Tips and Info on Mold Part 2

March 20, 2003

Excerpts from:
Federal Register
Publication Date: 04/05/1994
Publication Type: Proposed Rules
Fed Register # 59:15968-16039
Title: Indoor Air Quality

Microbial Contamination
Microbial contamination of building structures, furnishings, and HVAC system components contribute to poor indoor air quality problems, especially those related to building-related illnesses. OSHA believes that consequent health effects constitute material impairment of health [Exs. 3-61, 4-41]. These can be categorized as irritation, pulmonary, cardiovascular, nervous system, reproductive, and cancer effects.

Irritation effects, either from the physical presence of bioaerosols or from exposure to VOCs released by biologicals, have been demonstrated in susceptible workers [Ex. 3-32]. In addition, water leakage on furnishings or within building components can result in the proliferation of microorganisms that can release acutely irritating substances into the air. Typically, where microorganisms are allowed to grow, a moldy smell develops. This moldy smell is often associated with microbial contamination and is a result of VOCs released during microbial growth on environmental substrates [Ex. 4-41].

Pulmonary effects which have been associated with exposure to bioaerosols include rhinitis, asthma, allergies, hypersensitivity diseases, humidifier fever, spread of infections including colds, viruses, and tuberculosis, and the occurrence of Legionnaire's disease [Exs. 3-17, 3-32, 3-38, 3-61B, 3-188, 3-440A, 3-446, 3-500, 4-41, 4-144, 4-214].

Cardiovascular effects manifested as chest pain, and nervous system effects manifested as headache, blurred vision, and impaired judgment, have occurred in susceptible people following exposure to bioaerosols [Exs. 3-32, 3-446]. It has been suggested that these effects may be caused by VOCs released by the microbiologicals, or they may be a complication of related pulmonary effects.

The development of cancer in susceptible people is possible following exposure to certain types of toxigenic fungi and mycotoxins. However, the probability of such exposures occurring in workplaces covered by this standard is probably limited. Mycotoxins (toxins produced as secondary metabolites by many fungi) are among the most carcinogenic of known substances, and are also acutely toxic. The American Conference of Governmental and Industrial Hygienists wrote "[t]he toxigenic fungi are common contaminants of stored grain and other food products and have caused well-described outbreaks of acute systemic toxicosis as well as specific organ carcinogenesis when such food is consumed * * * It appears clear that massive contamination with a highly toxigenic fungus strain of a site in which aerial dispersion of metabolic products occurred would be necessary to induce acute symptoms. However, considering the carcinogenicity of many fungal toxins, an examination of the risks of chronic inhalation exposure appears justified" [Ex. 3-61].

In summary, most of the health effects associated with SBS and BRI occur in indoor environments were concentrations of pollutants are much less than the OSHA Permissible Exposure Levels (PELs) (29 CFR 1910.1000) [Ex. 4-3]. It is important to point out that the PELs are chemical-specific standards that are not only based on health effects but also on technological feasibility, cost restraints and a "healthy" worker exposed for a 40-hour work week. In the industrial workplace, hazards are minimized by the use of administrative and engineering controls and the use of personal protective equipment. The nonindustrial environment, however, does not have these controls. Ventilation systems are designed only to remove occupant-generated contaminants, such as carbon dioxide and odors. These types of systems were not designed to dilute multiple point sources of contaminants that are typically found in nonindustrial workplaces (see section III). Unless adequate ventilation and source controls are utilized and adequately maintained, many of the chemical contaminants can concentrate to levels that induce symptoms. The possibility exists that synergistic effects occur. These effects occur not only between substances to enhance their toxicity but also by lowering the resistance to lung infection in susceptible persons.

To read the full Register: Federal Register on Indoor Air Quality

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