Home Mold Dangers

Keeping mold in check at home

12-01-2001 // Gabrielle deGroot Redford

EVER SINCE THOMAS STOCK'S HOME was flooded when a tropical storm dumped 35-plus inches of rain on Houston last June, he's been on the lookout for mold. Fortunately, as an expert on air pollution at the University of Texas School of Public Health, Stock knows exactly what to look for and where. He also knows how dangerous some molds can be when they're not detected and eradicated. After the storm subsided, he quickly took steps to dry out his house, avoiding any large-scale mold problems. But faced with unchecked mold growth in their homes, other Americans have not been so lucky.

Last February, Steve and Karen Porath of Foresthill, California, burned their dream house to the ground to get rid of toxic mold that sickened them and their newborn child. In May, the Delaware Supreme Court upheld a ruling that awarded $1.4 million to two women whose landlord had failed to address mold accumulations, causing the women to have asthma and other health problems. One month later, a jury awarded a family in Dripping Springs, Texas, $32 million after an insurance company mishandled the family's claim for mold damage in their 22-room mansion.

The culprit in all three of these cases was a mold called Stachybotrys chartarum, possibly the most dangerous of the thousands of molds that grow in this country. It produces mycotoxins that have been linked to numerous health problems, including respiratory illness, pulmonary hemorrhage, even memory loss. Other common indoor molds--among them Cladosporium, Penicillium, Aspergillus, and Altermaria--also may be hazardous.

Mold spores are everywhere--floating through the air indoors and out. Outdoors, they play a key role in the environment, breaking down leaves, wood and plant debris. Indoors, however, the spores settle on any wet spot and begin to grow. Molds belong to the fungi family, but unlike most other plants, they lack chlorophyll. They survive by digesting whatever material they land on. They don't necessarily need a tremendous amount of water, either. Molds can grow wherever there is excessive humidity or condensation, as well as areas with water leaks or flooding.

Molds can affect people's health in three primary ways, says Dr. Ruth Etzel, a pediatrician and medical epidemiologist with the U.S. Public Health Service. First, people can actually become infected with mold; that is, the mold can start growing inside them, usually in their lungs. This typically happens only in people whose immune systems are impaired, such as in cancer or AIDS patients.

Second, people can have an allergic reaction to molds. Symptoms range from a runny nose and scratchy throat to acute asthma attacks and even death. The severity of the symptoms depends on an individual's reaction to a particular allergen, as well as the length of time to which he or she is exposed.

Finally, people can have a toxic reaction to molds. Unlike molds that grow in the body or those that produce allergic reactions, notes Dr. Etzel, molds that produce mycotoxins can affect otherwise healthy people. Symptoms range from bleeding to respiratory illness that sometimes leads to death. Researchers have identified approximately 350 to 400 toxins produced by molds, and they are trying to figure out which toxins are the most deadly and to whom. "So far, we've found that if these very potent toxins come in contact with a young baby's lungs, they can have a very serious and sometimes life-threatening effect," Dr. Etzel says. "They seem to have the most damaging effect on growing cells."

Of the 5,000 known species of mold, approximately 50 are pathogenic (that is, they can grow inside the body), 150 are allergenic, and about 50 are capable of creating mycotoxins, says Doug Rice, laboratory director of Colorado State University's Environmental Health Services.

Rice is one of a handful of mycologists who travels around the country to help alleviate the problems associated with toxic molds. In the last year or so, as media attention to the problem has escalated, he has been called on time and again to educate people about molds. "It's important to remember that molds have been around a long time. Stachybotrys was first described in 1806," he says. "The reason there is a panic right now is that a few extreme cases have gotten the attention of the media."

Which is not to discount the potential health threats people may face. "If you put enough of a mold into an environment," Rice says, "it can overwhelm any immune system."

Most molds can be detected by smell. "One of the things I tell people is that the nose is an excellent mold detector," Dr. Etzel says. "Rather than calling in the experts right away, I would ask if you've noticed any musty or moldy smell." If you have, but you don't see any mold, it may be lurking under the carpet or in the walls. Small areas of mold can be cleaned with bleach, but the kind that's imbedded in the carpet or the wall may need to be removed. "If you have a wall full of mildew, that's not a healthy situation for anybody," Rice says.

The Environmental Protection Agency and the Centers for Disease Control and Prevention (CDC) recommend taking the following measures to prevent the growth of mold:

  • Watch for condensation and for wet spots.
  • Keep humidity levels in the house below 50 percent.
  • Use an air conditioner or dehumidifier during humid months.
  • Be sure the home has adequate ventilation, including exhaust fans in the kitchen and the bathrooms.
  • Fix leaky pipes as soon as possible.
  • Keep bathrooms (particularly tubs and shower stalls) clean and free of mold buildup.
  • Keep all of the heating, air-conditioning and ventilation drip pans clean, flowing properly and unobstructed.
  • Do not carpet bathrooms.
  • Remove and replace any flooded carpets.

"These days, we live in homes that are very different from the homes that our mothers and grandmothers lived in," Dr. Etzel says. "Our homes are much tighter, more energy efficient, and we rarely open the windows, so we don't have as much ventilation of the indoor environment. That has led to problems. The more we learn about molds, the smarter we can be about looking for them and getting rid of them in the indoor environment."

The EPA also provides information and recently released guidelines on mold remediation on its Web site, http://www.epa.gov/mold/moldresources.html. To obtain a written copy of the EPA guidelines, call 1-800-438-4318.

Living near water, Maryland writer Gabrielle deGroot Redford now checks her house regularly for signs of mildew and mold.

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