cross-contamination

Even if an item has no dairy in it, there may be cross-contamination from other products made with the same equipment.

Each of you should use your own towel to avoid cross-contamination.

Your poor laboratory practices leave too much opportunity for cross-contamination of samples.

I never read books in the genre I'm writing in—I worry about a subconscious cross-contamination of ideas.

Cross-contamination of testimony is a key issue when interviewing children as witnesses.