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Re: MCLS, VOCs, Child Cancer, and Sustainablilty



I think Donald's comment misses entirely the point of the memo to which he
is responding.  The point is, if there is data of a particular health effect
that is sufficiently reliable to use in making a risk assessment, then that
risk assessment and that health effect is used in setting the MCL and/or
MCLG.

Once upon a time, long ago and not so far away, the assumptions underlying
the setting of the MCLs and MCLGs were based on a lifetime consumption of 2
L per day, and DOSES were estimated based on a 70 kg adult.  We also used to
use a 10,000 population factor.  Now we use a different dose basis and a
higher population factor, at least 1,000,000.  That means that that if the
risk assessment shows one additional death per 1,000,000 at the extrapolated
dose, then the MCL is set at or below that level.

All of the above are based on linear or log-linear extrapolations from data
based on much higher doses.  The assumptions underlying that kind of
extrapolation are too numerous and too subject to question to be discussed
herein.

Ralph
Ralph E. Cooper, Ph.D., J.D.
14139 Woodstream
San Antonio, TX 78231
210-479-5490 (4)
cooperre@flash.net

-----Original Message-----
From: Donald Sutherland <donaldsutherland-iso14000@worldnet.att.net>
To: p2tech@great-lakes.net <p2tech@great-lakes.net>
Date: Friday, September 10, 1999 12:40 PM
Subject: MCLS, VOCs, Child Cancer, and Sustainablilty


>
>9/7/99
>
>Robert,
>If cancer is the number one killer of children in this country,
>and child cancer is on the rise according to the National Cancer Institute
>(NCI),
>and volatile organic compounds (VOCs) in drinking water can cause cancer in
>children according to the EPA,
>then establishing a MCL for VOCs in drinking water to protect children from
>cancer risk without using a Risk Estimate modeled on a child's weight and
>consumption patterns is without regard to the safety of this subpopulation.
>
>Particularly since child cancer is acute and on the rise.
>
>
>Shouldn't protecting children with MCLs for VOCs specifically designed with
>the risks associated with that subpopulation be the starting point for
>protecting the health of the nation?
>
>Donald Sutherland
>Member of the Society of Environmental Journalists
>donaldsutherland-iso14000@worldnet.att.net
>
>
>-----Original Message-----
>From: Robert A. Michaels <76517.747@compuserve.com>
>Date: Wednesday, September 08, 1999 10:16 AM
>Subject: Re: MCLS, VOCs, and USDW
>
>
>Folks,
>
>        As a health risk assessor, I have worked on preparing drinking
>water criteria documents at a consulting firm under contract to support US
>EPA promulgation of drinking water standards under the Safe Drinking Water
>Act.  I can say that the idea that MCLs are promulgated without regard to
>their safety to sensitive subpopulations, most notably infants and pregnant
>women, is unbalanced and incorrect.  A more correct concept is that MCLs
>may compromise stringency to establish standards attainable in practice in
>the near term, whereas MCLGs (Maximum Contaminant Level Goals) are more
>stringent, though they may be attainable only with long-range planning.
>Indeed, zero MCLGs for carcinogens may be unattainable ever, but
>approachable.
>
>        Concern expressed about MCL protectiveness to infants seems to have
>arisen from EPA use of the (once) standard assumption of a 70-kg adult
>drinking 2 L of water each day.  Consider, however, that infants often are
>breast-fed.  When not breast-fed, they typically consume commercially
>prepared formula, which may come ready-to-consume, or may require dilution
>with local water (or, more to the point, the local water is diluted with
>formula before consumption).  Finally, although the MCL may be expressed as
>a substance concentration in drinking water, that concentration typically
>was derived based upon internal doses attained in studies involving animals
>and/or humans; including studies of reproductive, fetotoxic, and
>teratogenic effects; as may have been available.  One of these effects may
>or may not represent the 'critical' effect which formed the reported basis
>for MCL derivation for a specific substance, but if the reported basis was
>different, that does not mean that reproductive, fetotoxic, and teratogenic
>effects were unconsidered in deriving the MCL.
>
>        In my view, the bottom line is that drinking water standards may be
>imperfect.  Some individual MCLs might be found to be inadequate, and
>perhaps should be revisited, especially in light of emerging research.
>However, in my experience MCLs do not wantonly disregard the need to
>protect infants, pregnant women, and other sensitive subpopulations.
>
>===============================
>Robert A. Michaels, PhD, CEP
>President
>RAM TRAC Corporation
>3100 Rosendale Road
>Schenectady, NY  12309-1510
>(518) 785-0976 (voice)
>(518) 785-0976 (telecopier)
>76517.747@compuserve.com
>===============================
>
>