]]]]]]]]]]]]]]]]]]      R(Human) = R(Rodent)       [[[[[[[[[[[[[[[[
                                                        (4/10/1989)


  Editorial, The Wall Street Journal, 10 April 1989, p. A14:1

          [Kindly uploaded by Freeman 10602PANC]

   It's no  wonder that  Meryl Streep  and the  Natural Resources
Defense Council have been  scaring people with the organization's
report on children, cancer and pesticides in food.  It's based on
rats.
   The role of rats  in the Great Food  Scare of 1989 doesn't get
much mention, say, when a  ``60 Minutes'' publicizes it.  This is
too bad, because if school systems across California are going to
ban apples or if people are taking the trouble to wash lettuce in
soapy water, they  ought to have  a better idea  of the basis for
their fears.
   It  is  derived  in  large part  from  equations  of  the sort
reprinted  nearby, which  attempt to  extrapolate cancer  risk in
humans, R(human), from  cancer risk in  rodents, R(rodent).  This
equation appears in the NRDC's  report as part of Appendix Three,
``Methodology  for  estimating   pre-schooler  cancer  risk  from
carcinogenic pesticides in food.''
   We suspect  Appendix Three  didn't get  much mention  when the
public, nodding off  in front of  televisions all across America,
first learned about the problem  with apples (``Cancer in apples?
More  at 11'').   It's  probably asking  too  much to  expect the
anchors to take an extra 20 seconds to discuss also the fact that
the  study is  based on  something known  as a  ``lifetime rodent
bioassay.''  It  wouldn't be too  much, however,  to ask everyone
who conveys the  results of these  food-cancer ``studies'' to put
the  rats  = humans  argument  into some  perspective.   In other
words, maybe public  policy would be better  served if the public
were given a chance to think rather than reasons to panic.
   The NRDC's pesticides-cause-cancer  report, for instance, came
out about  the same  time that  other scientists  were publishing
reports and studies  on the same subject.   Two months before the
NRDC report, the science magazine Nature published an article [15
December 1988, pp. 631-633]  by researchers from Carnegie-Mellon,
Case  Western Reserve  and the  University of  Washington raising
questions about the usefulness  of these rodent bioassay studies.
``Extrapolating from one  species to another,''  they wrote, ``is
fraught with uncertainty.''  Indeed, they pointed out that ``rats
and mice are more similar  biologically to each other than either
is to humans.''
   Also  about the  time Ms.  Streep and  her friends  had school
superintendents  cowering  from  apples,  the  National  Research
Council, an arm of the  National Academy of Sciences, released an
exhaustive study  of the available  data on disease  risk and the
American  diet.  It  recommended that  to  cut the  occurrence of
cancer and heart disease, Americans  ought to eat more fruits and
vegetables.  As to the chemicals that obsess the NRDC, the report
said, ``Exposure  to nonnutritive chemicals  individually, in the
minute  quantities  normally  present  in  the  average  diet, is
unlikely to make a major  contribution to the overall cancer risk
to humans in the United States.''
   It  may  turn  out  that the  brief  panic  the  NRDC  and its
publicists created  over food  chemicals was  a good  thing.  The
extremist wing  of the  environmental and  consumer movements has
been crying  wolf like this  for years.   Some scientists, public
officials, judges and journalists have  begun to decide it's time
to blow the  whistle on these  ``studies.''  A consumer columnist
for the Newark Star-Ledger, saying  he normally cast his lot with
``the  environmentalists and  organic  food mavens,''  called the
apple  scare  ``nothing  more  than  a  lot  of  hype  and hustle
generated by the National  Resources Defense Council.''  He wrote
that it was ``akin to economic terrorism.''
   So let the  NRDC and squads  of frightened Hollywood actresses
continue to flog  their food phobias on  the nation's talk shows.
In time,  the American  public is  likely to  figure out  what it
really  thinks   about  nutrition,  chemicals,   risk  and,  most
important, rodents.

          [The following insert appeared on p. A14:1-2]

-----------------------------------------------------------------
The  risk  in humans  will  be equal  to  that in  rats  if their
exposures in  MG/KG^2/3  equals  the  rat  exposure in mg/kg^2/3.
Thus, for these circumstances:
   R(human) = R(rodent) = q1 * (rodent) x MG/KG^2/3 x 1/kg^1/3
or:
   R(human) = q1*(rodent) x MG/KG x KG^1/3/kg^1/3= q1*(human)xMG/KG
if q1 * (human) = q1*(rodent) x K/G^1/3/kg^1/3.
   Replacing C in Eq. 6 by the relationship of Eq. 13 we obtain:

                                    [S]a MG /MG  x f(KG ) x g(T )
                                           a   A       a       a
   R(human) = q1*(human) x MG / KG       ------------------------ Eq. 18
                             A    A [S]a mg /mg x f(kg ) x g(T )
                                           a   A      a       a

           [Note: [S] stands for the summation-sign.]

Thus, the effect of taking into account the time course of cancer
risk is to modify the  usual EPA risk estimate, q1*(human)xMG/KG,
by  the ratio  of  the time  weighted  average of  the respective
carcinogenic effect in humans and rodents.

-- From: ``Intolerable Risk: Pesticides in Our Children's Food,''
     The Natural Resources Defense Council.
-----------------------------------------------------------------


      [The following is not part of the original article.]

William R. Havender.  Of Mice and Men: The Benefits and
   Limitations  of  Animal  Cancer  Tests.   New  York:  American
   Council On Science and Health, August 1984.

Lester B. Lave, et al.  ``Information Value of the Rodent
   Bioassay'',  Nature  336,  p.   631-633  (15  December  1988).
   (``Tests for human carcinogens using lifetime rodent bioassays
   are expensive, time-consuming and give uncertain results.  For
   most chemicals such tests are not cost-effective.'')

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