Sealants are commonly used to protect porous surfaces like wood or natural stone from damage caused by liquid and stains. However, some sealants contain harmful chemicals that can have negative health effects and harm the environment.
The composition of a sealant is dependent on the type and the intended purpose. One concern is that common sealants often contain fluoropolymers because of their oil and water repellent properties.1 Unfortunately, fluoropolymers are a type of PFAS (Per-and Polyfluoroalkyl Substances), which break down very slowly, resulting in buildup in people and the environment over time.3
What to avoid:
The health effects of PFAS are abundant:
PFAS persist in the environment and bioaccumulate because of the strong bonds between their carbon and fluorine atoms.3 This results in PFAS-treated countertops being toxic and continuing to off-gas, especially if you re-seal your countertops over time. PFAS can also migrate from a food preparation surface to the food itself, or to household dust, leading to human exposure.1
PFAS can contaminate the environment and effect human health during manufacturing, use, and eventual disposal.1 This makes PFAS containing sealants incredibly harmful during every part of their life cycle.
Mold- and mildew-resistant sealants may contain fungicides, which can include arsenic. These chemicals should be disclosed, and interior locations that are not prone to moisture should not require mold- and mildew-resistant products.4
Silicone, polyurethane, and hybrid/modified polymer
Sealants that contain silicone, polyurethane, and hybrid/modified polymer often contain phthalates, which are known endocrine disruptors and have been linked to reproductive system damage and asthma. It’s best to avoid these types of sealants whenever possible.2
When specifying sealant and grout:
✓ Encourage manufacturers to fully disclose sealant content and associated health hazards of sealants through transparency documentation.
✓ Prefer caulk-type sealants over spray foam sealants. Spray foam often contains asthmogenic isocyanates and other chemicals of concern.2
✓ If foam sealing products are required, prefer those that are pre-formed, like foam sealant tape.2
✓ For a multi-purpose sealant, look for acrylic, latex, or siliconized latex sealants with very low VOCs (≤ 25 grams per liter).2
✓ Avoid mold- and mildew-resistant products unless necessary, as they often contain arsenic-based fungicides.2
✓ Choose dense slab surfaces such as porcelain or engineered stone that do not require sealing.
✓ Avoid silicone, polyurethane, and hybrid/modified polymer sealants when possible.
✓ If polyurethane or hybrid/modified polymer sealants are required, select phthalate-free products.1
✓ When using silicone sealants, avoid organotin catalysts. Prefer catalysts that are titanium-based.
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