What is arsenic

Arsenic is a highly poisonous naturally occurring chemical element found in air, water, food and soil; for most people, food is the major source of arsenic exposure. Arsenic can also be found due to contamination from human activity. Arsenic compounds are used to preserve wood, as pesticides, and in some industries. Arsenic can get into air, water, and the ground from wind-blown dust. Arsenic may also get into water from runoff. According to a 1999 study by the National Academy of Sciences, arsenic can cause bladder, lung, and skin cancer and may cause kidney and liver cancer ¹. Based on findings of increased risks of bladder- and lung-cancer mortality in three countries (Taiwan, Argentina, and Chile), the National Academy of Sciences subcommittee believes that the evidence is now sufficient to include bladder and lung cancer among the cancers that can be caused by ingestion of inorganic arsenic. The study also found that arsenic harms the central and peripheral nervous systems, as well as heart and blood vessels, and causes serious skin problems. Arsenic also may cause birth defects and reproductive problems. These health impacts are caused when arsenic contaminates drinking water supplies. Arsenic enters water supplies either from natural deposits in the earth or from industrial and agricultural pollution. Inorganic arsenic is a confirmed carcinogen and is the most significant chemical contaminant in drinking-water globally.

Arsenic can be found in either organic or inorganic forms:

• Inorganic arsenic: Inorganic arsenic compounds are found in soils, sediments, and groundwater and is sometimes found in low levels in food. Inorganic arsenic occur either naturally or as a result of mining, ore smelting, and industrial use of arsenic. In the past, inorganic forms of arsenic were used in pesticides, primarily on cotton plants and paint pigment. They were also used as wood preservatives and as a treatment for a variety of ailments. Today, usage of arsenic-containing pesticides and wood preservatives is restricted. The Environmental Protection Agency (EPA) has classified inorganic arsenic as a human carcinogen. People are most likely to be exposed to inorganic arsenic through drinking water and to a lesser extent through various foods. Water sources in some parts of the United States have higher naturally occurring levels of inorganic arsenic than other areas ². Other sources of inorganic arsenic exposure include contact with contaminated soil or with wood preserved with arsenic. Inorganic arsenic is converted in the body into the breakdown product (metabolite) called dimethylarsinic acid (DMA). Dimethylarsinic acid and arsenobetaine were found to be the major components of urinary total arsenic levels.
• Organic arsenic: Organic arsenic compounds are found mainly in fish and shellfish. People are exposed to organic arsenic by consuming seafood. There are limits to levels of arsenic allowed in seaweed products, seafood including fish and some types of shellfish (such as prawns, crabs and lobsters), rice and cereals.
• Arsine is a gas consisting of arsenic and hydrogen. It is extremely toxic to humans, with headaches, vomiting, and abdominal pains occurring within a few hours of exposure. EPA has not classified arsine for carcinogenicity.

You may be exposed to arsenic by:

• Taking in small amounts in food, drinking water, or air
• Breathing sawdust or burning smoke from arsenic-treated wood
• Living in an area with high levels of arsenic in rock
• Working in a job where arsenic is made or used

Researchers have also found that a patient with severe arsenic poisoning being exposed by consuming multiple dietary supplements ³, ⁴. Dietary mineral supplements are commonly used and often derived from natural sources that might contain arsenic.

Exposure to arsenic can cause many health problems. Being exposed to low levels for a long time can change the color of your skin. It can cause corns and small warts. Exposure to high levels of arsenic can cause cancer and death.

Key facts

• Arsenic is naturally present at high levels in the groundwater of a number of countries.
• Consuming very high levels of arsenic can cause poisoning and death.
• Arsenic is highly toxic in its inorganic form. Inorganic arsenic compounds (such as those found in water) are highly toxic while organic arsenic compounds (such as those found in seafood) are less harmful to health.
• Globally, it is estimated that 100 million people are exposed to elevated levels of arsenic from drinking contaminated water ⁵.
• Contaminated water used for drinking, food preparation and irrigation of food crops poses the greatest threat to public health from arsenic.
• You cannot smell, taste or see arsenic in water.
• Arsenic is not easily absorbed through the skin.
• Long-term exposure to arsenic from drinking-water and food can cause cancer and skin lesions. It has also been associated with cardiovascular disease and diabetes. In utero and early childhood exposure has been linked to negative impacts on cognitive development and increased deaths in young adults.
• The most important action in affected communities is the prevention of further exposure to arsenic by provision of a safe water supply.
• Water contaminated with arsenic can still be used for hand washing, bathing, washing clothes and in the garden (with caution).
• Tests are available to measure your exposure to arsenic. See your doctor if you are concerned about the level of arsenic in your body.
• Elevated levels of arsenic in many domestic wells (groundwater) have been found in some parts of the U.S.
• Groundwater water from domestic wells should never be used for drinking, bathing, filling swimming pools and paddling pools, food production or cooking unless it has been professionally tested and treated if necessary.
• Water testing for arsenic can be done by any National Association of Testing Authorities (NATA) accredited chemical laboratory.
• Professionally designed and maintained water treatment systems can reduce arsenic levels in water supplies.

If you are concerned about your exposure to arsenic, you should consult your doctor.

How can I tell if arsenic levels in my drinking water are elevated?

It is not easy to tell if your drinking water is contaminated by arsenic as you cannot smell, taste or see it. The only way to know if your water contains arsenic is to have it professionally tested. On January 22, 2001, EPA adopted a new standard for arsenic in drinking water of 0.01 mg/l or 10 parts per billion (ppb) ⁶.

How do I test for arsenic in my drinking water?

Water testing for arsenic can be done by any National Association of Testing Authorities (NATA) accredited chemical laboratory. Check with the laboratory first to find out how to collect and transport the water sample. You may want to contact the EPA for advice (https://www.epa.gov) or your state or local health department for more information.

Can I reduce the level of arsenic in my drinking water?

Yes. It is possible to reduce the level of arsenic in your household drinking water by using a variety of treatment processes. However, these processes are not simple and it is strongly recommended that you obtain advice from a professional water treatment company.

Do all foods have arsenic?

Arsenic may be present in many foods including grains, fruits, and vegetables where it is present due to absorption through the soil and water. While most crops don’t readily take up much arsenic from the ground, rice is different because it takes up arsenic from soil and water more readily than other grains. In addition, some seafood has high levels of less toxic organic arsenic.

How does arsenic get into foods?

Arsenic is present in water, air and soil and is absorbed by some food crops as they grow. It is not an additive or ingredient in these food crops and cannot be completely eliminated from food.

Do organic foods have less arsenic than non-organic foods?

Because arsenic is naturally found in the soil and water, it is absorbed by plants regardless of whether they are grown under conventional or organic farming practices. The FDA is unaware of any data that show a difference in the amount of arsenic found in organic rice versus conventionally grown rice.

What about arsenic in rice?

