Bruce Ames and carcinogens and fruits and vegetables and how news media can twist the truth

]]]]]]]]]]]]     PROF. BRUCE AMES REBUTS CBS     [[[[[[[[[[[[[[[               
             [From Priorities, Fall 1989, pp. 38-39]

[Published by  the American Council  on Science  and Health, 1995
Broadway, 16th Floor, New York, NY, 10023-5860, (212) 362-7044]

          [Kindly uploaded by Freeman 10602PANC]

Dr. Bruce Ames,  noted biochemist and  Chairman of the Department
of Biochemistry  at the  University of  California, Berkeley, was
also interviewed by Mr. Bradley.   His comments to ``60 Minutes''
were  also distorted,  as CBS  did their  best to  discredit him.
Specifically,  the  producers  misquoted  Dr.  Ames  --  and then
brought on Dr. William Lijinsky and allowed him, uncritically, to
challenge  the  distorted  statements  attributed  to  Dr.  Ames,
without allowing Dr.  Ames a rejoinder  to clarify points.  Below
is  the  letter Dr.  Ames  wrote  to Don  Hewitt,  ``60 Minutes''
producer, following the [14 May 1989] airing of the interview.

June 29, 1989

Mr. Don Hewitt
Executive Producer
524 West 57th Street
New York, N.Y. 10019

Dear Mr. Hewitt:


``60 Minutes''  interviewed me  for its  second program  on Alar,
which was shown on May 14, 1989.  Mr. David Gerber, the producer,
and  Mr.  Ed  Bradley,  the  interviewer,  grossly  distorted the
scientific arguments  I presented,  thus dishonestly discrediting
me.  The program dealt both  incompetently and dishonestly with a
scientific issue and was therefore unprofessional.  I assume that
such an egregious mistreatment of  a scientific issue was made by
``60 Minutes'' in  order to buttress  its previous scientifically
flawed  coverage  of the  Alar  issue [broadcast  on  26 February
1989], rather than to pursue the truth.

The focus of my discussion in  the interview was that the fear of
cancer  from  the   breakdown  product  of   Alar  was  based  on
misinterpretation of the meaning  of animal cancer tests.  Below,
I briefly summarize  the relevant facts,  which are documented in
greater  detail  in the  enclosed  papers.  I  also  indicate how
Gelber distorted the facts to make his case.

Of  all chemicals  tested at  high  doses in  both rats  and mice
(about  400   chemicals),  about  half   are  carcinogens:  thus,
carcinogens,  as defined  by  such tests,  are  extremely common.
Synthetic industrial chemicals  account for almost  all (-85%) of
the chemicals tested.   However, despite the  fact that more than
99.9%  of the  chemicals  humans eat  are  natural, only  a small
number (about 70)  of natural chemicals have  been tested in both
rats and mice; again, about  half are carcinogens.  These results
imply that synthetic  chemicals, except in  the case of high-dose
occupational exposure,  are unlikely  to be  responsible for much
human cancer.   This is in  agreement with the  conclusion of the
epidemiologists  who   study  human  cancer:   only  a  minuscule
proportion, if any,  of cancer is  likely to be  due to pesticide

Nature's pesticides are one  important group of natural chemicals
that we have investigated.  All  plants produce toxins to protect
themselves  against fungi,  insects, and  predators such  as man.
Tens  of  thousands   of  these  natural   pesticides  have  been
discovered, and  every species of  plant contains its  own set of
different toxins, usually a few  dozen.  In addition, when plants
are  stressed or  damaged,  such as  during  a pest  attack, they
increase their  natural pesticide levels  many fold, occasionally
to levels  that are  acutely toxic  to humans.   We estimate that
99.9% of the pesticides we eat are all natural.

