N-Nitrosodimethylanime, usually called NMDA, is one of the group of chemical contaminants called nitrosamines. It results largely as a by-product of adding chloramine and chlorine to drinking water.

According to Dr. Joseph Mercola:

NDMA is a potent hepatotoxin that causes fibrosis of the liver in rats and has actually been used to stimulate mice to grow cancer for experimental purposes.

NDMA is associated more with municipal wastewater effluents, so it is believed that consumer products are the largest contributor, rather than natural nitrogen sources. Although sewage treatment plants remove some of the quaternary amines that lead to NDMA, many make it through the treatment process due to the sheer volume of them in our wastewater.

According to the California Department of Public Health:

“Given the NDMA detections associated with drinking water sources and treatment, NDMA is a good candidate for future regulation (i.e., establishment of a drinking water standard, also known as a maximum contaminant level or MCL).”

NDMA is essentially colorless, odorless, and nearly tasteless, so you would never know it was in your water unless you were testing for it. Reverse osmosis filters have been demonstrated to remove only about 50 percent of NDMA.

The fact that NDMA is toxic in very minute concentrations, difficult to detect, slow to biodegrade, and travels through the soil with great ease, makes it of particular concern for public health.

Animals that ingest NDMA from food, water, or contaminated air develop serious health problems ranging from non-cancerous liver damage to liver and lung cancer. People poisoned with NDMA (unfortunately, there have been intentional poisonings) died from severe liver damage and internal bleeding.

According to the CDC’s Public Health Statement:

“Although there are no reports of NDMA causing cancer in humans, it is reasonable to expect that exposure to NDMA by eating, drinking, or breathing could cause cancer in humans. Mice that were fed NDMA during pregnancy had offspring that were born dead or died shortly after birth. However, it is not known whether NDMA could cause the death of human babies whose mothers are exposed during pregnancy.”

Regulation: Currently unregulated, but EPA is considering establishing an MDA. There is currently no NSF standard for NDMA.

Treatment: As the article above indicates, reverse osmosis is only about 50% effective at reducing NDMA. Carbon filtration, the usual standby for chemical contaminants, is largely ineffective. UV can be used, but the dosage required to break down NDMA. is far higher than those of standard residential UV systems used to inactivate bacteria and viruses. At present there is no recommended residential treatment for the reduction of NDMA. (Reverse osmosis, which is partially effective, is the best known treatment.)