Human toxicity as a criterion in the environmental assessment of products

As part of a life cycle assessment methodology methods are developed for the semiquantitative screening and for the quantitative assessment of potential contributions to toxicity towards human beings through exposure in the environment to emissions occurring during the life cycle of a product. The assessment proceeds through the steps of classification, characterization, normalization and valuation. In the classification step attention is focused on intrinsic toxicity, low biodegradability and potential for bioconcentration as properties that predicpose a substance for ecotoxicity. No concrete values are given but a semiquantitative screening method is proposed as tool for the classification. In the characterization the potential contribution to ecotoxicity from the compound is quantified in three compartments of the environment: Air, water, groundwater and soil. A characterization method is developed involving an analysis of the generic fate of the substance in the environment, its transfer efficiency to human beings and its potential effects. The fate analysis involves the passage of a wastewater treatment plant, redistribution through evaporation, deposition and biodegradation in the environment. The transfer efficiency is modelled in a standard scenario for indirect exposure of human beings through intake of fish, plants, meat and dairy products. The effect analysis consists in the determination of the highest oral dose or air concentration that is expected to cause no effects in human beings through a lifelong exposure. For all four compartments characterization factors are presented that express the toxicity potential of the substance in terms of a volume of the considered compartment. For normalization of the characterized emissions three different reference scenarios are suggested representing the situations of non exceedence of: ? The carrying capacity anywhere within Denmark or the European Union. ? The existing Danish political reduction targets for toxicity scaled to the year 2000 and applied to present Danish emissions. ? The presently occurring emissions within Denmark. The normalization references derived for each of these scenarios are presented as personal equivalents for citizens in the considered region. Valuation Applying the "distance to target principle to the present Danish political reduction targets for toxicity a weighting factor is derived to be used in the quantitative weighing of the potential contribution to toxicity against the potential contributions to other environmental effect types.