Surprisingly few plant  toxins have been  tested in animal cancer
bio-assays, but among  those tested, again  about half (20/42) are
carcinogenic.  Even though only a tiny proportion of plant toxins
in our diet have been  tested, natural pesticide carcinogens have
been shown to  be present in the  following foods: anise, apples,
bananas, basil, broccoli,  brussels sprouts, cabbage, cantaloupe,
carrots,  cauliflower, celery,  cinnamon, cloves,  cocoa, coffee,
comfrey   tea,   fennel,   grapefruit   juice,   honeydew  melon,
horseradish,  kale,  mushrooms,  mustard,  nutmeg,  orange juice,
parsley, parsnips,  peaches, black  pepper, pineapples, radishes,
raspberries, tarragon,  and turnips.   Thus, it  is probable that
almost every  plant product  in the  supermarket contains natural
carcinogens.  The levels of the  known natural carcinogens in the
above plants  are almost  always much  higher than  the levels of
man-made pesticides,  and many are  in the range  of thousands to
millions of parts  per billion.  I pointed  out to ``60 Minutes''
that a glass  of the suspect  Alar-contaminated apple juice posed
only  1/10th  the  possible carcinogenic  hazard  of  the average
peanut butter sandwich and 1/50th that  of a mushroom, as well as
other   relevant   comparisons  [see   ``Pesticides,   Risk,  and
Applesauce,'' Science, May  19, 1989].  Furthermore,  we need not
be alarmed by the presence of low doses of synthetic toxins and a
plethora  of  natural  toxins  in  our  food.   Humans  are  well
protected by many layers of general defenses against low doses of
toxins -- defenses which do not distinguish between synthetic and
natural  toxins.    In  addition,  new   research  suggests  that
conventional worst-case extrapolations from very high-dose rodent
cancer tests to very low-dose  human exposures to chemicals, such
as  the  NRDC  performed,   enormously  exaggerate  the  possible

Additionally, there  is a fundamental  trade-off between nature's
pesticides and man-made pesticides.  We can easily breed out many
of  nature's  pesticides, but  then  we will  need  more man-made
pesticides to protect our crops  from being eaten by insects.  In
contrast, growers are  currently breeding some  plants for insect
resistance  and   unwittingly  raising  the   levels  of  natural

Although  I am  considered  one of  the  world's leaders  in this
field, and I  devoted a day of  my time to  explain in detail the
above  points to  Gelber/Bradley, they  chose  to ignore  most of
these  facts.   The points  that  were  covered on  the  air were
handled in the following incompetent and unprofessional manner.

(1) My discussion of natural carcinogens was grossly misquoted:

Bradley: ``Dr.  Lijinsky disputes Ames'  claim that  99.9% of all
carcinogens come from natural foods.''

This   obviously  incorrect   claim   was  never   made   by  me.
Gelber/Bradley  made it  up.   What I  stated  was that  99.9% of
chemicals we ingest  are natural.  It  is well known  that 30% of
human cancer  is due to  smoking and another  large percentage of
cancer is  due to  viruses, hormones,  sunlight, alcohol, dietary
imbalances,  radon,  and  occupational  causes.   Thus,  Lijinsky
rebutted  a  statement  made  up  by  Gelber/Bradley,  and,  as a
consequence, publicly discredited me.   When I asked Gelber where
he got that statement from, he couldn't come up with an answer.

(2)  Gelber/Bradley  grossly  misquoted  me  again  and  publicly
discredited me in two unjustifiable ways.

          Bradley: ``Well, who's right?   This is the most recent
          listing   of   carcinogens   published   by   the  U.S.
          government's National  Toxicology Program.   That's the
          agency  which determines  which chemical  compounds are
          known to  cause tumors in  animals or  humans.  It does
          not  support Dr.  Ames' claim  that  there are  tens of
          thousands of carcinogens in  natural food.  He believes
          further tests will  show he's right.   But for now, the
          national toxicology  survey lists  just 148 substances,
          and the compounds  in celery and  broccoli aren't among
          them.  One  compound that  is, is  the one  produced by

          (a) The attribution to me  of the statement ``there are
              tens of thousands of  carcinogens in natural food''
              is not right.

          (b) Bradley's statement that the natural carcinogens in
              celery and  broccoli aren't listed  by the National
              Toxicology Program  (NTP) is  not correct.   In the
              ``60  Minutes''  interview,  I  said  that Brussels
              sprouts,  cabbage,  broccoli,  and  celery  contain
              carcinogens.   Gelber later  phoned me  asking what
              these carcinogens  were.  The  information on three
              of  these foods  was  in the  article ``Pesticides,
              Risk, and Applesauce,'' which  I had sent to Gelber
              and which he had promised to read before he came to
              interview me, and which has since been published in
              Science.   Nevertheless, I  told  him on  the phone
              that allyl  isothiocyanate is  in cabbage, Brussels
              sprouts, and  broccoli, and  that 8-methoxypsoralen
              is in  celery, and  that both  plant compounds were
              found  to  be carcinogens  by  the NTP  in  its own
              bioassay program.  Bradley said  in the quote above
              that these compounds are not in the latest NTP list
              of carcinogens, thus discrediting  me.  The list he
              waved was years  old.  The compounds  are, in fact,
              on other lists that NTP sends out to all interested
              parties several times  a year: allyl isothiocyanate
              was evaluated by NTP as positive for carcinogenesis
              in    1982   and    8-methoxypsoralen    in   1988.
              Gelber/Bradley could have  clarified this easily of
              they  had  wanted to,  but,  apparently, scientific
              truth was not on their list of priorities.

