Abstract

Elevated dioxin concentrations in Dutch cow's milk originating from areas near municipal solid waste (MSW) incinerators triggered an extensive research programme in the Netherlands, including (1) emission measurements of all Dutch municipal solid waste (MSW) incinerators, (2) compliance of MSW incinerators with licences and directives, (3) dispersion and occurrence of dioxins in air, soil and cow's milk, and (4) dioxin exposure of the Dutch population. These investigations resulted in a large number of reports. This report provides a comprehensive overview of research results and associated policy implications. Seven out of the twelve incinerators did not comply with the licenses, whereas nine of them did not satisfy the Incineration Directive 1985. Technical management and process control were found to be unsatisfactory in several cases. Dioxin emissions varied between 2,2 to 360 ng TEQ/m3 flue gas. Four installations were closed down in 1990. Near several MSW incinerators dioxin concentrations in milk were found exceeding the milk standard of 6 pg/g fat. Milk and related products from these areas were banned from consumption. The milk standard was based on the result of an exposure analysis that at this value less than 1% of the Dutch population would exceed the TDI of 10 pg TEQ/kg body weight. At background dioxin concentrations in milk and related products (2 pg TEQ/g fat), the TDI is exceeded by a small fraction of children below 7 years of age. A mathematical chain model was developed that succeeded in quantitatively relating dioxin emissions with amounts in cow's milk. In addition, this model showed that emissions below the required level of 0.1 ng/m3 (to be satisfied at 30 November 1993) will make a negligible contribution to levels in cow's milk. Great efforts are presently made to reduce the emissions to this required level. Therefore, it may be expected that in the near future exceedance of the milk standard will not occur anymore in the Netherlands. At some sited levels of 3-4 pg TEQ/g fat will endure because of dioxins that have accumulated in soil from high emissions in the past. Although the dioxin problem in the Netherlands has triggered drastic improvements in emissions, it has at the same time aroused opposition from the Dutch population against incineration of municipal waste. Therefore a delay in growth in incineration capacity may be expected.