The European Commission has put forward a proposal for an amendment to the 1994 Council Directive on the Incineration of Hazardous Waste. The existing legislation lays down very strict limit values for emissions of heavy metals and dioxins into the air. The proposed amendment seeks to limit the emissions into water of these toxic substances. In particular, the proposal restricts the release of cadmium and mercury compounds and dioxins to the technically feasible minimum, in order to protect human health and the environment. The proposal from the Commission sets specific emission limit values for the pollutants contained in the waste water generated by the exhaust gas cleaning systems of plants for the incineration of hazardous waste. Discharges into the aquatic environment of waste water must be limited as far as possible. The proposal sets out the strict conditions under which such discharges can take place. It also provides the necessary provisions for monitoring of emissions by sampling and analysis, as well as ensuring that the principle of non-transfer of pollution from air to water is respected. The proposed limit values (monthly average) are as follows: mercury compounds - 0.01 mg/l; cadmium compounds - 0.02 mg/l; dioxins - 0.5 mg/l. For a series of ten other heavy metals and their compounds also covered by the proposal the total limit is 5 mg/l. Cadmium and mercury compounds and dioxins are amongst the most toxic substances for ecosystems and human beings. The effects of dioxins are well known, in particular since the Seveso accident in Italy in 1976. They affect the central nervous system, cause liver damage and chloracne. Heavy metals, such as mercury and cadmium, accumulate in the biosphere and in the kidneys and liver and can cause severe damage to these organs. The effects of mercury have been well known since the so called "Minimata-disease" (named after a fishing village in Japan), where mercury accumulated in fish and caused paralysing effects and severe defective vision when consumed by the local population. The proposed amendment therefore represents an important step forward in the protection of human health and the aquatic environment.