Toxic Mold Information and Litigation

In recent years, mold and so-called "toxic mold" have become the subject of mounting health concerns as well as numerous lawsuits. 

What Is Mold and Where Does It Grow?

Mold is a form of fungus that grows both indoors and outdoors and thrives in warm, damp, and humid environments. There are over a thousand different varieties of indoor mold, and the good news is that the presence of a moderate amount of mold in your home is generally not harmful to your health. Most health problems related to mold exposure arise only when there is a build-up of high concentrations of mold for some reason.

Mold spreads by generating spores, and like so many nuisances in life, mold spores are able to survive for long periods even in harsh, dry environments in which mold itself could not grow -- which is one of the things that makes mold so hard to eliminate. Mold spores are invisible to the eye and can become airborne -- an important consideration during efforts to clean up and eliminate a mold infestation.

Where mold is found. Some amount of mold is more or less everywhere all the time. Its many forms are so common and it travels so easily that trying to make your home or any other building totally mold-free would be next to impossible. But high concentrations of mold -- which might result from flooding, for example -- can be cleaned up and eliminated for the most part (though such cleanup may in some cases prove costly and laborious).

Because mold thrives in warm, damp, and humid places, indoor mold is most commonly found in areas of high moisture and low ventilation, such as bathrooms and basements. It is also commonly found in and around leaks in roofs, pipes, windows, or where there has been flooding. Potted plants are also a common location for mold.

Because of its resilience, mold also grows in all sorts of common building materials. It thrives in wood and wood products, paper and paper products such as wallpaper, ceiling tiles, drywall, and cardboard. It grows in fabrics such as carpets and upholstery. It can also be found in other building products including paint and insulation. It even likes dust.

How mold travels. Mold travels in all sorts of ways, including through open doors and windows and through air conditioning, heating, and ventilation systems. It can be carried indoors on shoes and clothing or brought inside by pets.

Detecting and preventing mold. You may detect mold by seeing it (usually in the form of spots of almost any color) or smelling its musty odor. Once mold can be detected either by sight or smell, it may have built up a high enough concentration to present a health hazard, and you should take steps to eliminate it (a procedure called "mold remediation").

Because mold generally thrives in warm, damp, and humid environments, a helpful way of approaching mold prevention is to focus on moisture and ventilation. Keeping suspect areas of your home dry and well-ventilated will usually be enough to prevent the appearance of mold.

What Is "Toxic Mold"?

The term "toxic mold" is somewhat misleading and has led to misunderstandings and confusion regarding the health-related dangers of mold. In high enough concentrations, all molds -- toxic or otherwise -- may cause health problems. As a result, some sources refer to all mold as "toxic mold."

Strictly speaking, however, there is no such thing as toxic mold. A few forms of mold are called "toxigenic," meaning that under certain conditions they can produce small molecular toxins, called "mycotoxins." These mycotoxins are usually spread by way of the mold's spores and may be the cause of potentially serious health problems if ingested in sufficient quantities over time.

In contrast with mold in general, which is to be found virtually everywhere, toxigenic molds are less common. Two of the best-known examples of so-called "toxic mold" include:

Stachybotrys chartarum. Sometimes called S. chartarum or Stachybotrys atra, and popularly known as "black mold," this toxigenic mold is a greenish-black fungus that requires a moist environment in which to grow and is most commonly found in flood-damaged buildings. The mycotoxins produced by Stachybotrys chartarum are potent, but there is some evidence that only a few strains of Stachybotrys chartarum are toxigenic, indicating that this particular type of "toxic mold" may be quite rare.

Aspergillis. Aspergillis is a family of molds, and only some aspergillis molds are toxigenic. The mycotoxins produced by toxigenic strains of Aspergillis are less potent than stachybotrys chartarum mycotoxins, but infestations of Aspergillis mold are probably far more common. Aspergillis may be found in any of the mold-friendly environments discussed above.

Though some people become ill from these mycotoxins and toxigenic mold, many of the more common health problems thought to be potentially mold-related may be caused by mold that is not strictly speaking toxic (or toxigenic).

How to Get Rid of Mold

As noted above, there is always a little mold present in any building, and this does not generally pose a health risk to its occupants. Once a mold infestation has been detected, however, clean-up and removal of the mold (often referred to as "mold remediation") is strongly recommended, regardless of whether the mold is toxigenic or not. 

Hard surfaces. Removal of mold from hard surfaces can normally be achieved by using special cleaning methods or "protocols" developed specifically for eliminating mold. It is very important to strictly follow such cleaning protocols because of the danger of mold spores being released and spreading invisibly during cleanup.

Porous surfaces. Where mold has infested porous or absorbent surfaces, however, usually the only viable solution is removal and replacement of the material that has been infested. This includes everything from rugs to drywall, wallpaper to ceiling tiles. Where mold has penetrated behind walls and inside building materials, extensive renovations may be required.

