Science has long known that arsenic is toxic to humans. Exposure to high doses over a brief period can lead rapidly to organ failure and death. At lower doses over a longer time, arsenic exposure is associated with cancer, diabetes, impaired neurological development, behavioral changes and more.
But the mechanism of arsenic’s toxicity is poorly understood. To complicate matters, it appears that some of the same qualities that make it so deadly may actually have a therapeutic effect in specific circumstances. And, importantly, since arsenic is all around us, most people have some exposure.
At the University of Maine’s Department of Molecular and Biomedical Sciences, professors Carol Kim and Julie Gosse are learning more about arsenic and the ways it functions in the body. By advancing scientific understanding of its mechanisms, they hope to promote science-based environmental regulations and medical interventions that can mitigate arsenic’s toxic effects.
Like its elemental cousins lead and mercury, arsenic (As) is found in naturally occurring deposits from which it leaches into water and soils. It also can be released more rapidly into the environment through natural processes, such as volcanic activity and erosion, and through human activity such as mining and agriculture.
Arsenic is found in manufactured products as well, including wood preservatives, paints, dyes, metals, soaps and medicines, and workers in these industries may be exposed. Arsenic-containing waste is present in many landfills and dumps. In some cultures, arsenic in high doses has been used as an effective therapy for acute asthma attacks, although its mechanism has been poorly understood and its therapeutic value is offset by its long-term risks.
In Maine, arsenic is present in many public and private water supplies, most often at levels below the 10 parts per billion (ppb) cap designated as “safe” by the U.S. Environmental Protection Agency, following a 2001 rule change that took effect in 2006. Prior to this change, the EPA’s allowable standard was 50 ppb.
Public water supplies are closely monitored for arsenic and that information is available to the public through individual water utilities and the governmental agencies that oversee them. But private wells are unregulated and may contain much higher levels. Concerns remain that exposure to arsenic over time — even at very low levels, perhaps below the current 10 ppb limit — poses a significant and pernicious risk to human health.