Health fears over mold are overblown

Something of a cottage industry has sprung up in the real estate business in recent years as frivolous lawsuits and over-hyped news accounts have racked homeowners and renters alike with fear. Mainstream media, seeking a story to sensationalize their coverage, have reported horrible problems linked to a so-called "toxic mold." Meanwhile, mold inspection and abatement firms have popped up as fast and as prolifically as the fungus they purport to hunt and kill.

Many legal and health experts say, however, that one of the greater threats to real estate owners, rather than coming from mold, comes from this cottage industry trying to separate property owners and buyers from their cash. The mold inspection and abatement industry has little regulation, and no program exists in Oregon, or nationally, to certify the knowledge and expertise of mold inspectors.

Moreover, the problem that inspectors are hired to seek and eradicate may often be just as easily and efficiently handled by a property owner with no high-tech equipment and little expense, according to Shannon Levitt, a public health educator with Oregon's Department of Human Services.

Virtually everyone is familiar with mold in some form. More than 1,000 kinds of the fungus are known to grow on everything from bread to fruit to wood and tile. The "mildew" in bathrooms and showers is actually mold whose spores have latched onto a dirty surface and begun to grow.

Mold grows anywhere it has moisture to support it, a food source to supply it, and the right temperature. A single mold organism is microscopic, and its spores spread through the air completely invisible to the human eye. Virtually every time we inhale, we breathe in mold spores.

Molds really are beneficial. They aid in the decomposition process of organic material, and certain molds are used to produce a variety of products from antibiotics to cheese to stone-washed jeans. Though not generally hazardous to people, some molds purge themselves of toxic by-products as they decompose—or eat—the materials they use for food.

In the 1990s, lawyers and reporters alike were swarming after a major TV network news program aired a report about a supposedly super-lethal kind of mold they called toxic mold, or "black mold." The report said inhalation of the mold or its spores could cause severe health problems, and linked the organism to a "sick building syndrome," where mold hidden in walls or other voids was making people gravely ill. It also linked the organism to a series of deaths where patients died from severe bleeding in their lungs.

What the news report didn't note is that the mold cited, stachybotrys, commonly is found in homes and is not itself toxic. A biology professor at the University of Wisconsin at LaCrosse, Tom Volk, notes that "stachybotrys is a moderately common inhabitant of moist areas in homes." The organism can crop up anywhere there is plenty of moisture, including toilets, bathroom walls, crawlspaces and more.

"High spore counts of any fungi in a building can be detrimental to health for various reasons," Professor Volk writes on his web site, tomvolkfungi.net.

Volk says that stachybotrys has not been proven to cause harm to humans or animals in "sick buildings," though he does note that direct consumption of the organism, especially in animal feed, can make animals sick because of the toxins the mold produces.

The National Center for Environmental Health, a branch of the Centers for Disease Control and Prevention, also says there is no scientific evidence to show any link between stachybotrys and any sudden and serious illness other than an allergic reaction. NCEH notes that severe allergic reactions to any mold occur principally among workers who are exposed to large amounts of the mold, such as farmers exposed to moldy hay.

Levitt, the health educator from Oregon's DHS, says virtually everyone lives with mold in their homes and in the general environment without suffering any ill effects. The toxic chemicals that some molds release can be harmful, but generally are not found in sufficient quantities. On the other hand, the mere presence of the right kind of mold could cause an allergic reaction in some people in the same way as can be caused by such items as shellfish, nuts, pollen or a bee sting. The severity of allergic reactions varies by individual and can range from mild itching, redness or cold-like symptoms to the rare, but deadly, anaphylaxis.

Doctors warn that even a person who has never had allergies can experience an allergic reaction, whether it be to mold or any substance. For that reason, and because people exposed to large amounts of some molds can develop health problems from coming into contact with the toxins those molds release, Levitt says that it's important to keep mold growth under control in the home.

