An Environmental Assessment of Mold Concentrations and Potential Mycotoxin Exposures in the Greater Southeast Texas Area

Abstract

An assessment of indoor air quality in homes from the greater Houston and Southeast Texas area was sampled over a three-month period to ascertain the potential toxic exposure to molds and mycotoxins. In 2001 Houston experienced widespread flooding due to Tropical Storm Allison. The slow receding waters allowed molds to proliferate to great levels and affected many homes and businesses in and around the Houston area. Source (air) and surface (swab, tape, and bulk) samples were taken in fungal contaminated residences to measure the amounts of airborne and surface contaminants. Indoor airborne counts of fungal spores that were identified to be 80% or more of the outside counts of similar fungal genera were classified as indoor air contaminants. This study identified species of Aspergillus, Penicilliulm, and Cladosporium at levels ranging from 80% to 20 times greater than the corresponding outdoor readings in the greater Southeast Texas area. Aspergillus and Penicillium species are considered potentially toxic to humans at elevated levels due to their ability to produce mycotoxins. Cladosporium is considered nonpathogenic, but can still cause allergenic reactions from hyphal fragments. Surface sampling which is utilized for identification of visible mold contaminants, identified species of Aspergillus. Penicillium, Chaetomium, Cladosporium, and Stachybotrys ranging from 1 to 100 total colony counts (1-100% for tape and bulk noncultured assays) contingent upon the extent of visual contamination. The numerical values from surface sampling were used primarily to identify the degree of visual contamination, as well as, identify any molds that may have been too heavy to become aerosolized.