Rice, a staple of the global diet, is a leading dietary source of inorganic arsenic, both because of how commonly it’s consumed and because as rice plants grow, the plant and grain tend to absorb arsenic more readily than other food crops.

Preliminary data that have now been confirmed indicated that rice had higher levels of inorganic arsenic than other foods, in part because as rice plants grow, the plant and grain tend to absorb arsenic more readily than other food crops. Rice is a staple in the U.S. diet and is widely consumed, including by infants. Additionally, rice intake, primarily through infant rice cereal, is about three times greater for infants than adults in relation to body weight.

On April 1, 2016, the FDA released data that had been gathered to complete its review of arsenic in rice and rice products. The data were needed to enhance the agency’s understanding of arsenic in infant rice cereals. The data show the levels of inorganic arsenic in 76 rice-only cereals for infants and almost 36 multigrain and non-rice infant cereals and other foods commonly eaten by infants and toddlers. The infant rice cereals were found to have an average level of 103 parts per billion (ppb) inorganic arsenic.

The FDA’s data show that nearly half (47 percent) of infant rice cereals sampled from retail stores in 2014 were below 100 ppb inorganic arsenic, the level set by the European Union for rice and rice products destined for infants and children. It also found that a large majority (78 percent) was at or below 110 ppb inorganic arsenic.

The FDA compared these infant rice cereal samples to more than 400 samples it collected at the same time of other foods commonly eaten by infants and toddlers. The non-rice foods were found to be well below 100 ppb inorganic arsenic.

In 2013, the FDA released a broader set of test data for the levels of inorganic arsenic, which covered most types of rice grain and rice-based foods and beverages eaten in the United States, approximately 1,300 samples of rice and rice products in all. Among the rice/rice product categories in this larger data set, average levels of inorganic arsenic ranged from 1 ppb in infant formula up to 160 ppb in brown rice with other rice-containing products in between.

For its evaluation, the FDA considered “rice products” to include foods that contain rice grains (such as breakfast cereals or rice cakes) or rice-derived ingredients (such as rice flour or brown rice syrup).

Based on its testing, the FDA on April 1, 2016 proposed an action level, or limit, of 100 parts per billion (ppb) for inorganic arsenic in infant rice cereal. This level, which is based on the FDA’s assessment of a large body of scientific information, seeks to reduce infant exposure to inorganic arsenic.

The proposed limit stems from extensive testing of rice and non-rice products, a 2016 FDA risk assessment that analyzed scientific studies showing an association between adverse pregnancy outcomes and neurological effects in early life with inorganic arsenic exposure, and an evaluation of the feasibility of reducing inorganic arsenic in infant rice cereal.

The FDA found that inorganic arsenic exposure in infants and pregnant women can result in a child’s decreased performance on certain developmental tests that measure learning, based on epidemiological evidence about arsenic, including dietary exposures.

Is rice from some parts of the country or world safer?

The goal of the FDA’s sampling was to provide an accurate measure of the average levels of inorganic arsenic in a wide range of rice varieties and rice products in the U.S. market, not to make state or country comparisons. To arrive at valid comparisons for more specific factors such as state or country or brand comparisons, one would first have to compare the same type of rice (e.g., white, jasmine, brown), and for most types of rice there are too few samples among our test data to support such comparisons. Further, numerous other factors can influence the arsenic concentration in rice, including soil composition, brands of fertilizer used, seasonal variability, and growing practices, particularly water use practices. For these reasons, though the FDA provide their analytical results in their entirety and caution against making any state-to-state or country-to-country comparisons.

What is FDA recommending to consumers about eating rice and rice products?

Based on the currently available data and scientific literature, the FDA’s advice for consumers, including pregnant women, is to eat a well-balanced diet for good nutrition and to minimize potential adverse consequences from consuming an excess of any one food. Additionally, parents should follow the advice of the American Academy of Pediatrics and feed their infants and toddlers a variety of grains as part of a well-balanced diet.

Based on the FDA’s findings with respect to inorganic arsenic in rice,the agency offers the following advice to parents and caregivers of infants.

• Feed your baby iron-fortified cereals to be sure she or he is receiving enough of this important nutrient.
• Rice cereal fortified with iron is a good source of nutrients for your baby, but it shouldn’t be the only source, and does not need to be the first source. Other fortified infant cereals include oat, barley and multigrain.
• For toddlers, provide a well-balanced diet, which includes a variety of grains.

What are the health risks associated with arsenic exposure?

Long-term exposure to high levels of arsenic is associated with higher rates of skin, bladder, and lung cancers, as well as heart disease. The FDA is currently examining these and other long-term effects.

Are arsenic levels regulated?

Yes. Several US government agencies regulate arsenic levels and exposures.

The EPA limits concentrations of arsenic (in all forms) in drinking water to 10 ppb (parts per billion). The Food and Drug Administration (FDA) has set a limit of 10 ppb in bottled water, and has also proposed a limit of 10 ppb in apple juice. There are no federal limits for arsenic in most foods.

The EPA has also set limits on the amount of arsenic that industrial sources can release into the environment and has restricted the use of arsenic in pesticides.

The Occupational Safety & Health Administration (OSHA), the federal agency responsible for health and safety regulations in most workplaces, limits workplace exposure to inorganic arsenic to 10 micrograms per cubic meter of air, averaged over an 8-hour period. When working at potentially higher exposure levels, OSHA requires employers to provide personal protective equipment such as respirators.

In drinking water

Public drinking water systems in the United States are required to test for arsenic and to keep it below a certain level (10 parts per billion). If your drinking water comes from a public source, you can find out about the levels of certain substances in your drinking water, including arsenic, by contacting your local water system. Each system is also required to give its customers an annual report on water quality known as a Consumer Confidence Report. This report lists the levels of certain chemicals and other substances in the water. You can also contact the EPA’s Safe Drinking Water Hotline at 1-800-426-4791 for information about drinking water safety.

If you get your water from a private source such as a well, you may want to have your water tested for arsenic levels by a reputable laboratory. People who live in areas with high levels of arsenic in the water may consider using alternative sources of drinking water, such as bottled water. (The US Food and Drug Administration [FDA] sets the standards for allowable levels of arsenic in bottled water.) Common household water filters do not effectively remove arsenic.

In foods

Some foods naturally contain more arsenic than others. As mentioned above, rice and rice products are a particular concern because they are a major food source in many parts of the world and are included in the diets of many infants and children. The levels of arsenic in these products and their possible health effects are areas of active study. At this time, neither the FDA nor the American Academy of Pediatrics (AAP) recommend specific limits on how much rice or rice products should be eaten, but they do recommend that families eat a wide variety of foods for a well-balanced diet that includes grains other than rice, such as wheat, barley and oats. This can help limit any possible health effects from eating too much of any one type of food.

