THE MONTHLY ADJUSTMENT

In the wake of heavy rainfall and flooding caused by hurricanes Katrina, Rita, and Wilma, there is a great potential for mold contamination of buildings and for human exposures to large amounts of mold. Whether or not this constitutes a major public health concern is a matter of current interest. The object of this article is to give insurance adjusters a basic understanding of what mold is and what threat molds pose to human health. The floods of water in 2005 will most likely be followed by floods of lawsuits with individuals and companies claiming damages from mold contamination of their homes and businesses. This has obvious ramifications for the insurance industry.

INTRODUCTION AND BACKGROUND INFORMATION

Molds are members of the fungus family that also includes yeasts and mushrooms. Molds are ubiquitous in outdoor and indoor environments and always have been. It is normal to find molds, mildew, and other members of the fungi family in the air and on surfaces, both indoors and outdoors. When people are exposed to high enough levels of mold, however, they can experience adverse health effects. These effects can range from mild allergic-type symptoms to life-threatening infections.

Besides oxygen from the air, molds need three things in order to grow and proliferate. These are 1) a food source, 2) moisture, and 3) a place to grow. Like all living organisms, molds need a source of food. Molds utilize cellulose and proteins as food sources. This is in fact their function in the natural world. Without the action of molds, bacteria, and other "decomposers", dead material would accumulate and litter the world. In the indoor environment, molds use cellulose-containing building materials (for example, wood, sheet rock, wallpaper, etc.) as food sources. 

Mold problems in buildings are almost always the result of the accumulation of water or moisture. This can come about when water enters an indoor space because of a damaged roof, a flooding event, plumbing leaks, improperly designed or operated air conditioning systems, damp basements, combustion sources, or other sources of indoor moisture. This is an obvious problem now on the Gulf Coast where severe storms have caused large amounts of rainfall and severe flooding. In most cases, molds can proliferate if wet materials are not dried out within several days time. This is especially true in warmer climates.

The third requirement for mold growth, a place to grow, is easily met in most indoor environments. Molds only have to have a surface on which they can gain a foothold and grow. Molds are often found on ceiling tiles, walls, behind wall paper, on insulation, and even growing on wooden wall studs. 

WHAT LEVELS OF MOLDS ARE OF CONCERN?

There are no widely accepted standards or guidelines for mold exposures like there are for exposures to chemicals. The main reason for this is that there is a wide range of sensitivity to molds and other microbial agents between individuals and a variety of other factors that are specific to the individual person's indoor environment. Because there are no established standards, the evaluation of health risks of exposure to microbial agents, including molds, is a more qualitative process and requires a greater degree of scientific and professional judgment.

What is usually done to evaluate the potential for mold problems is to measure airborne mold levels both indoors and outdoors of the subject building. It is generally acknowledged that indoor air quality is usually acceptable if indoor levels of molds are less than one-half to one-third of outdoor levels. There is concern for occupant's health if indoor mold levels exceed these fractions of outdoor levels, or if significant amounts of species of mold are found indoors which are not concurrently found outdoors. If either of these conditions is found to exist, it is evidence that there is a source of mold proliferation indoors. 

Recent surveys have measured outdoor and indoor mold levels in residential and commercial buildings at various locations throughout the country. These investigators found that the average number of molds in outdoor air was between 500 and 600 colony-forming units per cubic meter (CFU/m3). The average mold levels seen in the air at nearby indoor locations were between 100 and 200 CFU/m3. Airborne levels of indoor mold thus typically average three to five times lower than corresponding outdoor levels. Less than 10% of all buildings surveyed had indoor levels of molds in excess of 1000 CFU/m3. (Note: since individual mold spores are too small to see and count, mold samples are cultured and allowed to grow. The numbers of mold colonies that grow up in culture are then counted. This number is then divided by the total volume of air sampled, giving the number of "colony-forming units" per cubic meter of air.) These survey data give us at least a rough idea of what "normal" levels of molds are in indoor air.

WHAT ARE THE HUMAN HEALTH EFFECTS OF OVER-EXPOSURE TO MOLDS?

Much has been written about lately in the scientific literature and in the lay press concerning the health threat posed by mold exposure. In some cases the news media has sensationalized the hazards posed by molds. After all, as I mentioned earlier, molds are found virtually everywhere and have been present on earth long before humans were. For molds to all of a sudden become something akin to a plague does not make sense. Tossing around terms like "toxic mold" may sell newspapers and magazines, but there are really very few instances where the most hazardous types of molds are present in great enough quantities to be a real threat to most people's health.

The first thing to keep in mind is the basic toxicological tenet that "the dose makes the poison". Small amounts of mold exposure pose little or no risk, but just like anything else (including water or oxygen) if the exposure is great enough, harm can result. Human exposure to excessive amounts of mold can cause a variety of adverse health effects. Mold exposure can affect the respiratory system, the immune system, the skin and eyes, and the nervous system. In each case, there is a range of effects depending on the amount of exposure, the type(s) of mold present, and the individual's innate susceptibility to molds. These adverse health effects can be caused by exposure to both viable and sterile molds, volatile organic compounds released by molds, or by a class of chemicals called mycotoxins, which are released by some molds under certain environmental conditions.

Respiratory effects include less serious and short-term effects such as nose, throat and lung irritation to intermediate and longer-term illnesses such as chronic sinusitis, asthma, and hypersensitivity pneumonitis to very serious and potentially life-threatening diseases such as respiratory fungal infections. There is also a range in immune response to mold exposure. The most common of these effects are the allergies from which many people suffer. More serious effects can include hypersensitivity and anaphylactic reactions, immunosuppression, and allergic bronchopulmonary aspergillosis (from over-exposure to Aspergillus mold). The symptoms relating to the skin and eyes range from minor skin irritation and rashes to dermatitis, conjunctivitis, and in severe cases, cutaneous fungal infections. Nervous system effects of over-exposure to molds can include headache, fatigue, and dizziness.

Widespread news coverage has suggested a huge public health threat from molds. This has engendered popular concern bordering on hysteria in some cases. The weight of the scientific evidence, however, shows that otherwise healthy individuals are only very rarely affected by mold exposure (other than having allergic symptoms). People with compromised immune systems (for example, cancer patients receiving chemotherapy, organ transplant patients taking immunosuppressive drugs, AIDS patients, and patients with uncontrolled diabetes) are the populations most at risk for the more serious mold-related infections and other conditions.

SUMMARY AND CONCLUSIONS

Molds and other microbial agents are present everywhere. Despite recent "scares" portrayed in the media, it is relatively rare for mold exposure to cause serious health problems for most people. It is undeniable that there are cases of over-exposure to molds and there certainly are some individuals who are especially at risk. With all of the water damage from the recent hurricanes, the potential for mold growth in the Gulf Coast region is a very definite concern. The insurance industry should be vigilant, but not unduly swayed by media reports suggesting that mold exposures will have catastrophic effects on public health.

An excellent resource for more information on molds, health effects of mold exposure, and mold remediation strategies is a Web Site operated by the U.S. Occupational Safety and Health Administration (OSHA). That site is www.osha.gov/SLTC/molds.