THE USE OF BIOCONCENTRATION FACTORS IN ESTIMATING THE 2,3,7,8-TCDD CONTENT OF COWS MILK

Five models for estimating the 2,3,7,8-TCDD contamination of cow's milk from air are compared with field data from a known source of dioxin in Austria. Bioconcentration from soil is a very minor pathway for contamination of hay in this setting, leading to underpredictions of greater than an order of magnitude. Direct deposition of particulate produces better results, but vapor transfer of PCDD/PCDF to plants should be considered. A bioconcentration factor from dry hay to milk fat of 1.7 was observed, less than that assumed by the five models. 2,3,7,8-TCDD equivalents transferred from air to milk fat less efficiently than 2,3,7,8-TCDD. Important model parameters should be based on experiments which accurately represent the modelled situation. © 1990.