NDMA in Reclaimed Wastewater

N-Nitrosodimethylamine (NDMA) occurs in various foods and alcoholic beverages. It is detected in cigarette smoke and has also been detected in some drinking water and wastewater systems as a byproduct of chlorination and/or chloramination. It was used in the past in rocket fuel but is no longer manufactered.

Click here for the current USEPA risk assessment for NDMA.

In California, the Santa Clara Valley Water District and the city of San Jose funded a study that detected NDMA in recycled water used for irrigation into shallow groundwater. Concentrations of 3 to 4 parts per trillion (ppt) were found down to 30 feet in ground water. No one drinks the water and so there is no immediate health risk. Click here for the June 14, 2011 Silicon Valley Mercury News report. 

The California Public Health Goal (PHG) for NDMA is 0.003 ug/L (or 3 ppt). The PHG is based on linear-extroplation of animal toxicological data and represents a 1:1,000,000 theoretical risk of cancer. Click here for the California PHG document.

There are a number of strategies that can be used to minimize the formation of NDMA or to eliminate it altogether.  Perhaps we’ll take a look at these processes in a future post.


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