Abstract

In this report, results are given of a monitoring program on dioxin levels in cow's milk, over the period from June to August 1990, from dairy farms in the vicinity of municipal solid waste incinerators (MSWs) and a metal reclamation plant in the Netherlands. Levels are expressed in picograms of 2,3,7,8-TCDD toxicity equivalents (TEQ) per gram of milk fat and calculated on the basis of international toxicity equivalence factors (TEF) of individual congeners. Samples consisted of time-averaged sampling of cow's milk during periods of one month of in total 27 dairy farms in the neighbourhood of the MSWs of Amsterdam, Duiven, Leiden and the Lickebaert area and a farm near the metal reclamation plant of Culemborg. In addition milk samples from the vicinity of the former MSWs of Zaandam and Alkmaar were analysed. The following conclusions have been drawn. 1. Dioxin levels in milk from the vicinity of the former MSWs of Zaandam and Alkmaar of June-August 1990, were strongly decreased when compared to the levels of April-May 1990. From July 1990, levels were below the critical level of 6 pg TEQ/g milk fat. 2. Levels in milk of June and July of farms near the MSW of Amsterdam were between 1.8+-0.1 and 2.6+-0.2 pg TEQ/g of fat, and are comparable to the levels of July 1989 and April-May 1990. 3. In the vicinity of the MSWs of Duiven and Leiden and the metal reclamation plant in Culemborg, dioxin levels were comparable to the corresponding levels of April and May 1990. The levels were above the Dutch background level (0.8-2.5 pg TEQ/g) but below the critical level of 6 pg TEQ/g of fat. 4. Dioxin levels in milk from the Lickebaert area show remarkable fluctuations with time. Levels of most dairy farms were above the critical level of 6 pg TEQ/g of fat.