Re[2]: [at-l] Katadyn Micropur Tablets

[jbryankramer@xxxxxxx (J Bryan Kramer)]

"Chlorine kills bacteria, including disease-causing organisms and the
nuisance organism, iron bacteria. However, low levels of chlorine, normally
used to disinfect water, are not an effective treatment for giardia cysts. A
chlorine level of over 10 mg/1 must be maintained for at least 30 minutes to
kill giardia cysts."

http://ohioline.osu.edu/b795/b795_7.html

As for cryptosporidium it sounds as if the cysts are rather resisitant to
chlorine (Cryptosporidium is 240,000 times more resistant to chlorination
than Giardia (Jakubowski, 1995) levels of 15,000 ppm Chlorine don't seem to
be effective.) but actual clinical infections are rare. The organism seems
to be common in public water supplies. However it also seems as if the only
population at risk is the AIDS population who had 85% of reported cases in
NYC. About 80% of the population has antibodies to crypto so subclinical
infections seem to be the rule. Why it flared up in Minnesota and other
places is a mystery. Even filtration is not very effective unless the filter
media is an actual 1 uM material or less. Nominal 1 uM filters are
ineffective. All cases traced to public water systems occured on systems who
produced water that met EPA guidelines.

http://www.earthinstitute.columbia.edu/library/earthmatters/march99/Pages/pa
ge14.html

http://biology.kenyon.edu/slonc/bio38/hannahs/crypto.htm

So even tho crypto may be resistant it doesn't normally cause disease.
Rather interesting but darn little you can do about it on the trail beyond
boiling all your water.

Bryan


"Si vis pacem para bellum"

> >"...how about naming these pathogens that are not killed by
> chlorination?" asks
> >JB.
>
> As far as I know chlorination kills some of most pathogens in
> drinking water.
> But I've read reports that some pathogen's -- giardia and crypto...  come
> immediately to mind, are not killed in percentages that would
> ensure against
> humans being infected,
>
> Weary
>
>
>
>