Final answer:
Unused or expired medications should be returned to take-back systems or local drug take-back programs for proper disposal to prevent environmental pollution.
Step-by-step explanation:
Expired or unused medications can be returned to specific facilities for proper disposal. In Europe, there are typically take-back systems in place for the collection of unused or expired drug residues. However, in the United States, there are primarily voluntary initiatives on a local basis. It is important to avoid disposing of pharmaceuticals by flushing them down the toilet or sink, as studies in Germany have found that a significant percentage of pharmaceuticals are disposed of in this manner, which can contribute to environmental pollution. Instead, individuals should look for local drug take-back programs or inquire at their pharmacy about safe disposal methods.