]]]]]]]]]]]]]]]       FOOD IRRADIATION II       [[[[[[[[[[[[[[[[[
                    By A. Stewart Truswell              (9/11/88)
           British Medical Journal, 6 June 1987, pp. 1437-8
             [Kindly uploaded by Freeman 10602PANC]

   Microwave  irradiation of  food  has become  accepted  as just
another form of cooking.  "Food irradiation" is, however, usually
used  to mean  treatment with  waves a  million times  shorter --
[gamma]  rays,  x   rays,  or  electron   beams.   This  type  of
irradiation cannot  be done  in the  family kitchen;  it requires
expensive equipment.
   These rays  penetrate into  a food  and produce  brief intense
ionisation  and  consequent  changes  in  the  largest molecules,
notably  DNA  (including that  of  micro-organisms).  Temperature
rises only a little so  the food does not look  as if it has been
cooked  with heat.   Low doses  of  ionising radiations  (under 1
kilogray (kGy))  will inhibit  sprouting of  potatoes and onions,
delay  ripening  of  some  fruits,  disinfect  cereal  grains  of
insects, and  eradicate trichinella in  pork.  Intermediate doses
(5 to  10 kGy) will  extend the  shelf life of  foods by reducing
microbial loads and eliminate  non-sporing pathogens from spices,
chicken,  and  fish.   About   50kGy  are  needed  for  bacterial
sterilisation.   (The  gray is  the  unit in  the  Systeme [grave
accent over the  first 'e'] International  d'Unites [acute accent
over  the 'e']  of absorbed  energy  as radiation  passes through
matter and is equal to 1 joule  per kg.  It has replaced the rad,
with 1 kGy equalling 100 kilorads.)
   Irradiated food  was used  for astronauts.   In Britain  it is
subject to government  control [1] and  at present permitted only
for patients  who need sterile  diets as part  of their treatment
[2] and for  preparing the rations  of experimental animals.  The
Joint  Expert  Committee  on Food  Irradiation  of  the  Food and
Agriculture   Organisation,  the   International   Atomic  Energy
Authority, and  the World  Health Organisation  concluded in 1981
that irradiation of food up to an  overall dose of 10 kGy is safe
[3], and the Codex Alimentarius Commission has accepted this as a
food  standard [4].   Irradiation is  now permitted  for specific
foods in 30  countries [5], though  some of them  do not yet have
their own  processing plants.  Last  year the  United States Food
and Drug Administration gave  permission for irradiation of fresh
fruits and vegetables  up to 1  kGy (and spices  at higher doses)
[6, 7].
   The question of food irradiation is important in all countries
because  it may  carry  a lower  risk  than some  of  the various
chemicals  currently used,  for  example, to  delay  sprouting of
potatoes and onions and to  fumigate infested shipments of grain.
Until  there  is  international  agreement  on  labelling,  small
amounts of irradiated  foods (like spices)  may be moving between
countries  without  indicating their  processing  history  to the
   In  Britain the  Advisory  Committee on  Irradiated  and Novel
Foods  reported  last  year  and  agreed  with  the international
committee  that ionizing  irradiation of  food  up to  an overall
average dose of 10 kGy by [gamma] rays or x rays with energies up
to 5 MeV or by electrons with  energies up to 10 MeV "presents no
toxicological  hazard and  introduces  no special  nutritional or
microbiological   problem."    With   these   doses   significant
radioactivity  cannot   be  produced   in  the   food.   Chemical
compounds, radiolytic products, are  formed but only in milligram
amounts or less, and most are  not unique -- they occur naturally
before or after conventional processing.  Review of toxicological
evidence does not  show that irradiated  foods are mutagenic, and
laboratory animals fed  on irradiated rations  have been healthy.
Irradiation  does not  produce dangerous  mutant micro-organisms.
Losses  of nutrients  are comparable  to those  from conventional
cooking: vitamin  C and  thiamine are  reduced; vitamin  E may be
more  affected;  and  there  is  insufficient  information  about
folate.  When and  if irradiated foods  are permitted the British
committee advises mandatory inclusion of "irradiated" in the name
of the food -- "irradiated potatoes" like "pasteurised milk."
   When  international  and  several  national  expert committees
agree with our own  committee that a process  is safe all that is
usually required is  for the government to  set limits and define
safe operational procedures.  Industry then decides whether it or
the consumer can  afford the new process  and for which products.
But  there  is  resistance  to  food  irradiation  among ordinary
people, who fear  (especially after Chernobyl)  that the food may
be  radioactive.  Some  professional  people have  also expressed
anxiety [8-10].  There  are four main  concerns.  Firstly, can we
safely  dismiss the  few toxicological  studies that  appeared to
show adverse effects?  Discussion focuses [8-10] on a report from
India [11] of increased polyploidy  [having more than two sets of
chromosomes] in cultured leucocytes [white blood cells] from four
children with kwashiorkor [a severe protein-deficiency malnutrion
of children]  who were  given freshly  irradiated wheat  (but not
others later given stored irradiated wheat).  Other scientists in
India  [12]  and  elsewhere  think  that  these  experiments were
statistically inadequate,  and they  have been  unable to confirm
them in large numbers of animals and people [13, 14].
   The second concern is that  irradiation may be used to conceal
bacterial  contamination  of  spoilt  food  without  inactivating
toxins generated  by earlier  bacterial contamination  [10].  But
the  same need  for good  hygiene applies  equally to  other food
processes like canning  and freezing.  Thirdly,  there could be a
novel  pattern  of nutrient  loss  either from  the  radiation or
because  irradiated  "fresh" foods  may  be older  when  they are
eaten.   The  British committee  conceded  that the  data  on the
effects of irradiation  on the nutrient content  of foods are not
comprehensive  --  but  they are  more  extensive  than  for many
accepted methods  of food processing.   The committee recommended
that if irradiation is permitted  in Britain the nutrient content
of  irradiated  food  and   its  consumption  pattern  should  be
monitored.  The fourth  worry is that we  are unable to recognise
that  a  food  has been  irradiated.   Several  laboratories have
searched for substances that would  enable an analyst to diagnose
that  a  food  has  been irradiated.   It  is  unlikely  that any
characteristic substance would be found across all types of foods
after low  dose irradiation, but  different diagnostic substances
might yet be found in individual foods.
   I  see  no  reason  why   the  government  should  not  permit
irradiation of stored winter potatoes and  onions at 1 kGy and of
listed spices  at moderate dosage.   This should  be coupled with
registration  and control  of  all irradiation  plants  and clear
labelling  regulations.  One  problem  is that  the toxicological
evidence is poorly collected, reviewed, and presented.  The World
Health Organisation  is planning  a publication  [5], and  I hope
that this -- or perhaps  a government publication -- can assemble
the large  amount of toxicological  work that has  been done over
the past 30  years in the  International Project in  the Field of
Food  Irradiation,  in  the  United  States,  at  Leatherhead  in
Britain, and in many other Countries.

