Know Your Environment. Protect Your Health.

Total trihalomethanes (TTHMs)

Lovelock Correctional Center Nevada Department of Corrections

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.

 

12

Samples

0

Samples exceeding legal limit (MCL)

12

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20180.515 ppb220.510 ppb - 0.520 ppb
20196.94 ppb220.770 ppb - 13.1 ppb
20200.630 ppb220.570 ppb - 0.690 ppb
20210.700 ppb220.680 ppb - 0.720 ppb
20220.615 ppb220.560 ppb - 0.670 ppb
20232.65 ppb221.80 ppb - 3.50 ppb

ppb = parts per billion

State, National, and Health Guidelines for Drinking Water

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 Lab ID Result
2018-08-22A8H3466-010.520 ppb
2018-08-22A8H3466-020.510 ppb
2019-08-14A9H2322-0113.1 ppb
2019-08-14A9H2322-020.770 ppb
2020-08-06ADH0970-010.570 ppb
2020-08-26ADH2942-010.690 ppb
2021-08-26AEI00009-010.680 ppb
2021-08-26AEI00009-020.720 ppb
2022-08-25AFH3731-010.670 ppb
2022-08-25AFH3731-020.560 ppb
2023-08-21DA58054-13.50 ppb
2023-08-21DA58054-21.80 ppb