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EWG's Tap Water Database

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Chloroform

Arapahoe Cnty Wwwa

Chloroform, one of the total trihalomethanes (TTHMs), is formed when chlorine or other disinfectants are used to treat drinking water. Chloroform and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Read More.

In addition to tap water disinfection, chloroform pollution in the environment also comes from industrial discharges from pulp and paper mills, and from urban wastewater effluent. Human studies show that chloroform damages the kidneys, liver and central nervous system. In animals, chloroform causes infertility, birth defects and cancer.

Click here to read more about disinfection byproducts.

 

24

Samples

0

Samples exceeding legal limit (MCL)

0

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2010ND70ND
2011ND40ND
2012ND70ND
2013ND10ND
20142.80 ppb112.80 ppb
20150.978 ppb440.660 ppb - 1.40 ppb

ppb = parts per billion.

State and national drinking water standards and health guidelines

Health Guideline 0.4 ppb

The health guideline of 0.4 ppb for chloroform was proposed in 2018 by the California Office of Environmental Health Hazard Assessment as a one-in-a-million lifetime risk of cancer. Values greater than one-in-a-million cancer risk level can result in increased cancer cases above one in a million people.

ppb = parts per billion.

EPA Maximum Contaminant
Level Goal (MCLG)70.0 ppb

A non-enforceable federal health guideline. For cancer-causing chemicals, these health goals are typically set to zero.

ppb = parts per billion.

All test results

Date Result
2010-01-25ND
2010-01-25ND
2010-01-25ND
2010-02-01ND
2010-02-01ND
2010-04-05ND
2010-04-05ND
2011-01-19ND
2011-04-01ND
2011-04-01ND
2011-04-01ND
2012-01-13ND
2012-01-13ND
2012-01-23ND
2012-01-23ND
2012-04-06ND
2012-04-06ND
2012-04-09ND
2013-01-08ND
2014-11-112.80 ppb
2015-05-050.850 ppb
2015-05-051.40 ppb
2015-05-051.000 ppb
2015-05-050.660 ppb