0141619 



found for many metals under chronic exposure conditions as opposed 

 to acute poisoning are due to the fact that in acute poisoning, 

 the animal usually dies before a large tissue metal accumulation 

 can occur. Buck et al . (1976) suggested 10 ppm in liver and 

 kidney tissue as diagnostic of arsenic poisoning. The 5 ppm cattle 

 liver arsenic hazard level recommended for the Helena Valley is 

 therefore most applicable to chronic arsenic poisoning. 



The toxic hazard level for cattle hair (Table 5) was selected 

 based on: 1) the maximum normal or background concentration 

 reported in the reviewed literature (2.7 ppm arsenic), and 2) 

 toxicity was observed at concentrations as low as 0.8 ppm (Riviere 

 et al. 1981). Toxic arsenic concentrations in cattle hair tended 

 to be low (1-3 ppm) in acute poisoning and higher (2.4 - 21.0 ppr.: 

 in prolonged or chronic exposure (Table 3). The differences in 

 hair arsenic accumulation between acute and chronic cases has 

 resulted in a range of values (1.4 to 3 ppm) which may be toxic in 

 acute cases but not toxic in chronic cases. The toxic hazard 

 level of >3 ppm in cattle hair, if statistically significant, 

 should be an indication of excessive exposure to this element. 



Milk arsenic levels remained low (<1 ppm) even under moderate 

 exposure to arsenic (Peoples 1964). The toxic hazard level for 

 cattle milk (1.5 ppm) was based on this level observed in a 

 chronic toxicity case reported by Underwood (1977). 



2.1.2.2 



'oxic arsenic hazard levels for horses 



Few arsenic toxicity data for horses were found in the 

 literature. The toxic hazard levels for horse kidney and liver 

 tissues, 10 ppm and 7-15 ppm respectively, were concentrations 

 reported by Puis (1981) (Table 6). The toxic level for arsenic in 

 horse hair, 4 ppm, was based on a study by Lewis (1972) of horses 

 in the Helena Valley. Arsenic content of mane hair in affected 

 horses ranged from to 4.5 ppm. The mane hair of one horse that 

 died of the "smoked syndrome" contained 4.4 ppm arsenic. Two out 

 of the three affected animals had mane hair arsenic levels greater 

 than 4 ppm. No subclinical evaluation was attempted in this study 

 and the affected animals also exhibited high concentrations of 



] ? 



