Hi all…hidden within this article is some information on the potential fate of 3 intentionally introduced toxins in distribution systems. The main focus of the study is an assessment of how various pathogens/toxins may attach to different pipe materials. The biocidal ability of copper in particular is confirmed and there is some good information on which pathogens/toxins which may be able adhere to various pipe materials. The author indicates that some toxins can adhere to one or more of the 7 pipe materials tested. For toxins in which this is the case, the original contamination event could be mitigated as there is a lot of surface area in the distribution system. On the other hand, if the toxins/pathogens are not inactivated/transformed fairly quickly they can slough off later, prolonging the length of the exposure event. This from the conclusions:
“Adherence studies with botulinum type A neurotoxin complex demonstrated that the toxin was not stable in water. If a contamination with botulinum toxin occurred in a water system, within hours the toxin would break down in the presence of water before it was able to adhere to the pipe material. Aflatoxin had a moderate level of adherence to three pipe materials (HDPE, PVC, and DIE) after a 24 h incubation period at 18–20°C and a moderate to high level of adherence to five of seven pipe materials (HDPE, PVC, DIE, ACI, and copper) after a 7 day incubation period at 18–20°C…At both temperatures, the day seven matrix controls appeared stable in water when compared to the day zero matrix controls, suggesting that the water did not affect the stability of the toxin. Based on the apparent stability of the toxin in the test water, along with a lower recovery of toxin after 24 h incubation, it appears that the toxin (aflatoxin) may bind tightly at the beginning and then slough off over time. Adherence studies with brevetoxin demonstrated a high level of adherence to one out of seven pipe materials (HDPE) after a 7 day incubation period at 2–8°C and 18–22°C.”
If you are concerned about the intentional introduction of toxins and/or microbial agents into drinking water I have a collection of papers and reviews on the topic to bring you up to speed, just contact me by replying to this e-mail or at wbanderson@uwaterloo.ca.
Bill
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Adhesion and Decontamination of Biological Contaminants in Drinking Water Distribution Systems
Sandip Chattopadhyay
Exposure and Health (2016) 8:199–210
http://link.springer.com/journal/12403/8/2?wt_mc=alerts.TOCjournals
Abstract
The introduction of pathogenic biological contaminants into a water distribution system may result in short term and long-term exposures and subsequent effects on human health if these contaminants adhere to the internal surfaces of pipes, potentially forming biofilms. These studies evaluated the degree to which selected biological contaminants representative of biological warfare threats or natural contamination adhere to water distribution system pipe materials under different temperature and exposure conditions, and whether water distribution pipes can be remediated using common chemical treatment procedures. The adherence levels of Bacillus anthracis spores, Burkholderia thailandensis, Vibrio cholerae, Salmonella enterica subsp. enterica serovar Typhi (referred to as S. typhi), aflatoxin, and brevetoxin to seven pipe materials were evaluated. Most of the biological contaminants tested were shown to have some level of adherence to high-density polyethylene (HDPE), polyvinyl chloride (PVC), aged black iron pipe (ACI), and steel pipe coated with epoxy (DIE) pipe materials using a single test concentration of organisms or toxin after incubation for 7 days at room temperature. Of the seven materials tested, HDPE appeared to be the most adherent pipe material with some levels of adherence measured for all six of the biological contaminants. Shortened incubation times appeared to reduce the overall adherence for three of the biological contaminants evaluated. Three chemical treatments…were evaluated for their ability to remediate these biological contaminants from selected pipe material/ biological contaminant combinations. Sodium hypochlorite was the most effective for reducing the adherence of the bacteria and B. anthracis spores but not as effective against aflatoxin as the other treatments…”
