IICRC S520 Mold Remediation Standard: Separating Fact from Fiction (Part 3)
In the first two installments of this series on the S520, we discussed the philosophical shift away from numerical visible levels of mold contamination that the S520 Standard represents; the definitions of words used throughout the Standard; and the outline of the Standard, along with some of the major points covered in order to answer questions I receive from remediators, IEPs, insurance companies, legislators and others.
This article delves into Chapters 1 and 2 of the IICRC S520 Reference Guide to give an idea of how comprehensive the S520 really is, particularly as it pertains to health effects. Remember, these are only brief excerpts from the new standard.
IICRC S520 Reference Guide:
Chapter 1: Fungal Ecology (excerpts)
There are approximately 60,000 to 80,000 described species of fungi (molds and yeasts). The majority of fungi are saprobes; that is, they utilize non-living organic material for food...Molds develop from unique, microscopic seed-like structures called spores. Spores are not visible to the unaided eye. When spores settle on a surface under appropriate moisture and temperature conditions, they absorb water, swelling to 2-3 times their original size, and begin to form thread-like structures known as hyphae. As the hyphae grow, they interweave to form a tangled mass known as a mycelium. With continued growth, a mycelium, unlike a spore, becomes visible to the naked eye. The mycelium extends across the surface material, generally in a circular pattern, with hyphae growing above and below the food source. When the fungus matures, spores will form within specialized structures or individually on the aerial hyphae. The spores can then be carried away by air currents, moisture droplets or insects to new environments to start the reproductive cycle over again...
...Normal building flora usually associated with microenvironments include viable (living) and non-viable (dead) microorganisms, such as environmental and human source bacteria and common fungi (yeasts and molds) and their associated antigens, spores, toxins, volatile metabolites and enzymes. In the absence of rapid attention to water damage (intrusion and/or accumulation) and preventive programs of routine climate control, maintenance, and cleaning, micro-environmental reservoirs can quickly become sources of contamination through extensive accumulation of settled spores (Condition 2) and mold amplification (Condition 3).
As available moisture increases over time, such as moisture intrusion into ceiling spaces and wall cavities, the microbial ecology of materials and surfaces changes. Competition among organisms begins to favor those with increasingly higher moisture requirements. If a water-damaged environment is not promptly and properly remediated, many environmental mold spores that are typically present...will germinate, grow and multiply on building materials, eventually leading to material degradation and potential negative effects upon the quality of the indoor air. Thus, the goal of mold remediation is to return the indoor environment to a state of normal fungal ecology (i.e. types and concentrations of molds typically found in non-water damaged, environmentally well-maintained structures, and reflective of the ecological and climatic elements of the geographical region in which the building is located)...
Chapter 2: Health Effects from Indoor Mold Contamination (excerpts)
Although the health effects of exposure to certain types of molds in the outdoor environment have been long recognized and described in the medical literature, the specific effects of exposure to those that arise in the indoor environment are only a relatively recent area of concern and investigation. The complexity of fungal contamination in indoor environments, including the variety of molds, the changing conditions (moisture, temperature, building envelope and mechanical ventilation dynamics), concentrations and forms (hyphae, spores), presents unique challenges in assessing occupant health risks. Understanding the types and relative significance of actual health risks is critical to developing and implementing appropriate remediation methods, both from a clinical as well as a public health perspective.
...In general, building dampness (moist and/or wet conditions), and the resulting potential increase in mold contamination, have significant impact on the health of occupants. A recent review of 61 peer-reviewed articles demonstrates that dampness in buildings is consistently associated with an increased risk for symptoms in respiratory airways, as well as self-reported tiredness, headache and airways infections.16 Another review of case reports, case-control studies and cross-sectional studies from a 15-year period has concluded that ". . . evidence of an association between respiratory problems and the presence of fungi and dampness is strong."17
...A considerable amount of research information indicates that the growth and dissemination of fungi in water-damaged buildings results in the production of certain toxins that may be responsible for BRS and/or certain other supposed health effects.
