88 CIRCULAR 9 7 7, U. S. DEPARTMENT OF AGRICULTURE 



application this dose averages less than 5 mg. per kilogram of body 

 weight. 



From the standpoint of subacute or chronic toxicity, 25 p. p. m. in 

 the diet damages tissue. A feeding level of 50 p. p. m. causes gross 

 toxic effects. No information on the effects of lower feeding levels 

 is available. 



The U. S. Public Health Service has investigated the toxicity of 

 dieldrin when used in sprays. With proper precautions a concentra- 

 tion of 0.625 percent is regarded as safe. Sprays containing 0.25 

 percent of dieldrin proved acutely toxic to calves. Single treatments 

 with a 0.1 -percent concentration did not cause gross toxic symptoms. 

 Older cattle tolerated single exposures at much higher concentrations, 

 as is true for other chlorinated hydrocarbon insecticides. Repeated 

 treatments with 0.5-percent sprays caused accumulative toxic effects 

 in cattle. 



Dieldrin is readily stored in fat and excreted in milk of cattle 

 when it is consumed in the diet or absorbed through the skin. Like 

 DDT, its residues are slowly eliminated. 



Generally dieldrin is considered more toxic to animals than the 

 other chlorinated hydrocarbon insecticides previously discussed. 

 However, it is also much more toxic to insects. The smaller amounts 

 required for insect control may offset the greater toxicity to animals. 



Dieldrin should not be used for insect control except by trained 

 personnel under responsible supervision. 



Special Precautions in Using Dieldrin 



Do not apply on man. 



Do not use inside homes except for spot treatments at a concentration 

 of 0.5 percent as a spray or 1 percent as a dust. 

 Do not contaminate ponds or streams. 

 Do not apply or allow to drift where livestock may feed. 

 Avoid contact with skin, eyes, and clothing. 

 Do not inhale vapors. 

 Consult a physician if contact or ingestion has occurred. 



ALDRIN 



Insofar as is known, aldrin is similar to dieldrin in mammalian 

 toxicity and storage in fat. Like dieldrin it should also be used 

 only by trained personnel under responsible supervision and with 

 the same precautions as outlined for dieldrin. 



HEPTACHLOR 



Available data on the mammalian toxicity of heptachlor are limited, 

 but the oral toxicity appears to be similar to that of aldrin and 

 dieldrin. Little information is available regarding its chronic toxicity, 

 storage in fat of animals, and excretion in milk. 



Heptachlor should be used only by trained personnel under respon- 

 sible supervision and with the same precautions as outlined for dieldrin. 