Concerns have also been raised about arsenic levels in some fruit juices (particularly apple juice). The FDA has tested the arsenic levels in many apple juice products and has stated that it is confident in the overall safety of apple juice for children and adults. The American Academy of Pediatrics (AAP) does not have specific recommendations regarding arsenic in fruit juices, but it has stated that children don’t need to drink fruit juice to have a well-balanced, healthy diet. The American Academy of Pediatrics (AAP) recommends limiting the intake of all sweet beverages, including juice, because of the risk for poor nutrition, obesity, and childhood cavities.

At work

If there is a chance you may be exposed to arsenic at work, important ways to reduce or prevent exposure include:

• Making engineering changes, such as substituting safer materials for more hazardous ones, enclosing a process that could expose workers to hazards, or ventilating a work area.
• Using personal protective equipment, such as gloves and respirators, as part of a workplace protective program.
• Using good work practices, such as changing clothes after work, washing work clothes regularly, and keeping food out of the work area.

If you are concerned about arsenic exposure in your workplace, discuss the situation with your employee health and safety representative or your employer. If needed, Occupational Safety & Health Administration (OSHA), the federal agency responsible for health and safety regulations in most workplaces, can provide more information or make an inspection.

In pressure-treated wood

Some pressure-treated lumber products contain an inorganic arsenic compound known as chromated copper arsenate (CCA) that helps protect the wood against rot and insects. The sale of chromated copper arsenate-treated lumber for most residential (home) uses was stopped at the end of 2003. However, many structures such as home foundations, decks, fences, or playground play sets that contain chromated copper arsenate-treated lumber are still in use.

It is not clear if skin contact with arsenic from pressure-treated lumber can cause health problems, other than skin irritation in some people. However, a larger concern has been raised with its use around children, especially in play sets. Children might swallow small amounts of arsenic if they put their hands in their mouths after touching the wood or the soil around it.

A child’s exposure to arsenic in chromated copper arsenate-treated playground equipment could vary based on many factors, including the amount of arsenic released from the chromated copper arsenate-treated wood, the amount of arsenic picked up on hands, the number of days the child plays on the wood, and the amount of arsenic transferred to the mouth by hand-to-mouth activity.

If you aren’t sure if a wooden play set contains arsenic, contacting the play set manufacturer might help you find out. But if this information isn’t available, it is safest to assume that it does.

To reduce exposure, the US Consumer Product Safety Commission (CPSC) recommends that parents and caregivers make sure children’s hands and other exposed body parts are thoroughly washed with soap and water after playing on all pressure-treated wood playground equipment. It has also been suggested that children not eat while on wooden playground equipment.

People concerned about arsenic exposure at home from wooden decks or play sets may want to consider applying a sealant on existing chromated copper arsenate-treated lumber surfaces each year. This may lower the amount of arsenic released from the wood.

The US Consumer Product Safety Commission also recommends that chromated copper arsenate-treated wood not be used where routine contact with food or animal feed can occur, such as in areas used to plant vegetables, fruits, or herbs. If you have a garden vegetable planter made with chromated copper arsenate-treated wood, put a plastic liner in it before filling it with soil to reduce exposure to chromated copper arsenate.

Arsenic can also be released into the air when cutting or burning chromated copper arsenate-treated lumber. If you are cutting pressure-treated lumber, it is important to use proper safety equipment, including a mask, to limit your exposure, and to clean up any sawdust promptly. Do not burn pressure-treated lumber.

The EPA does not currently recommend removal of chromated copper arsenate-treated lumber, but if you decide to remove chromated copper arsenate-treated wood in a play set, deck, or other structure, contact the EPA or your state or local solid waste management offices to get instructions on how to dispose of it safely.

Can I be tested for arsenic poisoning?

Yes. There are tests available to measure arsenic in your urine, hair and fingernails. The urine test is used to detect a recent arsenic exposure (within the past several days). Tests of your hair and fingernails may be used to detect continuing arsenic exposure over the past 6-12 months, but are less reliable. But these tests are not done routinely – they require sending the samples to a special laboratory. Furthermore, even though these tests may detect exposure to elevated levels of arsenic they cannot predict the affect on your health. It is best to discuss their significance with your doctor.

A urine test is the most reliable method for identifying arsenic exposure within the past several days. But it can’t detect long-term exposure because most arsenic leaves the body in urine within a few days. This test also can sometimes be misleading, because the organic forms of arsenic in fish and shellfish can give a high reading even if you haven’t been exposed to the more toxic, inorganic forms of arsenic. For this reason, labs sometimes use a more complicated test to separate “fish arsenic” from other forms.

Tests of hair and fingernails can detect high-level arsenic exposures during the past 6 to 12 months, but these tests are not as good at detecting lower levels of exposure.

These tests can only measure arsenic levels. Unless the levels detected are very high, none of these tests can tell for certain if you are likely to have health problems in the future.

If a person has been exposed to very high amounts of arsenic over a short time, treatment to lower arsenic levels in the body may be recommended, especially if the levels are potentially life-threatening. But in cases of chronic exposure to lower levels of arsenic, the most important thing may be to remove the source of the arsenic to stop further exposure and allow the body to get rid of what remains. Some health problems caused by arsenic may improve over time, but others may not.

Because arsenic exposure can increase the risk of skin, bladder, lung, and possibly some other cancers, people who have been exposed should learn about other risk factors for these cancers and about things they can do that may help lower their risks.

Not smoking is especially important if you have been exposed to arsenic. Both arsenic exposure and smoking can increase your risk of lung, kidney, and bladder cancer. Tell your doctor if you develop symptoms that could be caused by these cancers, including a new cough (especially if it is bloody), hoarseness, blood in the urine, or a change in your urine habits (having to go more often, having pain when going, etc.). These symptoms are more likely to be caused by something other than cancer, but it is important to have them checked out.

Arsenic exposure and too much sun can both increase your risk of skin cancer. Practice sun safety and tell your doctor about any signs and symptoms such as new skin bumps or sores, or changes in old skin problems.

If you have been exposed to arsenic, ask your doctor about a proper schedule for skin exams. Based on your arsenic exposure and other factors, your doctor might consider using other early detection testing, such as urine cytology (checking urine for cancer cells under a microscope), although it’s not clear how helpful such testing is.

You can also contact specialists in environmental and occupational medicine. They can assess exposure levels, evaluate current health problems that may be related to the exposures, and give you information concerning future risk and how to limit it. You can find qualified professionals and facilities by checking with the Association of Occupational and Environmental Clinics (http://www.aoec.org/).

How can I reduce my exposure to arsenic?

If your drinking water is contaminated by arsenic do not drink or prepare any food with it. Seek another source of water e.g. bottled water, scheme drinking water or rain water.

What can I use my water for if it is contaminated by arsenic?

Arsenic is not easily absorbed through the skin. Water contaminated with arsenic can still be used for hand washing, bathing, washing clothes and in the garden. However, care should be taken if you want to water vegetables such as beetroot, turnips, carrots, and potatoes as they can concentrate arsenic in their skin. Also care should be taken to ensure that pets and other animals do not drink contaminated water.

