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2.0 LITERATURE REVIEW AND HAZARD LEVELS FOR LIVESTOCK 



There are three general -approaches to determining the body 

 burden of heavy metals in livestock. These are: 1) analyzing 

 internal organ tissues; 2) analyzing accessible body fluids and 

 materials; and 3) the _i_n vivo determination of heavy metals 

 utilizing radiometric analyses. A considerable amount of data has 

 been published on background and elevated heavy metal levels in 

 livestock organs. In most situations these organs are not 

 available for large scale studies. Liver and bone samples may be 

 procured through biopsy procedures. Data on blood, milk, hair, 

 feces and urine are more limited, but sufficient in some parame- 

 ters to allow their use in a livestock survey for some heavy 

 metals. The third method offers much promise in future studies 

 but facilities for radiometric determinations are few at this 

 time. The following sections outline documented levels of 

 selected heavy metals in various animal substances and their sig- 

 nificance in determining toxicosis. All values are reported on a 

 wet weight basis unless noted. 



2 . 1 Arsenic 



2.1.1 Arsenic literature review 



Arsenic poisoning is the second most common metaloid toxin. 

 The element is ubiquitous and has been found in all plant and 

 ar.:nal tissues under normal background conditions (Schroeder and 

 Baiassa 1966). Several forms: arsanilic acid; sodium arsanilate; 

 3-n i tro-4-hydroxyphenylarsonic acid, have been used as feed addi- 

 tives to increase weight gain and feed efficiency and to control 

 disease in swine, poultry and other livestock. 



Most documented cases of arsenic poisoning in livestock have 

 been acute or subacute, usually from ingesting treated forage 

 (Edwards and Clay 1979, Weaver 1962, McCulloch and St. John 1940, 

 Selby et al. 1974, Selby et al. 1977), contaminated feed 

 (Beregland et al . 1976, Selby et al . 1977), dipping powder and 

 herbicides (Moxham and Coup 1968) and various refuse (McParland 



