The paper considers materials on the substantiation of criteria, indices, and their gradation for a new variant of the hygienic classification of hazards of water-contaminating substances. Emphasis is placed on the significance of a ratio of the maximally inactive concentrations (MIC) in terms of the toxicological sign of harmfulness to the threshold concentrations (TC) in terms of their effects on the organoleptic properties of water and on the general sanitary regime of water reservoirs. Only two types of late effects of substances, which are of individual significance for classification, such as carcinogenicity and reproductive effects, are identified. It is stated that a class of hazard may be toughened for high-stable substances, but neither the stability nor any other indices of the potential hazard of substances is the ground for reducing their hygienic standards in water.
In the context of increasing concerns regarding sustainable development, healthcare workers must consider practices that are not harmful to the environment. 'Primum non nocere' is of great value for the residues of pharmaceuticals and biocides resulting from medical prescriptions. Stockholm County Council has developed a simple classification system covering both environmental risks and hazards of pharmaceuticals according to their persistence, bioaccumulation and toxicity. This classification, which is easy to understand and well accepted among Swedish medical doctors, could be a model for other countries and useful to general medical doctors wishing to be environmentally conscious in their prescribing. Limited information is available on both the fate and ecotoxicity of pharmaceuticals and biocides in the aquatic environment. The primary concern regarding the environmental impact of pharmaceuticals seems to be drug classes such as antibiotics, oestrogens, cytostatic agents, contrast agents and disinfectants. Performing a full ecological risk assessment of pharmaceuticals and biocides is difficult because of a lack of data on exposure scenarios, target aquatic species and dose-response relationships.
Analysis of soil C and O horizon samples in a recent regional geochemical survey of Nord-Tr?ndelag, central Norway (752 sample sites covering 25,000 km2), identified a strong enrichment of several potentially toxic elements (PTEs) in the O horizon. Of 53 elements analysed in both materials, Cd concentrations are, on average, 17 times higher in the O horizon than in the C horizon and other PTEs such as Ag (11-fold), Hg (10-fold), Sb (8-fold), Pb (4-fold) and Sn (2-fold) are all strongly enriched relative to the C horizon. Geochemical maps of the survey area do not reflect an impact from local or distant anthropogenic contamination sources in the data for O horizon soil samples. The higher concentrations of PTEs in the O horizon are the result of the interaction of the underlying geology, the vegetation zone and type, and climatic effects. Based on the general accordance with existing data from earlier surveys in other parts of northern Europe, the presence of a location-independent, superordinate natural trend towards enrichment of these elements in the O horizon relative to the C horizon soil is indicated. The results imply that the O and C horizons of soils are different geochemical entities and that their respective compositions are controlled by different processes. Local mineral soil analyses (or published data for the chemical composition of the average continental crust) cannot be used to provide a geochemical background for surface soil. At the regional scale used here surface soil chemistry is still dominated by natural sources and processes.