Using in vitro/in silico data for consumer safety assessment of feed flavoring additives--A feasibility study using piperine.

Consumer health risk assessment for feed additives is based on the estimated human exposure to the additive that may occur in livestock edible tissues compared to its hazard. We present an approach using alternative methods for consumer health risk assessment. The aim was to use the fewest possible number of animals to estimate its hazard and human exposure without jeopardizing the safety upon use. As an example we selected the feed flavoring substance piperine and applied in silico modeling for residue estimation, results from literature surveys, and Read-Across to assess metabolism in different species. Results were compared to experimental in vitro metabolism data in rat and chicken, and to quantitative analysis of residues' levels from the in vivo situation in livestock. In silico residue modeling showed to be a worst case: the modeled residual levels were considerably higher than the measured residual levels. The in vitro evaluation of livestock versus rodent metabolism revealed no major differences in metabolism between the species. We successfully performed a consumer health risk assessment without performing additional animal experiments. As shown, the use and combination of different alternative methods supports animal welfare consideration and provides future perspective to reducing the number of animals.

Cadmium: placental mechanisms of fetal toxicity.

Subcutaneous injections of 40 mumol/kg of CdCl2 given to rats on day 18 of pregnancy produced a high incidence of fetal death and placental necrosis. Fetuses directly injected with CdCl2 in utero were resistant to cadmium levels far in excess of fetal levels associated with fetal death following maternal injection. Thus cadmium-induced fetal death was not the result of a direct effect of cadmium on the fetus. Similarly, exposure of fetuses or dams to Cd-metallothionein did not produce fetal death. Placental histological changes and high placental accumulations of cadmium suggested placental mechanisms for the toxicity. Histological changes were observed as early as 12 hours after injection and were characteristic of local circulatory responses. Blood flow measurements with radiolabelled microspheres indicated that uteroplacental blood flow was decreased 40 per cent and 75 per cent at 12-16 hours and 18-24 hours after injection. Studies on the initial responses of the placenta to cadmium exposure revealed that biochemical and ultrastructural changes could be observed in the placenta prior to alterations in blood flow and fetal death. No ultrastructural changes were observed in the uterine vascular endothelium. Thus cadmium-induced fetal death was not the result of direct effects of cadmium but may be the result of a placental effect of the heavy metal. A proposed mechanism for the induction of fetal death is that high placental accumulations of cadmium result in trophoblastic damage which leads to a local circulatory response to the injured tissues and a decrease in uteroplacental blood flow. It is the decrease in nutrient and oxygen transport to the fetus that results from trophoblastic damage and blood flow alterations that ultimately induce fetal death.