212 BERYLLITTM 



Intake Levels. Beryllium has become of interest biologically on 

 account of its high toxicity and the industrial hazard that it may produce 

 (Be-1). Fatal doses for the rat are 0.4 mg/kg, intravenous, and 5 to 

 10 mg/kg, intraperitoneal (Be-2). Since the isotope preparation is 

 carrier-free, it may be used for evaluation of normal metabolism of the 

 element. Be'^ was found to be metabolized differently when administered 

 to rats with and without carrier (Be-3). 



Radioassay. Since Be^ emits only gamma rays, absorbers and gamma 

 counting can be used to eliminate any beta contaminants. However, if 

 autoradiograms are to be made, the original preparation should be freed 

 of such contaminants (Be-2). 



Chemistry. No volatilization losses have occurred with wet- or dry- 

 ashing (Be-4). Methods have been described which permit separations 

 from biological material and estimation of 0.05 ^g (Be-4, Be-5). 



Typical Methods. About 20 /xc Be^ was injected intramuscularly in 

 the rat. Tissues and excreta were dried at 150°C for 2 days, ashed at 

 550°C for 24 hr, and measured with a Geiger counter through a lead filter 

 of 0.99 g/cm- (Be-2). In another study various solutions and routes of 

 administration were used. Doses were 33 to 300 /xc per rat and 0.9 mc 

 per dog. Small tissues were placed in 10-ml porcelain capsules, covered 

 with concentrated HNO3, dissolved, and dried. Larger samples were 

 wet-ashed with HNO3 and then diluted to 25 or 500 ml, ahquots of which 

 were deposited in the porcelain capsules and dried. Radioactivity was 

 measured with a mica-end-window counter through a 0.5-g/cm^ absorber 

 (Be-6). 



Autoradiographic studies with Be'' have been described making use of 

 an intensifying screen of 0.5-mil gold or platinum foil placed between the 

 histological section and the emulsion (Be-7). Effects of chemical form 

 and pH on the distribution have been reported (Be-8). 



Be-1. Sachs, Frances L., and Kathryn D. Ballentine: Beryllium Toxicology, Carbide 

 and Carbon Chemicals Company, Y-975, July 17, 1953. 



Be-2. Crowley, Joseph F., Joseph G. Hamilton, and Kenneth G. Scott: The Metabo- 

 lism of Carrier-free Radioberyllium in the Rat, J. Biol. Chem., 177 : 975-984 

 (1949). 



