About Drinking Water Contaminants

Almost 95% of all New Yorkers receive water from public water supply systems in New York State. The Department of Health oversees the delivery of drinking water to make sure that it is safe for people to drink.

The Department of Health works with local health departments to regulate public water supplies and commercial bottled water suppliers, to protect water sources, and to provide financial assistance to public water suppliers. Health departments also review and approve plans for proposed realty subdivisions, and set standards for building individual water supplies and wastewater (septic) systems.

Under the federal Safe Drinking Water Act (SDWA), the United States Environmental Protection Agency (USEPA) sets national limits on contaminant levels in drinking water. New York State also adopted new drinking water standards for public water systems that set maximum contaminant levels (MCLs) for perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), and 1,4-dioxane. USEPA and New York State regulate how often public water systems must monitor and report drinking water contaminants

The New York State Environmental Public Health Tracker uses data from the Safe Drinking Water Information System (SDWIS) and local health departments to report concentrations of drinking water contaminants. All data are for public drinking water and do not include private well water data.  For, PFOA, PFOS and 1,4-dioxane, the data presented may be source water monitoring data prior to any available treatment or being delivered to the customer. Data may also include water sources that are out of service. As a result, these data may not reflect the actual levels that people are drinking.  People should always contact their water supplier or refer to their Annual Water Quality Report to find out more about levels of contaminants in finished drinking water. 

About 1,4-Dioxane

1,4-Dioxane is a synthetic industrial chemical commonly associated with chlorinated solvents and was widely used as a chemical stabilizer in other formulations. It is also a byproduct or contaminant in consumer products such as laundry detergent. 1,4-Dioxane has been found in groundwater at sites throughout the United States, particularly in the sole source aquifer of Long Island and industrial and hazardous waste sites.  New York State public drinking water standards have set maximum contaminant levels of 1 microgram per liter or part per billion for 1,4-dioxane.

1,4-Dioxane and Health

Laboratory studies show that 1,4-dioxane caused liver cancer in animals exposed at high levels throughout their lifetime. Other types of cancer have also been reported, although less consistently than liver cancer. There is no evidence of 1,4-dioxane cancer effects in humans. The United States Environmental Protection Agency considers 1,4-dioxane a likely human carcinogen based upon studies of animals exposed to high levels of this chemical over their entire lifetimes. 

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About Arsenic

Arsenic is a metal found in ores of copper, lead and other minerals, and in soil, groundwater and surface water. Arsenic compounds are used in wood preservatives and have been used in commercial pesticides. Contamination of drinking water may occur if arsenic gets into surface or groundwater after dissolving from minerals in the ground. It may also occur after the past use of arsenic-containing pesticides and improper waste disposal by smelting operations.

In 2001, the USEPA reduced the maximum contaminant level for arsenic in drinking water from 0.05 parts per million to 0.010 parts per million (equivalent to 0.01 milligrams per liter) based on an re-assessment of chronic health risks and the need to achieve additional health protectiveness in public water systems. As of 2006, all public water systems are required to meet the new federal standard of 0.010 parts per million.

Arsenic and Health

Some people exposed to high levels of arsenic in drinking water for long periods of time developed a characteristic darkening and thickening of the skin on the hands and feet. Long-term exposure to high levels of arsenic is also associated with nerve and liver damage, high blood pressure, damage to the vascular system (i.e., blood vessels of the heart and brain), and may lead to learning deficiencies. There is increasing evidence that long-term exposure to high levels of arsenic in drinking water increases the risk of lung, skin and bladder cancer. The US EPA classifies arsenic as a human carcinogen. Chemicals that cause adverse health effects in humans after high levels of exposure may pose a risk of adverse health effects in humans exposed to lower levels over long periods of time.

