SBIR-STTR Award

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. OBJECTIVES: Technical Objectives: Phase I technical objectives are important and must be met before the efficacy of fatty/organic acid formulations as moldicides for wood-based materials can be more fully understood. Objective #1: Identify most effective ratio of adjuvants, fatty acids and/or L-lactic acid, as a potential synergist, that are most stable as a) formulation concentrates (greater than 2 months), b) dilutions in water at 10, 30 and 60 minutes and c) liquids (will not crystallize or solidify) at reduced temperature (35, 40 and 50 degrees, F). Objective #2: Determine which of the most stable formulations is superior as a moldicide and anti-sapstain, where the fatty acid/emulsifier/synergist combinations and a commercial moldicide product (IPBC) will be compared for control against sapstain and a consortium of three mold fungi. Both dip and vacuum-pressure treatment methods will be tested. Other important tasks would include: a) a preliminary cost assessment of the most promising experimental formulations compared to current treatment methods and b) obtaining comments and suggestions relating to Phase I data from potential end-users. APPROACH: The research team will include Robert Coleman (Summerdale, Inc., Verona, WI) and Carol Clausen, Vina Yang and Patti Lebow (US Forest Service, Forest Products Laboratory, Madison, Wisconsin) and support staff at the US Forest Service, Forest Products Laboratory and Summerdale, Inc. Objective #1. Identify those combinations of fatty acids (C3, C7 - C9 and C8/C10 mix), emulsifiers (Emsorb 6915 and PE 1198), synergist (L-lactic acid) and adjuvants (Competitor, Sylgard 309, ProNatural, Surflex QW391 and Exacto 390) that are stable as formulation concentrates (greater than 2 months) and also stable as dilutions in water at 10, 30 and 60 minutes. Moldicide formulations will include active ingredients (fatty acids) and a synergist (L-lactic acid) that are: cost effective, natural, GRAS compounds and compatible in effective moldicide formulations. The three primary ingredients in the moldicide formulation will be: a) an active ingredient (AI) or fatty acid (C3, C7 - C9 and C8/C10 mix), b) a synergist (L-lactic acid) and c) an emulsifier (using a dual emulsification system). Objective #2: Determine which fatty acid species (C3, C7 - C9, C8/C10) is most effective as an anti-sapstain and wood moldicide, using experimental formulations comprising a dual emulsification system (sorbitan monolaurate and phosphate ester), an organic acid synergist (L-lactic acid) and/or adjuvant designed to increase formulation distribution and penetration. Application via dip and vacuum-pressure treatments will be evaluated for treated, kiln-dried southern yellow pine (SYP). Moldicide activity of leached versus unleached, C8-treated stakes will also be evaluated to determine whether C8 and/or selected adjuvants remain in SYP after prolonged exposure to water. Test organisms and inoculum preparation: Mold fungi, Aspergillus niger 2.242, Penicillium chrysogenum PH02, and Trichoderma viride 20476 will be grown on 2% malt agar and individual spore suspensions will be prepared by washing the surface of a 2-wk old culture of each fungus with 10 mL of sterile deionized (DI) water according to ASTM standard D4445-91 (1998). Mold test (southern yellow pine stakes): Specimens (7 x 20 mm cross section by 7 cm long and 75 x 100 mm by 12.5 mm thick) will be cut from southern pine and conditioned at 27degrees, C, 70% relative humidity (RH). Twelve random replicate specimens will be dip-treated for ~15 seconds in each moldicide formulation and held overnight according to the ASTM standard test method D4445-91 (1998) or ASTM D3273-00 (1986). For the stake test, treated specimens will be arranged over 4 layers of blotting paper saturated with 25 mL DI water and a polyethylene mesh spacer in sterile disposable Petri dishes (150 x 25 mm) (B-D Falcon, Los Angeles, CA, USA). Untreated specimens dipped in DI water will serve as controls. Specimens will be sprayed with 1 ml of individual mold spore inocula, sealed in polyethylene bags to prevent drying and incubated at 27oC and 70% RH for 8 - 12 weeks. Only formulations that provide the best protection from consortia of test fungi will be further tested on large specimens (planks) against a mixed mold and sapstain inoculum

Summerdale, Inc. and Forest Products Laboratory (FPL) will focus on above-ground applications of waterborne preservatives for indoor and outdoor residential lumber. Specifically, fatty acid-based formulations +/- adjuvants will be targeted for use on a) indoor lumber and wood composites and b) exterior residential (above ground) such as decking. However, further Phase II development of outdoor residential markets will depend on Phase II results from replicated leach trials. Fatty acid/adjuvant control of mold/decay fungi and termites must be sufficient; i.e., where preservative is retained and pesticide performance is acceptable after standard leach trials. Also, multi-year field trials, testing both stake and above-ground durability of treated specimens, are planned. The trials provide a very rigorous examination of preservative long-term efficacy. In-ground stake testing of several formulations has already been initiated. It is conceivable that formulations may not show long-term protection during prolonged, in-ground contact. Nevertheless, durability of treated-wood for exterior residential (above-ground) can be determined from the accelerated stake and above-ground test results. Over 82% of all waterborne preservatives were used on lumber and timber. An estimated 183.2 million pounds of waterborne preservatives were applied in 2004 and that the largest market for treated wood was residential. The largest growth was for copper-rich ACQ (and CA) and inorganic boron preservatives. ACQ, alone, had 46.7% of the waterborne preservatives market in 2004. Over the last several years, MCQ (micronized copper quats) has penetrated this market. Currently, copper-based preservatives are used to pressure treat lumber for numerous residential applications such as decking, outdoor furniture, fences, play structures, etc. Novel fatty acid-based preservatives, as exterior treatments, can be: a) potential "stand-alone" replacements for selected copper-based products (i.e., ACQ) used above-ground and b) as combination treatments with selected, existing products. An effective stand-alone product and/or a combination treatment should be of interest to a licensee. An acceptable, stand-alone formulation, relative to an existing wood preservative, should have improved or superior deterioration control and comparable or improved cost and other features (better human and environmental safety, less metal