0141655 



The 10 ppm toxic hazard level for horse liver tissue is 

 based on Schmitt et al. (1971), Eamens et al. (1984) and Buck et 

 al. (1976). Schmitt et al. (1971) found a range of 9.0 to 48 ppm 

 lead in horse liver tissue of animals exposed to industrial 

 pollution near Trail, British Columbia. Eamens et al . (1984) 

 found 10.0 ppm lead in liver tissue of a horse exhibiting 

 clinical toxicity symptoms. Similar levels (11.8-17.2 ppm) were 

 found associated with clinical toxicity by Knight and Burau 

 (1973). With the exception of one horse with a liver tissue lead 

 concentration of 11.4 ppm (Dollahite et al. 1978), all horse 

 liver tissue samples with >10 ppm lead were associated with 

 toxicity. Puis (1981) gave ranges of 4 to 50 ppm and 10 to 500 

 ppm in horse liver tissue as indicative of chronic and acute 

 toxicosis, respectively Buck et al. (1976) indicated that the 10 

 ppm lead concentration in liver tissues was diagnostic of lead 

 poisoning . 



The reports of Lewis (1972) and Burrows and Borchard (1982) 

 are the basis of the toxic hazard level for horse hair. Lewis 

 (1972) found elevated lead concentrations (9.6 to 25.8 ppm) in 3 

 of 4 affected horses studied in the Helena Valley. The effects 

 of the interaction of elevated levels of other metals on the 

 apparent toxicity noted in this study were not documented. 

 Burrows and Borchard (1982) studied ponies on diets of contami- 

 nated hay (from the Coeur d'Alene River Basin, Idaho) and on 

 diets with added lead acetate and found hair lead concentrations 

 of 12.2 and 13.4 ppm for the two groups respectively. These 

 authors suggested that the interaction of cadmium in the contami- 

 nated hay "markedly increased ... the severity and rapidity of 

 development of the clinical toxicologic signs and hematologic 

 changes" . 



No elevated horse milk data were found in the reviewed 

 literature (Table 17). The toxic hazard level is the Level 

 published by Puis (1981). 



2.3.2.3 Toxic lead hazard levels for sheep 

 Fick et al. (1976) found concentrations of lead in sheep 

 olood from 0.18 to 0.28 were nontoxic. Blaxter (1950a) noted 

 sheep blood lead levels of _> 0.45 ppm were associated with 

 toxicosis, which was the basis of the toxic hazard level for this 



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