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About Atrazine

Atrazine is a human-made pesticide widely used to control weeds among corn, sorghum, pineapple, citrus and other crops. It is also used for weed control on industrial and non-agricultural land. Atrazine generally gets into drinking water by runoff into surface water or by leaching into groundwater after crop application or improper waste disposal. Its chemical breakdown in water is slow. The USEPA sets the maximum contaminant level for atrazine in drinking water at 0.003 parts per million (equivalent to 0.003 milligrams per liter)

Atrazine and Health

Numerous studies in humans provide suggestive evidence for an association between atrazine exposure and certain cancers, as well as adverse effects on reproduction and birth outcomes. These studies generally have limitations, including inadequate measures of atrazine exposure, small sample sizes, limited statistical power and the inability to control for confounding factors (other than atrazine exposure) which could have contributed to the observed increases in risk. Therefore, these studies cannot be used to conclude that atrazine causes cancer or other health effects in humans. Long term exposure to high levels of atrazine causes breast cancer in one species of rats, but because of biological differences between rats and humans, this type of cancer may not be relevant to humans. Breast cancer is not associated with human atrazine exposure. Exposure of laboratory animals to high levels of atrazine damages the heart, liver and kidneys, and reduces the weight of offspring born to animals exposed before, during and after pregnancy.

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About Di(2-ethylhexyl)phthalate (DEHP)

Di-2-ethylhexyl phthalate (DEHP), is a human-made liquid chemical that has almost no odor. It is added to plastics to make them flexible, and is present in many plastic products, such as tablecloths, shower curtains, garden hoses, swimming pool liners, rainwear, dolls, packaging film and sheets, and medical tubing. DEHP gets into drinking water when it moves out of plastic products, or through improper waste disposal. The USEPA sets the maximum contaminant level for DEHP in drinking water at 0.006 parts per million (equivalent to 0.006 milligrams per liter).

DEHP and Health

Information on the health effects of DEHP in humans is limited. Laboratory animals exposed to high levels of DEHP had damage to the liver, the male reproductive organs and the developing fetus. Studies in young laboratory animals provide evidence that the developing male reproductive system may be particularly sensitive to the effects of DEHP. DEHP causes cancer in laboratory animals exposed to high levels for their lifetimes. Chemicals that cause cancer in laboratory animals at high levels of exposure may also increase the risk of cancer in humans exposed to lower levels over long periods of time. Whether DEHP causes cancer in humans is unknown.

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About Disinfection By-products (TTHM and HAA5)

Trihalomethanes (TTHMs) and haloacetic acids (HAA5) are groups of chemicals that are formed in drinking water during disinfection when chlorine reacts with naturally occurring organic material (e.g., decomposing vegetation such as tree leaves, algae or other aquatic plants) in surface water sources such as rivers and lakes. They are disinfection byproducts and include the individual trihalomethane chemicals: chloroform, bromoform, bromodichloromethane, and chlorodibromomethane. They also include individual haloacetic acid chemicals: chloroacetic acid, dichloroacetic acid, trichloroacetic acid, bromoacetic acid and dibromoacetic acid. The amount of TTHMs and HAA5 formed in drinking water during disinfection can change from day to day, depending on the temperature, the amount of organic material in the water, the amount of chlorine added, and a variety of other factors. Disinfection of drinking water by chlorination is beneficial to public health. Drinking water is disinfected by public water suppliers to kill bacteria and viruses that could cause serious illnesses, and chlorine is the most commonly used disinfectant in New York State. All public water systems that use chlorine as a disinfectant contain trihalomethanes to some degree. The USEPA sets a maximum contaminant level of 0.08 parts per million (equivalent to 0.08 milligrams per liter) for TTHMs and 0.06 parts per million (equivalent to 0.06 milligrams per liter) for HAA5.

Disinfection By-Products and Health

Some studies suggest that people who drank chlorinated drinking water containing TTHMs and HAA5 for long periods of time (e.g., 20 to 30 years) have an increased risk of certain health effects. These include an increased risk for cancer and for low birth weight, miscarriage and birth defects. The methods used by these studies could not rule out the role of other factors that could have resulted in the observed increased risks. In addition, other similar studies do not show an increased risk for these health effects. Therefore, the evidence from these studies is not strong enough to conclude that TTHMs or HAA5 were major factors contributing to the observed increased risks for these health effects. Studies of laboratory animals show that some TTHMs and HAA5s can cause cancer and adverse reproductive and developmental effects, but at exposures much higher than exposures that could result through normal use of disinfected water. The risks for adverse health effects from trihalomethanes in drinking water are small compared to the risks for illness from drinking inadequately disinfected water.

