Contaminated areas are usually old horticultural areas or point sources from termite treatments. Sheep do accumulate OC residues. However, results from Agriculture Western Australia experiments indicate they reduce levels more rapidly than cattle when removed from the treated area. The level of OCs in an animal is related to the intake of residues, amount of fat present and the stage of production of the animal, that is, whether it is growing, lactating or losing weight.
Residues can also appear in the wool.
Fat levels greater than the MRL have been recorded in mature sheep but they are able to 'rundown' the level of OCs in their bodies very quickly once placed on clean grazing land. This may happen on soils contaminated with either DDT or dieldrin. Soil testing showing levels of dieldrin over 0.1ppm indicates the paddock or area tested has a high potential for producing sheep with body fat OC levels above the allowable MRL unless managed effectively. Contaminated sheep cannot be sold for human consumption. Sheep that have grazed on a clean area of the farm, or off-farm, for an adequate period, can be sold for slaughter for human consumption.