Abstract

Since April 20 1990, the municipal solid waste incinerator (MSWI) AVI- Zaanstad in the Netherlands is closed down. One of the reasons for the closing down were high emission rates of dioxins resulting in increased dioxin levels in cow's milk from dairing farms in the vicinity. Since the emission measurement consisted of six observations on three consecutive days, estimates of the yearly emission are accompanied with a great uncertainty interval. The increased dioxin levels in cow's milk indicate that deposition was on average significantly above the background deposition. Dioxin levels in soil in the vicinity of the MSWI were significantly higher than the background level. From the emission measurement a yearly emission of 178 g TEQ was calculated with a great uncertainty, caused by the wide range of individual measurements. From concentrations in the soil it is estimated that the emission of the MSWI, during life time, must have been 290 g TEQ per year on average. The operation of the installation and technical problems in the process that occurred in the past make such high emissions feasible. Dioxin levels in fat of sheep (milk and beef) residing in the same area can be higher up to a factor 2-2.5 compared with fat of cow's milk. Results from a current study on the kinetics of dioxins in sheep should provide evidence for the assumption that dioxin levels in sheep can be higher than in cows.