Although there are hundreds of genera of mold that can appear in the indoor environment, only a relatively small number of them (and a limited number of species within each genus) are of concern in terms of water-damaged, organic (carbon-containing) building materials, and of significant health effects unique to the indoor environment. While much attention has been given to health concerns regarding Stachybotrys chartarum, certain species of Aspergillus and Penicillium, as well as Fusarium, some other genera commonly observed colonizing water-damaged building materials, are also capable of producing a class of compounds known as mycotoxins.27 Mycotoxins form the basis for the term "toxic mold;" however, a more appropriate term is "toxigenic mold," which indicates the capability of producing the toxins.
Regardless of the unclear clinical effect and lack of established methods for mycotoxin exposure assessment . . . it has been generally recognized in the environmental health and industrial hygiene fields that the predominance of these "toxigenic" molds in water-damaged buildings is consistently associated with occupant health complaints described above as BRS.1, 3 AIHA's recommendation that, " . . . the confirmed presence of Stachybotrys chartarum, Aspergillus versicolor, A. flavus, A. fumigatus and Fusarium moniliforme requires urgent risk management decisions to be made . . ." is based on the strong association between mold growth resulting from water damage to the building and the likelihood of spread of mold contaminants throughout a building, with the resultant risk of occupant exposure and illness.3
Immunological studies of occupants in heavily mold-contaminated buildings have failed to demonstrate significant immunocompromised states in occupants, either as clinical infections or through markers of immune status.22, 25, 26 Some laboratory research on certain mold mycotoxins has suggested that immunological effects can occur from exposure; but these effects have not been demonstrated in occupants of mold-contaminated buildings. The rationale that infants and the elderly are at increased risk from infectious diseases from indoor mold exposure due to varying degrees of immune dysfunction appears to be based more on conservative public health principles rather than definitive clinical or epidemiological studies.
...Microbial volatile organic compounds (MVOCs) are gas-phase metabolites and typically are recognized by the human nose as "musty, moldy" and "mildewy" odors. While their presence is often an indicator of active microbial growth and moisture problems inside wall or other building cavities, the aforementioned occupant health effects do not appear to be toxicologically associated with exposure to one or more MVOCs.
The entire foregoing discussion of what is known and unknown about mold health effects is directly pertinent to the rationale behind the principles and methods of remediation recommended in this Standard and Reference Guide. Much more clinical and epidemiological research is needed to explain and understand the mechanisms of illness, actual agents of disease and dose-response relationships, as well as to improve exposure assessment. It is crucial to recognize that "laboratory testing and theoretic speculation about possible mechanisms are important, but no more so than direct, straightforward observation of what actually happens in human populations".43
From a public health perspective, in the absence of explicit, complete scientific understanding of a particular risk; conservative measures are appropriate to ensure that risk to occupant health is minimized. There is sufficient information at present to justify remediating mold contamination, including not only mold growth at the site of water intrusion or accumulation, but also mold contamination (i.e., spores, fragments, and other byproducts) that may result from dissemination from the source to distant sites in the building, including flooring, bedding materials, other furnishings, HVAC systems, and other contents. In these locations, spore-related contaminants may be difficult to remove short of complete replacement. Temporary relocation of occupants and thorough containment in partially impacted areas are appropriate measures to prevent further occupant exposure to contaminants during remediation activities.
There is no scientific evidence to support the assertion that only susceptible individuals are at risk from mold exposure in residential and workplace environments. In some cases where prevalent occupant illness has been adequately documented, consideration of temporary relocation of all occupants during remediation (as opposed to just those who vocally complain or seek medical attention) is warranted from a public health perspective. In hospitals and other health care facilities where infectious diseases are of particular concern, the approach to mold remediation may require additional precautions for occupant health.
The next (and final) article on IICRC S520 will cover Chapters 3-12 of the Reference Guide. As you can see, this is an extremely important document for every cleaner/restorer/remediator to have on his or her bookshelf.