Burying prion-infected carcasses of cattle, deer and other animals in lime may actually enhance the spread of those infectious proteins through soil, a new study suggests. Placing quicklime on carcasses once was thought to be the best way to foster quick decay of bodies and to prevent the spread of disease.
The study is scheduled for the April 15 issue of ACS’ Environmental Science & Technology, a semi-monthly journal.
In the study, Joel A. Pedersen and colleagues from the University of Wisconsin cite the need for safe methods of disposing of prion-infected carcasses, noting that prions can resist harsh conditions such as strong disinfectants and dry-heat temperatures of 1,100°F that destroy other disease-causing agents and that prions can remain infectious in the soil for at least three years. Pedersen and colleagues investigated the effect of different conditions (pH, salinity) on the adsorption, or attachment, of prions to sand particles.
They found that prions become less firmly attached to sand particles, and thus potentially more mobile, under alkaline conditions. These conditions would be produced by lime, as well as in older landfills. In the natural environment, acidic conditions may keep prions near the soil surface, increasing the risk that animals will ingest prions and become infected, the report says. The team is conducting further research to determine whether these expectations are borne out.