Arsenic Link to Diabetes Strengthens With Each New Study
By Terri Hansen
Arsenic, even for a poison, is one nasty brew. Long-term ingestion of the metallic substance can result in thickening and discoloration of the skin, stomach pain, nausea, vomiting, diarrhea, numbness in hands and feet, partial paralysis and blindness. The U.S. Environmental Protection Agency (EPA) classifies inorganic arsenic as a Group A human carcinogen, and since the ‘90s, exposure to it has been linked to an increased risk of diabetes mellitus.
New findings by a group of scientists add support for the theory that there is a link between arsenic and diabetes. Two of the studies co-authors are on an expert panel of the U.S. Department of Health and Human Services National Toxicology Program investigating the link between environmental chemicals and diabetes and obesity.
“Our panel of experts who met last January concluded there is sufficient evidence to link high arsenic exposure in drinking water to diabetes,” said the study’s principal investigator Miroslav Styblo, Ph.D., a biochemist and associate professor with the Department of Nutrition, University of North Carolina at Chapel Hill. “With low levels, there is significant uncertainty. Our data also suggests that if you have certain genetic makeup you are at higher risk.”
Styblo said typical exposure rates in the U.S. are lower than in most studies found to be associated with diabetes.
Arsenic occurs naturally in bedrock and soil, and is released through natural activities like volcanic action. Ninety percent of industrial arsenic in the U.S. is used as a wood preservative. Mining, smelting, and agriculture also contribute to arsenic releases.
To protect consumers of public water systems from the effects of long-term, chronic exposure to arsenic the EPA lowered the arsenic standard for drinking water from 50 parts per billion to 10 ppb in 2001.
Styblo and eight other scientists studied populations in the Zimapan and Lagunera regions of Mexico to determine whether exposure to arsenic in drinking water is correlated with increased prevalence of diabetes. Their research was published August 24 in the journal Environmental Health, and is “very relevant” for the Native American population, said study co-author Dana Loomis, Ph.D., an epidemiologist and professor and chair of the Department of Epidemiology and Eppley Cancer Institute, University of Nebraska Medical Center, in Omaha.
“Most American Indians are living in the Western U.S.,” Loomis said. “It’s in that part of the country that elevated areas of arsenic exposures are found. It’s incorporated into the bedrock geology. Because of the way desert water systems work the concentrations can be enhanced, especially in arid parts of the West.”
Arizona, Utah, Nevada, and California in particular are worrisome areas for arsenic contamination. A further report adds the states of Washington and Alaska to the list.
The Navajo Nation has 270,000 federally recognized members living on its sprawling 26,000 square mile reservation on parts of northeastern Arizona, southeastern Utah, and northwestern New Mexico. One-quarter of reservation homes lack utilities. Water supplies that do not meet U.S. Safe Drinking Water Act standards, particularly in the rural and remote areas of the reservation are of heightened concern.
“There are some high contents of arsenic known on the Navajo Nation,” said George Breit, Ph.D., a geologist with the Denver, Colorado U.S. Geological Survey, and one of the world’s leading experts on arsenic contamination in groundwater. Breit cites a study of the area of Hopi Buttes T’sezhin Bii that reported several rock samples with more than 100 ppm.
Breit said all earth materials contain some arsenic; whether it can be transferred to water depends the reactivity of its binding phase when placed in a different environment than the one in which it originally formed.
“There are four general environments in which arsenic is present in sufficient concentrations in ground water to be of concern,” Breit said. “The Navajo Nation has environments in which all four of these mechanisms may exist.”
The Navajo Tribal Utility Authority is the only provider of drinking water for its reservation-based tribal members that meet the requirements of the Safe Drinking Water Act. Although the utility is extending its system, unregulated water is still the only water source for one-quarter of the homes on the reservation.
When the Din’e Environmental Institute of the Din’e College and the University of Nevada tested unregulated water supplies in 2008, they found that levels of arsenic and other contaminants including uranium exceeded the EPA Maximum Contaminant Levels.
The Din’e Environmental Institute tested water supplies in the eastern region of the Navajo Nation during the past four summers. “We typically test water in the livestock wells because a lot of people are still not hooked up to water supplies,” said Din’e College chemistry teacher Barbara Klein. “Even though the wells might not be potable, they end up drinking from it. Our focus is uranium, but at the same time we do test for arsenic.”
