Cross-contamination

Contamination of one product by another, typically through shared equipment, air handling, materials or people in a multiproduct facility. The usual controls are cleaning validation with health-based limits, dedicated or single-use equipment, segregation and airflow design. Japanese GMP texts write the word with a different second character from the everyday word for 'crossing' (交差); the reading is the same. Cleaning limits derived from a permitted daily exposure (PDE) are the approach in current EU and PIC/S guidance, and a Japanese customer auditing a multiproduct line will ask how each limit was derived.