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EWG's Tap Water Database — 2019 UPDATE

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Cancer-causing Volatile Organic Compounds

October 2019

Summary

Many tap water contaminants can move from water into air and can enter the body through the skin after a shower or bath. The federal government classifies such substances as volatile organic compounds, or VOCs. These pollutants originate in multiple sources, including gasoline, solvents, paints, cars, carpets and shower curtains.

Between 1987 and 1992, the federal government set legal limits for 21 different VOCs in tap water. No new or updated federal standards for VOCs have been set since then. The legal limits allow much greater VOC exposure than the amounts many public health agencies consider pose minimal harm to human health.

The full range of potential VOC contaminants in everyday environments may include hundreds of chemicals. Most worrisome are those that harm the developing fetus or increase the risk of cancer. This report highlights 12 carcinogenic VOCs EWG believes should be regulated as a group of tap water contaminants.

Carcinogenic VOCs in tap water

In 2011 the Environmental Protection Agency recommended establishing a single regulatory standard for a group of carcinogenic VOCs, but it has not yet proposed a new standard. Of the 12 VOCs listed in the table below, the EPA recommended including nine in a group of potentially carcinogenic VOCs. EWG believes three additional chemicals should be added to the list: 1,4-dioxane, styrene and 1,1,2-trichloroethane.

Carcinogenic VOC* Federal legal limit, in ppb Level posing one-in-one-million cancer risk1 Reference Classification2
1,2,3-Trichloropropane N/A 0.0007 California public health goal Likely to be carcinogenic to humans
Vinyl chloride 2 0.05 California public health goal Known human carcinogen
Tetrachloroethylene (PCE or PERC) 5 0.06 California public health goal Likely to be carcinogenic to humans
Carbon tetrachloride 5 0.1 California public health goal Likely to be carcinogenic to humans
Benzene 5 0.15 California public health goal Known human carcinogen
1,1,2-Trichloroethane 5 0.3 California public health goal Possible human carcinogen
1,4-Dioxane N/A 0.35 EPA one-in-a-million cancer risk level Likely to be carcinogenic to humans
1,2-Dichloroethane 5 0.4 California public health goal Probable human carcinogen
Styrene 100 0.5 California public health goal Reasonably anticipated to be a human carcinogen
1,2-Dichloropropane 5 0.5 California public health goal Carcinogenic to humans
Trichloroethylene (TCE) 5 0.5 EPA one-in-one-million cancer risk level Carcinogenic to humans
Dichloromethane (methylene chloride) 5 4 California public health goal Likely to be carcinogenic to humans

* Click on a contaminant above to see its nationwide testing results.

1. Concentration that corresponds to a one-in-one-million cancer risk as defined by the California Office of Environmental Health Hazard Assessment and the EPA Integrated Risk Information System, or IRIS.

2. Carcinogenicity classifications come from the EPA IRIS program, except for two contaminants, styrene and 1,2-dichloropropane, which have not been assessed by IRIS for carcinogenicity. In 2011, the National Toxicology Program classified styrene as “reasonably anticipated to be a human carcinogen.” In 2016, the International Agency for Research on Cancer classified 1,2-dichloropropane as “carcinogenic to humans.”

What are the health effects of exposure to VOCs?

VOCs can cause various types of cancer. For instance:

Some VOCs are not known to cause cancer but can cause other serious health problems. For example, toluene, ethylbenzene and xylene are toxic to the liver, kidneys and nervous system. Toluene is reported to harm the hormone system.

How do VOCs get in water?

VOCs are used in a wide variety of industrial and commercial products and processes. Commercial and residential applications, as well as disposal at municipal and industrial landfills across the country, have contributed to VOC contamination of drinking water supplies.

A 2006 U.S. Geological Survey study of groundwater and drinking water wells found VOCs in 90 of 98 aquifers tested nationwide, with the most frequent detections in California, Nevada, Florida and the New England and mid-Atlantic states. Some groundwater samples were contaminated with more than one VOC.

Is there a safe level of VOCs in water?

For most individual VOCs, limits that pose the one-in-one-million cancer risk defined by the California public health goals or the EPA are adequate. But the levels of some VOCs, such as trichloroethylene, need to be more strict to protect children.

Even these benchmarks may fall short, because people are exposed to VOCs and other pollutants simultaneously. That’s why EWG urges federal and state health agencies to regulate carcinogenic VOCs as a group.

What can I do to reduce my exposure to VOCs in drinking water?

There are many sources of VOC exposure:

For many tap water quality concerns, shoppers can use EWG’s Water Filter Buying Guide to find a product that will remove specific water contaminants. Here’s what to look for:

Following the advice of federal and state public health agencies, EWG recommends that people whose water comes from a private well test their water quality regularly. This is especially important for private well owners in areas where there may be underground fuel storage tanks, or those near gas stations, dry-cleaning facilities and landfills.

