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United States Department of Agriculture ^ ^ lujiculuue 

 Bureau of Biological Survey ; If' ^- •^-x'""^"'" 



Wildlife Research and Mana gement Leaflet 6,S'-^:0 - "' 



Washington, D. C. * May 1935 



THE POSSIBIL ITY OF SECONDARY POISONING FROM THALLIUM USED 



IN THE C O NTROL OF RODENT S - ■ 



By F. E. Garlough, Director, Control Methods Research Laboratory, Denver, Colorado 

 . Section of Predator and Rodent Control, Division of Game Management 



Contents 



,.'J; ""[" Page I ' ■ "■ Pg^gg 



Introduction '......■.'..'.....^. ._..'. .'.../„,.... 1 | Possibility of secondary poisoning 



Lethal dose for mammals'......"..".."..,.!.... 1 j in man 2 



Lethal dose for birds '.'. 2 I . , 



Introduction ,' , "' ,,.,/! 



The possibility of secondary poisoning of birds 'and mammals through eating 

 carcasses of animals killed by thallium sulphate has JDeen extensively studied at 

 the Control Methods Research Laboratory maintained by the Burea.u of Biological 

 Survey at Denver, Colo. Thallium sulphate is used under certain conditions in the 

 control of ground squirrels, prairie dogs. rats, and other rodents, and of moles. 

 The birds and mammals studied as possible agents in secondary poisoning have been 

 ducks, pigeons, quail, hawks, ravens, mice, white rats, brovm. rats, ground squirrels, 

 prairie dogs, rabbits, porcupines, sheep, and cattle. The results of the laboratory 

 studies and of investigations in the field have thrown sufficient light on the pos- 

 sibility of secondary poisoning to indicate that it v/ould be remote. 



Lethal Dose for Mammals 



The weights of the mammals used have run from a few grams (in the case of 

 mice) to 375 kilograms (847 pounds, in cattle), and the results demonstrate that 

 for each one the lethal dose when administered orally is almost in direct propor- 

 tion to the body weight, being about 25 milligrams (0.4 grain) per kilogram (2. 2 

 pounds). This unifcrmity indicates that, per kilogram, of body weight, in man the 

 lethal dose of thallium sulphate is probably as great. 



Deaths of mammals have been recorded from a dosage less than 25 milligrams 

 per kilogram, and because of individual variations survivals have been reported 

 from greater dosages. The cases in which the lethal doses have been less, however, 