Is arsenic a metal?

Yes. Arsenic is sometimes found in its pure form as a steel grey metal, arsenic is usually part of chemical compounds. These compounds are divided into 2 groups:

• Inorganic compounds (arsenic combined with elements other than carbon): These compounds are found in industry, in building products (such as some “pressure-treated” woods), and in arsenic-contaminated water. This is the form of arsenic that tends to be more toxic and has been linked to cancer.
• Organic compounds (arsenic combined with carbon and other elements): These compounds are much less toxic than the inorganic arsenic compounds and are not thought to be linked to cancer. These compounds are found in some foods, such as fish and shellfish.

What is arsenic used for?

Arsenic compounds have been used in many ways, including:

• As a preservative in pressure-treated lumber
• In pesticides
• As a preservative in animal hides
• As an additive to lead (such as in lead-acid batteries) and copper
• In some glass manufacturing
• As arsine gas to enhance electrical junctions in semiconductors

Some of these uses have been discontinued in the United States.

Although arsenic can be poisonous in higher doses, it has also been used in some medicines. In the 1800s and early 1900s, arsenic was commonly used to treat diseases such as syphilis and psoriasis. A form of arsenic is still used to treat an uncommon blood cancer known as acute promyelocytic leukemia.

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 can also be exposed to higher levels of arsenic in some other ways. Very high doses have been used in murder or suicide attempts. Some jobs may expose workers to high levels over long periods of time when they breathe in or swallow dust that contains arsenic compounds, but such exposures are now rare in the United States.

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 (although the organic form found in seafood is likely to be much less harmful).

Arsenic in food

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.

Arsenic 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. In parts of Taiwan, Japan, Bangladesh, and western South America, high levels of arsenic occur naturally in drinking water.

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).

Arsenic at work

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.

Arsenic in the community

Communities near previous or current agricultural or industrial sources may be exposed to arsenic. Industrial buildings such as wood preservative and glass factories can contaminate nearby air, soil, and water. Communities near smelters, or near farm fields or orchards where arsenic pesticides were used, may also have contaminated soil. Burning fossil fuels (such as coal) and tobacco can also release small amounts of arsenic into the air.
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 chromated copper arsenate-treated wood.

The use of chromated copper arsenate in pressure-treated lumber for most residential (home) 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 chromated copper arsenate.

Where is arsenic found?

Arsenic is a natural component of the earth’s crust and is widely distributed throughout the environment in the air, water and land. It is highly toxic in its inorganic form.

People are exposed to elevated levels of inorganic arsenic through drinking contaminated water, using contaminated water in food preparation and irrigation of food crops, industrial processes, eating contaminated food and smoking tobacco.

Long-term exposure to inorganic arsenic, mainly through drinking-water and food, can lead to chronic arsenic poisoning. Skin lesions and skin cancer are the most characteristic effects.

A new study by the U.S. Geological Survey and Centers for Disease Control and Prevention estimates about 2.1 million people in the U.S. may be getting their drinking water from private domestic wells (private or homeowner wells) considered to have high concentrations of arsenic, presumed to be from natural sources ². About 44 million people not connected to public water supply distribution systems and people in rural areas of the United States in the lower 48 states use water from domestic wells for household water use ⁷. Because high concentrations of arsenic in water are not evident by taste or smell, the only way to know how much arsenic is in drinking water is to have it tested, a precaution utilized infrequently by domestic well owners ⁸.

Geogenic arsenic affects many domestic wells in the U.S ⁹ and is thus a national public health concern ⁸. Recent work in the U.S. indicates that low-level arsenic may impact fetal growth ¹⁰ and may be related to preterm birth ¹¹. In the U.S., domestic well water quality is generally not regulated. This means that it is largely up to the well owner to understand the arsenic hazard and take steps to mitigate any exposure risk.

Studies of arsenic in domestic wells in the U.S. commonly refer to percentages of wells with arsenic >10 μg/L, the U.S. Environmental Protection Agency (USEPA) Maximum Contaminant Level (MCL), based on observations from various databases ¹².

Using a standard of 10 micrograms of arsenic per liter (μg/L)– the maximum contaminant level allowed for public water supplies — the researchers developed maps of the contiguous U.S. showing locations where there are likely higher levels of arsenic in groundwater, and how many people may be using it.

Figure 1. Estimated population with arsenic greater than 10 micrograms per liter

[Source ¹³]

Figure 2. Locations of domestic wells and arsenic concentration ranges

[Source ²]

Nearly all of the arsenic in the groundwater tested for this study and used to map probabilities is likely from natural sources, and is presumed to be coming primarily from rocks and minerals through which the water flows.

The findings highlight the importance of private well owners working with their local and state officials to determine the best way to test and, if necessary, treat their water supplies.

Fortunately, in most areas of the country and with appropriate safeguards, the majority of homeowners can get good quality drinking water from private wells,. But this study is a good reminder that prudent, routine testing of the groundwater, including its interaction with the water supply system, is an essential first step so homeowners and their families can confidently drink water from their wells.

Arsenic problem globally

Arsenic contamination of groundwater is widespread and there are a number of regions where arsenic contamination of drinking-water is significant. It is now recognized that at least 140 million people in 50 countries have been drinking water containing arsenic at levels above the WHO (World Health Organization) provisional guideline value of 10 micrograms of arsenic per liter (μg/L) ¹⁴.

Arsenic in Bangladesh has attracted much attention since recognition in the 1990s of its wide occurrence in well-water in that country. Since this time, significant progress has since been made and the number of people exposed to arsenic exceeding the Bangladesh drinking-water quality standard has decreased by approximately 40%. Despite these efforts, it was estimated that in 2012 about 19 million and 39 million people in Bangladesh were still exposed to arsenic concentrations above the national standard of 50 μg/L and the WHO provisional guideline value of 10 μg/L respectively ¹⁵. In a highly affected area of Bangladesh, 21.4% of all deaths in the area were attributed to arsenic levels above 10 μg/L in drinking-water ¹⁶. A similar dose-response function has been found in other parts of Bangladesh, and these these results have been combined with national survey data to estimate an annual death toll of nearly 43,000 ¹⁷.

The symptoms and signs caused by long-term elevated exposure to inorganic arsenic differ between individuals, population groups and geographical areas. Thus, there is no universal definition of the disease caused by arsenic. This complicates the assessment of the burden on health of arsenic.

Similarly, there is no method to distinguish cases of cancer caused by arsenic from cancers induced by other factors. As a result, there is no reliable estimate of the magnitude of the problem worldwide.

In 2010, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) re-evaluated the effects of arsenic on human health, taking new data into account. JECFA concluded that for certain regions of the world where concentrations of inorganic arsenic in drinking-water exceed 50–100 μg/L, there is some evidence of adverse effects. In other areas, where arsenic concentrations in water are elevated (10–50 μg/L), JECFA concluded that while there is a possibility of adverse effects, these would be at a low incidence that would be difficult to detect in epidemiological studies.

