The substantiation of the maximum daily permissible doses of lead and cadmium in everyday diet

The article is dedicated to the bright memory of Prof. Shtabsky B.M. (the 90th anniversary) and comprises a fragment of results of experimental investigations conducted under his supervision in 1984-1989 years. They are related to the methodological approaches to the conducting acute, subacute, and chronic experiments, as well as analysis of the results and verification of the maximum daily permissible dose (DPD) of lead and cadmium in the everyday diet. In the acute experiments it has been established that lead nitrate belongs to the group of the low-toxic compounds, Cadmium nitrate belongs to the mid-toxic compounds, while both are considered to be highly cumulative. The toxicity and the level of cumulation does not depend on the carrier – water, milk, vegetable oil. In subacute and chronic experiments the comparative toxicity of Ionic (comes with water and nourishment) and biocommunicated (liver and kidney homogenate, cottage cheese) forms of metals in the range of doses 1/10-1/100000 LD50 and additionally 1/500000 LD50 for cadmium has been studied. Toxicometrically significant distinctions under the action of the afore-mentioned forms have not been detected. The excretion of δ-aminolevulinic acid and coproporphyrin with urine, and concentration of SH-groups in the blood plasma and liver tissue and protein in urine under the effect of cadmium in the effect of lead appeared to be the most demonstrative. Both metals possess clear gonadotoxical effect, they cause genetic effects, which can be determined by cytogenetic method, and in the Ames test with presence of liver S-9 microsomal fraction. Maximal non-effective supra-background dose DE050 0,0015 mg/kg for lead, and 0,00005 mg/kg for cadmium have been established on the basis of analysis of “dose-effect” dependency in subacute and chronic experiments, having taken into consideration results obtained according to the method of loading by same metals. Taking into the account natural metallic background dose of with daily diet (0,0025 mg/kg for lead, 0,0005 mg/kg for cadmium of the body weight), the DPD of lead and cadmium in everyday diet is recommended at the level of 0,004 mg/kg and 0,00055 mg/kg of the weight of the body respectively.