ABSTRACT 



Passage of the radioactive isotopes, 

 strontium-89, cesium-137, and ruthenium- 

 106, through the skin of the little tunny, 

 Euthynnus alletteratus , was measured by 

 using pieces of skin separating two sea 

 waters, one of which contained the isotope. 

 The diffusion of these isotopes through the 

 tissues under the skin of iced fish was ob- 

 served after a number of days of contact with 

 the skin surface. 



After 4 days contact of the skin with the 

 radioactive solutions, the activity from 

 cesium of the deep muscle tissues was equal 

 to that on the skin surface. On the other 

 hand, after 8 days the activity of the deep 

 tissues was only 4 percent of the skin- 

 surface activity for strontium-89 and one 

 percent for ruthenium -106. 



Cesium entered the fish through the skin 

 very readily and ruthenium scarcely at all. 

 Except for cesium, diffusion through the fish 

 tissues was slow. 



PASSAGE OF FISSION PRODUCTS THROUGH 

 THE SKIN OF TUNA 



In relation to "fallout" from nuclear -bomb 

 tests, it is of interest to measure the amounts 

 of radioactive isotopes known to be present in 

 mixtures of fission products which would pass 

 through the skin of fish held under refrigera- 

 tion on fishing vessels. Presumably, radio- 

 active materials contaminating the skin of 

 such fish could enter and spread through the 

 tissues thus contaminating the whole fish. 

 The present study intended to test this assump- 

 tion, considers the penetration of radioactive 

 strontium, cesium, and ruthenium common 

 products of nuclear fission, through the skin 

 of the little tunny, Euthynnus alletteratus 

 (Rafmesque), and their diffusion through the 

 tissues. 



It is accepted generally that the skin of 

 marine fishes is relatively impermeable. 



This might be expected in such a group in 

 which the osmotic pressure of the blood is 

 below that of sea water. Discussions of the 

 literature regarding the permeability of the 

 skin of various species of fish are presented 

 by Bond (1933) and by Wunder (1936) . In 

 dead fish, however, penetration of salts 

 through the tissues is a process of diffusion 

 which varies in rate depending on a number 

 of factors. The rate of penetration of sodium 

 chloride is low, resulting in small quantities 

 in the tissues of tuna held in cold brine for as 

 long as almost two months, according to the 

 work of Land and Farber (1939) and of Godsil 

 (1940). The factors regulating salt penetra- 

 tion into fish during brine freezing were 

 considered by Bolston and Pottinger (1954), 

 but as far as could be ascertained, no work 

 has been reported on the penetration of radio- 



