About Haloacetic Acids (HAAS)

What are haloacetic acids?

Haloacetic acids (HAAs) are organic compounds containing chlorine and/or bromine. HAAs are mo st commonly formed when drinking water is disinfect ed with chlorine (chlorinated) to kill bacteria and viruses. The chemical reaction of chlorine with natural plant material found in water produces HAAs. Sometimes HAA s in drinking water reach levels that could possibly be harmful to human health. Levels of HAAs in water ca n vary from day to day depending on such things as the amount of acid in the water, the season, wate r temperature, concentration of chlorine, and the amount of plant material in the water.

How can HAAs affect my health?

The low levels of HAAs found in drinking water are highly unlikely to cause any human health problem s. There is some evidence from animal studies that exposure to high levels of HAAs in drinking water over many y ears may increase a person’s risk of getting cancer. In early studies, expos ure to HAAs in drinking water showed a possible association with human reproductive and developmental problem s. However, recent studies have not found this association.

How might I be exposed to HAAs?

The major route of exposure is through ingestion of chlorinated drinking water. Skin conta ct with chlorinated water is not a major route of exposure because HAAs are not easily absorbed through the skin.

Are there tests that can be done to tell if a person has been exposed to HAAs?

Yes. Special blood and urine tests can show if a pe rson has been exposed to high levels of HAAs or HAAs metabolites (breakdown products). However, HAAs and their metabolites ca nnot be detected in the blood or urine when a person has been exposed to low levels of HAAs over a long period of time.

Is there any drinking water standard to protect people from exposure to HAAs?

Yes. To protect human health, the U.S. Environmental Protection Agency (EPA) has established an acce ptable maximum HAAs level for public drinking water. This level is called the HAAs maximum contam inant level (MCL) and is measured in parts per billion (ppb). The HAAs MCL is 60 ppb for public drin king water. Public drinking water with HAAs MCL measurements below this level is considered safe to drink.

What happens if HAAs levels are above the standard?

The EPA requires public water systems to test drinking water for HAAs on a regular basis. If a certain numbe r of samples exceed the acceptablemaximum HAAs level, the public water system mu st take corrective actions to reduce the levels of HAAs.

(OVER)Where can my physician or I get more information on HAAs?

For more information about health effects of HAAs: Virginia Department of Health Division of P ublic Health Toxicology, 109 Governor Street Richmond, VA 23219 (804) 864-8182

http://www.vdh.virginia.gov/epi/publichealthtoxicology/index.asp

For advice and information about drinking water treatment methods: Virginia Departm ent of Health, Office of Drinking Water, 109 Governor Street Richmond, VA 23219 (804) 864-7500

http://www.vdh.virginia.gov/drinkingwater

Prepared by: Ram K. Tripathi, Ph.D.

Toxicologist

Division of Public Health Toxicology

Haloacetic Acid FAQ