0141735 



Table 45. Water quality criteria for arsenic, cadmium, lead 



and zinc. 



Use As Cd Pb Zn Reference 



mg/L 



DRINKING 



WATER 0.05 0.01 0.05 5 EPA 1983, USPHS 1962 



LIVESTOCK 



WATER 0.2 0.05 0.1 25 NRC 1974 



LIVESTOCK 



WATER 0.5 0.05 0.1 50 Dyer and Johnson 1975 



LIVESTOCK 



WATER 0.05 0.01 0.05 — Federal Water Pollu- 

 tion Control Adminis- 

 tration 1968 (FWPCA) 



Standards for arsenic have been based on total arsenic and 

 are usually reported on the toxicity of arsenic trioxide (Peoples 

 1983). Methylated forms have been shown to be one hundred times 

 less toxic than inorganic forms. With the exception of rats, 

 arsenic is rapidly eliminated from the bodies of most animals 

 (Peoples 1964). Chronic toxicity in livestock has been demon- 

 strated at levels of 50 mg/kg forage (NRC 1980). Problems may 

 occur on the most contaminated soils (greater than 100 ppm 

 arsenic) if livestock ingest considerable quantities of the soil. 

 A survey of water quality in the Helena Valley in 1972 found no 

 arsenic values greater than 0.03 mg/L (Soukup 1972). Dyer and 

 Johnson (1975) suggested 0.5 mg/L may be a more appropriate 

 maximum level for arsenic in livestock water but, given the 

 possibility of intake from other sources, the 0.2 mg/L level may 

 provide a better margin of safety. Arsenic toxicosis may still 

 occur in very extreme cases in which ingestion of soil by live- 

 stock is the major contributing factor. 



Both lead and cadmium tend to accumulate in animal tissues 

 and therefore are more prone to cause toxicosis in chronic 

 poisoning cases. Allcroft (1951) found that both soluble and 

 insoluble (lead acetate and lead carbonate respectively) forms of 

 lead were absorbed at about the same rate. Puis (1981) has given 



135 



