From: kasab@luther.che.wisc.edu (John J. Kasab) 
Subject: Re: NRDC Criticizes Domenici Plan to Gut Drinking Water Protections
Organization: University of Wisconsin - Madison
Date: 5 Sep 92 01:33:09 CDT
Originator: kasab@luther.che.wisc.edu

In article <...> bjgaed@bb1t.monsanto.com writes:
>In article <...> bhjelle@carina.unm.edu () writes:
>> In article <...> des@helix.nih.gov (David E. Scheim) writes:
>
>[Stuff about L-Tryptophan deleted]b
>> 
>>>On the other hand, even though breast cancer rates are rising alarmingly, 
>>>though we know many of these "trace" pesticides are carcinogenic, and 
>>>though we have no idea of how much of these "trace" contaminants accumulate 
>>>into our drinking water, which we injest with far less knowledge or choice, 
>>>it certainly makes sense to remove any protections against these 
>>>contaminants.
>>>
>> Yes. Since we all agree that precious little data supports the
>> role of bad drinking water in carcinogenesis, we should just
>> break the bank of innumerable rural communities to regulate
>> the matter to death. Good logic.
>> Brian
>-- 
>
>That last bit is not very constructive.
>First, those "carcinogenic" contaminants have for the most part never
>been shown to cause cancer in humans.  Furthermore they probably never 
>will be because there will never be a significant number of humans 
>exposed to any of these materials in sufficient concentration 
>to even gather evidcence of human carcinogenesis.  And that is the point
>I think we need to make in dealing with these issues.

I agree that the last bit wasn't constructive.  As a chemical engineer, I
have been sensitized to people's concerns about chemical risks.  And
there are several instances where an activity is a high-risk activity for
cancer; most prominently with smoking.  However, from a purely technical
point of view, there will not ever be an ethical way to prove that
smoking _causes_ cancer--it will simply be highly correlated, and it
_could_ be that the Martians beam cancer rays into people who smoke
because they show up better in IR, or whatever.

In the case of traces (ppm levels) of contaminants in drinking water, there
are two major fears that need to be addressed.  First, people do not have
much direct control over what comes out of their tap--they get what they
get, for the most part, and my understanding is that buying bottled water is
rather expensive for the long haul.  Second, children tend to be at greater
risk for exposure to these things, and children drink tap water.  Parents
tend to get kind of prickly (at best :) when presented with nebulous threats
to their children.

>There are two pieces of real evidence:  
>animal models and human exposure data.
>For most, if not all, of the "carcinogens" found in drinking water the 
>animal models give us some value of risk of cancer, given a certain 
>exposure and *assuming* that we can transfer the numbers from the 
>animal model to human exposure.  When you do this you find that for 
>the most part the risk of human cancer is vanishingly small.

But it does exist, and as any probability text will tell you, even events
with a zero probability can occur (if this confuses you, don't feel bad, I
didn't believe it myself :).  The practical upshot of this is that there is
some risk associated with drinking these contaminants, but it will probably
never be quanitfied.  And if it's a marginal risk that I can have eliminated
by means of government regulation, why shouldn't I push to have it done?

After all, while an extra two deaths to cancer may not be significant
statistically, it is significant to me if I'm one of those two, or know one
of those two.  But given the enourmous number of suspectied carcinogens we
are exposed to daily (I hope you're not eating a peanut butter sandwich
while you read this--you know that aflatoxins, which are highly
carcinogenic, are found on slightly moldy nuts :), it would be difficult at
best to point to _one_ specific trigger unless you were exposed at levels
that would be reasonably high.  (And even then, it's hard to be sure; I
mean, you could breathe benzene all your career, and it _could_ be those 5
ppm of antimony you drank daily that did you in.)

>First, should Albuquerque spend $250 million to eliminate, say, less 
>than two excess cancer deaths per year?  

You are rather naively assuming that because Albuquerque doesn't spend $250 M
on water cleanup that it wouldn't ordinarily have to spend that it would
spend it "more wisely" on, say, preventative medicine.  More likely, it will
go to fund police departments, or get kicked back to taxpayers (or other
people, depending on how clean your government is :), or whatever.

>Second, it can be argued that you wouldn't have to spend any money to 
>remove these contaminants from drinking water if they weren't there in 
>the first place, so why not just ban the pesticides or whatever other 
>contaminants you may find and eventually they just won't be there.  

The main problem with this point is that it assumes that these compounds are
not terribly persistent in the environment.  Unfortunately, the desireable
characteristics of most pesticides is what makes them so hazardous--after
all, their primary purpose is to kill things, and it's helpful if they kill
things longer.  So, most pesticides, such as chlordane, tend to persist.
Also, they do not necessarily move quickly through the soil to get to the
water supply, thus even if we were to stop using all pesticides tomorrow, it
could be years before the levels became undetectable.

>We simply cannot afford to continue to seriously impair our economy by 
>spending vast sums of money to reduce very, very small risks.  We 
>*have* to prioritize our problems and spend those funds on the 
>problems which will give the greatest return on our investment in 
>improved health of the population.  

Spoken like a true engineer!  However, political decisions such as this one
are rarely made on their scientific merits, but on who raises the most
clamor.  And our society displays some distrust of the chemical industry in
these matters.  And when put in terms of "Well, we could spend $250M and
save what we think might be two lives, or spend $250M and (say) try to lower
infant mortality rates" you are trying to prioritize one group over another.
This comes off as a little cold-hearted, really.

I'm not sure what the answer is--I can sympathize with communities that
would be required to spend huge sums for what would seem to be a nominal
improvement in quality of life.  On the other hand, I feel that the state
has an interest in demanding and receiving safe drinking water (promotes
the General Welfare, don't you know).

Oh, well, just my thoughts...
JK
-- 
-------------------------------------------------------------------------------
  John Kasab                             "I rarely speak in absolutes."
Arpanet: kasab@cae.wisc.edu              (alt: kasab@luther.che.wisc.edu)
      The NSF and UW--Madison don't speak for me, nor I for them.
Newsgroups: sci.chem