                                               A Stewart Truswell
                                    Professor of Human Nutrition,
                                             University of Sydney
Wolfson College,
Oxford OX26UD

 1  Ministry of Health. Irradiation of Food.  London: HMSO, 1964.
      (Committee on Medical and Nutritional Aspects of Food
      Policy.  Report of the working party.)
 2  Department of Health and Social Security, Ministry of
      Agriculture, Fisheries and Food.  Report on the safety and
      wholesomeness of irradiated foods by the advisory
      committee on irradiated and novel foods.  London: HMSO,
 3  Food and Agriculture Organisation, International Atomic
      Energy Authority, World Health Organization.  Wholesomeness
      of irradiated food.  Geneva: WHO, 1981.  (WHO Technical
      Report Series No 659.)
 4  Codex Alimentarius Commission.  Codex general standard for
      irradiated foods and recommended international code of
      practice for the operation of radiation facilities used in
      the treatment of foods. Vol 15, edition 1. Rome: CAC, 1984.
 5  World Health Organisation.  Food Irradiation.  Geneva: WHO,
      1987.  (In Point of Fact No. 40.)

 6  Kader, AA.  Potential applications of ionizing radiation in
      postharvest handling of fresh fruits and vegetables.  Food
      Technology 1986; 40 117-21.
 7  United States Department of Health and Human Services, Food
      and Drug Administration.  Irradiation in the production,
      processing and handling of food; final rule.  Washington
      DC: US Government Printing Office, 1986. (FDA 21: CFR Part
      179.  Federal Register 18 April: 51 No 75.)
 8  Anonymous.  More research into safety of irradiated food
      urged. [News.]  BMA News Review 1987 April: 11.
 9  British Medical Association, Board of Science and Education.
      Irradiation of foodstuffs.  London: BMA, 1987.
10  Webb T, Lang T. Food irradiation: the facts. Wellingborough,
      Northants: Thorsons, 1987.
11  Bhaskaram C, Sadasivan G.  Effects of feeding irradiated
      wheat to malnourished children.  Am J Clin Nutr 1975; 28:
12  Kesavan PC.  Indirect effects of radiation in relation to
      food: facts and fallacies.  Journal of Nuclear and
      Agricultural Biology 1978; 7:93-7.
13  Brynjolfsson A.  Wholesomeness of irradiated foods: a review.
      Journal of Food Safety 1985; 7:107-26.
14  Food and Agriculture Organization, International Atomic
      Energy Authority.  Results of feeding trials of irradiated
      diets in human volunteers: summary of the Chinese studies.
      Rome: FAO, 1986.  (Results reported at a seminar for Asia
      and the Pacific on the practical application of food
      irradiation, Shanghai, People's Republic of China, April
                         *      *      *

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