J. F. LOUTIT 



(which is one of the assumptions made by the United Nations Scientific 

 Committee) — an equilibrium \vill be reached for cumulative fall-out at 12 

 times the present level, but the contamination of lowland pastures in the 

 United Kingdom will have risen only three to four times. For annual crops 

 the contamination is likely to be intermediate between 12 and four at about 

 seven times the present level. For hill pastures the final equilibrium should 

 exceed the present levels by smaller factors even than three to four. It is to 

 be expected that the levels in milk will, as before, closely follow the levels in 

 the corresponding pastures. 



Russell rightly points out that differences in agricultural conditions may 

 cause a very large variation in the relative magnitudes of the factors which 

 cause the contamination of the plants. Conditions in the United Kingdom 

 determine the uptake there, but not necessarily elsewhere. Thus, while milk 

 in Frome, Somerset, has been relatively constant in radio-activity of ^"Sr 

 since 1955, the reported values for milk in New York, U.S.A., have risen 

 steadily. In the United Kingdom, particularly the southern part, permanent 

 grazings contribute largely to the cow's normal diet. In the U.S.A. cattle 

 are fed largely on annual crops. 



From these predictions of the future values of foodstuflTs at equilibrium 

 one could calculate the future contamination of the average Briton. The 

 average diet is known from the statistics of the Ministry of Agriculture, 

 Fisheries and Food. About half of the dietary calcium comes from milk and 

 milk products; over 20 per cent comes from mineral chalk added to flour; 

 and the miscellaneous remainder is mainly from vegetable sources. Bryant 

 et al.^, we have already noted, have made a retrospective survey of the levels 

 recently obtaining in a British diet and the following is a summarized version 

 of their Table IV: 



1199 



46^50 —40 S.U. 



217 



