Abstract

In this paper, results are reported of a monitoring study on levels of PCDDs and PCDFs in cow's milk form dairy farms in the vicinity of two municipal solid waste incinerators (MCWs) in the Netherlands. Levels are expressed in picigrams 2,3,7,8-TCDD toxicity equivalents (TEQ) per gram of milk fat, calculated on the basis of international toxicity equivalence factors (TEF) of individual components. Samples consisted of time-averaged sampling of cow's milk during periods of one month of in total ten dairy farms, five near Alkmaar and five in the Lickebaert-area. Samples were collected in the period from July to September 1991. The following conclusions have been drawn. In the area near the MSW at Alkmaar levels were between 0.7 +/- 0.1 and 2.4 +/- 0.1 pg TEQ/g of fat and remain far below the Dutch legislation level for dioxins in cow's milk (6 pg TEQ/g of fat). These values are comparable with the Dutch background level for dioxins in cow's milk (0.8-2.5 pg TEQ/g of fat). Dioxin levels in cow's milk in the Lickebaert area were between 4.3 +/- 0.2 and 8.3 +/- 0.4 pg TEQ/g of fat. In September, all dairy farms investigated produced milk with dioxin levels above the Dutch legislation level for dioxins in cow's milk. The mean level (6.3 pg TEQ/g of milk fat) of five dairy farms in this area increased in the period July-September 1991 compared to the mean level in the preceding quarter of a year (5.3 pg TEQ/g of fat).