Monday, December 10, 2012

Dark Secrets about Black Mold

by EH

Many of us likely start our day with a wonderful hot shower. Showering is a great time to relax and reflect on life.  Perhaps your eyes drift upwards to the ceiling while you contemplate what type of muffin you will eat this morning.  “What are those black spots on the ceiling”, you wonder…Don’t worry, if you ignore them they’ll probably just go away on their own. Days go by and you’ve forgotten all about the black specks that completely clash with the striped wallpaper in your bathroom.  Next thing you know, the black spots have formed a large hideous clump of blackness on your ceiling.  What’s worse is that the blackness is spreading to all parts of your bathroom! Oh well, that’s why you have roommates right?  They must have some sense of hygiene.  Besides you just cleaned the bathroom two weeks ago, so it’s not your problem this time. Next thing you know, you are experiencing a shortened attention span, confusion, hallucinations (no, not from the mushrooms you ate two days ago), impaired learning abilities and diarrhea.  Congratulations! You may have the toxic black mold Stachybotrys chartarum growing rampantly in your bathroom.  Good thing you passively approached that situation.

Figure 1.  Hyphae and Spores of S. chartarum.  The left picture
 shows a typical hyphae structure.  The right picture shows
 that the spores are ovoid in shape. (Andersen et al. 2003)
So now that you are too confused to reflect on your poor decisions, and luckily you won’t remember your mother scolding you for the disgusting mold present in your bathroom, lets learn about S. chartarum.  S. chartarum is a spore forming fungus that grows in high moisture environments usually on material high in cellulose content (4).  This mold is most commonly found after flooding and water damage, but your long showers have provided a perfect environment for this mold to grow in (I’d still just blame the landlord – that’s easier).  So why are you getting sick?  We eat molds all the time right – I mean cheese is delicious!  Unfortunately for us, S. chartarum produces many neurotoxins classified as trichothecene mycotoxins (3).  Trichothecene mycotoxins are potent inhibitors of protein synthesis in eukaryotic organisms.  What’s worse is that the spores of S. chartarum have been shown to contain theses toxins (3). S. chartarum typically grows in a sporulating form and forms hyphae which hold spores on the end (1).  These spores are small enough that they can become airborne and spread the mold to other places in your bathroom.   At the same time, you probably inhaled some with all the steam produced from the shower.

So now that you’ve inhaled these spores which contain trichothecene mycotoxins, let’s talk a little bit about the toxin.  The LD50 of trichothecene mycotoxins range from 0.5mg/kg – 300mg/kg in mice models (2).  This is good news, since it is unlikely you would receive a lethal dose.  Seriously, the air would be incredibly foggy with the concentration of spores necessary to kill you and if you choose to shower in that environment, you asked for it. Just because it won’t kill you, doesn’t mean it can’t make you sick.  Sickness from these mycotoxins are normally mild with general symptoms of nausea, headache and general malaise, but in severe cases neurological impairments can occur (2).  Now for the fun facts about trichothecene mycotoxins!  These toxins are incredibly hard to destroy. They can withstand freezing temperatures, UV light, and 500°F (3).  That’s some serious resilience! According to the CDC, the best way to deal with these toxins is by using bleach as a cleaning agent.  Not only is the toxin incredibly stable, but T-2 trichothecene mycotoxins are used in biological warfare.  What! Seriously?  Yes; according to Dr. William Deagle, the United States military reportedly conducts 90% of its current biological weapons research on these toxins. So now not only are you sick from this toxin, but you are on the short list of domestic terrorism for not cleaning your bathroom.  On a side note, if you do decide to clean your bathroom with bleach, don’t mix it with ammonia since that will produce mustard gas and then the FBI will really be onto you.

Figure 2.  S. chartarum  growth behind

a shower wall.
By now, you’re probably terrified of your bathroom and have vowed to never take a shower again.  Don’t worry, it’s not as dangerous as it sounds.  Most black mold found in your shower is NOT S. chartarum.  Usually it is either a species of Penicillin or Aspergillus.  But you should still clean this up, since Aspergillus creates aflatoxin mycotoxins which are one of the most powerful carcinogens (5).  Usually large S. chartarum growth is the result of a flood or a pipe breaking.  However this doesn’t mean it’s not lurking in the walls behind your shower. So, if you ever experience water damage, be sure to check for S. chartarum growth in the walls immediately to avoid horrible future consequences.  If you think you can move far north to avoid this fungus, think again.  S. chartarum is present worldwide so no matter where you live, it’s important to be conscious of potential water damage or damp areas.  The reason it is found worldwide is the ability of spores to withstand harsh climate types.  While it grows best in humid environments, the pathological effects were first characterized by the Russians when S. chartarum contaminated straw in 1938.  The workers became sick within two to three days of exposure.  To identify the effects of the disease, the workers rubbed some of the fungus onto their arms.  So if you are feeling brave, try to characterize it without seeing an expensive specialist!

So to summarize, S. chartarum is a fungus which grows best on cellulose in a humid environment.  This makes it a big problem after water damage as the humidity allows the organism to grow rapidly.  It is disseminated into nature through the production of spores which are highly resistant to selective environments. The spores contain trichothecene mycotoxins which can cause sickness when inhaled. The mycotoxins are extremely stable and can withstand extreme environments. This makes them difficult to remove without the help of bleach.  Exposure to the toxins can result in general discomfort, but high doses of it can cause neurological disorders. For these reasons, you should listen to your mother and maintain a clean shower.  Even if the mold is not S. chartarum, other molds such as Penicillin and Aspergillus can cause illness as well.  Cleaning mold will prevent large scale home remolding projects from having to occur.  And most importantly, you will feel better!

1.     Andersen, B., Nielsen, K., Thrane, U., Szaro, T., Taylor, J., Jarvis, B. (2003) Molecular and phenotypic descriptions of Stachybotrys chlorohalonata sp. Nov. and two chemotypes of Stachybotrys  found in water-damaged buildings.  Mycologia; 95(6): 1227-1238.
2.     Fung, F., & Richard, C. (2004)  Health Effects of Mycotoxins: A toxicological Overview.  Clinical Toxicology; 42(2): 217-234.
3.     Jarvis, B., Sorenson, W., Hintikka, E., Nikulin, M., Zhou, Y., Jiang, J., Wang, S., Hinkley, S., Etzel, R., Dearborn, D. (1998) Study of Toxin Production by Isolates of Stachybotrys chartarum and Memnoniella echinata Isolated during a Study of Pulmonary Hemosiderosis in Infants.  Applied Environmental Microbiology; 64(10): 3620-3625.
4.     Murtoniemi, T., Nevalainen, A., Hirvonen, M. (2003).  Effect of plasterboard composition of Stachybotrys  growth and biological activity of spores.  Applied Environmental Microbiology; 69(7): 3751-3757.
5.     Yu, J., Butchoko, R., Fernandes, M., Keller, N., Leonard, T., Adams, T. (1996) Conservation of structure and function of the aflatoxin regulatory gene aflR from Aspergillus nidulans and A. flavus.  Current Genetics; 29(6): 549-555.


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