Transfer of Airborne Polychlorinated Dibenzo-<i>p</i>-dioxins and Dibenzofurans into Dairy Milk

Abstract

Polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) in dairy milk predominantly originate from contaminated fodder ingested by the cows. In the presented field study transfer rates were determined for 12 2,3,7,8-chlorosubstituted PCDD/F on their pathway from atmospheric deposition onto grass and into the milk of dairy cows. Samples of aerial deposition and fodder were collected simultaneously over periods of 35−100 days; milk samples were taken at the ends of these sampling periods. In the transfer from air onto fodder about 35% of the atmospheric PCDD/F fallout as determined by passive sampling using Bergerhoff vessels was retained on the grass. No congener specificity was observed in this transfer step. The levels in atmospheric fallout and in grass varied considerably among single samples, whereas the PCDD/F concentrations in milk were rather constant. However, the averaged transfer rates from grass to milk were in good accordance with data reported in the literature. Keywords: PCDD; PCDF; atmospheric deposition; grass; cow's milk