Organometallic Compounds

Abstract

Among the microbicidal organometallic compounds, the organomercury and organotin compounds are those which should be mentioned first, for they are the ones that have been used for material protection on a large scale throughout the world. Today, however, there is a strong movement throughout in favour of their substitution in view of their toxicity and especially their ecotoxicity. Organomercury compounds, in particular, have already been largely substituted and are no longer of much importance as microbicides for material protection. In the truest sense of the word they may be termed biocides, since they are effective not only against microbes, but also against all forms of life. Although Hippocrates already knew of the toxicity of mercury compounds he could not anticipate the environmental problems that were to arise through their excessive use — problems rooted in the fact that these compounds are biodegradable only to the stage of methyl- or dimethylmercury, both of which are extremely toxic (Lakowitz & Anderson, 1980). They diffuse rapidly across permeability layers such as membranes. Methyl- and dimethylmercury therefore accumulate in living organisms, especially those at the end of the food chain, such as predatory fish and animals dependent on fish. Without this accumulation the lethal doses of mercury compounds would be less problematical. If a quantity of mercury compounds is absorbed by a human, about 10% of it is carried to the brain.

Sources for toxicity data, if not otherwise indicated: Registry of toxic effects of chemical substances (1990). Department of Health and Human Services, Cincinnati, USA. Lexikon der Hilfsstoffe für Pharmazie, Kosmetik und angrenzende Gebiete (1989), Ed. H P. Fiedler, Editio Cantor, Aulendorf Germany. Product information and safety data sheets of microbicide suppliers. All indications are given in good faith and conscience. This also applies for the ’maximum working place concentrations’ (MWC), the ’acceptable daily intake’ (ADI) values and to the data with regard to ecotoxicity and biodegradability of microbicides which, as far as accessible, were also incorporated.