fishable lakes and land used for animal grazing or food...

Health risk assessment of incinerator air emissions incorporating background ambient air data

Ingestion of contaminated fish can be an important human exposure pathway for dioxins and furans emitted from waste incineration plants. A new method for calculating fish contamination resulting from dioxin and furan emissions has been developed to overcome some of the problems of those currently used. The method is based on evidence that the major determinant of fish dioxin and furan uptake is sediment concentrations. Only two steps are necessary to calculate fish tissue levels. Step 1: Calculation of the concentration of dioxins and furans in particulate matter entering the lake or pond, and hence, the resulting sediment concentration. Step 2: Calculation of fish concentrations utilizing fish-to-sediment ratios for the various dioxin and furan isomers.

Helen M. Goeden

Papers

Cancer risks from arsenic in drinking water.

Current Breast Milk PFAS Levels in the United States and Canada: After All This Time, Why Don’t We Know More?

Erratum: "Potential for Manganese-Induced Neurologic Harm to Formula-Fed Infants: A Risk Assessment of Total Oral Exposure".

Health risk assessment of incinerator air emissions incorporating background ambient air data

Estimation of human exposure from fish contaminated with dioxins and furans emitted by a resource-recovery facility.