Metabolism, metal, human, effect

Difficulties in evaluating the relevance of animal data for humans are well known. However, it seems that the available data on lead metabolism and health effect in children (i.e. McCabe, 1979 Ziegler et al., 1978) are in reasonably good agreement with results obtained in experimental animals. Therefore, it could be assumed that some of the results presented here for other metals might be also relevant for children. 

The Critical concentrations with respect to the soil organisms should be related to a low effect level on the most sensitive species. The effects on the process of metabolism and other processes within the organisms should be considered and also the diversity of the species, which is most sensitive to the heavy metals, has to be accounted. Critical limits must refer to the chronic or accumulated effects. For assessment of the critical concentrations in crops and in drinking water, human-toxicological information is required. In general, for establishing critical loads we should also account the additive effects of the different metals and combination effect between the acidification and biogeochemical mobilization of the heavy metals in soils and bottom sediments. 

The acute toxicity of HCN and cyanide is a consequence of the affinity of these substances for various heavy metals, such as iron or copper, by forming cyano complexes. The effect on cytochromes, which results in an efficient inhibition of respiration, is most important. In addition, numerous other metabolic processes are affected (for a review, see Solomonson, 1981). The lefhal dose of cyanide for humans is considered to be about 1 mg per kg... 

Measurement of underivatized propranolol enantiomers in serum using a celluIose-tris(3,5-dimethylphenylcarbamate) high performance liquid chromatographic (HPLC) chiral stationary phase" (54). A method for the direct measurement of the enantiomers of propranolol in human serum was developed using the OD CSP and a mobile phase composed of hexane 2-propranol W,W-dimethyloctylamine (92 8 0.01, v/v/ v). The assay was validated for use in pharmacokinetic and metabolic studies and was subsequently used in the investigation of the effect of cimetidine on the metallism and clearance of propranolol enantiomers (60). 

Stable complexes with EDTA and its related compounds are formed with most polyvalent metal ions, hence their wide use in chelation therapy. Pure EDTA is a white crystalline solid with a relative molar mass of 292.1. It is a weak, tetrabasic acid which is sparingly soluble in water. EDTA is not metabolized in the human body and is effectively non-biodegradable in the environment. 

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