Highlight on Stachybotrys chartarum (atra)

Stachybotrys chartarum (atra) is a greenish-black fungus found worldwide that colonizes particularly well in high-cellulose based materials, such as straw, hay, paper and building materials. While wet it looks black and slimy, perhaps with white edges. When dry it appears less shiny. It is not the only, nor is it the most common black mold to be found in these conditions. Stachybotrys chartarum grows and sporulates in the temperature range of 2-40 degrees C.

Stachybotrys chartarum (atra) is capable of producing several toxins including macrocyclic trichothecenes (satratoxins H, G, F, roridin E, verrucarin J, and Trichoverrols A and B).

This fungus, or mold, grows only on cellulose materials that have been very wet for more than a few days or so. If the material is wet and is not cleaned and dried, the fungus may grow and spread. It is not found in the green mold on bread or the black mold on the shower tiles. (It does not grow on plastic, vinyl, concrete products, or ceramic tiles).

Common areas for this molds’ growth include water soaked wood, ceiling tiles, wall paneling, unpainted plaster board surfaces, cotton items, cardboard boxes, and stacks of newspapers. If you have had plumbing leaks, roof leaks, a flooding basement, or a sewer backup in the past year, look for the fungus or a musty odor. After the area dries, the fungus will not continue to grow, but the black dust caused by the fungus can be sucked into the air conditioning system, spread throughout the facility, and effect sensitive people.

The criteria for conducting an investigation for Stachybotrys chartarum includes the confirming the presence of visible fungi, evidence of water damage, and usually, symptoms consistent with an allergic or toxic response to Stachybotrys chartarum.

When testing for this particular contaminant an environmental microbiology laboratory must supply specific culture media for the detection of Stachybotrys chartarum, such as malt extract agar (MEA), corn meal agar (CMA), cellulose agar, etc. It is important that all air and bulk samples be sent to an environmental laboratory where the laboratory director, supervisor and analyst have training and experience in environmental bacteriology and mycology. The laboratory should participate in the AIHA Environmental Microbiology Proficiency Analytical Testing (EMPAT) program.

Air Filters-The First Line of Defense

Your first line of defense against Stachybotrys chartarum is your air filter. Stachybotrys chartarum is actually quite large in size (5.7 micron average). Medium efficiency ASHRAE grade filters, such as the Farr 30/30 or Farr 20-20 are very effective at removing Stachybotrys chartarum from the airstream.

Your air filters are only as effective as the mechanism that holds them in your HVAC system. Assure that your filters fit snugly in their frames or tracks and that there is no air bypass to allow the mold to bypass this important line of protection. A ¼" gap around a 24" by 24" filter will allow 18% air bypass, or the equivalent of air moving untreated through a 3" hole in the middle of the filter.

If your facility has a problem with this fungus, Farr Company recommends the application of 80-85% ASHRAE grade filtration as an additional safety measure.

You should also assure that air changes to the space are high enough to remove contaminants at a level consistent with maintaining proper indoor air quality. During normal HVAC operation seven air changes per hour is sufficient.

Contaminated facilities should increase air changes to 10-12 air changes per hour. During remediation air changes should be as high as possible, even in the range of 20-30 air changes per hour.

Health Effects

Stachybotrys chartarum has been documented to produce a series of potent toxins including satratoxins and other toxins affecting the immune system. In recent years, Stachybotrys chartarum has been involved in the contamination of homes in Cleveland, Ohio. The US Environmental Protection Agency and the Cleveland Department of Health now speculate that this fungus may be responsible for the cluster of acute pulmonary hemolysis/hemosiderosis cases that occurred between 1993 and the present. To date, 9 of the 36 infants from these homes have died.

It has now been suggested that the following adult symptoms occur from exposure to Stachybotrys: adverse effects on the central nervous system, eyes, skin, and upper and lower respiratory tract, and, possibly, chronic fatigue. Other adult symptoms are immune suppression, bleeding and adverse reproduction effects.

Given these serious potential threats to human health, it is essential that any occupied environment known to be contaminated with this toxin-producing organism should be considered a potential health hazard.

 

For immediate assistance in this area be sure to contact your sales representative at DP Filters, Inc. 

(800) 397-1590