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EWG's Tap Water Database — 2019 UPDATE

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Total trihalomethanes (TTHMs)

East Milton Water System

Trihalomethanes are cancer-causing contaminants that form during water treatment with chlorine and other disinfectants. The total trihalomethanes group includes four chemicals: chloroform, bromodichloromethane, dibromochloromethane and bromoform. Read More.

Studies conducted in the U.S. and Europe have found that drinking tap water that carries disinfection byproducts increases the risk of developing bladder cancer. In animal studies, all trihalomethanes cause liver, kidney and intestinal tumors. Some human epidemiological studies also reported an association between disinfection byproducts and an increased risk of problems during pregnancy, including spontaneous miscarriage, cardiovascular defects, neural tube defects and low birth weight.

The health guideline of 0.15 parts per billion, or ppb, for the group of four trihalomethanes, or THM4/TTHM, was defined in a peer-reviewed scientific study by EWG and represents a one-in-one-million lifetime cancer risk level.

Click here to read more about disinfection byproducts.

 

34

Samples

0

Samples exceeding legal limit (MCL)

14

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20122.13 ppb64ND - 6.00 ppb
20130.191 ppb102ND - 1.50 ppb
20140.285 ppb126ND - 1.40 ppb
20152.55 ppb21ND - 5.10 ppb
20161.30 ppb21ND - 2.60 ppb
2017ND20ND

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 0.15 ppb

The health guideline of 0.15 parts per billion, or ppb, for the group of four trihalomethanes, or THM4/TTHM, was defined in a peer-reviewed scientific study by EWG and represents a one-in-one-million lifetime cancer risk level.

EPA Maximum Contaminant
Level (MCL) 80 ppb

The legal limit for the group of four trihalomethanes, established in 1998, was based on the need for residual disinfectant levels in water served to customers and the cost of treatment. This limit does not fully protect against the risk of cancer due to exposure to trihalomethanes.

ppb = parts per billion

All test results

Date Result
2012-07-103.40 ppb
2012-07-106.00 ppb
2012-07-10ND
2012-07-10ND
2012-07-101.50 ppb
2012-07-101.90 ppb
2013-08-120.410 ppb
2013-08-12ND
2013-08-12ND
2013-08-121.50 ppb
2013-08-12ND
2013-08-12ND
2013-10-07ND
2013-10-07ND
2013-10-07ND
2013-10-07ND
2014-01-08ND
2014-01-08ND
2014-01-08ND
2014-01-08ND
2014-04-161.40 ppb
2014-04-160.340 ppb
2014-04-16ND
2014-04-160.290 ppb
2014-07-080.680 ppb
2014-07-080.320 ppb
2014-07-08ND
2014-07-080.390 ppb
2015-08-19ND
2015-08-195.10 ppb
2016-08-03ND
2016-08-032.60 ppb
2017-08-14ND
2017-08-14ND