[Intoxication and detoxication of heavy metals by humic acids]

Humic acids are naturally occurring phenol body polymerisates which form chelate compounds with heavy metals. Their wide occurrence in soils and surface waters has made them a major reactant to toxic and essential heavy metals in the biosphere. Humic acids, by ways of fixation or solution of trace elements or change of their own toxicological parameters, may exercise influence on ecological circulation, depending on both pH and ion strength of the medium concerned. While the detoxicating action of humic acids is likely to play the major role in natural ecosystems, their effects on heavy metal ion toxicity to experimental animals were found to depend on the technique of application. Enzymatically synthesized phenol body polymerisates are considered to be appropriate model substances for further studies into correlations between humic acids, on the one hand, and heavy metals, on the other.