Q: I’ve found that there are instances when the use of caulk for home improvement projects is unavoidable. What is the relative toxicity of this product, and what are some of the least hazardous brands?
—Stacy Halyard, Malibu, CA
A: Acrylic, latex, and silicone, combined in various ways, are the three basic ingredients used to make caulk. Acrylic and latex are recommended for most applications, and silicone is a necessary ingredient for waterproof caulking around areas such as bathtubs or sinks. The most toxic chemical found in caulks is mineral spirits, a mixture of toxic, petroleum-based solvents that are classified as volatile organic compounds (VOCs). Because different waste chemicals from the crude oil refining process are used each time mineral spirits are made, and several different substances are referred to as “mineral spirits,” the specific contents of them are often indeterminable. According to the Agency for Toxic Substances and Disease Registry, breathing mineral spirits “can affect your nervous system and cause dizziness, headaches, or a prolonged reaction time. It can also cause eye, skin, or throat irritation.”
DAP’s Acrylic Latex Caulk (available with or without silicone) does not contain mineral spirits or any other hazardous chemicals on the required reporting list, according to its Material Safety Data Sheet (MSDS). One hundred percent silicone formulas such as Dow Corning’s 100 Percent Silicone Sealant are also made without mineral spirits and are inert when dried. Both products are widely available. Another good choice is Safecoat Caulking Compound, a nontoxic, water-based caulk made from a modified acrylic copolymer.
Debra Lynn Dadd is an internationally known expert on healthy home environments and author of Home, Safe Home (Putnam, 1997).