TRANSFER OF AIRBORNE POLYCHLORINATED DIBENZO-P-DIOXINS AND DIBENZOFURANS INTO DAIRY MILK

Polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) in d airy 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 atmosph eric deposition onto grass and. into the milk of dairy cows. Samples o f aerial deposition and fodder were collected simultaneously over peri ods of 35-100 days; milk samples were taken at the ends of these sampl ing periods. In the transfer from air onto fodder about 35% of the atm ospheric PCDD/F fallout as determined by passive sampling using Berger hoff vessels was retained on the grass. No congener specificity was ob served in this transfer step. The levels in atmospheric fallout and in grass varied considerably among single samples, whereas the PCDD/F co ncentrations in milk were rather constant. However, the averaged trans fer rates from grass to milk were in good accordance with data reporte d in the literature.