The transfer of arsenic to sheep tissues

There is the potential for arsenic to enter the human food chain via ingest ion by grazing animals. Data on the transfer of arsenic to ruminants have b een too sparse to allow the development of dynamic models to predict change s in the arsenic contents of different tissues following ingestion. A study is described during which a group of 6-month-old lambs were given a single oral administration of (AsCl3)-As-73. Subsequently, concentrations of As-7 3 in the tissues of groups of lambs slaughtered at intervals over a period of 181 days were determined. A true absorption coefficient of 0.46 +/- 0.05 5 (mean +/- S.E.) was determined which is considerably lower than expected from previous studies of non-ruminant animals which demonstrate complete ab sorption for inorganic arsenic. The resultant data were used to develop a c ompartment model to describe arsenic behaviour in sheep tissues. The derive d model accounted for 80 % (n = 100) of the observed variation in the data. The model predicts that arsenic concentrations in tissues rapidly (< 40 da ys) reach equilibrium with the dietary intake level. Equilibrium transfer c oefficient values (the ratio of the arsenic concentration in a tissue to th e daily dietary intake of arsenic) for the important food-chain tissues wer e calculated as: (2.5 +/- 0.67) x 10(-3) days/kg calculated as: (2.5 +/-0.6 7) x 10(-3) days/kg for muscle, (9.1 +/- 1.96) x 10(-3) days/kg for liver a nd calculated as: (2.5 +/- 0.7) x 10(-3) days/kg (1.1 +/- 0.14) x 10(-2) da ys/kg for kidney.