Posted By John Webster You have said it yourself. You cannot be sure if the bags are uncontaminated, so you must assume that they are. Now is there any risk of that contamination being infectious? If you are talking about path samples from patients sent for analysis, then some of them are likely to contain pathogenic material. If so, the bags will have to be disposed of as clinical waste. At the moment, the current practice of medical path labs autoclaving everything before disposal as low risk clinical waste for heat treatment is under review. Basically there is concern at the efficacy of lab autoclaves. If an autoclave CANNOT be guaranteed to render waste safe, then it needs to go for incineration as "high risk" waste, not for heat treatment with "low risk" clinical waste. If it CAN be guaranteed to do the job, then we should only need to dispose of the waste with the domestic type waste stream, not then heat treat it.