Preventing microbial contamination in waterborne paint is a problem faced by manufacturers across the United States and around the world. Bacteria are the primary threat against product quality, but some yeasts and mold can also cause spoilage without an effective preservation package. Contamination impacts paint and paint performance in obvious ways such as bulging cans, foul odor, viscosity changes and color changes, as well as in more subtle ways such as pH drift.1
Biocides, including those used for paint preservation, must be registered in the United States under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), which was first enacted in 1947, revised in 1972, and further amended in 1996 (7 U.S.C § 136 et seq.). The EPA states, “All pesticides distributed and sold in the United States must be registered by the EPA based on scientific data showing that they will not cause unreasonable risks to human health, worker or the environment when used as directed on product labeling.”2 Shown in Table 1 are some of the commonly used FIFRA-registered biocidal actives for in-can (wet-state) paint preservation against microbial attack. A large portion of biocidal actives used in modern paint formulations have been registered for more than 40 years. It is important to note that registered biocides are reviewed by the EPA every 15 years, and in each review more and more data regarding the environmental fate, ecological toxicity and exposure data for the biocides is required to maintain registrations.