Nadakavukaren JJ, Ingermann RL, Jeddeloh G, and Falkowski SJ. “Seasonal Variation of Arsenic Concentration in Well Water in Lane County, Oregon” Bulletin of Environmental Contamination and Toxicology. 1984 Sep; 33(3): 264-269.
Tchounwou PB, Centeno JA, and Patlolla AK. “Arsenic Toxicity, Mutagenesis, and Carcinogenesis—A Health Risk Assessment and Management Approach.” Molecular and Cellular Biochemistry. 2004 Jan; 255(1-2): 47-55.
(reviewed by Grace Wang)
The Nadakavukaren et al. paper describes a study of variations of arsenic concentrations of water samples from 14 water wells in rural areas of Lane County conducted over a period of 13 months in 1975 and 1976. The 14 wells in this study serve local residents for garden, irrigation, and domestic purposes. They are chosen for this study based on a history of high arsenic levels, though none is near agricultural arsenic sources. The authors use atomic absorption spectroscopy to measure arsenic levels in water samples. In most of the wells, they report an observed general trend of fluctuating arsenic levels following a seasonal pattern: higher in summer, lower in winter. In many of the wells, the arsenic concentration reaches as high as 2 ppm, greatly exceeding the maximum limit of 0.05 ppm set by the U.S. Public Health Service. Furthermore, the varying pattern coincides with rainfall pattern in the area (high precipitation in winter, low in summer). To determine whether or not the lower arsenic level in winter is due to surface rainwater dilution, they measure the concentration of coliform bacteria, which are associated with surface water. The results suggest that dilution was not a significant factor in the drop of well-water arsenic level in winter. A few wells do not follow the trend, their arsenic levels remain constant throughout the study. The authors concluded that well water arsenic concentration in Lane County vary seasonally. While they suggest that aquifer, water usage, and water depth may contribute to the observed variations, they do not have enough evidence to accurately determine the cause of variations.
Tchounwou et al. present a comprehensive review of the effect of arsenic on human health and current methods of risk assessment and management. People in many areas of the world are subject to chronic arsenic exposure. Arsenic comes from both industrial and natural sources. Exposure to arsenic by inhalation, dermal contact, and ingestion can have severe effects on human health, including various forms of cancer, diabetes, cardiovascular diseases. Although precise molecular mechanisms of arsenic's carcinogenic activities are yet unknown, in vitro studies have shown that arsenic inactivates enzymes (particularly mitochondrial enzymes). In addition, it causes genome instability, oxidative stress, altered growth factors, resulting in abnormal cell morphology as observed in cell cultures. The authors urge further study in dose-response relationship between exposure to arsenic and cancer formation. Current research is also studying potential treatments of arsenic poisoning, including a promising chelation treatment.Critique
The Nadakavukaren et al. paper is a good source of historical information. It is relevant to our project because it is specific to our local water supplies. The conclusions of the paper are based on data analysis, thus is reliable. However, the major drawback of the study is that although it offers a trend in seasonal variation of arsenic levels in well water, it does not provide adequate explanation of the observations. Furthermore, this study was conducted thirty years ago. Since then, there have been changes in water regulation, pollution sources, and possibly precipitation patterns; these changes could cause a change in current arsenic variation patterns. Also, it does not directly address arsenic levels in the Willamette River. It would be helpful to find a follow-up study, or a similar study of water in the Willamette River. Also, the paper would be more valuable if additional geographical sources of groundwater distribution can show a positive relationship between well water in Lane County and the Willamette River.
The Tchounwou et al. review is an excellent supplementary paper to the Nadakavukaren et al. paper. While the previous paper reveals that arsenic is found in local water supplies, this review directly addresses the effects of arsenic (especially arsenic in drinking water) on human health. The reported findings should be reliable because they consist of results from many different laboratories. Since this study is published in 2004, the information is up to date. This paper provides excellent descriptions of diseases caused by arsenic poisoning, and even some molecular mechanisms of arsenic activity in biological systems. Also, it covers a broad range of topics, from arsenic pollution sources and effects on humans to exposure assessment and risk management. One drawback is that the language is fairly scientific and the text includes many jargons, such that it may be difficult for readers who are not familiar with background knowledge in chemistry, molecular biology, and physiology.
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