A risk assessment model for mycotoxin-producing molds on human health in indoor environments

Miller RV, Martinez-Miller C, Bolin V. Aerotech Monitor. 2000; 3:4-5. (Review)

Purpose: The authors proposed a risk assessment model that would lower the threshold of mold exposure as compared to the model previously proposed by Burge and colleagues.

Design: Hypothesis-generating proposal

Outcome: The authors reviewed the risk assessment model developed by Harriet Burge in 1996. Burge's model indicated that most indoor mold growth is insufficient to result in a sufficient amount of mycotoxins to produce deleterious health effects. Miller and colleagues argued that the high incidence of respiratory symptoms reported by individuals with indoor mold exposure suggests that the threshold would be considerably lower than predicted by Burge's model. Miller et al., pointed out that other factors, including the immunosuppressive activity of mycotoxins, render certain patient populations more vulnerable to the toxic effects of indoor molds. The authors also hypothesized that multiplicative rather than additive interactions may exist between various chemical byproducts of the different molds growing together indoors, resulting in the need for a lower amount of each mycotoxin to reach the threshold for damaging tissue. Miller et al., proposed that the number of "contact points" of mold spores with tissue may be a more reliable measure of risk than the estimate from Burge's model, which estimated the dose of toxin to which an individual would need to be exposed before health effects occurred.

Significant Quotes: "Based on this model, it becomes apparent that most exposures to mold-contaminated buildings would not be expected to cause adverse health effects. However, the number of incidences where individuals exposed to mold-contaminated buildings exhibit respiratory distress suggests that the threshold may be considerably lower than predicted in this model, or that a number of additional variables should be factored into the model." (p. 4).

"Since the modes of activity of trichothecenes differ from aflatoxins and other mycotoxins, the combinations of mycotoxins could be additive or even synergistic, which could significantly reduce the amount of either mycotoxin required to induce an immunosuppressive or toxic effect. Immunosuppressive and combinational effects of multiple mycotoxins may constitute major components in the adverse health effects reported by many of the victims of mold exposure." (p. 4).

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