Organic Acid Formulations for Wood Protection: Inhibition of Mold Fungi

Humans are exposed constantly to molds in the environment, both indoors and outdoors. Problems arise when the immune system is suppressed (HIV infection, cancer treatment), over-responsive (allergy) or when exposures are exceedingly high (irritation and mycotoxin effects). Many people are allergic to molds, and allergic responses include hay fever and asthma. Certain molds such as Stachybotrys chartarum (or atra), and various species of Aspergillus, Fusarium and Penicillium produce mycotoxins or volatile organic compounds (VOCs) that can be irritating when present in high concentrations and on occasion, can be quite toxic to humans and animals. Because of the recent increase in mold mitigation claims, as well as increased public awareness about indoor air quality, the need for improved protection of cellulose-based building materials from mold infestations has been hastened. Mold claims, including pre- and post-construction, exceeded $3.0 billion in the U.S. in 2002, more than double the $1.3 billion paid in the previous year. While mold fungi do not cause structural damage to wood, the presence of mold is indicative of inadequate surface drying of condensation, chronic high humidity, or water intrusion. Chronic moisture issues can result in structural damage which often begins with growth of mold fungi followed by presence of decay fungi (i.e., brown-rot and white-rot fungi). Eventually, chronic moisture problems and decayed wood can attract other pests such as termites. Moreover, spores from mold fungi can be particularly problematic not only as human and animal allergens but also due to their recalcitrance to chemical remediation. Among the three primary wood infestations (termite attack, mold and decay fungi), spores from mold fungi appear to be the most resistant to chemical treatments; hence, mold spores are more difficult to suppress and control. A number of problems may attribute to excess moisture in existing structures, such as flawed design, poor construction practices or maintenance, poor site drainage, leaky roofs/plumbing, inadequate insulation, improper ventilation, etc. No matter how meticulous the maintenance on a building is, nearly every structure will encounter a moisture event that may be as obvious as flooding or as subtle as a chronic leak inside a wall that only becomes apparent in advanced stages of biological activity. Since even the best moisture management practices cannot prevent eventual moisture intrusion, economical biocides that are suitable for interior use are needed. In addition to being effective against mold fungi, they must be nontoxic to occupants, nonvolatile, environmentally acceptable, safe to handle, and possess low solubility. Surface treatment of dimension lumber or engineered products with mold inhibitors would add an additional layer of protection for in-service wood products and lessen the impact of current indoor air quality issues.