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About Nitrate

Nitrate naturally occurs in several foods, particularly vegetables. It is also used as a preservative in meats such as bacon. Nitrate is used to make lawn, garden and agricultural fertilizers and is found in sewage and wastes from farm animals. It generally gets into drinking water by runoff into surface water or by leaching into groundwater after land application or improper disposal of sewage or animal waste. The maximum contaminant level for nitrate is set by the USEPA at 10 parts per million (equivalent to 10 milligrams per liter).

Nitrate and Health

Infants are particularly sensitive to nitrate. High levels of nitrate in drinking water have caused serious illness and sometimes death in infants under 6 months of age. This serious illness occurs because nitrate is converted to nitrite in the body and nitrite reduces the ability of the infant's blood to carry oxygen. Symptoms of the illness can develop rapidly and include shortness of breath and blueness of the skin (blue baby condition). Exposure to nitrate in drinking water at levels above 10 milligrams per liter (10 mg/L) increases the risk of developing the illness. Because the effects of nitrate and nitrite are additive, water containing more than 10 mg/L of total nitrate/nitrite should not be used to prepare infant formula or other beverages for infants. Although older children and adults are generally less sensitive than infants to the effects of nitrate, those who have certain gastrointestinal disorders (for example, achlorhydria or atrophic gastritis) that substantially reduce stomach acid and favor the production of nitrite from nitrate may have a greater risk for illness than the general population.

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About PFOA and PFOS

Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) are two types of per- and polyfluoroalkyl substances (PFAS), that are regulated in New York State. PFAS may travel through soil into groundwater, and then into sources of drinking water. These human-made chemicals have been widely used in various consumer, commercial, and industrial products since the 1950s. PFAS unique properties make them resistant to heat, oil, stains, grease, and water and useful in a wide variety of everyday products. PFAS do not break down easily and remain in the environment. Because of widespread use, PFAS releases into the environment have been detected in surface water, groundwater, animals, and humans. New York State public drinking water standards have set maximum contaminant levels of 10 nanograms per liter or parts per trillion each for PFOA and PFOS.

PFOA and PFOS and Health

The available information on the health effects associated with PFOA and PFOS, like many chemicals, comes mostly from studies of high-level exposure in laboratory animals. Less is known about the chances of health effects occurring from lower levels of exposure, such as those that might occur in drinking water. As a result, finding lower levels of chemicals in drinking water prompts water suppliers and regulators to take precautions that include notifying consumers and taking steps to reduce exposure.

PFOA and PFOS have caused a wide range of health effects when studied in animals that were exposed to high levels. The most consistent findings in animals were effects on the liver and immune system and impaired fetal growth and development. The US EPA considers PFOA and PFOS as having suggestive evidence for causing cancer based on studies of animals exposed to high levels of this chemical over their entire lifetimes. Additional studies of high-level exposures of PFOA and PFOS in people provide evidence that some of the health effects seen in animals may also occur in humans.

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About Radium

Radium is a naturally occurring radioactive metal that can exist in different forms called isotopes. The main isotopes of radium are radium-226 and radium-228. Radium is formed when the naturally occurring metals uranium and thorium in soil begin to break down, or decay.

Radium is naturally present at very low levels in rocks and soil. Sometimes naturally high concentrations of radium are found in groundwater in different areas of the United States. As these natural deposits erode they are absorbed into the soil, taken in by plants and sometimes enter drinking water sources. The USEPA sets maximum contaminant level for radium in drinking water at 5 pick/L (5 picocuries per liter) for radium-226 and radium-228 combined. It is important to note that everyone is exposed to low levels radium through breathing, eating, or drinking. Miners and industrial workers are exposed to higher levels of radium through work. The communities and individuals who live near industrial coal burning sites, mines, radioactive waste disposal sites, or those who get their drinking water from a private well may be exposed to higher concentrations of radium.

Radium and Health

There is no clear evidence that exposure to the naturally occurring low levels of radium normally present in the environment is likely to result in harmful effects. However, long-term exposure to radium above the maximum contaminant level in drinking water may result in health effects including anemia, cataracts, and fractured teeth. Long-term exposure to higher concentrations of radium may also increase a person's risk in developing bone cancer, and other kinds of cancers.