Arsenic in water and food

The greatest threat to public health from arsenic originates from contaminated groundwater. Inorganic arsenic is naturally present at high levels in the groundwater of a number of countries, including Argentina, Bangladesh, Chile, China, India, Mexico, and the United States. Drinking-water, crops irrigated with contaminated water and food prepared with contaminated water are the sources of exposure.

Fish, shellfish, meat, poultry, dairy products and cereals can also be dietary sources of arsenic, although exposure from these foods is generally much lower compared to exposure through contaminated groundwater. In seafood, arsenic is mainly found in its less toxic organic form.

One of the most comprehensive studies of arsenic in food was published in 1993 ¹⁸. Food collected in Canadian cities in the years 1985-1988 was analyzed for total arsenic, and the food groups containing the highest mean arsenic concentrations were fish (1,662 ng/g), meat and poultry (24.3 ng/g), bakery goods and cereals (24.5 ng/g), and fats and oils (19.0 ng/g). The average daily dietary ingestion of total arsenic by Canadians was estimated to be 38.1 µg (48.5 µg for adults) and varied from 14.9 µg for children 1-4 years old to 59.2 µg for males 20-39 years old. Previous estimates for Canadians were 16.7 µg per day and 30 µg per day ¹⁹.

Those figures are comparable with data from other countries: United States, 62 µg per day ²⁰; United Kingdom, 89 µg per day ²¹; Austria, 27 µg per day ²²; and New Zealand, 55 µg per day ²³. Assuming that those figures have general application, it is apparent that individuals receive a considerable daily dose of arsenic from food.

On the basis of the U.S. Food and Drug Administration (FDA) Total Diet Study, Adams et al. ²⁴ provided the most thorough analysis of arsenic in the U.S. diet to date. Out of about 5,000 foods regularly consumed in the United States, 234 were selected as being representative, and excess caloric diets were constructed from those foods for total diet studies. (The diet consisted of 82 foods from 11 food groups in quantities for a 14-day intake with excessive energy intake of 4,200 kcal per day.) The results indicate that food contributes 93 % of the total intake of arsenic, and seafood contributes 90 % of that 93 % (see Table 1). Mean arsenic intakes by groups of individuals were estimated in 1982-1991, and those results are given in Table 2. The results from the latter years are generally lower than those from the peak period 1984-1986.

The average arsenic intakes reported in Table 3 are generally higher than those reported for earlier years (Table 2). The new numbers probably reflect an increase in the consumption of seafood (Tables 1 and 5).

Table 1. Foods Containing Arsenic at Concentrations above 50 ppb as Determined by the FDA Total Diet Study for Market Baskets Collected from 1990 through 1991

Fish	Meat	Vegetable
Tuna in oil	Turkey breast	Rice, cooked
Fish sticks		Rice cereal
Haddock, fried		Mushrooms, raw
Shrimp, boiled		Olive/safflower oil
Tuna noodle casserole
Fish sandwich
Clam chowder

[Source ²⁵]

Table 2. Mean Total Daily Arsenic Intakes (µg/d) as Determined by the FDA Total Diet Study for Market Baskets Collected from April 1982 through April 1991

Population-Group Age	Arsenic Intake (µg/d) and Years of Collection (Number of Collections)
(Sex)a	1982-84 (8)b	1984-86 (8)c	1986-88 (8)c	1988-90 (8)c	1990-91 (5)c
6-11 mo	4.9	7.4	6.2	3.6	3.2
2 yr	12.2	15.8	12.8	9.3	9.0
14-16 yr (F)	23.0	29.3	23.5	17.5	16.9
14-16 yr (M) 27.7	35.7	28.7	20.6	20.3
25-30 yr (F) 31.0	39.5	31.3	23.7	23.3
25-30 yr (M) 45.3	58.1	45.6	34.0	34.6
60-65 yr (F) 35.2	45.3	34.8	26.7	26.6
60-65 yr (M) 43.8	56.6	43.1	32.7	33.4

a) F = female; M = male.
b) In calculating intakes, “trace” concentrations were assigned a value of one-half the limit of quantitation; the “trace” concentration assigned to arsenic during those years was 0.01 mg/kg of diet.
c) In calculating intakes for this time period, “trace” concentrations were estimated by the analyst.

[Source ²⁵]

Table 3. Estimated Average Inorganic Arsenic Intakes for Various Age and Sex Groups as Determined by the FDA Total Diet Study for Market Baskets Collected in 1991-1997

Population Group		Total Arsenic Intake (µg/d)	Inorganic Arsenic Intakea (g/d)		Total Inorganic Arsenic Average Intake (µg/d)
Age (Sex)b	Weight (kg)c		Seafood	Others
6-11 mo	7	2.15	0.09	1.25	1.34
2 yr	13	23.4	2.11	2.30	4.41
6 yr	22	20.3	1.74	2.90	4.64
10yr	64	13.3	1.01	3.20	4.21
14-16 yr (F)	53	21.8	1.85	3.30	5.15
14-16 yr(M)	64	15.4	1.21	3.30	4.51
25-30 yr (F)	62	27.5	2.46	2.90	5.36
25-30 yr (M)	79	56.6	5.19	4.70	9.89
40-45 yr (F)	67	36.8	3.38	3.00	6.38
40-45 yr(M)	81	46.8	4.28	4.00	8.28
60-65 yr (F)	67	72.1	6.93	2.80	9.73
60-65 yr(M)	81	92.1	8.84	3.70	12.54
70+ (F)	62	45.4	4.25	2.90	7.15
70+ (M)	74	69.4	6.63	3.10	9.70

a) Based on the assumption that 10 % and 100% of the total arsenic is inorganic arsenic in seafood and all other foods, respectively. Seafood includes seven TDS food items (tuna, fish sticks, haddock, shrimp, tuna noodle casserole, clam chowder, and fish sandwich).
b) F = female; M = male.
c) Self-reported weights from the data tapes of the U.S. Department of Agriculture.