References

Environmental Protection Agency. Integrated Risk Information System Assessment for 1,2-Dichloroethane. 1987. Available at cfpub.epa.gov/ncea/iris2/chemicalLanding.cfm?substance_nmbr=149.

California Office of Environmental Health Hazard Assessment. Public Health Goal for 1,2-Dichloropropane in Drinking Water. 1999. Available at oehha.ca.gov/media/downloads/water/chemicals/phg/12dcpf.pdf.

Environmental Protection Agency. Integrated Risk Information System Assessment for 1,1,2-Trichloroethane. 1987. Available at cfpub.epa.gov/ncea/iris2/chemicalLanding.cfm?substance_nmbr=198.

EPA. Integrated Risk Information System Assessment for Benzene. 2000. Available at cfpub.epa.gov/ncea/iris2/chemicalLanding.cfm?substance_nmbr=276.

EPA. Integrated Risk Information System Assessment for Vinyl Chloride. 2000. Available at cfpub.epa.gov/ncea/iris2/chemicalLanding.cfm?substance_nmbr=1001.

EPA. Integrated Risk Information System Assessment for 1,2,3-Trichloropropane. 2009. Available at cfpub.epa.gov/ncea/iris2/chemicalLanding.cfm?substance_nmbr=200.

EPA. Integrated Risk Information System Assessment for Carbon Tetrachloride. 2010. Available at cfpub.epa.gov/ncea/iris2/chemicalLanding.cfm?substance_nmbr=20.

EPA. Basic Questions and Answers for the Drinking Water Strategy Contaminant Groups Effort. EPA 815-F-11-002, 2011. Available at nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P100NRW9.TXT.

EPA. Integrated Risk Information System Assessment for Dichloromethane. 2011. Available at cfpub.epa.gov/ncea/iris2/chemicalLanding.cfm?substance_nmbr=70.

EPA. Integrated Risk Information System Assessment for Trichloroethylene. 2011. Available at cfpub.epa.gov/ncea/iris2/chemicalLanding.cfm?substance_nmbr=199.

EPA. Integrated Risk Information System Assessment for Tetrachloroethylene. 2012. Available at cfpub.epa.gov/ncea/iris2/chemicalLanding.cfm?substance_nmbr=106.

EPA. Integrated Risk Information System Assessment for 1,4-Dioxane. 2013. Available at cfpub.epa.gov/ncea/iris2/chemicallanding.cfm?substance_nmbr=326.

EPA. Volatile Organic Compounds’ Impact on Indoor Air Quality. 2016. Available at epa.gov/indoor-air-quality-iaq/volatile-organic-compounds-impact-indoor-air-quality.

International Agency for Research on Cancer. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 71. Re-Evaluation of Some Organic Chemicals, Hydrazine and Hydrogen Peroxide. 1999. Available at monographs.iarc.fr/ENG/Monographs/vol71/index.php.

International Agency for Research on Cancer. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 82. Some Traditional Herbal Medicines, Some Mycotoxins, Naphthalene and Styrene. 2002. Available at monographs.iarc.fr/ENG/Monographs/vol82/index.php.

International Agency for Research on Cancer, IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 100F. Chemical Agents and Related Occupations. 2012. Available at monographs.iarc.fr/ENG/Monographs/vol106/index.php.

International Agency for Research on Cancer. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 106. Trichloroethylene, Tetrachloroethylene and Some Other Chlorinated Agents. 2014. Available at monographs.iarc.fr/ENG/Monographs/vol106/index.php.

International Agency for Research on Cancer. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 110. Some Chemicals Used as Solvents and in Polymer Manufacture. 1,2-Dichloropropane. 2016. Available at monographs.iarc.fr/ENG/Monographs/vol110/mono110-03.pdf.

National Toxicology Program. Report on Carcinogens: Styrene. 2011. Available at ntp.niehs.nih.gov/ntp/roc/content/profiles/styrene.pdf.

P.J. Squillace et al. VOCs, Pesticides, Nitrate, and their Mixtures in Groundwater Used for Drinking Water in the United States. Environmental Science and Technology, 2002, 36(9):1923–1930.

U.S. Geological Survey. The Quality of Our Nation’s Waters. Volatile Organic Compounds in the Nation’s Ground Water and Drinking-Water Supply Wells. 2006. Available at pubs.usgs.gov/circ/circ1292.

Water Research Foundation. Background Technical Information for Carcinogenic Volatile Organic Compounds (cVOCs). 2015. Available at www.waterrf.org/resources/Lists/ProjectPapers/Attachments/62/4457_BackgroundInfo_cVOCs.pdf.