The teachers and students choose an area, and test livestock wells, artesian wells, and springs. “We typically test for bacteria,” Klein said. “Samples are sent for testing for heavy metals. We pay most attention to arsenic and uranium.” (Klein said they’ve found dangerously high levels of uranium in areas where there are a lot of reclaimed and un-reclaimed uranium mines.)
When the EPA, Indian Health Service, DHHS, U.S. Centers for Disease Control and Prevention (CDC), NTUA, and Navajo representatives formed the Navajo Access Workgroup to undertake a 2010 project to map the water infrastructure, their results indicated a funding need for a ‘Shiprock to Sweetwater’ project to address high arsenic in the source water of a swath of 1,001 homes.
Water safety is the focus of Forgotten Peoples, a grassroots non-governmental organization incorporated on the Navajo Nation. Program director Marsha Monestersky said their advocacy resulted in the Navajo Nation issuing a Declaration of Public Health Emergency in the Black Falls/Box Springs region in the southern portion of the western agency of the Navajo Nation in January of 2010. “We have the EPA test results and the data that show all the water sources in [that region] exceed EPA standards for arsenic and uranium,” she said. Their organization received an Environmental Excellence award from the Navajo Nation EPA in 2009, and a $20,000 environmental justice grant from the EPA that same year.
“Our job is really hard because a lot of people we’re working with have cancer, and there’s a lot of diabetes,” Monestersky said. “Every time they build a dialysis center it can’t accommodate all the patients, the need is so great.”
Arsenic is a concern elsewhere. The Fort McDowell Yavapai Nation in Arizona objected to the Southeast Land Exchange and Conservation Program two years ago in part because the subsequent new mining would expose the tribal community to, “abundant deposits of … poisonous arsenic.”
Arsenic got top billing on the Tohono O’odham Nation’s list of environmental health threats in their Comprehensive Cancer Prevention and Control Plan: 2010-2015 sponsored by the CDC. “All Americans,” said TON’s Environment and Cancer Committee in the report, “including the O’odham are entitled to clean water under the Safe Drinking Water Act. Whether arsenic is linked to illness or cancer is not as critical as the fact that low-level chronic exposure to the human body is not a healthy thing.”
At the time of the report arsenic concentrations in their water ranged from trace amounts to 1,000 parts per ppb. At least 23 of their communities have water with elevated levels of arsenic, and 17 of their 35 public water systems have arsenic levels from 10 ppb up to 32 ppb, above the EPA standard for arsenic but considered low compared to other areas in Arizona. Their report also cites an earlier study linking arsenic exposure through drinking water with a higher prevalence of Type 2 diabetes.
TON’s pilot arsenic treatment using iron oxide adsorption reduced arsenic at a public water system from 33 ppb to less than 1 ppb. Andrew Lorentine, their Manager of Community Health Services said since their report was issued they’ve resolved much of the problem.
In Alaska, some of their high arsenic levels occur naturally, and some is produced by military and mining operations, said Pamela Miller, program director for the Alaska Community Action on Toxics.
“At Kivalena’s Red Dog Mine, there is concern that emissions from the mining operations are transmitted atmospherically,” Miller said. “Fish have elevated levels of arsenic in their muscle and liver. A study found that levels found in fish were higher in Alaska than in California. We’re concerned about the levels of arsenic in groundwater, but we also recognize arsenic can be transported in the air, and deposited in waters and taken in by sea creatures important to tribal subsistence.”
Regardless of the arsenic to diabetes link, Styblo said that the primary reason for the diabetes epidemic is U.S. is obesity. “I think it’s fair to say exposures in the U.S. are lower than most studies found to be associated with diabetes. If arsenic contributes, it’s relatively minor. It is possible that arsenic may work with obsesogens, but obesity remains the number one explanation.”
Obesogens are environmental contaminants that promote obesity. Diabetegens promote diabetes. Arsenic does not seem to promote obesity, but acts as a direct diabetegen, Styblo said. Other organic and inorganic compounds are also thought to cause diabetes. “Most of them seem to promote obesity first; diabetes is a secondary effect, i.e. resulting from obesity.”
The significance, Styblo said, “is because we have tens of millions people worldwide who are exposed to high arsenic, so it’s still affecting a very large number of people. Arsenic is known as a carcinogen; it’s only recently people like us that became interested in its toxicology.” Loomis agrees, “Even a minor cause is important when large numbers of people are exposed to it.”