Is GAC (Granular Activated Carbon) Carcinogenic?
October 30, 2010The following is published by permission from it’s author, noted pool chemistry researcher, Alan Lewis
I only recently came across this piece of research in the course of my preparations for research I am involved in the University of New South Wales dealing with N- nitrosamines. It is entitled:
“Unexpected Role of Activated Carbon in Promoting Transformation of Secondary Amines to N-Nitrosamines”
Environ. Sci. Technol. April 2010 44, 4161 -68 Lokesh Padhye et al
This peer reviewed article deals with a known carcinogen (NDMA- Nitrosodimethylamine) – which even though found in minute quantities in drinking supply waters and pools spas and hot-tubs – is considered more potent than THMs.
The surprise here is that the then unexpected part of this research, is that until now, Activated Carbon is commonly used in domestic home filters acquired readily in most local supermarkets in anglo-saxon countries around the world. I guess it will take some time before this penny will drop. The activated carbon is meant to remove the amines from the potable water delivered to houses in the western world after chloramination involving the injection of monochloramines into the supply line as a mode of disinfection designed to last long distances in old in ground water supply systems. Most people are buying the filters because they fear from the “chloramine” tastes in the water. Is this a case of “damned if you do and damned if you don’t?”
Now that it has been discovered that “… the activated carbon can catalyzes transformation of secondary amines (dimethylamines for example) -to yield (detectable) trace levels of N-Nitrosamines in the presence of ambient Oxygen.”
It should be made clear that very low levels of N-Nitrosamines are considered carcinogenic.
All those familiar with the processes for eliminating “undissolved” Ozone from Ozonation systems in pools; drinking water; and probably potable drink manufacture; also pass the water through GAC (Granulated Acitivated Carbon) filters. So this too is of great concern to the aquatic industry since there must be countless centers using Ozone for disinfection and sending their off gas through destruction filters filled with GAC.
From this it can readily be seen that here should be some urgency about undertaking measures to prevent the formation of N-Nitrosamines wherever there are AC filters. This is here and this is now!
Hopefully there will be a lot of responses to this appeal of mine…..
As a footnote: These findings add credence to the idea that UV photolysis of pool water may be catalyzing trichloramines to form Trihalomethanes – which also utlises the presence of small particles of organic carbon (in the form of lint; skin hair etc) in heavily loaded indoor heated pool water.
Alan Lewis Pool Consultant Aquazure
Alan Lewis Pool Consultant Aquazure
email: aquazure34@gmail.com