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DEVELOPMENT OF AN ENVIRONMENTAL RELATIVE MOLDINESS INDEX FOR US HOMES
Citation:
VESPER, S. J., C. MCKINSTRY, R. A. HAUGLAND, L. J. WYMER, K. D. BRADHAM, P. ASHLEY, D. COX, G. DEWALT, AND W. FRIEDMAN. DEVELOPMENT OF AN ENVIRONMENTAL RELATIVE MOLDINESS INDEX FOR US HOMES. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL MEDICINE. Lippincott Williams & Wilkins, Philadelphia, PA, 49(8):829-833, (2007).
Impact/Purpose:
1. Develop and publish a standard method or guidance document for QPCR analysis of microorganisms in environmental samples (air and water filtrates and dust).a standard method or guidance document for QPCR analysis of microorganisms in environmental samples (air and water filtrates and dust). Publication will involve a consensus standards organization. 2. Use QPCR methods to monitor childhood exposures to mold as a part of field studies, in order to establish whether a relationship exists between molds encountered in indoor environments and asthma-related health problems.
Description:
As part of the HUD American Healthy Homes Survey, dust samples were collected by vacuuming 2 m2 in the bedroom plus 2 m2 in the living room of a nationally representative 1096 homes in the USA using the Mitest sampler. Five mg of sieved (300 µ pore, nylon mesh) dust was analyzed by mold specific quantitative PCR for the 36 EPA Mold Panel Species. On this basis, an environmental relative moldiness index (ERMI) was created with values ranging from about -10 to 20 (lowest to highest). In order to try to reduce the cost of this analysis, the number of test species was reduced by selecting only those species with a national average concentration of 30 cell equivalents (CE) per mg dust or greater. Only 19 of 36 species met this criterion. (In 40% of the homes, an additional 46 species were quantified from the same dust sample. All of these species had average concentrations less than 30 CE per mg dust.) These 19 species were then categorized into two groups based on their coefficient of variation (CV). If the CV was > 9, the mold was placed in Category 1 (10/19) and the other molds were placed in Category 2 (9/19). Using these Categories, the sum of the log-transformed concentrations of three Category 2 molds (C. herbarum, A. alternata and C. cladosporioides Type 1) was subtracted from the sum of the log-transformed concentrations of the ten Category 1 molds (Aspergillus niger, A. ochraceus, A. penicillioides, A. restrictus, A. sydowii, Chaetomium globosum, Eurotium amsteldoami, Paecilomyces variotii, Penicillium chrysogenum and Wallemia sebi). Assembling these values for the 1096 AHHS homes from lowest to highest produced the American relative moldiness index (ARMI). The correlation between the ERMI and ARMI values was 0.88. The ERMI or ARMI scales may be useful as a standard for mold exposure estimates in epidemiological studies.