Richard Casady wrote:
On Wed, 12 Sep 2007 00:44:05 GMT, Jere Lull wrote:

You say that viruses are smaller than sodium or chloride ions? I got
A's in college chemistry, and I have trouble believing it.

Smaller isn't necessarily the issue with retention of ionic species. A
membrane that electrostatically adsorbs ions can still pass much larger
non-polar molecules and materials.

As I understand him from the past, the viruses are broken down to toxic
chemicals that will pass.

Thank you for relaying that little tidbit. I remain skeptical. I may
drop by the local waterworks and look at a few trade magazines. Check
out the ads for the millions of gallons a day RO plants.

Casady

There are a number of studies showing that RO membranes (which are not
absolute porosity filters, but are spiral wound depth filters) are not
100% viral retentive, or bacterial retentive (especially for Giardia
oocytes, and certainly not for mycoplasma) when challenged with a
significant upstream population. The prevalence of these organisms (and
almost-organisms) in seawater is, however, extremely low, and a 2 to
3-log reduction (about what the literature seems to support) gives a
very high probability of 100% removal. Safer than tap water, by a long shot.

As for viral proteins being toxic, the only studies I'm aware of have
been done on the common viral pesticides, where no oral toxicity has
ever been observed - doesn't mean it can't happen, but given how rapidly
protein is denature in the stomach, it's pretty unlikely. For
injectables, some hepatotoxicity has been shown in mice injected with
solubilized viral proteins - hence my reluctance to inject RO water
while out sailing...

The DNA/RNA does not appear to be orally toxic either.

Keith Hughes