[Source ²⁵]

Table 4. Arsenic Concentration in Food and Cigarettes (Values in ppm, Wet Weight)

Food (Sample No.)	Total	Inorganic	Organic	% Inorganic
Vanilla ice cream (1)	0.016	0.0042	<0.002	26
Cured pork (1)	0.013	0.018	<0.007	144
Pastrami (1)	0.024	0.024	<0.009	99
Chicken (1)	0.022	0.0090	0.012	41
Sole (1)	4	0.022	4.4	1
Tuna (1)	1.1	0.025	1.2	2
Pickerel (1)	0.14	0.022	0.086	15
Shrimp (1)	0.65	0.10	0.52	16
Rice (1)	0.24	0.1	0.16	43
Special K cereal (1)	0.27	0.070	0.15	26
Bread (1)	0.024	0.012	<0.006	50
Flour (1)	0.011	0.0076	<0.005	69
Apple juice (1)	0.012	0.0088	<0.002	73
Tea (1)	0.035	0.0091	0.025	26
Cigarettes (1)	0.18	0.11	0.03	61

[Source ²⁵]

Table 5. Arsenobetaine in Marine Animals

Animal (No. of Species)	Arsenic Concentration (mg/kg, Wet Wt.)	Arsenobetaine Content (% of Total Arsenic)
Fish
Elasmobranchs (7)	3.1-44.3	≥94
Teleosts (17)	0.1-166	48 to >95
Crustaceans
Lobsters (4)	4.7-26	77 to >95
Prawns (5)	5.5-20.8	55 to >95
Crabs (6)	3.5-8.6	79 to >95
Molluscs
Bivalves (4)	0.7-2.8	44-88
Gastropods (6)	3.1-116.5	58 to >95
Cephalopods (3)	49	72 to >95

[Source ²⁵]

Arsenic in rice

Rice has higher levels of inorganic arsenic than other foods, in part because as rice plants grow, the plant and grain tend to absorb arsenic more readily than other food crops. In April 2016, the FDA proposed an action level, or limit, of 100 parts per billion (ppb) for inorganic arsenic in infant rice cereal ²⁶. This level, which is based on the FDA’s assessment of a large body of scientific information, seeks to reduce infant exposure to inorganic arsenic. The agency also has developed advice on rice consumption for pregnant women and the caregivers of infants.

Based on the FDA’s findings with respect to inorganic arsenic in rice, the agency offers the following advice to parents and caregivers of infants:

• Feed your baby iron-fortified cereals to be sure she or he is receiving enough of this important nutrient.
• Rice cereal fortified with iron is a good source of nutrients for your baby, but it shouldn’t be the only source, and does not need to be the first source. Other fortified infant cereals include oat, barley and multigrain.
• For toddlers, provide a well-balanced diet, which includes a variety of grains.

Also based on the FDA’s findings, it would be prudent for pregnant women to consume a variety of foods, including varied grains (such as wheat, oats, and barley), for good nutrition. This advice is consistent with long-standing nutrition guidance to pregnant women from the American Congress of Obstetricians and Gynecologists to have half of their grains consist of whole grains.

Published studies, including new research by the FDA, indicate that cooking rice in excess water (from six to 10 parts water to one part rice), and draining the excess water, can reduce from 40 to 60 percent of the inorganic arsenic content, depending on the type of rice – although this method may also remove some key nutrients.

Is it ok for me to eat rice and give it to my children?

Consumers can certainly eat rice as part of a well-balanced diet. Based on our scientific assessment, we think it would be prudent for parents and caregivers to feed their infants a variety of fortified infant cereals, rather than to rely solely on infant rice cereal. We also encourage pregnant women to eat a variety of foods, including varied grains.

Many infants with esophageal reflux tendencies rely on infant rice cereal as it is relatively easy to keep down. What does the FDA recommend for these infants instead of rice?

Wheat, barley and other grain-based infant cereals also readily absorb liquid and are similarly effective for infants with esophageal reflux tendencies. FDA recommends that children eat a well-balanced diet for good nutrition and to minimize potential adverse consequences from consuming an excess of any one food. Parents of such infants may wish to consult with their child’s pediatrician on which infant cereals would best meet their child’s needs.

Can the consumer do anything to offset or reduce the arsenic in rice?

Published studies, including research by the FDA, indicate that cooking rice in excess water (from six to 10 parts water to one part rice), and draining the excess water, can reduce 40 to 60 percent of the inorganic arsenic content, depending on the type of rice. The FDA recognizes that consumers do not typically prepare rice in this manner, similar to preparing pasta, and some may not wish to do so. Such preparation has been shown to lower the nutritional value of enriched polished and parboiled rice (reducing the levels of folate, iron, niacin and thiamin by 50 to 70 percent; these nutrients are added to polished and parboiled rice as part of the enrichment process).

The new FDA research also shows that rinsing rice before cooking has a minimal effect on the arsenic content of the cooked grain. Rinsing does, however, wash off iron, folate, thiamin and niacin from polished and parboiled rice. The tables below provide additional information on the study’s findings.

Table 6. Percent reduction with rinsing rice

Rice	Inorganic Arsenic	Iron	Niacin	Thiamine	Folate
Brown	0	10	0	0	12
Polished	16	71	85	83	87
Parboiled	9	81	28	51	73

Table 7. Percent reduction with cooking in excess water (averaged 6:1 and 10:1 ratios)

Rice	Inorganic Arsenic	Iron	Niacin	Thiamine	Folate
Brown	50	0	0	42	45
Polished	43	46	42	39	43
Parboiled	61	75	53	64	62

Industrial processes

Arsenic is used industrially as an alloying agent, as well as in the processing of glass, pigments, textiles, paper, metal adhesives, wood preservatives and ammunition. Arsenic is also used in the hide tanning process and, to a limited extent, in pesticides, feed additives and pharmaceuticals.

Tobacco

People who smoke tobacco can also be exposed to the natural inorganic arsenic content of tobacco because tobacco plants can take up arsenic naturally present in the soil. Also, in the past, the potential for elevated arsenic exposure was much greater when tobacco plants used to be treated with lead arsenate insecticide.

Arsenic poisoning signs and symptoms

The clinical appearance of the noncancer manifestations of arsenic intoxication in humans is dependent on the magnitude of the dose and the time course of exposure. Although the toxicokinetic and toxicodynamic interaction between those two measures has not been well characterized, several general findings emerge from the available data. Unusually large doses of inorganic arsenic can cause symptoms ranging from nausea, vomiting, and diarrhea to dehydration and shock. Long-term exposure to high levels of inorganic arsenic in drinking water has been associated with skin disorders and increased risks for diabetes, high blood pressure, and several types of cancer. Inorganic arsenic and arsenic compounds are considered to be cancer-causing chemicals. Forms of organic arsenic (for example, arsenobetaine) found in seafood are not known to be toxic to humans.

Diffuse or spotted hyperpigmentation, the initial nonmalignant cutaneous effect of chronic arsenic ingestion, can first appear within 6 months to 3 years of chronic ingestion at concentrations in excess of approximately 0.04 mg/kg per day ¹. Lower exposure rates, on the order of 0.01 mg/kg per day or higher, can also result in hyperpigmentation after intervals as long as 5 to 15 years. Palmar-plantar hyperkeratoses, the other principal nonmalignant cutaneous manifestation of chronic arsenic exposure, usually follows the initial appearance of arsenical hyperpigmentation within a period of years.

