ECOLOGICAL HAZARD ASSESSMENT OF DIOXINS - HAZARDS TO ORGANISMS AT DIFFERENT LEVELS OF AQUATIC FOOD WEBS (FISH-EATING BIRDS AND MAMMALS, FISH AND INVERTEBRATES)

An ecological hazard assessment was performed for 2,3,7,8-tetrachlorod ibenzo-p-dioxin in the aquatic environment, taking into account four d ifferent classes of species which differ with respect to their positio ns in aquatic food webs: invertebrates, fish, birds preying on aquatic organisms, and mammals preying on aquatic organisms. The most sensiti ve toxicological endpoints for each class were selected from the liter ature. These endpoints were extrapolated to no effect concentrations ( NECs) in water with a two-level food chain model as indicator for seco ndary poisoning. From the results it is concluded that fish-eating bir ds and mammals experience larger hazards from dioxins and related comp ounds than fish. The limited data available appear to indicate that in vertebrates are rather insensitive to dioxins. The study indicates tha t assessment of secondary poisoning affects environmental quality crit eria setting and risk assessment.