Bacteria Endotoxins and Moisture

Gram-negative bacteria are common in the environment, particularly in water or on water-damaged building materials and in areas where mold growth has occurred. As part of their life cycle, gram-negative bacteria produce endotoxins during growth, division, death and lysis. Consequently, endotoxins are commonly found in water associated with floods and chronic leaks. Additionally, significant levels of endotoxins have been reported in contaminated ventilation systems, sumps, humidifiers, wastewater treatment plants and even in swimming pools.

Levels of endotoxins have been associated with indoor air quality complaints and certain respiratory diseases in many types of buildings. In addition, employees in occupational settings where organic dusts or water-containing endotoxins are aerosolized are at a greater risk of exposure and consequently of contracting certain respiratory diseases.

Inhaled endotoxins have been associated with many pulmonary diseases. Endotoxins have been thought to be responsible for the adverse health effects after inhalation of organic dusts. Some inhalation studies showed that endotoxins can cause fever, cough, dyspnea, headache, nose and throat irritation, diffuse aches, nausea, shortness of breath and chest tightness, acute air flow obstruction and airway inflammation. Endotoxin exposure may also result in reduced lung function. In the indoor environment, chest tightness, mild fever, and flu-like symptoms experienced by building occupants may be associated with endotoxin exposure.

Endotoxins can be isolated from air, water and dusts with air sampling being the most common way to assess exposure.

Endotoxins are very stable in the environment and are not destroyed by heat or chemical treatments. Therefore, controlling water sources and growth of gram-negative bacteria are the primary means of reducing exposure. Removal of contaminated sources and high-efficiency particulate air (HEPA) vacuuming of dusts helps to reduce accumulated endotoxins and to minimize potential health effects.