0141623 



"will have little if any effect on the health and performance of 

 poultry." Exposure of livestock to excessive cadmium may result 

 more from ingesting contaminated soils than from contaminated 

 forage. 



The liver and kidneys are the main reservoirs of cadmium in 

 vertebrates (Tables 8-11). Concentrations in muscle tissue are 

 always quite low (Doyle et al . 1974, Osuna et al . 1981, Mills and 

 Dalgarno 1972), but elevated forage cadmium levels will cause 

 slight increases in muscle concentrations as well as significant 

 increases in liver and kidney cadmium levels (Johnson et al . 

 1981). All studies of elevated cadmium in diet or water refer- 

 enced in Table 11 produced increased cadmium levels in liver and 

 kidneys. Other pathogenic states or abnormalities were produced by 

 varying additions of dietary cadmium. In studies of lambs and the 

 Long Evans strain of laboratory rats, 5 mg/kg in the diet or 

 drinking water caused reduced growth or hypertension (Doyle et al. 

 1974, Schroeder and Vinton 1962). The experimental periods were 

 long in both examples, 163 days for lambs and 1 year for rats. 

 Production of metal lothionein by internal organs protects the 

 animal from damage by the elevated concentration of the toxic 

 metal until this protective mechanism is thwarted by prolonged 

 overexposure. This mechanism is discussed more fully in Appendix 

 section 6.1.2. 



The determination of the exposure of livestock to cadmium is 

 difficult because of the scarcity of data on cadmium in readily 

 available samples such as hair, blood or urine. The few documents 

 available indicate that animal hair is a controversial tool for 

 this assessment. Limited data suggest the background range for 

 cattle hair cadmium concentrations will be 0.6 ppm or less (Powell 

 et al. 1964, Wright et al . 1977). Available data suggest that 

 cadmium in animal hair will likely be significantly correlated to 

 dietary intake at diet levels above 50 ppm. Interpretation of 

 hair data from lower diet levels may be difficult. Hammer et al . 

 (1971) showed a relationship between cadmium in human hair and the 

 exposure ranking of the samples. He also found a similar rela- 

 tionship in East Helena, Montana (Hammer et al . 1972). The work 



23 