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About Tetrachloroethene (PCE)

Tetrachloroethene (PCE, PERC) is also called tetrachloroethylene and perchloroethylene.  Itis a colorless human-made liquid used as a solvent for dry cleaning fabrics, for removing grease from metal, and as an intermediate (building block) in the manufacture of other chemicals. It is found in some consumer products such as paint and spot removers, water repellents, silicone lubricants, adhesives and wood cleaners. Contamination of drinking water may occur if tetrachloroethene leaches into groundwater from leaking storage sites or after improper waste disposal. The USEPA sets the maximum contaminant levels for PCE at 0.005 parts per million (equivalent to 0.005 milligrams per liter).

PCE and Health

An association exists between people in the workplace being exposed to high levels of tetrachloroethene in air and certain forms of cancer, although the association does not prove that the cancers were caused by tetrachloroethene. Tetrachloroethene causes cancer in laboratory animals exposed to high levels over their lifetimes. Chemicals that cause cancer in laboratory animals also may increase the risk of cancer in people who are exposed to lower levels over long periods of time.

People exposed to high levels of tetrachloroethene in air show nervous system effects and slight changes to their liver and kidneys. Some studies show a slightly increased risk of some types of reproductive effects among workers (including dry-cleaning workers) exposed to tetrachloroethene and other chemicals. The reproductive effects associated with exposure included increased risks of spontaneous abortion, menstrual and sperm disorders, and reduced fertility. The data suggest, but do not prove, that the effects were caused by tetrachloroethene and not by some other factor or factors. Exposure to high levels of tetrachloroethene has caused liver and kidney damage in laboratory animals and has changed their behavior.

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About Trichloroethene (TCE)

Trichloroethene (also known as trichloroethylene or TCE) is a colorless, human-made liquid which is used primarily as a solvent for removing grease from metal. It has a variety of other uses such as a dry-cleaning solvent and as a chemical intermediate (building block) in the production of other chemicals. TCE can contaminate drinking water after improper use or disposal. The USEPA has set maximum contaminant levels for TCE in drinking water at 0.005 parts per million (equivalent to 0.005 milligrams per liter).

TCE and Health

Studies of people exposed for long periods of time to high levels of TCE consistently detect an association between TCE exposure and increased risks for certain types of cancer. The strongest evidence is for kidney cancer, non-Hodgkin's lymphoma and liver cancer. In laboratory animals, lifetime exposures to TCE causes tumors in the liver and kidneys. The USEPA has concluded that TCE is carcinogenic in humans by all routes of exposure.

Long-term exposure in the workplace to high levels of TCE in air is linked to non-cancer health effects on the central nervous system and irritation of the mucous membranes. Some studies also reported an increased risk for adverse effects on human fetal development in the offspring of women who lived in areas with elevated concentrations of TCE in air or drinking water. In laboratory animals, exposure to high levels of TCE has damaged the central nervous system, immune system, liver and kidneys, and adversely affected reproduction and development of offspring.

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About Uranium

Uranium is a naturally occurring radioactive element found in nearly all rocks, soils, and air. Uranium can travel through the wind and settle onto water, land, and plants. In most areas of the United States, naturally occurring low levels of uranium are found in drinking water, and sometimes naturally high concentrations of uranium are found in places with elevated levels in rocks and soil.

The USEPA sets the maximum contaminant level for uranium in drinking water at 0.03 parts per million (equivalent to 0.030 milligrams per liter) to prevent possible risks to human health. It is important to note that everyone is exposed to low levels uranium through breathing, eating, or drinking. Miners and industrial workers are exposed to higher levels of uranium through work. Communities and individuals living near industrial metal processing sites, uranium mines, or radioactive waste disposal sites may be exposed to higher concentrations of uranium.

Uranium and Health

Most of the uranium ingested through drinking or eating is not absorbed and leaves the body. Since uranium is a heavy metal, long-term exposures to higher concentrations above the maximum contaminant level for drinking water may result in kidney damage. Uranium is mildly radioactive and has not been found to cause cancer in animals or humans, even at very high doses over long periods of time. The USEPA has not classified natural or depleted uranium as a carcinogen.

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