however if all did that would become a u201c worst case u201d scenario in the lettuce box the absorbent pad was observed to increase in weight as it picked up free moisture experience gained in other food packaging investigations using chicken beef and fish indicates that in food packaging this free fluid is often laden with bacteria this leads to the last assumption 5 that 80 of the bacteria are mobile in the free fluid and this fluid ends up being contained in the absorbent pad and 20 are exposed to the apertured film layers with these assumptions it was concluded that to simulate the u201c worst case u201d bacterial exposure the apertured film surface should be inoculated with 1 81 u00d7 10 8 colonies per square meter the test protocol was carefully calibrated to deliver these levels to expand this range and gain a better understanding of the performance of these materials several other concentrations were used in addition both higher and lower concentrations please recognize that this was a unique customized protocol in which a challenge test was performed by loading or inoculating materials with a carefully controlled bacterial loading of different concentrations controlled atomization was used for the apertured film and a traditional direct fluid inoculation was used for the absorbent pad all materials were provided with additional moisture in the form of a sterile buffered misting.