Some trace organics are known to volatilize readily when surface applied, although soils and sludge itself can drastically reduce these volatizilation losses. Under the Amendments to the Resource Conservation and Recovery Act of 1985, the US Environmental Protection Agency (EPA) was directed to improve the ability to characterize hazardous waste. Trace organics may accumulate in animal food products following direct sludge ingestion during grazing. Using a bioassay test for identifying a sludge contaminated with an organic chemical(s) could provide an additional degree of safety in managing sewage sludge applications to agricultural and forest soils. Trace organics can enter edible parts of plants by two processes: 1, uptake from the soil solution, with translocation from roots to shoots, or 2, absorption by roots and shoots of volatile organics from the soil. The residue of polychlorinated biphenyls (PCBs) in waste materials such as municipal sludge can be depleted of the more volatile and more easily biodegraded lower chlorinated compounds.