Weeks to months of ongoing ingestion of inorganic arsenic at doses of approximately 0.04 mg/kg per day or higher can result in overt nonspecific gastrointestinal complaints, such as diarrhea and cramping, and hematological effects, including anemia and leukopenia ¹. A sensory predominant axonal peripheral neuropathy can also occur after months to years of this level of exposure. Such gastrointestinal, hematological, and neurological effects generally improve or resolve following cessation of exposure. Irreversible noncirrhotic portal hypertension appears to have occurred after years of arsenic ingestion at concentrations of 0.01 to 0.02 mg/kg per day or higher. Recent studies from Mexico suggest that those low concentration rates can also perturb porphyrin metabolism; however, the impact of this disturbance on clinical function is not fully determined.

Peripheral vascular disease has been associated with chronic arsenic ingestion in epidemiological studies conducted in populations exposed via drinking water in Taiwan. Clinical-case series and case reports also linked arsenic ingestion to peripheral vascular disease in subjects exposed to arsenic in drinking water in Latin America and northern Mexico and to arsenic from multiple sources in Japan and Germany (Moselle vintners). The patients with peripheral vascular disease were drawn from populations in areas where arsenic exposure occurred over a period of years at concentrations sufficient to result in cutaneous manifestations. However, data on the latency and progression of arsenic-induced peripheral vascular disease remain sparse.

Recent epidemiological investigations in the arsenic-affected areas of southwestern Taiwan associated cumulative arsenic ingestion with a risk of hypertension and cardiovascular disease mortality. Although investigators estimated individual arsenic doses in several studies, the reports do not reveal the extent of the cardiovascular risk, in the absence of cutaneous effects, from exposure to low concentrations of arsenic. A small cross-sectional study conducted in Michigan suggested a possible link between chronic exposure to low concentrations of arsenic and hypertension. However, a cohort study of individuals exposed to higher concentrations of arsenic in medication revealed no evidence of increased cardiovascular mortality. Cohort studies of occupational arsenic exposure have suggested a small increase in cardiovascular-related mortality, but the relationship has not been found consistently. Recently, a study conducted in the Layang Basin of northeastern Taiwan reported that chronic ingestion of groundwater containing arsenic at a concentration as low as 0.1 to 50 µg/L was associated with an increased prevalence of cerebrovascular disease ¹. However, uncertainties relating to that study’s design and negative findings in other cohorts require that the relationship between arsenic exposure and cerebrovascular disease undergo further evaluation.

Recent studies in southwestern Taiwan and Bangladesh associated chronic arsenic ingestion in drinking water with an increased risk of diabetes mellitus. The study subjects were drawn from populations with overt cutaneous signs of arsenic intoxication; information is lacking on the magnitude of the potential risk associated with exposure to low concentrations of arsenic. Two small Swedish case-control studies suggested that arsenic exposure of smelter workers and art glass workers might also be associated with an increased risk of diabetes mortality.

Inorganic arsenic has been shown to have immunomodulating and immunotoxic effects in experimental models. Subacute or chronic arsenic exposure at high doses (more than 0.05 mg/kg per day) has been associated with a decline in peripheral leukocytes, the capacity of arsenic to suppress aspects of the immune response might have formed the basis for its former use as a therapeutic agent ¹. The potential effect of exposure to low concentrations of arsenic on immune function has not been adequately investigated in field research; however a small cross-sectional study from Michigan is consistent with an immunomodulating effect ¹. The potential effect of ingested arsenic on respiratory function has been suggested by studies from Chile, West Bengal, and the United States, but the specific pathology of the effect has not been investigated.

Arsenic administered parenterally has been shown to be teratogenic in a number of mammalian species, but there is little evidence to suggest teratogenicity by oral or inhalation routes ¹. Although some studies show an association between arsenic exposure and adverse pregnancy outcomes, they are inadequate to draw firm conclusions. No effects on fertility were observed in a multigeneration study in mice; however, arsenic does accumulate in the epididymides of hamsters, mice, and marmosets and in the testes of marmosets, suggesting that potential reproductive effects of arsenic should be investigated further.

Short-term exposure

The immediate symptoms of acute arsenic poisoning include vomiting, abdominal pain and diarrhea. These are followed by numbness and tingling of the extremities, muscle cramping and death, in extreme cases.

Acute (short-term) high-level inhalation exposure to arsenic dust or fumes has resulted in gastrointestinal effects (nausea, diarrhea, abdominal pain); a sore throat and irritated lungs; central and peripheral nervous system disorders have occurred in workers acutely exposed to inorganic arsenic.

Swallowing high levels of arsenic can cause things like:

• Stomachache
• Nausea and vomiting
• Diarrhea
• Muscle weakness and cramping
• “Pins and needles” sensations in hands and feet
• Skin changes or rashes
• Bruising (caused by blood vessel damage)

Exposure to high enough amounts of arsenic can be fatal.

Contact with the skin can cause redness and swelling, although it’s not known if it can cause other health problems.

Long-term exposure

Exposure to lower levels of arsenic over longer periods of time can cause many of the same health problems listed above. It can also result in:

• Irregular heartbeat
• Liver and kidney damage
• A shortage of red and white blood cells, which can lead to fatigue and an increased risk of infections

Skin changes are a common sign of chronic arsenic exposure. The first symptoms of long-term exposure to high levels of inorganic arsenic (for example, through drinking-water and food) are usually observed in the skin, and include pigmentation changes (darkened patches), skin lesions and hard patches (thickened skin) on the palms and soles of the feet (hyperkeratosis). These occur after a minimum exposure of approximately five years and may be a precursor to skin cancer.

In addition to skin cancer, long-term exposure to arsenic may also cause cancers of the bladder and lungs. The International Agency for Research on Cancer (IARC) has classified arsenic and arsenic compounds as carcinogenic to humans, and has also stated that arsenic in drinking-water is carcinogenic to humans.

The US National Research Council has noted that as many as 1 in 100 additional cancer deaths could be expected from a lifetime exposure to drinking-water containing 50 μg/L of arsenic ²⁷.

Other adverse health effects that may be associated with long-term ingestion of inorganic arsenic include developmental effects, diabetes, pulmonary disease, and cardiovascular disease. Arsenic-induced myocardial infarction, in particular, can be a significant cause of excess mortality. In China (Province of Taiwan), arsenic exposure has been linked to “Blackfoot disease”, which is a severe disease of blood vessels leading to gangrene. This disease has not been observed in other parts of the world however, and it is possible that malnutrition contributes to its development.

Arsenic is also associated with adverse pregnancy outcomes and infant mortality, with impacts on child health (1), and exposure in utero and in early childhood has been linked to increases in mortality in young adults due to multiple cancers, lung disease, heart attacks, and kidney failure (2). Numerous studies have demonstrated negative impacts of arsenic exposure on cognitive development, intelligence, and memory (3).

