Arsenic-containing well water may be to blame for increased rates of bladder cancer in New England, according to a new study published by the National Cancer Institute on Monday. Bladder cancer is 20 percent higher in populations residing in New Hampshire, Main, and Vermont, where a significant portion of the population depends on private wells.
Researchers from Dartmouth College and the state Department of Health and Human Services found that private dug wells, generally less than 50 feet deep, are more susceptible to arsenic contamination, and basically, the older the well, the more dangerous it is.
There are a few ways arsenic enters the environment. It can be released naturally via volcanic activity and forest fires, eventually seeping into the soil. Or it can be introduced through industrial processes such as product production, commercial farming, mining, and smelting. Arsenic is found in many metals, as well as paints, dyes, soaps, and semiconductors.
Arsenic contamination may also occur as a result of pesticide use. From 1920 to 1950, arsenic-based pesticides were sprayed heavily on crops such as apples, blueberries, and potatoes, according to the National Institute of Health. Research suggests that the arsenic in pesticides may have leached into groundwater, and eventually the tap.
Previous research shows drinking water with high arsenic levels increases the risk for bladder cancer. The NIH says even low to moderate levels of arsenic can cause cancer.
In this study, scientists found the longer people drink the water, the higher their risk becomes, among both men and women.
Individuals who consumed the most well water had nearly twice the risk of developing bladder cancer compared to those who drank the least, say scientists. The correlation was even stronger in people who drank water from dug wells, specifically.
“Most of the dug well use occurred a long time ago, during an era when arsenic concentrations in private well water were largely unknown. However, the risk was substantially higher if the dug well use began before 1960 (when application of arsenic-based pesticides was commonplace in this region) than if dug well use started later,” said NIH.
Arsenic-based pesticides were deemed unsafe by the U.S. Environmental Protection Agency in 2006 and were largely phased out over the next three years. In July 2010, the EPA announced that the cancer causing effects of inorganic arsenic were “much higher than previously thought,” due to an increase in cancer diagnoses tied to arsenic exposure.
Households living on private wells are more vulnerable to contamination because the wells are not subjected maintenance by municipalities or federal regulations. For protection, NIH encourages residents to test their well every three years.
“There are effective interventions to lower arsenic concentrations in water,” said the study’s author Debra Silverman, Sc.D., chief of the Occupational and Environmental Epidemiology Branch, NCI. “However, emerging evidence suggests that low to moderate levels of exposure may also increase risk,” she added.
The maximum level of arsenic allowed in drinking water is 10 micrograms per liter.