Instill in the students that they should be looking for a program where they are learners, not providers. (Remind them that if they provide care for individuals beyond their scope of training, it is dangerous, unethical, and potentially fatal for their health profession aspirations.)
Begin by looking for programs that follow the Forum on Education Abroad standards and guidelines.
The Forum on Education Abroad is a membership association recognized by the US Department of Justice and the Federal Trade Commission as the Standards Development Organization for the field of education abroad. If a study abroad program is a member of the Forum on Education Abroad, they implicitly agree to follow the standards of good practice and Forum Guidelines, including the Guidelines for Undergraduate Health-related Programs Abroad.
Students should do their own assessment as well, considering these questions. Link to How to Evaluate an Organization or Provider: Checklist for Students.