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Cadmium transfer from whole milk to cream, rennet, or lactic curds was studied before and following a repeated oral cadmium administration to three lactating ewes and one cow. Before cadmium administration, the cadmium levels in milk were around 0.4 microg/L in ewes and less than 0.2 microg/L in cow. Throughout cadmium administration the mean cadmium levels in milk were 3.3+/-1.4 microg/L in ewes and 2.5+/-1 microg/L in cow. During cadmium administration, 86% of cadmium in ewe milk was dispersed in the skimmed milk and 17% in the cream, whereas only 72% was dispersed in the cow skimmed milk and 27% in the cow cream. Most of milk cadmium was associated with casein fractions. About 70% of milk cadmium was transferred to the rennet or lactic curds of ewe. The remaining cadmium present in whole milk, about 9%, was transferred to the rennet or lactic curd whey. In cow, the proportion of cadmium associated with rennet or lactic curds, rennet curd whey, and lactic curd whey was, respectively, 60%, 56%, 14% and 12% of total milk cadmium. The fraction of total cadmium transferred from milk to its milk products, whatever the species, ranged from 94% to 103%. The factor of concentration of cadmium from whole milk to milk products ranged from three to six. We suggest that the excretion of cadmium into milk is mainly achieved via the milk casein secretion. This is, to our knowledge, the first in vivo study where the cadmium transfer from milk to its milk products after repeated cadmium oral administration to ewe and cow has been studied.

The evolution of bone changes induced by fluoride after the end of exposure was investigated in lambs. Sodium fluoride (NaF) was given orally at a dose of 3.5 mg/kg per day to 14 animals for 120 days. A group of 7 control and 7 treated lambs was slaughtered at the end of NaF administration (T120) and another group 120 days after the end of NaF exposure (T240). At T120, the bone fluoride content (BFC) was very significantly increased in treated animals. The histomorphometric analysis confirmed that fluoride induces an increase in bone formation (the osteoid perimeter and area were 3-fold and 4.5-fold higher respectively in treated than in control animals). The number of osteoblasts was significantly augmented. Serum osteocalcin level was twice as high in treated animals compared with controls. The bone formation rate at the tissue level (BFR) doubled after treatment, but the apposition rate (Aj.AR) was half that in the control group. The mineralization lag time (Mlt) was 120 days in treated animals compared with 42 days in controls. At T240, BFC had decreased by 50% compared with the level at T120, but it was still significantly higher than in controls. The osteoid and osteoblastic parameters were 2 and 1.3 times higher than in control animals. BFR remained significantly increased in treated animals, but Aj.AR and Mlt were similar in control and treated animals. In conclusion, after 4 months of NaF exposure fluoride induced an increase in osteoblast natality and bone formation at the tissue level, associated with a toxic effect at the individual cell level.(ABSTRACT TRUNCATED AT 250 WORDS)