Yet, health concerns pale in contrast to the more common damage wrought by mold:  damage to building materials.  If allowed to spread, mold can fairly rapidly decompose the organic components of a house. Framing, siding, subfloors, carpeting, cabinets, drywall—all can be severely damaged by mold, and repair costs for this kind of damage can run into the tens of thousands of dollars, depending on the extent of mold growth.

In an extreme case reported on the NBC television program "Dateline," a couple in North Carolina¹ claimed having to pay more than $100,000 after mold rotted the wood in their stucco house. According to the TV report, moisture leaked in through cracks in the stucco and became trapped. Unable to evaporate, the moisture led to mold growth that went undetected until the wood was rotting away.

Levitt says moisture trapped in walls or crawlspaces can cause mold to grow unseen, and the resulting damage can go unnoticed for a time. Eventually, however, the burgeoning mold and decaying house parts will produce a musty odor that should create suspicion. If that happens, don't despair. All that needs to be done, Levitt says, is to eliminate the moisture, and clean or replace the moldy material.

While repairs can be expensive in certain rare instances, most mold-related problems are relatively easy and inexpensive to handle. The important thing is to keep homes properly maintained and cleaned so that moisture is not allowed to enter or become trapped.

Even homes in warm, dry climates can be susceptible if moisture makes it in. Moisture can be introduced from a variety of sources including faulty air conditioners and improperly maintained sprinklers. Even building and health officials now admit that government standards for energy efficiency may contribute to moisture accumulation that leads to mold growth. Energy-efficient construction techniques help trap moisture indoors by making homes more airtight.

Levitt says it doesn't necessarily take an expert to clean up a mold problem. It doesn't even take an expert to identify one. The national CDC actually recommends against testing of suspected mold found in the home.

"Sampling and culturing are not reliable in determining your health risk," the CDC says on its web site.² "Reliable sampling for mold can be expensive, and standards for judging what is and what is not an acceptable or tolerable quantity of mold have not been established."

"If you are susceptible to mold, and mold is seen or smelled, there is a potential health risk; therefore, no matter what type of mold is present, you should arrange for its removal," the CDC recommends.

If you can see or smell mold, it’s time to act, says Levitt. Also, any area that has sustained past or ongoing water damage should be thoroughly checked. Remember, mold growth may be found hidden in walls, floors, ceilings or other voids if moisture has gotten inside. Surfaces that show condensation or that are warping or discolored may indicate moisture problems.

Common sources of moisture that may lead to mold growth include:

• Leaky roofs or damaged gutters
• Poor drainage next to a foundation
• Plumbing leaks, such as those from pipes, fixtures or appliances
• Dampness in a basement or crawl space
• Leaking around windows or doors
• Steam from bathing or cooking
• Exhaust from poorly vented clothes dryers
• Cooling or heating system problems
• Rainfall on buildings under construction that is not allowed to evaporate before voids are sealed
• Flooding
• Drain and sewer pipe clogs

A moisture meter, a device used by many home inspectors, is helpful to confirm the presence of moisture inside walls or under floors. If a meter detects moisture, the covering over the moist area must be removed in order to determine how much, if any, damage has occurred. (This may also be helpful in determining the source of the moisture.)

Moisture meters are not inexpensive, however, so hiring a qualified home inspector might be a better bet. An experienced home inspector can provide a more thorough inspection of the home, along with a written report and photos, for little more than the price of the least expensive moisture meter, which runs about $250. Meters can be purchased over the Internet or from local building supply stores. They're also available at major home centers like Home Depot and Lowe's. A high-end meter can cost more than $1,000.

Here are some simple steps to help reduce moisture and inhibit mold growth:

1. Periodically inspect pipes and plumbing fixtures, and repair, if needed.

2. Use an exhaust fan when cooking or showering.

3. Make sure dryer vents and exhaust fans in bathrooms, kitchens, etc., work properly by putting a square of toilet paper up to the grille while the fan is on. The fan should hold the toilet paper in place. Make sure fans are vented to the outdoors, not into a crawlspace or attic.

