[Dioxin-l] Re: Poor efficacy of residual chlorine in drinking water distribution

[pat.costner@dialb.greenpeace.org]

Dear Mr. Bell,

I urge you to give the abstract of the study by Payment (1999)  a 
more careful reading.  You have interpreted it to say that "E coli is 
inactivated by residual chlorine throughout the distribution 
system."  This differs considerably from the actual wording of the 
abstract, as follows: 

    "Except for Escherichia coli, microorganisms remained relatively
    unaffected in water from the distribution systems tested. When
    sewage was added to the water samples, indigenous thermotolerant
    coliforms were inactivated only when water was obtained from
    sites very close to the treatment plant and containing a high
    residual chlorine concentration." 

You then note, " Given that E coli is a principal contaminant of
sewage (and in turn the water supply system), and can be highly
pathogenic (eg E coli 0157), this abstract can easily be used to
 make a case for chlorination of water supplies."   With this, I
 would suggest that you have missed a major finding of the study:

    "Clostridium perfringens was barely inactivated, suggesting that
    the most resistant pathogens such as Giardia lamblia,
    Cryptosporidium parvum, and human enteric viruses would not  
   be inactivated. "

 Please note that the Clostridium perfringens used by Payment
 (1999) as an indicator for Giardia lambia, Cryptosporidium
 parvum, and human enteric viruses, was "barely inactivated".  
Giardia lambia and Cryptosporidium parvum also commonly occur in
sewage and have been identified as the causative agents in
numerous disease outbreaks.  For example, in his
recent review  -- "Microbiological Safety of  Drinking Water: United 
States and Global Perspectives",  Environ Health Perspect 107
( Suppl 1):191-206 (1999) -- Ford notes as follows: 

    "G. lamblia and C. parvum 
    Smith and Lloyd (111) have  recently reported that these two protozoa 
    are responsible for     more than 600 million infections worldwide, of which a
    significant proportion are waterborne. For example, 60% of Giardia cases 
    are estimated to be waterborne in the United States (84), with a point 
    estimate of the annual incidence of giardiasis of 260,000 cases (2).
    Until recently, giardiasis was the most frequently reported waterborne
    disease ( 112,113). Cryptosporidiosis has now overtaken giardiasis,
    with a point  estimate of 420,000 annual waterborne cases in the United 
    States (2)." 

In summary,  your suggestion that the findings by Payment (1999)  
"can easily be used to make a case for chlorination of water 
supplies"  stands in direct opposition to Payment's conclusion:

    "... the maintenance of a free residual concentration in a 
    distribution system does not provide a significant inactivation 
    of pathogens, could even mask events of contamination of the 
    distribution, and thus would provide only a false sense of 
    safety with little active protection of public health." 

On 10 Jan 00, at 0:20, david bell wrote:
[Dioxin-l] Re: Poor efficacy of residual chlorine

From:           	"david bell" <burnt_paper@hotmail.com>
To:             	dioxin-l@venice.essential.org
Subject:        	[Dioxin-l] Re: Poor efficacy of residual chlorine in drinking water distribution
Date sent:      	Mon, 10 Jan 2000 00:20:26 GMT

> If I read the abstract below correctly, E coli is inactivated by residual
> chlorine throughout the distribution system. Given that E coli is a
> principal contaminant of sewage (and in turn the water supply system), and
> can be highly pathogenic (eg E coli 0157), this abstract can easily be
> used to make a case for chlorination of water supplies.
> 
> I am not sure what to make of the abstract; viruses can be very difficult
> to kill, and (I believe) some clostridia have a spore, again making them
> very difficult to disinfect. I don't know that E coli isn't a much more
> representative bacterial pathogen than the others this abstract measures.
> 
> david bell

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Pat Costner
Greenpeace
P.O. Box 548
 or 512 County Road 2663
Eureka Springs, Arkansas 72632
ph: 1 501 253 8440
fx: 1 501 253 5540
em: pat.costner@dialb.greenpeace.org
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