How many people who grew up drinking from a well have bothered to test the level of arsenic in their drinking water?
According to a University of Maine alumnus, that knowledge could be a matter of life and death.
Bruce Stanton, director of the Center for the Environmental Health Sciences at Dartmouth Medical School, sought to bring some of the dangers associated with arsenic to light Feb. 23 with a speech titled “Arsenic: A global public health crisis.”
“150,000 Mainers … drink well water that is contaminated with arsenic,” Stanton said to roughly 50 individuals gathered in the McIntire Room of the Buchanan Alumni House.
Stanton’s talk was part of the Distinguished Honors Graduate Lecture series, established in 2002 to highlight the accomplishments of Honors College alumni.
The World Health Organization, the Environmental Protection Agency and the Centers for Disease Control all list arsenic as the No. 1 agent of concern to public health, having linked chronic exposure to the toxin to increased chances of contracting several types of cancer, diabetes, childhood learning disabilities, heart disease, reproductive difficulties and other serious medical maladies.
As of 2001, the EPA lists the acceptable level of arsenic in drinking water as 10 parts per billion, or one arsenic molecule for every billion of water.
If evaluated by the standards used to regulate other toxins, the amount of allowable arsenic may still be too high — tests have concluded one in a million individuals will show negative health repercussions from as little as .045 parts per billion.
“When you expose mice to 10 parts per billion, their ability to reproduce went down by 50 percent,” Stanton said.
Stanton explained that when the EPA adjusted the level to 10 parts per billion in 2001 — for the roughly 100 years prior, it had been 50 parts per billion — a cost-benefit analysis played a key role.
“They actually wanted it to be five [parts per billion], but it would be too expensive,” Stanton said. “It would have been too expensive to treat public water supplies, so 10 was decided.”
For Mainers, the main culprit when it comes to arsenic contamination is private wells, the majority of which go untested by their owners. Stanton referred to a study that found one in 10 of Maine’s private wells have levels of arsenic higher than the EPA-accepted level.
“Public water supplies are regulated — private wells are not,” Stanton said. “So that’s where Mainers are getting the arsenic.”
That study also found wells with arsenic levels as high as 5,000 parts per billion, with the highest concentration of contamination in the Machias area. Stanton characterized wells with levels exceeding 100 parts per billion as “not uncommon.”
While surface reservoirs like lakes usually carry low levels of the toxin, Maine’s reliance on groundwater sources locked up in bedrock formations affects the amount of arsenic in two ways.
First, the water that is eventually drawn by wells comes into direct contact with veins of arsenic in the rock, a problem not usually seen with surface aquifers. Second, since many bedrock aquifers are isolated from surrounding wells, the amount of arsenic can vary drastically from location to location.
“Just because your neighbor’s well is safe does not mean your well is safe,” Stanton said.
“The odd thing is, when we move up here to New Hampshire or to Maine, we come here because of the pristine environment,” he said.
Outside of the Pine Tree State, a major player in arsenic exposure is found in one of the more widely eaten staple foods worldwide: rice.
“Rice cereals and biscuits have levels of inorganic arsenic which could easily be consumed in doses well above that found in drinking water,” Stanton said.
Rice plants utilize environmental silicone to form supporting stems, drawn from the waterlogged fields in which they grow. However, in areas where the water supply contains high levels of arsenic, the plants take up the more abundant toxin along with silicone, leaving large amounts in the harvested grain.
This accumulation can leave toxin levels in one cup of rice equivalent to that found in one liter of water contaminated with 10 parts per billion of arsenic.
The problem with rice becomes even more difficult to regulate when one considers the amount of processed foods that use the grain as a base. Stanton held up a container of organic baby food to illustrate his point: The pesticide-free claims made on the container lull the consumer into a false sense of security about the product’s safety.
Those on restricted diets should be especially aware of their food choices’ ingredients.
“Some people on special diets drink rice milk,” Stanton said. “Rice milk has been measured at 50 parts per billion.”
For those who do find their water sources to be contaminated, the case is not without hope. Stanton briefly discussed both point-of-entry and point-of-use water treatment systems, which filter out arsenic from contaminated well water.
Successes have also been seen in the agricultural sector, where silicone- or iron-enriched soils have been shown to reduce the uptake of arsenic by rice plants.
For Stanton, however, the easiest solution is the best.
“Like they say in toxicology, ‘It’s the dose that makes the poison,’” he said. “Like everything else, you try to minimize your exposure to toxins.”