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

Heavy metal toxicity has proven to be a major threat and there are several health risks associated with it. The toxic effects of these metals, even though they do not have any biological role, remain present in some or the other form harmful for the human body and its proper functioning. They sometimes act as a pseudo element of the body while at certain times they may even interfere with metabolic processes. Few metals, such as aluminium, can be removed through elimination activities, while some metals get accumulated in the body and food chain, exhibiting a chronic nature. Various public health measures have been undertaken to control, prevent and treat metal toxicity occurring at various levels, such as occupational exposure, accidents and environmental factors. Metal toxicity depends upon the absorbed dose, the route of exposure and duration of exposure, i.e. acute or chronic. This can lead to various disorders and can also result in excessive damage due to oxidative stress induced by free radical formation. This review gives details about some heavy metals and their toxicity mechanisms, along with their health effects.

https://sciendo.com/pdf/10.2478/intox-2014-0009

Toxicity, mechanism and health effects of some heavy metals

Approximately 200 studies that examined the relationship between fruit and vegetable intake and cancers of the lung, colon, breast, cervix, esophagus, oral cavity, stomach, bladder, pancreas, and ovary are reviewed. A statistically significant protective effect of fruit and vegetable consumption was found in 128 of 156 dietary studies in which results were expressed in terms of relative risk. For most cancer sites, persons with low fruit and vegetable intake (at least the lower one-fourth of the population) experience about twice the risk of cancer compared with those with high intake, even after control for potentially confounding factors. For lung cancer, significant protection was found in 24 of 25 studies after control for smoking in most instances. Fruits, in particular, were significantly protective in cancers of the esophagus, oral cavity, and larynx, for which 28 of 29 studies were significant. Strong evidence of a protective effect of fruit and vegetable consumption was seen in cancers of the pancreas and stomach (26 of 30 studies), as well as in colorectal and bladder cancers (23 of 38 studies). For cancers of the cervix, ovary, and endometrium, a significant protective effect was shown in 11 of 13 studies, and for breast cancer a protective effect was found to be strong and consistent in a meta analysis. It would appear that major public health benefits could be achieved by substantially increasing consumption of these foods.

Fruit, vegetables, and cancer prevention: A review of the epidemiological evidence

Arsenic removal from water/wastewater using adsorbents—A critical review

Arsenic round the world: a review.

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.

/pdf/contamination-of-drinking-water-by-arsenic-in-bangladesh-a-15o8nvbvr0.pdf

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

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.

Studies in Taiwan and Argentina suggest that ingestion of inorganic arsenic from drinking water results in increased risks of internal cancers, particularly bladder and lung cancer. The authors investigated cancer mortality in a population of around 400,000 people in a region of Northern Chile (Region II) exposed to high arsenic levels in drinking water in past years. Arsenic concentrations from 1950 to the present were obtained. Population-weighted average arsenic levels reached 570 microg/liter between 1955 to 1969, and decreased to less than 100 microg/liter by 1980. Standardized mortality ratios (SMRs) were calculated for the years 1989 to 1993. Increased mortality was found for bladder, lung, kidney, and skin cancer. Bladder cancer mortality was markedly elevated (men, SMR = 6.0 (95% confidence interval (CI) 4.8-7.4); women, SMR = 8.2 (95% CI 6.3-10.5)) as was lung cancer mortality (men, SMR = 3.8 (95% CI 3.5-4.1); women, SMR = 3.1 (95% CI 2.7-3.7)). Smoking survey data and mortality rates from chronic obstructive pulmonary disease provided evidence that smoking did not contribute to the increased mortality from these cancers. The findings provide additional evidence that ingestion of inorganic arsenic in drinking water is indeed a cause of bladder and lung cancer. It was estimated that arsenic might account for 7% of all deaths among those aged 30 years and over. If so, the impact of arsenic on the population mortality in Region II of Chile is greater than that reported anywhere to date from environmental exposure to a carcinogen in a major population.

/pdf/marked-increase-in-bladder-and-lung-cancer-mortality-in-a-3dtrjph0gl.pdf

Marked Increase in Bladder and Lung Cancer Mortality in a Region of Northern Chile Due to Arsenic in Drinking Water

Establishment of the maximum contaminant level that regulates the concentration of arsenic in public water supplies has been an extraordinarily protracted process. The U.S. Public Health Service set an interim standard of 50 mg per liter in 1942. It was another 60 years before the U.S. Environmental Protection Agency lowered the standard to 10 mg per liter, despite extensive epidemiological evidence of significant cancer risks. [ Smith et al .][1] of this Policy Forum consider how the regulatory process might interpret and respond more effectively to results from epidemiological studies.

 [1]: http://www.sciencemag.org/cgi/content/full/296/5576/2145

https://science.sciencemag.org/content/sci/296/5576/2145.full.pdf

Arsenic Epidemiology and Drinking Water Standards

An environmental tragedy is developing in West Bengal, India where a large population is drinking arsenic-contaminated water, and an alarming number of toxicity cases associated with ingestion of arsenic-contaminated drinking water have been reported. The source of the contamination is geological; arsenic Background A cross-sectional survey was conducted between April 1995 and March 1996 to investigate arsenic-associated skin lesions of keratosis and hyperpigmentation in West Bengal, India, and to determine their relationship to arsenic water levels. Methods In all, 7683 participants were examined and interviewed, and the arsenic levels in their drinking water measured. Results Although water concentrations ranged up to 3400 µg/l of arsenic, over 80% of participants were consuming water containing ,500 µg/l. The age-adjusted pre- valence of keratosis was strongly related to water arsenic levels, rising from zero in the lowest exposure level (,50 µg/l) to 8.3 per 100 for females drinking water containing .800 µg/l, and increasing from 0.2 per 100 in the lowest exposure category to 10.7 per 100 for males in the highest exposure level (>800 µg/l). However, 12 cases with keratosis (2 females and 10 males) were drinking water containing ,100 µg/l of arsenic. Findings were similar for hyperpigmentation, with strong dose-response relationships. Among those with hyperpigmentation, 29 cases were exposed to drinking water containing ,100 µg/l. Calculation by dose per body weight showed that men had roughly two to three times the pre- valence of both keratosis and hyperpigmentation compared to women apparently ingesting the same dose of arsenic from drinking water. Subjects who were below 80% of the standard body weight for their age and sex had a 1.6 fold increase in the prevalence of keratoses, suggesting that malnutrition may play a small role in increasing susceptibility. Conclusion The surprising finding of cases who had arsenic-associated skin lesions with apparently low exposure to arsenic in drinking water needs to be confirmed in studies with more detailed exposure assessment. Further research is also needed concerning susceptibility factors which might be present in the exposed population.

Allan H. Smith

Papers

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

Cancer risks from arsenic in drinking water.

Marked Increase in Bladder and Lung Cancer Mortality in a Region of Northern Chile Due to Arsenic in Drinking Water

Arsenic Epidemiology and Drinking Water Standards

Arsenic levels in drinking water and the prevalence of skin lesions in West Bengal, India