18 



MISC. PUBLICATION 



S. DEPT. OF AGRICULTUKE 



interesting observation "that stock make every effort to break bounds 

 in order to escape, it is thought, from the iodine deficient pasture to 

 other areas which are not deficient." 



It was observed in Xew Zealand by Hercus and others {263) "that 

 variation in the average amount of iodine in soils containing more 

 than 10 p. p. m. has little effect on the small incidence of goiter which 

 there exists; but as the amount of soil iodine decreases so the incidence 

 of goiter rises/'' The same report states that the most important 



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20 



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20 40 60 80 100 120 140 160 



AVERAGE AMOUNT OF IODINE IN THE SOIL (PARTS PER 10,000, 000) 



Figure 1. — Relationship between the average amount of iodine in the soils and 

 the regional incidence of goiter among school children in Xew Zealand. (Based 

 on data from Hercus, Benson, and Carter (264)-) 



causes of variation are (1) the combination of the iodine in the soil 

 (an analogy to the observation of Byers (104) concerning selenium), 

 and (2) the presence of abundant iodine in the drinking water in 

 regions in which the soil is relatively poor hi that element. 



The data of Hercus, Benson, and Carter (264) have been plotted 

 (fig. 1) in order to bring out these approximate relationships as clearly 

 as possible. The positions of the points indicate that several notable 

 exceptions occur in the inverse relationship between incidence of 

 goiter and soil iodine, but that there is a general agreement. 



A striking inverse correlation between the quantity of iodine in 

 the soils and foods and the incidence of goiter was reported by Hercus 

 and coworkers (263) in 1931. Their data are given in table 7. 



