Arsenic occurs naturally in rocks and soil, water, air, and plants and animals. It can be further released into the environment through natural activities such as volcanic action, erosion of rocks and forest fires, or through human actions. Approximately 90 percent of industrial arsenic in the U.S. is currently used as a wood preservative, but arsenic is also used in paints, dyes, metals, drugs, soaps and semi-conductors. High arsenic levels can also come from certain fertilizers and animal feeding operations. Industry practices such as copper smelting, mining and coal burning also contribute to arsenic in our environment.
Higher levels of arsenic tend to be found more in ground water sources than in surface water sources (i.e., lakes and rivers) of drinking water. The demand on ground water from municipal systems and private drinking water wells may cause water levels to drop and release arsenic from rock formations. Compared to the rest of the United States, western states have more systems with arsenic levels greater than EPA’s standard of 10 parts per billion (ppb). Parts of the Midwest and New England have some systems whose current arsenic levels are greater than 10 ppb, but more systems with arsenic levels that range from 2-10 ppb. While many systems may not have detected arsenic in their drinking water above 10 ppb, there may be geographic “hot spots” with systems that may have higher levels of arsenic than the predicted occurrence for that area
Why should I be concerned about
arsenic in my drinking water?
Although short-term exposures to high doses (about
a thousand times higher than the drinking water
standard) cause adverse effects in people, such
exposures do not occur from public water supplies
in the U.S. that comply with the arsenic MCL.
Some people who drink water containing arsenic in
excess of EPA’s standard over many years could
experience skin damage or problems with their
circulatory system, and may have an increased risk
of getting cancer. Health effects might include:
Thickening and discoloration of the skin, stomach
pain, nausea, vomiting, diarrhea, and liver effects;
reproductive, and endocrine (e.g.,
diabetes) effects; Cancer of the bladder, lungs, skin, kidney, nasal
passages, liver, and prostate.