Uptake of soil lead by living organisms

Concentrations of lead in roadside grass may reach several hundred mg kg (dry weight) but the bulk of this lead arises from surface deposition, and not from uptake from the soil. The degree of uptake from the soil by growing plants 

Many plants absorb considerable amounts of lead into the roots, but translocate only limited quantities into the above-ground portions. Table 4.4 shows the relationship between the lead content of lettuce and radish grown in contaminated soils and the concentration in the soil, in the absence of atmospheric contamination. In this instance lead concentrations in the soil are expressed as both total lead and available lead (AL-soluble Pb), the latter being defined as that soluble in an ammonium acetate-lactate solution [17]. In this study a significant correlation (P 0.05) between lead concentration in plants and AL-soluble lead in soil was found. 

The lead deposited in soils and vegetation can cause enhanced levels of lead in soil invertebrates. Earthworms have been studied extensively and have been found to accumulate several hundred mg kg of lead (dry weight) in extreme cases. Concentrations of lead in earthworms show correlation with the concentrations in roadside soil at the point of sampling. Small mammals living in the 

One point of concern has been the possible absorption of lead ingested by ruminant animals (cattle and sheep), with subsequent incorporation into the muscle or milk. It appears, however, that such animals absorb lead in the alimentary tract only very inefficiently, about 99% being excreted in the faeces [11]. Hence concentrations of lead in meat and milk can be very little affected. The mean concentrations of lead in meat and fish in the UK is 0.17 mg kg (range 0.01-0.70 mg kg ) and in milk 0.03 mg kg (range 0.01-0.08 mg 

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