Human Resources & Safety -What you should know about mold

Technical Corner: What you should know about mold

OSHA, the EPA and even Congress has recognized the mold problem found in businesses, schools and homes as monumental. But how does mold affect the environment and our health? And where does it come from? This informative article from OSHA, as well as the links to EPA, will shed some light.

For more information, you may also visit the EPA's mold resource section of their Web site or New York Committee for Occupational Safety and Health.

What is a Mold?

A mold is a type of fungus. Fungi are known in the plant kingdom as Eucaryotic Protists. They are Eucaryotic in that they possess cells, which have a true nucleus and a well-defined nuclear membrane. They are from the kingdom Protista since they are relatively simple, unicellular organisms. Most fungi are saprophytes and active producers of various hydrolytic enzymes; consequently they are of great value as scavengers of the environment. Many molds are capable of decomposing cellulose and lignin, the principal constituents of wood products. Filamentous fungi are excellent at growing on paints and wall preparations. Some fungi also grow well on rubber and plastic products, leading to their eventual degradation. Fungi and molds typically exhibit two phases of growth, a vegetative thallus type of growth and a fruiting phase. Spores are seed-like vehicles approximately two to 10 micrometers in diameter whereby the mold propagates itself. Both the vegetative (or thallus) and fruiting phase are responsible for spore production. When mold spores land on a damp spot, they may begin growing and digesting whatever they happen to land upon. Spores may be able to grow for years after they are produced. In addition, whether or not the spore is alive, the allergens within them may remain active for years. In the case of molds, such as Aspergillus and Penicillium, the spores are born on specialized plant structures known as conidia. During the vegetative phase of mold growth branching filaments, known as hyphae with diameters of approximately 10 to 50 micrometers, are formed. Entire masses of such filamentous structures are known as mycelium

It is estimated that there are between 50,000 and 250,000 species of fungi and about 200 have been implicated as being human pathogens. More than 1,000 different types of mold species have been found in the indoor home environment. All mold have the potential to cause health effects.

Many fungi (Aspergillus, Penicillium, Fusarium, Tricoderma, Memnoniella, and Stachybotrys atra chartarum) can produce illness through inhalation of the mold itself or through inhalation of potent mycotoxins (fungal metabolites). People performing renovations and cleaning of widespread fungal contamination may be at risk for developing Organic Dust Toxicity Syndrome (ODTS) or Hypersensitivity Pneumonitis (HP). ODTS may occur after a single heavy exposure to dust contaminated with fungi and produces flu-like symptoms. The normal response clearance mechanisms of the lungs are overwhelmed. It differs from HP in that it is not an immune mediated disease and does not required repeated exposures to a single causative agent. A variety of biological agents may cause ODTS including common species of fungi. HP may occur after repeated exposures to an allergen and can result in permanent lung damage. The symptoms of hypersensitivity pneumotitis resemble bacterial pneumonia. In industrial and agricultural settings, various forms of hypersensitivity pneumotitis have been reported including farmer’s lung, woodworker’s lung and malt worker’s lung. Farmer’s lung is caused by Thermoactinomycetes found in moldy hay, straw or grain dust.

Individuals exhibiting allergies may be at increased risk to mold contamination. Both the mold spores and fragments have been implicated in the allergic response. Molds can trigger asthmatic attacks in predisposed individuals and, the irritants produced by molds, may also worsen asthma in non-sensitized individuals. People with compromised immune systems may be additionally vulnerable to the deleterious effects of molds. Aspergillus fumigatus has been known to infect the lungs of these individuals. Trichoderma has also been shown to infect immune-compromised children.

Mycotoxins are mold by-products, which may cling to the surface of molds or can be carried about within the spores. At present, more than 200 mycotoxins have been identified from common mold species. Aflatoxin B is perhaps the best known of the mycotoxins and is produced by the molds of Aspergillus flavus and Aspergillus parasiticus. It is one of the most potent liver carcinogens known and there is also some evidence that Aflatoxin B can also cause lung cancer. Some molds, such as Aspergillus versicolor and Stachybotrys atra chartarum, are known to manufacture mycotoxins only when conditions are right. Recently, an investigation suggested an association between pulmonary hemorrhage in infants and exposure to Stachybotrys. However, these findings are not definitive. Many symptoms and health effects have been reported from mycotoxins including the following: immune system suppression, acute or chronic liver damage, acute or chronic central nervous system damage, endocrine effects and cancer.

Mold by-products can include mVOCs. Some compounds, which are manufactured by molds, are volatile and immediately released into the air. These substances are known as microbial volatile organic compounds. Such compounds have been implicated with complaints such as headaches, nasal irritation, dizziness, fatigue and nausea, which are common in mold-contaminated office environments. Glucans, another mold by-product, are small pieces of the cell wall, which can cause lung inflammation and airway restrictive disease. Exposures to very high levels of Glucans have also been implicated in the Organic Dust Toxic Syndrome, which had previously been mentioned.

In conclusion, the most common symptoms reported from exposure in indoor environments are runny nose, eye irritation, cough, congestion, and aggravation of asthma, headache and fatigue. Immunological reactions include asthma, HP, and allergic rhitinitis. Contact with fungi can also lead to dermatitis.