Endotoxins are a component of the lipopolysaccharide complexes that make up a part of
the outer layer of the cell walls of most gram-negative bacteria and some cyanobacteria.
Laboratory filter column tests to identify conditions under which endotoxins can be
released from biologically active drinking water treatment anthracite/sand filters showed
that endotoxin was produced in large quantities in the first few hours following
shutdown. However, accumulated endotoxin can be easily dealt with by immediately
backwashing or running filters to waste following periods of shutdown. Free chlorine,
monochloramine, and potassium permanganate were not particularly efficient at
inactivating endotoxin, with the maximum inactivation rate being 1.4 endotoxin units
(EU)/mL.h for free chlorine. Medium pressure ultraviolet irradiation was somewhat
effective (~0.55 EU/mL per mJ/cm<sup>2</sup>), although higher dosages than those currently being
employed in drinking water treatment would be required to effectively remove higher
concentrations. Using a range of drinking water endotoxin concentrations measured in
biofilter shutdown experiments and from values recorded in the literature, endotoxin
aerosolization associated with humidifiers was examined. A theoretical assessment
suggests that ultrasonic humidifiers are able to produce quantities of aerosolized
respirable endotoxin sufficient to easily induce adverse health impacts, including those
requiring medical attention. In addition to being a health hazard on its own, endotoxin
may exacerbate existing medical conditions and may confuse physicians attempting to
diagnosis multiple symptoms. Includes 22 references, table, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 410 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 18 |
| Published : | 11/01/2005 |
