MODEL OF THE FATE OF HYDROPHOBIC CONTAMINANTS IN COWS

A simple fugacity model is presented that describes the fate of trace organic pollutants in lactating cows. At steady state, the fraction of ingested contaminant that is transferred to the milk is constant for persistent compounds with log K(OW) < 6.5. Thereafter the fraction transferred decreases rapidly with increasing K(OW). The contaminant kinetics are similarly dependent on the properties of the compound, with superhydrophobic compounds showing longer half-lives. The model was successful in describing the measured steady-state behavior of chlorinated organic substances and did a reasonable job describing the kinetics obtained from feeding studies. An even simpler approach is suggested for calculating concentrations in nonlactating cattle, namely, dividing the amount of contaminant absorbed over the life of the animal by its body fat weight. The degree of absorption and the persistence of a compound are the key properties that determine whether it accumulates in animal foods.