Chronic (long-term) inhalation exposure to inorganic arsenic of humans is associated with irritation of the skin and mucous membranes and effects in the brain and nervous system. Chronic oral exposure to elevated levels of inorganic arsenic has resulted in gastrointestinal effects, anemia, peripheral neuropathy, skin lesions, hyperpigmentation, and liver or kidney damage in humans. Inorganic arsenic exposure of humans, by the inhalation route, has been shown to be strongly associated with lung cancer, while ingestion of inorganic arsenic by humans has been linked to a form of skin cancer and also to bladder, liver, and lung cancer.

Does arsenic cause cancer?

Exposure to high levels of arsenic has been linked to several types of cancer.

Researchers use 2 main types of studies to try to figure out if a substance or exposure causes cancer. A substance that causes cancer or helps cancer grow is called a carcinogen.

In studies done in the lab, animals are exposed to a substance (often in very large doses) to see if it causes tumors or other health problems. Researchers may also expose normal cells in a lab dish to the substance to see if it causes the types of changes that are seen in cancer cells. It’s not always clear if the results from these types of studies will apply to humans, but lab studies are the best way to find out if a substance could possibly cause cancer in humans before widespread exposure occurs.

Another type of study looks at cancer rates in different groups of people. Such a study might compare the cancer rate in a group exposed to a substance to the rate in a group not exposed to it, or compare it to what the expected cancer rate would be in the general population. But sometimes it can be hard to know what the results of these studies mean, because many other factors that might affect the results are hard to account for.

In most cases neither type of study provides enough evidence on its own, so researchers usually look at both lab-based and human studies when trying to figure out if something causes cancer.

Studies in people

Many studies have looked at arsenic’s potential to cause cancer. People can be exposed to arsenic in different ways (inhaling, ingesting, or through skin contact) and in different settings (in the workplace, in drinking water, in medical treatments, etc.), so it has been important to study different routes of exposure.

Workplace exposures

A number of studies have looked at cancer rates among people who worked with pesticides containing arsenic and those who worked in mines and copper smelters. These workers’ inhaled exposures were often very high. These studies have followed thousands of workers for as long as 40 or 50 years. They have consistently shown an increase in lung cancer risk with higher and more prolonged exposures.

Some studies have also suggested that workers exposed to arsenic might be at higher risk for other cancers, including cancers of the skin, stomach, and kidneys, as well as leukemias and lymphomas. However, the results from these studies have not been as convincing.

Exposure from drinking water

Studies of people in parts of Southeast Asia and South America with high levels of arsenic in their drinking water have found higher risks of cancers of the bladder, kidney, lung, skin, and, less consistently, colon, prostate, and liver.

In most of these studies, the levels of arsenic in the water were many times higher than those typically seen in the United States, even in areas where arsenic levels are above normal.

There have not been as many studies looking at arsenic in drinking water and cancer in the United States. This is largely because for most Americans who are on public water systems, drinking water is not a major source of arsenic. The studies that have been done have generally not found a strong link between cancer and the lower levels of arsenic exposure typically seen in the US.

Exposure from medicines

In older studies, some cancers have been linked to exposure to arsenic in medicines. The strongest link has been found with skin cancer.

What expert agencies say

Several national and international agencies study substances in the environment to determine if they can cause cancer. The American Cancer Society looks to these organizations to evaluate the risks based on evidence from laboratory, animal, and human research studies.

Based on the available evidence, several expert agencies have evaluated the cancer-causing potential of arsenic.

The International Agency for Research on Cancer (IARC) is part of the World Health Organization (WHO). Its major goal is to identify causes of cancer.

• IARC classifies arsenic and inorganic arsenic compounds as “carcinogenic to humans”, based on evidence from human studies that it can cause cancer of the lung, bladder, and skin. IARC also notes possible links between exposure to arsenic in drinking water and cancers of the kidney, liver, and prostate, although the evidence for these is not as strong.
• IARC classifies the organic arsenic compounds dimethylarsinic acid (also known as cacodylic acid) and monomethlyarsonic acid as “possibly carcinogenic to humans.”
• IARC classifies other organic arsenic compounds as “not classifiable as to their carcinogenicity in humans.”

The US National Toxicology Program (NTP) is formed from parts of several different government agencies, including the National Institutes of Health (NIH), the Centers for Disease Control and Prevention (CDC), and the Food and Drug Administration (FDA). In its most recent Report on Carcinogens, the NTP classifies arsenic and inorganic arsenic compounds as “known to be human carcinogens,”

The US Environmental Protection Agency (EPA) maintains the Integrated Risk Information System (IRIS), an electronic database that contains information on human health effects from exposure to various substances in the environment. The EPA classifies inorganic arsenic as a “human carcinogen,” based on evidence in human studies of links to lung, bladder, kidney, skin, and liver cancers.

Arsenic poisoning prevention and control

The most important action in affected communities is the prevention of further exposure to arsenic by the provision of a safe water supply for drinking, food preparation and irrigation of food crops.

The current recommended limit of arsenic in drinking-water is 10 μg/L, although this guideline value is designated as provisional because of practical difficulties in removing arsenic from drinking-water. Every effort should therefore be made to keep concentrations as low as reasonably possible and below the guideline value when resources are available. However, millions of people around the world are exposed to arsenic at concentrations much higher than the guideline value (100 μg/L or greater), and therefore the public health priority should be to reduce exposure for these people.

There are a number of options to reduce levels of arsenic in drinking-water.

• Substitute high-arsenic sources, such as groundwater, with low-arsenic, microbiologically safe sources such as rain water and treated surface water. Low-arsenic water can be used for drinking, cooking and irrigation purposes, whereas high-arsenic water can be used for other purposes such as bathing and washing clothes.
• Discriminate between high-arsenic and low-arsenic sources. For example, test water for arsenic levels and paint tube wells or hand pumps different colours. This can be an effective and low-cost means to rapidly reduce exposure to arsenic when accompanied by effective education.
• Blend low-arsenic water with higher-arsenic water to achieve an acceptable arsenic concentration level.
• Install arsenic removal systems – either centralized or domestic – and ensure the appropriate disposal of the removed arsenic. Technologies for arsenic removal include oxidation, coagulation-precipitation, absorption, ion exchange, and membrane techniques. There is an increasing number of effective and low-cost options for removing arsenic from small or household supplies, though there is still limited evidence about the extent to which such systems are used effectively over sustained periods of time.

Long-term actions are also required to reduce occupational exposure from industrial processes.

Education and community engagement are key factors for ensuring successful interventions. There is a need for community members to understand the risks of high arsenic exposure and the sources of arsenic exposure, including the intake of arsenic by crops (e.g. rice) from irrigation water and the intake of arsenic into food from cooking water.

High-risk populations should also be monitored for early signs of arsenic poisoning – usually skin problems.

References

1. National Research Council (US) Subcommittee on Arsenic in Drinking Water. Arsenic in Drinking Water. Washington (DC): National Academies Press (US); 1999. 4, Health Effects of Arsenic. Available from: https://www.ncbi.nlm.nih.gov/books/NBK230891
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