Number 183 July 1999
MAFF UK - EVALUATION OF THE RADIOLOGICAL IMPACT OF FREE FOODS FOUND IN
THE VICINITY OF NUCLEAR SITES
Index to MAFF UK Food Surveillance Information
Sheets, 1999
See also:
102: MAFF, UK - Undeclared
Irradiation of Foodstuffs Surveillance Exercise (March 1997)
108: MAFF UK - A Survey of
Radiocaesium Contamination Levels and Estimations of Dietary Intake of
Edible Wild Fungi (June 1997)
109: MAFF UK - A Survey of Natural
Radionuclides in UK and European Beers (June 1997)
110: MAFF UK - A Survey of Levels
of Radioactivity in UK Produced Beverages (June 1997)
153: MAFF UK - Assessment of the
Potential Variability of Naturally Occurring Radionuclides in Foodstuffs
Produced in the UK (July 1998)
199: MAFF UK - Multi-Element
Survey of Wild Edible Fungi and Blackberries (March 2000)
Summary
A survey on radioactivity levels in free foods collected from around
four UK nuclear sites has been completed.1
Free foods are foods collected from the wild (not cultivated). Over forty
samples of a range of foods were collected by members of the public over
1997 and 1998. Table 1 indicates which foods
were collected from each site for analysis. The samples were analysed by a
range of accredited methods for the following radionuclides: total
tritium, tritiated water, organically bound tritium, carbon-14,
sulphur-35, calcium-45, plutonium-239/240, americium-241 and total
uranium. The range of radionuclides varied from site to site as indicated
in Table 2. The objectives were: to find out
the range of 'free foods' collected from around nuclear sites; to find out
the quantities of food involved; and to assess how radiation doses (i.e.
the quantity of radiation) received from eating these 'free foods'
compared to doses from eating cultivated foods from around nuclear sites.
Over 80 different types of food were identified as being collected, some
in significant quantities. On average 2.5 types of food were collected per
person. Some people were noted to eat more than two foods at higher than
average rates
Radiation doses from free-foods consumption are comparable to those from
cultivated foods around the four nuclear sites studied. No annual dose was
calculated to exceed six microsieverts. The legal limit for artificial
(man-made) sources is 1000 microsieverts per annum. In comparison the
national annual average from all natural sources is over 2000
microsieverts.
Background
In England and Wales MAFF carries out surveillance programmes for
radioactivity in the food chain. Most of the routine surveillance is
targeted at foodstuffs produced in the vicinity of the major nuclear
installations. This work allows MAFF to demonstrate that exposures from
artificial sources of radioactivity are well within national limits and to
estimate doses received by members of the public consuming food that is
nationally available as well as that produced in the locality of nuclear
installations.
The majority of food samples are collected from cultivated land, with a
small proportion of samples being so-called 'free foods'. Free foods are
those collected from the wild. In the past it was assumed that free foods
did not make a significant contribution to the overall ingestion doses.
To test this assumption, as part of the Working Party on Radionuclides
in Foods (WPRF) surveillance programme, a survey looked at the collection
and consumption of free foods around four nuclear sites. Subsequent doses
from the consumption of these foods were studied.
Methodology
The four areas studied were around the Atomic Weapons Establishment
(Aldermaston); Nycomed Amersham (Cardiff); Hinkley Point nuclear power
station; and Sizewell nuclear power station.
A habit survey was conducted to identify people who make use of wild
foodstuffs around these sites. Members of the British Market Research
Bureau (BMRB) personally interviewed over 800 people. They were asked what
types of food they collected, in what quantity and from where, and to mark
the location on maps. They were also shown various sized containers and
asked to estimate how many 'containers worth' they collected. In addition
they were asked if they would be willing to collect foods for the project.
Those who volunteered were asked to collect a selection of foods from
their area. Sample selection was based on foods collected by the most
people and in the largest quantities. Sampling was extended by a year due
to a poor return from collectors. In the second year some samples were
requested from two collectors to increase the chance of obtaining the
required sample. In this way enough samples were obtained to give
meaningful results.
All samples were analysed for gamma-emitting radionuclides. The other
radionuclides selected for analysis were based on discharge data for each
site and on radiological significance.
Results
Between the 800 people interviewed over 80 different types of free food
were identified as being collected. Blackberries were the most collected
foods, but elderflowers and elderberries, as well as various types of
mushroom and nuts, were also popular. Most people collected more than one
type of free food, with the average being 2.5 types.
In contrast to cultivated foods the habit data suggest that some people
do consume several free foods at higher than average rates, although
generally the actual amounts are relatively low.
The results of estimates of doses from consumption of these free foods
is given in Table 3. At average rates of
consumption all were less than 2.9 microsieverts. At higher than average
no sample exceeded six microsieverts.
Interpretation
The doses from free foods were comparable to those from cultivated
foods. As such the National Radiological Protection Board recommended that
comprehensive surveys of free foods were not warranted at present.
However, for rigorous dose assessments free foods consumption may well
need to be taken into consideration.
Dose estimates, even at higher than average consumption rates, were all
below 6 microsieverts. These results are much lower than the national
average of over 2000 microsieverts from natural sources
Conclusion
At each of the sites studied a substantial number of collectors of free
foods could be readily identified. Over 80 different types of food were
identified as being collected, some in significant quantities. On average
they collected 2.5 types of food. Some people were noted to eat more than
two foods at higher than average rates. No subsequent estimated doses were
found to be significant, all being less than 0.3 per cent of the national
average from natural sources.
A follow-up project has been commissioned looking at levels of natural
radionuclides in free foods at locations remote from nuclear sites.
References
- Green, N., Hammond, D. J., Davidson, M. F., Wilkins,
B. T., Richmond, S. and Brooker, S. (1999) Evaluation of the
Radiological Impact of Free Foods found in the Vicinity of Nuclear
Sites. Memorandum of the National Radiological Protection Board.
NRPB-M1018.
Further Information
The full report of this study is held in the MAFF Library, Nobel House,
17 Smith Square, London, SW1P 3JR. Tel: + 44(0)20 7238 6575. If you would
like to consult a copy, please contact the Library giving at least 24
hours notice or, alternatively, copies can be obtained from the Library; a
charge will be made to cover photocopying and postage.
For further information please contact:
Mr P Tossell
MAFF, Joint Food Safety and Standards Group,
Radiological Safety and Nutrition Division,
Room 535 Ergon House,
c/o Nobel House,
17 Smith Square,
LONDON, SW1P 3JR.
Tel: +44 (0)20 7238 6177
Fax: +44 (0)20 7238 6537
e-mail: p.tossell@fsci.maff.gov.uk
Units of Measurement
Microsieverts are units of radioactive dose.
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These pages were last updated on 30 June 1999
