Which of the following is considered regulated medical waste?

Regulated medical waste is defined as waste that poses a potential risk to human health and the environment because it is contaminated with infectious substances or has been used in medical procedures. Biopsy tissue is considered regulated medical waste because it is human tissue that has been excised for pathological examination. Since this tissue may contain viable microorganisms or pathogens, it requires specific handling, segregation, and disposal procedures to mitigate the risk of infection.

Each of the other items mentioned does not fall under the same regulated classification. Used syringes, while they are potentially hazardous due to needlestick injuries, are often categorized differently based on the specific protocols of a facility. Paper towels, unless heavily contaminated with infectious materials, are typically considered general waste rather than regulated waste. Metal instruments, while needing proper decontamination and sterilization, do not fall under the regulated medical waste classification unless they are contaminated with blood or bodily fluids. Thus, due to its infectious risk, biopsy tissue is the correct choice for regulated medical waste.