How are people exposed to arsenic?
Arsenic occurs naturally in the environment, as well as being present in some man-made products. We normally take in small amounts in the air we breathe, the water we drink, and the food we eat. Most arsenic compounds have no smell or taste, so usually you can’t tell if arsenic is in your air, food, or water. People who live near current or former industrial or agricultural sources of arsenic can be exposed to higher levels by inhaling fumes or eating contaminated food. People can also take in higher levels of arsenic if they live in areas where arsenic levels are naturally high in the drinking water or if they eat a lot of rice or seafood.
For most people, food is the largest source of arsenic, although much of this is likely to be in the less dangerous, organic form. The highest levels of arsenic (in all forms) in foods can be found in seafood, rice, rice cereal (and other rice products), mushrooms, and poultry, although many other foods can contain low levels of arsenic. Rice is of particular concern because it is a major part of the diet in many parts of the world. It is also a major component of many of the cereals eaten by infants and young children. (Nearly all rice products have been found to contain at least some arsenic, although the levels can vary widely.)
In drinking water
Drinking water is an important and potentially controllable source of arsenic exposure. In fact, drinking water is a major source of arsenic exposure in some parts of the world. Water in some areas of the United States, especially in the West, also naturally contains arsenic. Most US areas with higher levels of arsenic in drinking water are rural communities. Albuquerque, New Mexico, is the only urban area in the US with substantial natural arsenic levels in drinking water. Arsenic levels tend to be higher in drinking water that comes from ground sources, such as wells, as opposed to water from surface sources, such as lakes or reservoirs.
Arsenic levels in public drinking water are regulated in the United States by the Environmental Protection Agency (EPA). Since January 2006, the maximum level of arsenic allowed in US drinking water is 10 μg/L (micrograms per liter), or 10 ppb (parts per billion). However, in states like North Carolina drinking water has been found to have 10 times the maximum level of arsenic allowed.
Arsenic has not been produced in the United States since 1985, although it is imported from other countries. In the past, workers in smelters and in plants that manufactured, packaged, or distributed products that contained arsenic had high exposures from breathing in arsenic fumes and dust.
Arsenic was a common ingredient in many pesticides and herbicides in the past. People who made, transported, applied, or worked around these products may have been exposed to higher levels of arsenic. Inorganic arsenic compounds have not been used in pesticides in the US since 1993, and organic compounds have been phased out of pesticides (with one exception used on cotton plants) as of 2013.
Today workplace exposure to arsenic can still occur in some occupations that use arsenic, such as copper or lead smelting, and wood treating. Regulations in place can help limit this workplace exposure.
In pressure-treated wood
Chromated copper arsenate (CCA) is a chemical preservative that helps protect wood from rot and insects. It was used to pressure-treat lumber that was used in some home foundations, decks, fences, playgrounds (play sets), and other structures for many decades. In fact, starting in the 1970s, most of the wood used in residential settings was CCA-treated wood.
The use of CCA in pressure-treated lumber for most residential uses was stopped at the end of 2003 although it is still used for industrial purposes. This was done because of concerns that some of the arsenic might leach out of the wood and enter the soil or be absorbed through the skin when the wood is touched. Wood that is frequently touched by children, such as that found in some playground equipment is a special concern.
People can also be exposed to arsenic by breathing in sawdust from cut arsenic-preserved wood or by breathing the smoke from burning this wood.
Pressure-treated lumber for residential uses is now made with other compounds that do not contain arsenic. However, any structures built from lumber that was pressure-treated before 2004 may still contain CCA.
What can high levels of arsenic exposure do to the human body?
Long-term exposure to arsenic in drinking-water is causally related to increased risks of cancer in the skin, lungs, bladder and kidney, as well as other skin changes such as hyperkeratosis (thickening of the skin) and pigmentation changes. These effects have been demonstrated in many studies using different study designs. Exposure–response relationships and high risks have been observed for each of these end-points.
Occupational exposure to arsenic, primarily by inhalation, is causally associated with lung cancer.
What other problems can arsenic cause?
Soluble inorganic arsenic is acutely toxic, and ingestion of large doses leads to gastrointestinal symptoms, disturbances of cardiovascular and nervous system functions, and eventually death.
Chronic arsenic exposure in Taiwan has been shown to cause blackfoot disease (BFD), a severe form of peripheral vascular disease (PVD) which leads to gangrenous changes. This disease has not been documented in other parts of the world, and the findings in Taiwan may depend upon other contributing factors. However, there is good evidence from studies in several countries that arsenic exposure causes other forms of PVD.
Conclusions on the causality of the relationship between arsenic exposure and other health effects are less clear-cut. The evidence is strongest for hypertension, cardiovascular disease, diabetes, and reproductive effects.
The American Cancer Society - https://www.cancer.org/cancer/cancer-causes/arsenic.html