Mold Growth in On-Reserve Homes in Canada: The Need for Research, Education, Policy, and Funding

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Mold and Health

Mold is a serious health risk in the dilapidated housing that characterizes much of the shelter available to the indigenous ("First Nations") people of Canada. Mold has been well documented as occurring in First Nations housing, but its health consequences remain implicit and the actual types of mold are understudied and largely unanalyzed. This article reviews the relevant conditions conducive to mold growth, what is known about the kinds of risks mold represents, the socioeconomic and historical factors that have led to this situation, and the circumstances that require action on the part of multiple levels of governance in Canada to address this issue.

Molds include all species of fungi that grow as multicellular filaments called hyphae. Over 100,000 types of mold are classified in the Zygomycota, Deutermycota, and Ascomycota phylums. Mold grows on solid culture media and gains nutrients through the decomposition of dead organic matter. Reproduction occurs both sexually and asexually within microscopic spores, which may contain one or several nuclei. Some spores can remain airborne indefinitely and are capable of surviving extreme levels of pressure and temperature variation. It is only when mold colonies grow as an interconnected group of hyphae called mycelium that mold becomes visible. Mycelium is far more widespread at low concentration levels than simple visual inspection would suggest (Prezant, Weekes, & Miller, 2008).

All molds secrete hydrolytic enzymes that break down starch, cellulose, and lignin into simpler substances that they can absorb. The ability of molds to decompose organic matter makes them invaluable components in the nutrient cycle. Many molds also secrete mycotoxins, however, which, along with the enzymes used to process organic matter, have evolved to inhibit the growth of other microorganisms (such as bacteria or insects) competing for the same nutrients. Some of these mycotoxins are neurotoxins, which gravely disrupt the nervous systems of competing organisms such as insects and also impact other organisms including humans. Some mycotoxins can be very dangerous when inhaled due to their effect on human respiratory (Hope & Simon, 2007) and neurological functions (Campbell, Thrasher, Gray, & Vojdani, 2004).

The impacts of mycotoxins on human health include allergic rhinitis, asthma, mucosal irritation, common cold symptoms, fatigue and weakness of concentration, general weakening of the immune system, and even death. Due to these dangers, mold is often treated as a hazardous material (Park & Cox-Ganser, 2011). Mold is dangerous to human health in several other ways. Mold spores are sufficiently small enough to be inhaled into the bronchial tubes, bypassing the mucosal barrier; consequently, some mold spores commonly yield allergic reactions including conjunctivitis, allergic coryza, inflammation of the respiratory tract, bronchial asthma, skin eczema, and "nettle rash" (Hardin, Kelman, & Saxon, 2003; Portnoy, Kwak, Dowling, VanOsdol, & Barnes, 2005).

Mold mycelium is also dangerous and is associated with mycosis and mycotoxicoses. Mycosis is the growth of a mold fungus on a human host, which can cause infectious diseases such as aspergillosis and penicilliosis (Jacob et al., 2002). Mycotoxicosis is anthropogenic intoxication due to the inhalation of the toxic by-products of mycelium metabolism, which can lead to delirium (Fung & Clark, 2004).

The adverse affects of mold (like most environmental illness) are age related and particularly pronounced in children (Ahluwalia & Matsui, 2011; Bearer, 1995; Jones, Recer, Hwang, & Lin, 2011; Koskinen, Husman, Meklin, & Nevalainen, 1999). This is due to a combination of their immature size, immune system vulnerabilities, confined exposure (they are kept inside), and misinterpretation of symptoms as sequential rhinoviruses (common colds). …