corrosivity, acceptable appearance of treated wood, etc.). Since dip and pressure treatments are used by wood preservers (typically at factories or lumber mills), both application methods for exterior applications will be examined. However, formulation development will be targeted toward both interior and exterior treatments and include control of mold and decay fungi and termites. Potential exterior treatments will also include a determination of formulation capabilities as an anti-sapstain. OBJECTIVES: Mold growth can significantly alter indoor air quality (IAQ), generating a variety of health effects in human occupants ranging from minor allergic reactions and exacerbation of asthma to pneumonitis. Individuals with pre-existing health issues or those that are immuno-suppressed are particularly susceptible to high loads of mold spores resulting from elevated interior moisture conditions although healthy individuals may also suffer from high levels of allergens, mycotoxins and volatile organic compounds resulting from a mold "bloom". Moreover, residential structures damaged by fungi and insects amounts to about $500,000,000/ year with labor costs estimated to be about $5 billion/ year. Poor IAQ and accompanying health repercussions have home builders and home owners alike concerned about mold issues, with additional steps to abate mold during construction and renovation already in progress. Currently, many mold protectants are commonly used in paint and coatings as short-term (<1 year) protection for gypsum board and wood products. However, there is a significant demand for effective, environmentally-acceptable moldicide treatments for low cost, long term protection of wood and wood-based products. Human health can be adversely affected by mold contaminants and also potentially from wood preservatives meant to prevent wood disease such as mold and decay fungi. Consumer safety groups, health officials and the EPA are now closely scrutinizing wood treatments used in residential construction. Products are required to exhibit minimal health and safety risk and in particular, proximity to drinking water sources and residential soils needs to meet current safety criteria. Global markets for wood preservatives have undergone a major transition over the last 8-10 years, spurred principally by societal demand for products with reduced human and environmental toxicities. However, very few unique, acceptable biocides have emerged while at the same time fungal resistance against existing biocides has increased. The discovery of synergistic combinations of selected natural adjuvants and specific fatty acids, as effective wood preservatives has established an excellent foundation for Phase II. Prolonged incubations (3 months) against both mold and decay fungi have shown that several formulations performed very well. Phase I data and observations for fatty acid-based chemistry matches very well with significant criteria, including cost and performances characteristics, required for a successful, "next generation preservative". A novel preservative acceptable to the public and meeting the needs of the wood preservatives industry should be a sound return on investment. Summerdale, Inc. and Forest Products Laboratory will focus on above-ground applications of waterborne preservatives for indoor and outdoor residential lumber. Specifically, fatty acid-based formulations +/- selected adjuvants will be targeted for use on a) indoor lumber and wood composites and b) exterior residential (above ground) such as decking. There is considerable interest from wood preservatives companies actively searching for effective pesticides having fewer environmental concerns. APPROACH: Phase II technical and commercial objectives are highly important and must be met to better understand the full potential of fatty acid formulations as wood preservatives. Both performance and cost determinants, relative to those of existing products and methodology, needs to be assessed. Two strategies for formulation development will occur. Both approaches will be done in tandem. Objective 1 builds on highly promising adjuvant/fatty acid chemistry as candidate fungicides and insecticides. The measurement of pesticide activity and retained active ingredients in leached and un-leached, treated blocks is a significant task. The second strategy pertains to custom, multi-fatty acid formulations designed to control a broader range of fungal (mold) species. Once the specificities of individual fatty acids for various species of mold fungi have been identified, custom formulations, comparing the most potent fatty acid (s) per mold species, can be prepared. The Phase II objectives include: 1. Determine pesticide activities of caprylic acid (C-8)/adjuvant combinations as fungicides (mold, decay) and as termiticides, comparing leached and un-leached, treated blocks. 2. Evaluate individual fatty acid (C-5 to C-10 and C8/C10) specificity for each of 4 mold strains (A. niger 2.242, P.chrysogenum PH02, Trichoderma viride20476, and Alternaria alternata). 3. Select appropriate fatty acid species to develop custom, higher potency formulations for controlling a broader range of mold fungi. A. Evaluate ingredient compatibility and stability of formulation concentrate and it's dilution in water. B. Screen moldicide activities of stable, compatible formulations against a consortium of: A. niger 2.242, P. chrysogenum PH02, Trichoderma viride20476 and Alternaria alternata. 4. Evaluate selected adjuvants/amendments (5, total) added to the most promising custom formulations (2) and compare with commercial products (2) and combination products (2); i.e., commercial product + custom formulation. A. Evaluate compatibility of formulation ingredients and stabilities of formulations and formulation dilutions in water. Select best formulations (2) and compare with 2 commercial products and 2 combination products for pesticide trials B. Determine moldicide, anti-sapstain, decay fungi and termiticide efficacy comparing leached and un-leached blocks C. Record cold storage temperatures of best formulations; i.e., determine formulation crystallization points. D. Determine moldicide efficacy of treatments applied to wood composites 5. Quantitate and analyze fatty acid and adjuvant remaining in leached blocks. 6. Continue multi-year outdoor stake trial and initiate above-ground trials to evaluate efficacy of pressure treatments. 7. Determine corrosivity of 2 fatty acid-based formulations. 8. Obtain participation from collaborators and potential licensees to conduct independent trials on most promising formulations as wood preservatives. 9. Conduct cost analysis of waterborne formulation treatment (s) for both interior and exterior residential applications (above-ground) and compare to commercial products and methodologies