4. Control bathroom exhaust fans with a twist-timer switch rather than a toggle switch, and set the switch to shut off 20 to 40 minutes after bathing is complete.

5. When installing a new exhaust fan, buy one rated to move at least 80 cubic feet of air per minute (80 cfm).

6. Make sure your air conditioning system is well maintained, and is the correct size for your home. A faulty system can create high humidity by cooling the air without removing water vapor.

7. Maintain your home's interior temperature above 60 degrees Fahrenheit in order to help prevent indoor condensation.

8. Inspect, clean and maintain your heating and cooling systems according to manufacturer specifications.

9. Regularly clean moist areas, such as bathrooms and kitchens.

10. Clean any moldy surfaces as soon as you notice them.

11. Avoid carpeting bathrooms, kitchens and basements.

12. Do not lay outdoor carpet or artificial turf over decks or wooden steps.

13. Keep gutters, downspouts and foundation drains free of debris.

14. Make sure that soil and flower beds adjacent to the house are sloped away from the foundation for the first 10 feet.

15. Be sure to have 6-mil black plastic sheeting on the ground in crawlspaces. Each sheet should have about 12 inches of overlap with the sheet next to it.

16. Occasionally check attic and subfloor crawlspaces for leaks and standing water. Especially look for water stains on roof sheathing and the underside of floor decking. Trace the stains to the area of their source and eliminate the source with proper patching or caulking.

17. If persistent standing water is found in a crawlspace, install a sump pump.

18. Use a dehumidifier, especially in coastal areas or areas with normally high humidity.

Once the moisture source has been eliminated, it's time to get rid of the mold. Damaged building materials must be replaced. But materials that were only moldy, and not damaged, need only be thoroughly cleaned and allowed to dry completely.

When working with moldy materials, it's best to handle them while they're still wet. Any materials being discarded should, if possible, be tied inside plastic bags and placed in a garbage can. Dry materials release more spores into the air. It's also wise to take precautions to avoid direct contact with the mold. Wear long-sleeve clothing and watertight gloves. Use of a dust mask will help minimize inhalation of dust or spores.

Some experts, including the CDC, say that soap and water should be sufficient to clean up a mold infestation. The moldy area must be thoroughly scrubbed, but soap and water alone may not be enough.

Levitt says commercial cleaning compounds are not necessary either. DHS recommends using a 10-percent bleach solution that can be mixed in a bucket at home. But remember, to be effective, the cleaning solution must reach all of the mold. Any mold that is not killed can multiply, causing the infestation to return. (Never add bleach to ammonia or to any cleaning compound that contains ammonia. Doing so will produce POISONOUS chlorine gas that can kill you.)

Of course, some things just can't be cleaned, even with a bleach solution, and should be discarded. These include porous or hard-to-clean items such as foam or fiberglass insulation, carpet, drapes, ceiling tiles, sheetrock, stuffed furniture, wicker, etc. Items that should do well after a thorough cleaning with a bleach solution (if they are not rotten or permanently discolored) include lumber, countertops, vinyl, ceramic, porcelain, grout, caulking, metal, plastic, rubber and glass.

Once the bleach solution has been used, allowing the material to dry thoroughly will make sure the mold is killed. Use a soap-and-water scrubbing to remove any remaining mold debris, then dry scrubbed areas completely. Voids like walls and floors should not be re-covered until building materials have air dried long enough to look and feel completely dry.

Mold is a manageable problem, but it must be promptly and properly addressed. An infestation that is not properly handled can result in thousands of dollars worth of property damage. In situations involving an extensive water problem, or a large mold infestation, it is often best to consult a qualified, professional home inspector before deciding how to proceed.

1.  Thompson, Leah; "Is your home crumbling around you?"; NBC News; March 22, 1999.

2.  National Center for Environmental Health; "Questions and Answers on Stachybotrys chartarum and other molds"; cdc.gov/mold/stachy.htm; Centers for Disease Control and Prevention; Nov. 15, 2005.