N-Nitrosodimethylamine (NDMA)
Cal American Water Company
N-Nitrosodimethylamine is one of the DNA-damaging, cancer-causing contaminants called N-nitrosamines that can form during water treatment with the use of certain disinfectants, such as chloramine. Read More.
Pollution of water sources with effluent from municipal wastewater treatment plants and runoff from animal feeding operations contributes to nitrosamine formation. Fifteen different nitrosamines are listed as carcinogens in the U.S. Department of Health and Human Services National Toxicology Program Report on Carcinogens. The federal government has not set a legal limit for nitrosamines in drinking water and water utilities typically do not test for these contaminants. California has set a public health goal for one of the most common nitrosamines, N-nitrosodimethylamine or NDMA, at 0.003 parts per billion in drinking water, a concentration that corresponds to an estimated one-in-one-million cancer risk.
Samples
Samples exceeding legal limit (MCL)
Samples exceeding
health guidelines
Testing results - average by year
| Year | Average result | Samples taken | Detections | Range of results |
|---|---|---|---|---|
| 2013 | N/A | 0 | 0 | N/A |
| 2014 | ND | 1 | 0 | ND |
| 2015 | 1.05 ppt | 2 | 1 | ND - 2.10 ppt |
| 2016 | 0.600 ppt | 2 | 1 | ND - 1.20 ppt |
| 2017 | 1.60 ppt | 2 | 1 | ND - 3.20 ppt |
| 2018 | ND | 2 | 0 | ND |
| 2019 | ND | 2 | 0 | ND |
ppt = parts per trillion
State and national drinking water standards and health guidelines
EWG Health Guideline 3 ppt
The EWG Health Guideline of 3 ppt for n-nitrosodimethylamine was defined by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer.
ppt = parts per trillion
All test results
| Date | Lab ID | Result |
|---|