Working Party on Antimicrobial Preservative Efficacy Tests. In the first, Davison et al 11 examined a variety of used ophthalmic products ,correlating the level of contamination seen in actual use with the level of antimicrobial efficacy as determined by the compendial test. They found that lhe BP criteria then in force and the then-proposed Ph Eur 'A' criteria, correlated with low contamination levels in actual consumer use. The second study in this series12 extended the evaluation to a wide range of medicinal products.It was found that meeting the Ph Eur A' criteria provided protection against contamination in actual consumer use in these different dosage forms as well. This correlation has also been observed with personal care products, where products that had more efficacious preservative systems (as detennined by compendial tests) were more highly resistant to contamination in a simulated patient abuse study 13.