Endotoxin is now recognized as a class of compounds found in the outer membrane of certain (``gram-negative") bacteria. Since these gram-negative bacteria are widespread in the environment, so are endotoxins. High levels have been reported from a variety of environments, such as cotton mills, agriculture or wastewater treatment facilities, industrial washwater mists, and contaminated room humidifiers, where water and gram-negative bacteria can be expected to be present. The most important kinds of reservoirs are recirculated water-based fluids that produce aerosols.
SUMMARY OF PROCEDURES
- Air samples are collected on endotoxin-free membrane filters, stored desiccated wherever possible, or stored at 4°C.
- Endotoxin analysis can be done on air, water, or bulk specimens.
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, and PVC and polypropylene materials cannot be used due to their affinity and binding with endotoxin.
Analytical Code: M014