A chronic problem
Arsenic has been notoriously used as a poison since ancient times. A fatal poisoning would require a single dose of inorganic arsenic about the weight of a postage stamp. But chronic toxicity can result from long-term exposure to much lower levels in food, and even to water that meets the 10-ppb drinking-water limit.
A 2004 study of children in Bangladesh (PDF) suggested diminished intelligence based on test scores in children exposed to arsenic in drinking water at levels above 5 ppb, says study author Joseph Graziano, Ph.D., a professor of environmental health sciences and pharmacology at Columbia University. He’s now conducting similar research with children living in New Hampshire and Maine, where arsenic levels of 10 to 100 ppb are commonly found in well water, to determine whether better nutrition in the United States affects the results.
People with private wells may face greater risks than those on public systems because they’re responsible for testing and treating their own water. In Maine, where almost half the population relies on private wells, the USGS found arsenic levels in well water as high as 3,100 ppb.
And a study published in 2011 (PDF) in the International Journal of Environmental Research and Public Health examined the long-term effects of low-level exposure on more than 300 rural Texans whose groundwater was estimated to have arsenic at median levels below the federal drinking-water standard. It found that exposure was related to poor scores in language, memory, and other brain functions.
Symptoms of chronic exposure
Chronic arsenic exposure can initially cause gastrointestinal problems and skin discoloration or lesions. Exposure over time, which the World Health Organization says could be five to 20 years, could increase the risk of various cancers and high blood pressure, diabetes, and reproductive problems.
Signs of chronic low-level arsenic exposure can be mistaken for other ailments such as chronic fatigue syndrome. Usually the connection to arsenic exposure is not made immediately, as Sharyn Duffy of Geneseo, N.Y., discovered. She visited a doctor in 2007 about pain and skin changes on the sole of her left foot. She was referred to a podiatrist and eventually received a diagnosis of hyperkeratosis, in which lesions develop or thick skin forms on the palms or soles of the feet. It can be among the earliest symptoms of chronic arsenic poisoning. But she says it was roughly two years before she was finally referred to a neurologist, who suggested testing for arsenic. She had double the typical levels.
“Testing for arsenic isn’t part of a routine checkup,” says Duffy, a retiree. “When you come in with symptoms like I had, ordering that kind of test probably wouldn’t even occur to most doctors.”
Michael Harbut, M.D., chief of the environmental cancer program at Karmanos Institute in Detroit, says, “Given what we know about the wide range of arsenic exposure sources we have in this country, I suspect there is an awful lot of chronic, low-level arsenic poisoning going on that’s never properly diagnosed.”
Emerging research suggests that when arsenic exposure occurs in the womb or in early childhood, it not only increases cancer risks later in life but also can cause lasting harm to children’s developing brains and endocrine and immune systems, leading to other diseases, too.
Case in point: From 1958 through 1970, residents of Antofagasta, Chile, were exposed to naturally occurring arsenic in drinking water (PDF) that peaked at almost 1,000 ppb before an arsenic removal plant was installed. Studies led by researchers at the University of California at Berkeley found that people born during that period who had probable exposure in the womb and during early childhood had a lung-cancer death rate six times higher than those in their age group elsewhere in Chile. Their rate of death in their 30s and 40s from another form of lung disease was almost 50 times higher than for people without that arsenic exposure.
“Recent studies have shown that early-childhood exposure to arsenic carries the most serious long-term risk,” says Joshua Hamilton of the Marine Biological Laboratory. “So even though reducing arsenic exposure is important for everyone, we need to pay special attention to protecting pregnant moms, babies, and young kids.”
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