Worldwide, cardiovascular disease is the leading cause of death. In a growing number of studies that began in Asia where chronic arsenic poisoning is a huge problem it has been found that drinking water contaminated with arsenic increases the risk of cardiovascular disease. The higher the levels of arsenic the higher the death rate. (The risk was significantly increased for anyone who smoked or had ever smoked.) This has been confirmed in recent years in studies performed in Bangladesh, Taiwan, Chile and Mexico. Older studies have linked long-term exposure to arsenic in drinking water to cancer of the bladder, lungs, skin, kidney, nasal passages, liver, and prostate. Non-cancer effects of ingesting arsenic include cardiovascular, pulmonary, immunological, neurological, and endocrine (e.g., diabetes) effects.
Arsenic exposure is not just a risk in Asia and South America. As recently reported in the New York Times a meta-analysis of data from the quarter century of data from the Strong Heart Study of 13 American Indian tribes and communities in three geographic areas: an area near Phoenix, Arizona, the southwestern area of Oklahoma, and western and central North and South Dakota found an association between chronic arsenic exposure and heart disease. The scientists compared urinary arsenic levels in the population and found that as levels of arsenic rose so did the incidence of atherosclerosis, stroke and heart attacks. For those with chronic long term exposure to arsenic the risk of cardiovascular disease could be as high as two times dependent on concentration of arsenic exposure. In general, though, the dose response is about 25% increase in death from cardiovascular disease from each increase in arsenic concentrations by about 115 parts per billion. The U.S. Environmental Protection Agency (EPA) drinking water standard for arsenic in public water supplies is 10 parts per billion.
The Bangladesh study (by Dr. Yu Chen et al) they quantified the relationship between even low levels of arsenic exposure and increased risk of death for smokers. Study participants who were current smokers, had smoked for at least 20 years, or had smoked for at least 10 pack years at the beginning of the study were found to be 2.2-2.7 times more likely to die from heart disease.
Arsenic is a ubiquitous metal in the earth’s crust. Arsenic occurs naturally in rocks and soil, water, air, and plants and animals. It can be further released into the environment through natural activities such as volcanic action, erosion of rocks, and forest fires, or through the use of arsenic by mankind. In the United States arsenic is still widely used as a wood preservative, but arsenic is also used in paints, dyes, metals, drugs, soaps, and semi-conductors. Agricultural use in fertilizer, mining, and smelting also have contributed to arsenic releases in the environment. People are also exposed to elevated levels of arsenic through diet.
Higher levels of arsenic tend to be found more in ground water sources than in surface water sources of drinking water like rivers and lakes. Compared to the rest of the United States, western states have higher naturally occurring arsenic levels- more groundwater basins have arsenic levels higher than the 10 ppb level the EPA has identified as safe. Parts of the Midwest and New England also have some areas where groundwater arsenic concentration are greater than 10 ppb, sometimes much greater. Though the EPA regulates public water supplies, in private wells (used by 13% of the U.S. population) you are on your own for ensuring that your water is safe. The USGS believes most groundwater basins have natural arsenic concentrations that range from 2-10 ppb (the most common testing method is accurate to 5 ppb). While many groundwater systems may not have detected arsenic in their water above 10 ppb, groundwater is not uniformly mixed like surface water. The USGS states ther may be geographic "hot spots" that may have higher levels of arsenic than the predicted occurrence for that area. You should test your groundwater to know it.
The most common source of arsenic contamination in ground water is the mobilization of naturally occurring arsenic on sediments. Given the right chemical conditions in the subsurface arsenic can dissolve into ground water used for drinking water. The U.S. Geological Survey (USGS) scientists have been conducting field experiments to understand the bio-geochemical processes that control arsenic mobility in ground water and might create hot spots or regions of elevated concentration of arsenic. Recent results published in the Journal of Contaminant Hydrology, show that chemical reactions between nitrate, iron, and oxygen can affect the mobility of trace amounts of arsenic. Septic systems can increase the nitrate level of groundwater. Site specific conditions, impact from your neighbors, or historic use of arsenic containing pesticides can impact the quality of your drinking water. Test you well, regularly so that you can take actions to protect your health (and don’t smoke).