Increasing amounts of sewage sludge will be applied to agricultural land over the next 10 years as a result of the prohibition of its disposal to the sea. The addition of potentially toxic elements (PTEs) to the soil via sewage sludge is controlled by European legislation designed to limit the accumulation of PTEs in soil which could give rise to toxicity to plants or livestock. However the possibility exists that direct ingestion of sewage sludge and soil together with grazed herbage may result in accumulation of PTEs in body tissues. To assess the extent of accumulation of PTEs by direct ingestion of soil and sewage sludge 12 groups of housed weaned lambs were given diets ad libitum comprising dried grass (900 g/kg total diet dry matter (DM)) and three different soils (100 glkg total diet DM). Soil was replaced by dried digested sewage sludge at levels ofO (level 0), 75 (level 1), 150 (level 2) and 300 g/kg soil DM (level 3). Voluntary intake of DM was markedly depressed by the inclusion of sewage sludge in the diet (on average by 24 g DM per g sewage sludge DM addition). There was no effect of sewage sludge on diet apparent digestibility. Live-weight gain was depressed (P < 0·001) by the addition of sewage sludge to the diet from 236 glday (level 0) to 141 glday (level 3). Liver and kidney weights were also reduced (P < 0·01). The apparent availability coefficients for Cd, Pb and Cu increased with increasing level of sewage sludge in the diet fP < 0·05), as did their concentrations in the liver and kidney (P < 0·01). Concentrations of Cd and Pb in liver increased from <0·07 mg/kg DM and <0·40 mg/kg DM (level 0) respectively to 0·61 mg/kg DM and 4·60 mg/kg DM (level 3) respectively at the end of the trial. Similarly the concentrations of Cd and Pb in kidneys increased from 0·19 mg/kg DM and <0·56 mg/kg DM (level 0) respectively to 0·80 mg/kg DM and 7·10 mg/kg DM (level 3) respectively by the end of the trial. No increases were observed in concentrations of Cd or Pb in muscle tissue. The main effect of type of soil on concentrations of PTEs in body tissues was not significant The daily rate of accumulation ofPb in kidney ranged from 1·1 to 51·5 uglg daily tissue DM growth during the first 57 days of the experiment and from 0·33 to 6·78 /xg/g daily tissue DM growth between day 57 and day 112. A decrease in the second period was also observed for Cd, with accumulation in kidney ranging from 0·31 to 4·44 fig/g daily tissue DM growth during the first 57 days and from 0·21 to 1·44 /jg/g daily tissue DM growth between day 57 and 112. Concentrations of Pb in liver of lambs given the highest level of sludge approached the statutory limit set for human food. The results indicate that in relation to accumulation of PTEs in liver and kidney there would appear to be little margin of safety with respect to the current United Kingdom statutory limits for the concentrations of Cd and Pb in sludge-amended soils. Confirmation of these results is required in the grazing situation.

1998). Accumulation of potentially toxic elements by sheep given diets containing soil and sewage sludge. 2. Effect of the ingestion of soils treated historically with sewage sludge. AbstractCurrent European Union legislation will increase the level of disposal of sewage sludge to agricultural land in the next 10 years. This increase may lead to an increase in ingestion, by grazing animals, of herbage with elevated levels of potentially toxic elements (PTEs) derived from sludge adhered to the herbage or sewage sludge-amended soil resulting in the accumulation of PTEs in body tissues, especially the liver and kidney. To assess the possible accumulation of PTEs from soils treated historically with sewage sludge, eight groups of housed weaned lambs were given either dried grass as a sole food (grass control), or diets comprising dried grass (0-9 of total diet dry matter (DM)) and soil (0-1 of total diet DM) from two experimental sites, plots within which had been treated 14 years previously with different quantities of sewage sludge. Soils from the two sites (Cassington and Royston) had contrasting physical characteristics, pH and contents of calcium. The soil from the site at Cassington was slightly acidic (pH 6-0) and had a concentration of calcium of 7-92 glkg DM whereas the soil from the site at Royston was alkaline (pH 8-0) and had a high concentration of calcium . Plots at each site had a range of concentrations of cadmium (Cd) in the soil up to three times the United Kingdom (UK) statutory limit of 3 mg Cd per kg DM. The soils from these two sites were designated control -no amendment with sewage sludge (0-69 mg Cd per kg DM), low (3-55 mg Cd per kg DM), medium (6-63 mg Cd per kg DM) and high (8-82 mg Cd per kg DM; Cassington soil only). Voluntary DM intake of diets by weaned lambs (mean 1436 glday) was not affected significantly by any dietary treatment. The concentrations of Cd in liver increased (P < 0-001) from 0-061 and 0-072 mg/kg DM (Royston and Cassington control, respectively) to 0-218 and 0-403 mglkg DM (Royston and Cassington medium, respectively) and 0-500 mg/kg DM (Cassington high). The concentrations of Pb in liver increased (P < 0-001) from 0-733 and 0-627 mg/kg DM (Royston and Cassington control, respectively) to 118 and 1-25 mg/kg DM (Royston and Cassington medium, respectively) and 1-18 mg/kg DM (Cassington high). Similar changes were observed for concentrations ofCd and Pb in kidney. A depletion of the concentration ofCu in the liverwas observed in all treatments containing soil in the diet. The rate of accumulation ofCd in the liver ranged from 0 to 0-35 \ig/g daily tissue DM growth and in the kidney ranged from 0 to 0-44 \iglg daily tissue DM growth. The rate of accumulation ofPb in the liver ranged from 0 to 6-01 yig/g daily tissue DM growth and in the kidney ranged from 0 to 0-63 \ig/g daily tissue DM growth. No significant accumulation of PTEs was observed in muscle tissue. It is concluded that the current UK statutory limits for the concentrations ofCd and Pb in soils treated with sew...

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Addition of sewage sludge to grassland may be reflected in ingestion of lead by animals with implications for the human food chain. The research reported here was part of a series of experiments conducted to investigate the possible risk to the health of livestock and humans associated with the use of sewage sludge in agriculture. The transfer of several elements to the body tissues of lambs was examined, including that of cadmium, copper, zinc and lead. The results for lead are reported in this paper.Weaned Kent lambs (6/treatment, 20 to 45 kg liveweight) were given dried grass ad libitum (Trial 1, indoor feeding) either as the sole feed (C) or with 100 g/kg DM of one of two soils (CM, sandy -pH 6.18; or RM, a calcareous loam - pH 7.55) which had been amended historically with sewage sludge and which contained 102 (CM) and 130 (RM) mg Pb/kg DM.

Sewage sludge contains a range of essential and non-essential elements for livestock nutrition, many of which are toxic at elevated levels. Where sludge is applied to the surface of pasture regularly, contaminants principally heavy metals will accumulate in the surface layer (Davis et al 1988), and may represent a potential health hazard for grazing animals through the direct ingestion of contaminated soil much greater than that from plant uptake. Whilst it is known that soil ingestion can supplement mineral intake with benefits to grazing animals in some situations, the potentially toxic effects of ingesting soil from heavily sludged pastures are of principal concern (Stark 1988). Bearing in mind the strategic importance of grassland for sludge disposal, it must be demonstrated whether existing soil metals limits (DoE 1988) will adequately protect grazing animals. The principal objective of the trial was to study animal growth performance as well as mineral balance from a diet with elevated copper levels derived from a sludge treated soil. Lambs were used for their greater sensitivity to copper than cattle, and the length of the trial simulated the normal finishing period of five months for lambs on pasture.