Answer to Question #9858 Submitted to "Ask the Experts"

Category: Radioactive Waste Disposal — Disposal

The following question was answered by an expert in the appropriate field:


We need to dispose of animal carcasses that have been injected with 125I. How can we dispose of this waste in New York State?


Several disposal mechanisms for animal/biological waste exist. The most common and simplest is radioactive decay in storage. However, decay mechanisms may be tied to a condition in the licensee radioactive material license, internal policies, protocols, or procedures. The decay mechanism allows the radioactive quantity to decay (~ 10 half-lives) prior to handling or disposing of the material.

Licensees may implement internal protocols based on regulatory guidance to determine whether a specific radionuclide could decay in storage or other disposal mechanisms are warranted. It is important to point out that the total activity, as well as the physical and chemical conditions of the matrices containing the radioactive constituents, could also create additional hazards that should be considered when deciding if a radioactive quantity could be allowed to decay in storage prior to disposal. As a rule of thumb, nuclides with half-lives equal to or lower than 100 days may be allowed to decay in storage prior to disposal. Consulting with the regulatory agency having jurisdiction regarding state-specific decay-in-storage policies is always recommended.

Commercial options are also available. Disposal of animal/biological and infectious materials that are contaminated with radioactive material must be disposed at a licensed facility. Each licensed facility has "Waste Acceptance Criteria" (WACs) protocols in place that vary depending on the disposal mechanisms. These WACs include, but are not limited to, the total activity and concentration limits, acceptable packaging materials, and conditions of waste material at the time of delivery. The most common and cost-effective mechanism of commercial disposal for such waste stream is incineration.

Currently, there are no options within the state of New York for commercial disposal of radioactive contaminated biological waste. However, disposal options for such waste stream are available at commercial processing facilities nationwide. In addition, waste brokers are available nationwide to provide packaging and transportation and/or assist in the disposal of radioactive contaminated animal/biological waste.

Because the half-life of 125I is 60 days, decay in storage will take almost two years; however, it may be the best option. The carcasses should be kept in a freezer to minimize biological hazards.

Manuel Diaz

Answer posted on 7 September 2011. The information posted on this web page is intended as general reference information only. Specific facts and circumstances may affect the applicability of concepts, materials, and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice. To the best of our knowledge, answers are correct at the time they are posted. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society.