Dissertations and Theses

Date of Degree

1-1-2019

Document Type

Dissertation

Degree Name

Doctor of Public Health (DPH)

Department

Environmental, Occupational, and Geospatial Health Sciences

Advisor(s)

Jean Grassman

Committee Members

Jean Grassman

Franklin Mirer

Marilyn Aguirre-Molina

David Kotelchuck

William Gallo

Subject Categories

Allergy and Immunology | Environmental Public Health | Public Health

Keywords

mold antigen extracts, mold allergy diagnosis, mold minimum risk levels, mold exposure and asthma, mold exposure and hypersensitivity pneumonitis

Abstract

Background: Asthma is a major health problem throughout the world, disproportionately affecting occupants of low-income housing, and exposure to damp and moldy living conditions is recognized as a significant risk factor for asthma and other respiratory diseases. However, there are no authoritative health guidance values (HGV's) for airborne mold, and current scientific thought holds that the establishment of such guidelines is not practicable. Nonetheless, environmental practitioners take air samples for mold as a routine component of their indoor environmental investigations and use the laboratory results as a tool together with other findings to guide recommendations for health protective actions. The absence of HGV's leaves the task of risk assessment to the environmental practitioner, which has led to inconsistent interpretations of laboratory results, undermining their credibility in the eyes of clients, physicians and the courts. Researchers have concluded that current scientific evidence does not support the measurement of specific indoor microbiologic factors, including airborne mold, but have recognized the need for rigorously designed studies that will contribute to the development of dose-response based HGV's.

Objectives: To assess the validity and usefulness of indoor mold air sampling results as a tool in providing health protective recommendations by: 1) examining the current body of scientific evidence that supports or rejects the validity of measuring indoor airborne mold levels in assessing respiratory health risk to atopic occupants; 2) conducting a study where the results would help to define a dose-response based quantitative benchmark for elevated levels of indoor airborne mold that present a respiratory health risk to atopic occupants, and; 3) assessing whether indoor airborne mold sampling results can be used as a tool to enable physicians to more accurately diagnose mold allergies by more closely aligning the mold antigen extracts used for skin and serum testing with the predominant genera and species of mold found in damp and moldy homes.

Methods: To accomplish these three objectives: 1) a systematic review was conducted that identified and isolated peer-reviewed observational studies published from 1989-2017 that measured the strengths of association between exposure to elevated levels of indoor airborne mold and asthma or other adverse respiratory health outcomes and that met the inclusion criteria of having assessed those associations by genus/genera and having accounted for susceptibility bias, and then evaluated the homogeneity of findings and the criteria used to define elevated levels of airborne mold; 2) a nested case-control pilot study was conducted where indoor airborne mold samples and outdoor controls were collected from the homes of 34 six and seven year-old children, randomly selected from within the 1,543 member Infant Wheeze Cohort in Havana, Cuba to assess the level at which exposure to Penicillium/Aspergillus-type mold in the indoor air presented a significantly increased risk of wheeze, and; 3) a database of laboratory results was built for all culture-type air samples taken by environmental practitioners across the U.S. and Canada from 2002-2017 and analyzed by a major U.S. microbiology laboratory to determine the predominant genera and species of molds found in damp and moldy homes, and then concordance was assessed between these results and information provided by physicians and clinical laboratories as to the species-specific mold antigen extracts used in the diagnosis of mold allergies.

Results: 1) The systematic review found that 20 of the 21 studies that met the inclusion criteria found significant associations between exposure to elevated levels of indoor airborne mold and one or more adverse respiratory health outcomes, irrespective of the wide range of criteria used to define elevated levels, and that the mold most commonly associated with these outcomes was Penicillium. 2) The nested case-control study found that children exposed to Penicillium/Aspergillus-type mold where indoor levels exceeded outdoor levels by > 200 structures/m3 were at significantly increased risk of wheeze (OR 13.17 95% CI,1.95-88.85). 3) The concordance study found that species representing > 50% of the Aspergillus fungal organisms and > 80% of the Penicillium fungal organisms found in damp and moldy homes are absent from the species-specific mold antigen extracts used by clinicians to diagnose mold allergies.

Conclusions: 1) The systematic review finds that current scientific evidence does support measuring mold in the indoor air as a tool in providing health protective advice to atopic occupants, but the evidence does not provide a basis for establishing HGV's for indoor airborne mold. 2) The nested case-control study suggests that defining elevated levels of airborne mold as indoor levels of Penicillium/Aspergillus exceeding outdoor levels by > 200 structures/m3 may be a useful benchmark for examination in larger similarly designed studies. 3) The concordance study suggests that mold allergies are being under-diagnosed by physicians resulting in the under-recognition of the need for environmental interventions that may improve patient outcomes, and that improving concordance will require a coordinated effort between clinicians and mold antigen extract manufacturers.

Available for download on Friday, December 10, 2021

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