Needless to say, mold remediation can be a costly and labor-intensive project. Care must be taken not to allow the release of mold spores during mold remediation; otherwise, the mold is likely to return. It is especially important to prevent mold spores from entering a building's ventilation system, through which the spores can quickly and easily spread throughout the building. Depending on the extent and location of the mold infestation, it may be advisable to hire professional mold remediators.

Landlord Legal Responsibilities for Tenant Exposure to Mold

With a few exceptions, landlord responsibilities regarding mold have not been clearly spelled out in building codes, ordinances, statutes, or regulations. Below is a discussion of the few states and cities that do have mold laws, and an explanation of how landlords can be held responsible for mold problems even absent specific laws governing mold.

State Laws on Mold

 Only a few states have taken steps toward establishing permissible mold standards. California, Indiana, Maryland, New Jersey, and Texas are among the few that have passed laws aimed at developing guidelines and regulations for mold in indoor air.

For example, California's "Toxic Mold Protection Act of 2001" authorizes the state's Department of Health Services (now called the Department of Health Care Services) to set permissible levels of indoor mold exposure for sensitive populations (like children, or people with compromised immune systems or respiratory problems). The California law also allows the DHCS to develop identification and remediation standards for contractors, owners, and landlords and requires landlords to disclose to current and prospective tenants the presence of any known or suspected mold. For a preliminary report on the implementation of the Act, see the DHS 2005 Report to the California Legislature, Implementation of the Toxic Mold Protection Act of 2001.

Local Laws on Mold

A few cities have enacted ordinances related to mold. For example:

  • New York City. Landlords in New York City must follow Department of Health guidelines for indoor air quality.
  • San Francisco. In San Francisco, mold is considered a legal nuisance, putting it into the same category as trash accumulation or an infestation of vermin. Tenants (and local health inspectors) can sue landlords under private and public nuisance laws if they fail to clean up serious problems. For details, check the San Francisco Department of Public Health website.

Where to Find Information on Mold-Related Laws

For information on mold rules and regulations in your state. check with your state department of environmental protection (find yours at the federal EPA website) or your state department of public health (the Centers for Disease Control and Prevention has a list).

To see whether your state is considering mold-related legislation that might affect residential rentals, see the website of the National Conference of State Legislatures and type “mold” into the search box on the home page. Look for the link to the “Environmental Health Legislation Databases Guide,” and once there, filter by “All States” and “Indoor Air Quality—Mold.”

For local mold-related rules, contact your city manager or mayor’s office or local health department. Check out State and Local Government on the Net ( for finding local governments online.

Mold and the Landlord's Duty to Maintain Habitable Premises

Even if your state or city doesn't have specific mold laws, your landlord may still be liable for a mold problem in your rental. Here’s an overview of the issues. 

Mold Caused by a Landlord's Failure to Fix Leaks

 Landlords in all states but Arkansas are responsible for maintaining fit and habitable housing and repairing rental property, and this extends to fixing leaking pipes, windows, and roofs -- the causes of most mold. If the landlord doesn't take care of leaks and mold grows as a result, you may be able to hold the landlord responsible if you can convince a judge or jury that the mold has caused a health problem.

Mold Caused by Tenant Behavior

 The liability picture changes when mold grows as the result of your own behavior, such as keeping the apartment tightly shut, creating high humidity, or failing to maintain necessary cleanliness. When a tenant's own negligence is the sole cause of injury, the landlord is not liable.

Mold Clauses in Leases

Some landlords include clauses in the lease that purport to relieve them from any liability resulting from mold growth. At least one court (in Tennessee) has refused to enforce such a clause, ruling that to do so would be against public policy. More cases from other parts of the country are sure to arise as mold litigation makes its way through the courts.

A smart landlord will try to prevent the conditions that lead to the growth of mold -- and tenants should be the landlord's partner in this effort. This approach requires maintaining the structural integrity of the property (the roof, plumbing, and windows), which is the landlord's job. You can help by preventing mold problems in your home in the first place and promptly reporting problems that need the landlord's attention.


Texas has been the leading state in Mold Litigation. However, most of the cases in Texas have been bad faith cases against insurance companies for failing to provide coverage for property damage caused by mold from things like leaking pipes. The hardest part of mold litigation cases involving personal health injuries is the lack of available scientific information tying mold to certain diseases. In order to win a personal injury case involving mold an expert must testify to causation of the medical damage to the mold. In order to do this there must be scientific information and studies available to use in court. The future of Toxic Mold Litigation and personal injury in Texas is unknown at this time, but it seems like it will only be a matter of time before these cases reach a jury. For more information on this issue see



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