| A. Caution: • There are no accepted threshold values, so relative value comparisons have to be made between the suspect area, and a non-suspect one under similar environmental conditions. • Since endotoxin levels may be significant in outside air, the latter may not be suitable for background levels, especially in environments known to have high levels of gram-negative bacteria (see above, 1st paragraph). • All sampling utensils must be certified endotoxin-free. PVC and polypropylene materials cannot be used due to their affinity and binding with endotoxin. |