Medwaste, Meet Mad Cow

Alice P. Jacobsohn

More than four years ago, the potential impact of the Washington, D.C.-based U.S. Environmental Protection Agency's (EPA) final medical waste incinerator rule was a major issue.

At the time, healthcare facilities scrambled to replace or retrofit incinerators, or outsource their waste collection and disposal needs. Pressure for pollution prevention and waste minimization began to increase. Commercial waste service companies adjusted their operations.

Since then, regulators and the regulated community have updated rules and began considering unusual diseases. For example, Congress passed a law requiring safety needle device use.

The Occupational Safety and Health Administration (OSHA), Washington, D.C., has issued new respirator rules and updated its recordkeeping and reporting rules to account for needle stick injuries. OSHA also is considering the management of Mycobacterium Tuberculosis, an organism that spreads by aerosolization.

The Food and Drug Administration (FDA), Rockville, Md., has issued new procedures for reusing single-use medical devices. The procedures require examining whether treatment methods inactivate bacteria in used devices and require a material integrity analysis before reuse.

The U.S. Department of Transportation (DOT), Washington, D.C., has expanded medical waste rules to include intrastate transport (effective Oct. 1, 1998) and has proposed several rules to update the agency's medical waste requirements, better define its jurisdiction and refine emergency response reporting requirements.

The attention paid to disposing of waste materials contaminated with unusual infectious substances has increased, too. Specifically, reports about Spongiform Encephalopathies (mad cow disease and scrapie) in Europe and the United States have led to mass slaughter of animals.

The human form is rare (variant Creutzfelt-Jakob disease), but no cure exists and the number of cases is rising. Consequently, animal carcasses and other waste materials must be managed properly to avoid spreading the disease.

The infectious agent is a prion (“pree-on”), a protein that lacks nucleic acid (DNA and RNA). In classical genetics, DNA (deoxyribonucleic acid) specifies the structure of RNA (ribonucleic acid), which then dictates the order of amino acids (building blocks) in a protein. Proteins sustain life.

Prions are unusual proteins because they pass directly from one generation to the next, or from one individual to another, avoiding the DNA-RNA route. Prions are difficult to disable because they are highly stable and can live for 150 years.

Researchers believe that the disease passes from eating infected animals, genetically from diseased parents, and, in some instances, from surgical operations (transfusions and transplants) from infected donors. Therefore, regulations have focused on banning animal product use in animal feed, animals and animal feed import restrictions, careful meat inspection, slaughtering and incinerating contaminated or potentially contaminated animals, and burying the carcasses or ash.

Recent studies question whether waste management disposal practices are sufficient. A National Institutes of Health, Bethesda, Md., study on hamsters infected with scrapie indicates that “normal” incinerator temperatures might be insufficient to inactivate prions. (Proceedings of the National Academy of Science, March 28, 2000, www.pnas.org/cgi/reprint/050566797.pdf.)

If this proves correct, then at least some of the prions in carcasses disposed of in Europe and America still may be capable of causing disease. The study will not be completed until 2003 and has not yet been replicated by other scientists.

Because the disease is rare, alternative technologies for disposal purposes have not been aggressively tested. State regulators are beginning to ask what rules to enact to ensure proper prion management.

Alice Jacobsohn is EIA's director of Public Affairs and Industry Research and manager of NSWMA's Medical Waste Institute. E-mail: [email protected].