APR 2 5 1931 
Technical Bulletin No. 238 
UNITED STATES DEPARTMENT OF AGRICULTURE 
WASHINGTON, D. C. 
THE PHARMACOLOGY OF THALLIUM 
AND ITS USE IN RODENT CONTROL^ 
By James C. Munch, Consulting Pharmacologist, and James Bii.rF^^ Associate 
Biologist, Division of Predatory -Aninval and Rodent Control, Bureau of 
Biological Survey 
CONTENTS 
Page 
Introduction. 1 
Review of the literature on thallium 2 
Occurrence and properties 2 
Determination.. 3 
Action of thallium on bacteria 4 
Action of thallium salts on animals 4 
Action of thallium salts on man 8 
Medicinal uses 10 
Antidotes for thallium poisoning 12 
Laboratory experiments.. . 12 
Method adopted for feeding experiments. 12 
Page 
Laboratory experiments — Continued. 
Feeding experiments 13 
Phvsiological action on rats 18 
Toxicity of thaUium to rabbits by intra- 
venous injection 18 
Summary - 19 
Literature 19 
Laboratory experiments with rodents 20 
Conclusions 20 
Bibliography 21 
INTRODUCTION 
The use of thallium as a rodent poison apparently originated about 
1920, when a company in Germany introduced a proprietary rat 
poison that had thallium as its toxic principle. Very few reports 
upon its action were found in the literature previous to July, 1924, 
when samples of poisoned grain and rat paste were obtained from 
this company for study. Preliminary examination showed that 
these products were toxic to wild and to white rats and led to an 
investigation of the minimum lethal dose of thallium salts when fed 
to white rats and when intravenously injected into rabbits. 
In August, 1925, the authors conferred w^th a representative of 
this company regarding the nature, mode of action, and use of its 
product in Germany and concerning plans for introducing it into 
the United States. The product was thoroughly discussed, and 
certain mimeographed circulars and information, as well as the 
company's method of chemical analysis, were submitted by the 
representative. 
Thallium compounds were introduced into use for the control 
of rodents, particularly certain species of prairie dogs and ground 
squirrels that had refused to take strychnine baits. Arrangements 
1 The experiments here reported upon were instituted as a cooperative project between the then Bureau 
of Chemistry and the Bureau of Biological Survey prior to the appointment of the senior author as consult- 
ing pharmacologist with the Biological Survey, following his service in th© pharmacology laboratory of the 
Bureau of Chemistry, now part of the Food and Drug Administration. 
37900°— 31 1 
