countermeasures as there is for plume countermeasures. Nevertheless, in order to gain maximum benefit from a particular countermeasure, it should be introduced at the appropriate time.
If a large agricultural area becomes contaminated then the time interval between contamination and potential consumption of the produce will depend upon a number of factors, for example, type of produce, time of year, time of day, etc. Fruit and green vegetables could, if no countermeasures were taken, be consumed a few hours after being contaminated. Uptake of radioactive materials by cows and goats and concentration in milk is a slower process. The peak level of iodine in cow's milk occurs about two days after a short release. Other radioactive materials take longer to reach peak concentration, for example, the concentration of caesium and strontium peak after about a week.
Open water sources and their catchment areas could become contaminated and hence contaminate drinking water. In general contamination of drinking water is likely to be less of a radiological hazard than other exposure routes. The time between deposition on the catchment area or surface of a reservoir and contaminated water reaching the consumer will depend upon a number of factors, but it is likely to be at least several hours and perhaps several days.
9.3 Legal Considerations
If countermeasures, such as banning the distribution, importation, sale and consumption of contaminated foodstuffs, are required in Hong Kong following any major accident it is clearly important that legislation is in existence which will give the relevant agencies the authority to implement such countermeasures. Such legislation must obviously also give the relevant agencies the right of access to any potentially affected area and the power to obtain samples. Such legislation is in existence in the United Kingdom (Ref 23).
9.4 Application of Countermeasures in General
If Hong Kong is affected by a radioactive plume, initial monitoring results should be used to estimate the likely levels of ground deposition. Methods by which such an assessment may be made are given in Chapter 7. This initial estimation must be based upon conservative assumptions. If the assessment indicates that the contamination of fruit. and green vegetables is likely to be significant then the distribution, sale and consumption of such produce should be banned pending more detailed monitoring results. If pasture is contaminated, or may be contaminated, consideration should be given to removing cattle, especially dairy cattle, from pasture and placing them on stored feeds.
Other foodstuffs which take longer to reach the consumer may be dealt with in a slightly longer timescale.
As time progresses the results of further monitoring will allow a better picture of the levels of contamination in or on foodstuffs to be built up. This will allow the geographical areas and particular produce requiring interdiction to be better defined. This may mean introducing new bans on some items of foodstuffs and relaxing existing bans on
others.
Attention will need to be given to the control of any potentially contaminated foodstuffs imported from the People's Republic of China.
Water supplies should also be monitored primarily to provide reassurance to the consumers. If however some water supplies were to be contaminated it may be possible to provide alternative supplies from unaffected areas, and/or alter the water treatment process to gain a greater reduction in the level of contamination in the water.
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