Tail hair as an indicator of environmental exposure of cows to lead and cadmium in different industrial areas

This study examines the use of tail hair from cows as a possible biomarker of environmental exposure to lead and cadmium around different industrial areas. Respective blood and tail hair samples were collected from a total of 317 apparently healthy cows above 3 years of age. This includes 287 cows reared in industrial and urban areas and 30 cows from areas free from polluting sources. Significantly ( P < 0.05 ) higher lead and cadmium residues were recorded in hair from cows reared around lead–zinc smelter and closed lead cum operational zinc smelter. However, cows from those areas had significantly ( P < 0.05 ) higher blood lead but not cadmium concentration as compared to respective control value. Although mean blood lead concentration in cows around aluminum processing plant and urban cum small industrial areas and that of cadmium around steel processing plant were significantly ( P < 0.05 ) higher than respective control, the mean hair lead and cadmium content remained statistically ( P > 0.05 ) comparable to that of respective control values. The blood lead was significantly correlated with hair lead ( r = 0.672 , P < 0.01 ) and cadmium ( r = 0.309 , P < 0.05 ) . There was a significant correlation between lead and cadmium concentration ( r = 0.610 , P < 0.01 ) in hair and a nonsignificant correlation between blood and hair cadmium suggesting that cadmium accumulation in hair was influenced by blood and hair lead concentrations in cows environmentally exposed to lead.