          (3) Gelber/Bradley  turned   the  Alar   issue  into  a
              question of  motives rather  than of  science.  For
              example,  they attempted  to  tie me  to  the ``bad
              guys''  --  the American  chemical  industry  -- by
              introducing me as follows:

              Bradley:  ``At  the   urging  of  the  agricultural
              chemical industry,  we spoke  with Dr.  Bruce Ames,
              chairman   of   the   Biochemistry   Department  at
              Berkeley.    Dr.   Ames  says   he   is  completely
              independent and does no consulting for industry.''

Gelber/Bradley, of course, could as  well have chosen to say that
I  am a  member  of the  National  Academy of  Sciences,  or have
received  a  long   list  of  scientific   honors  from  numerous

In any scientific controversy, a professional reporter wishing to
obtain  an  unbiased  view should  ask  advice  from  the leading
scientists in  the field.   Gelber did not  do this  in the first
Alar  program.  If  Gelber had  wanted  to obtain  a professional
scientific  opinion on  Alar he  could have  assembled a  list of
outstanding  scientists   in  the   field  by   consulting  Nobel
prizewinners or  other leading  scientists who  are familiar with
the field.  If these scientists were asked to name leaders in the
field, I am confident that I  would be near the top of everyone's
list -- not  just the agricultural  chemical industry's.  I doubt
if Lijinsky  would be  on anyone's  list.  Lijinsky,  who was the
scientist given the  most time on the  program, was introduced as
the head of  a chemical carcinogenesis lab  at the National Cancer
Institute (NCI),  yet Lijinsky  is not  an NCI  employee.  Gelber
didn't talk to any of  the leading chemical carcinogenesis people
at NCI,  e.g. Richard Adamson,  the head of  Cancer Etiology, for
their opinions of either Lijinsky or myself or Alar.

The theme of the ``60 Minutes''  program seemed to be that anyone
who has  consulted for or  is connected with  industry is biased,
without considering that bias can  exist on both sides.  Although
I do no consulting for industry or  law firms, I am aware from my
experience in 20  years in toxicology  that the American chemical
industry is extremely  competitive and consistently  tries to get
the best toxicologists  in the country to  advise them because it
is  in their  self  interest to  do so.   On  the other  hand, my
experience  with  the environmental  organizations  is  that they
specialize more in ideology than in expert science.  The activist
lawyers of the  NRDC and similar  organizations choose scientists
who  are selectively  interested in  rodent carcinogens  that are
produced  by chemical  companies,  and they  believe  that anyone
connected  with a  chemical company  or  industry works  only for
greed  (profit) while  they work  for altruism.   Perhaps feeling
virtuous  compensates  for   their  lack  of   success  in  being
competitive  in science.   Such scientists  can profit  very well
from their ``altruism''  by testifying for a  generous fee in the
flourishing toxic torts industry.  For example, testifying that a
few parts per billion of some man-made rodent carcinogen will, as
Lijinsky  phrased it,  ``put someone  over  the edge  and they'll
develop cancer''  can be very  lucrative.  But  Lijinsky's or the
NRDC's possible biases did not interest ``60 Minutes''.

I won't elaborate  on the many inaccuracies  in your treatment of
Elizabeth  Whelan.  The  American Council  on Science  and Health
(ACSH), directed by Dr. Whelan, is that rare creature, a ``public
interest'' organization that is based in science.  Dr. Whelan has
assembled  an  impressive  list of  knowledgeable  people  on her
scientific advisory  board.  I  have been  as impressed  with the
scientifically sound pamphlets that ACSH has published, as I have
been  unimpressed by  the  scientifically unsound  claims  of the

There  are  many  important issues  concerning  cancer  that ``60
Minutes''  could  tackle without  bankrupting  apple  farmers and
falsely convincing  the public  that their  apples are poisonous.
One real  issue in  environmental cancer  is how  a few ideologue
lawyers and second-rate scientists working through the media have
convinced   many   Americans  that   pesticide   residues,  water
pollution, and ``toxic chemical'' pollution are serious causes of
cancer or  birth defects, and  that what  this misdirected effort
costs the  country by  diverting attention  from real  to trivial

A final  thought: Reed  Irvine of Accuracy  in Media  (AIM) was a
pleasure to deal with, in contrast  to Gelber.  He was a stickler
for  detail and  cared about  scientific  integrity.  When  I was
first contacted by him, I didn't know who he was, but he deserves
more  than a  brushoff.   He raised  a  lot of  issues  that need
answers, and so does my letter.

Yours truly,

Bruce N. Ames
Professor and Chairman
Department of Biochemistry
University of California

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I like to call tops and bottoms in the market.
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