Most sealants contain chemicals that can be toxic in certain conditions, but the level of risk depends entirely on which type of sealant you’re dealing with. Dental sealants release trace amounts of a hormone-disrupting chemical that disappear within hours. Household caulks and construction sealants off-gas volatile compounds that irritate your lungs and skin. Driveway sealants made from coal tar contain known carcinogens. Here’s what you need to know about each one.
Dental Sealants and BPA Exposure
Resin-based dental sealants, the kind applied to children’s molars to prevent cavities, contain or release small amounts of bisphenol A (BPA). BPA is a synthetic compound that mimics estrogen in the body, which is why parents often worry about it. The exposure is real but extremely brief: saliva samples taken one hour after sealant placement have shown BPA levels ranging from 90 to 931 micrograms. By three hours, levels drop dramatically. After 24 hours, no BPA is detectable in saliva or blood.
This short burst of exposure has not been linked to any measurable harm. A five-year follow-up study of children who received dental sealants found no significant associations between sealant exposure and behavioral problems, IQ changes, or physical development. The children’s neuropsychological test scores and behavioral assessments were statistically indistinguishable from baseline, regardless of how many sealants they’d received.
If you want to minimize even that brief window of BPA exposure, there’s a simple fix. Having the dentist scrub the sealant surface with a pumice wash and rinse it with water right after placement removes the outermost layer where most BPA sits. This is already standard practice in many dental offices.
Household Caulks and Construction Sealants
The sealants you buy at a hardware store for bathrooms, windows, or gaps around your home are a different story. Silicone, polyurethane, and acrylic sealants release volatile organic compounds (VOCs) as they cure. These are gases that evaporate from the wet sealant into the air you breathe. Federal regulations cap VOC content at 400 grams per liter for interior sealers, though waterproofing sealers can contain up to 600 grams per liter.
Polyurethane sealants deserve extra caution. They contain isocyanates, a class of chemicals that react to form the flexible, durable seal you’re after. Isocyanates are potent respiratory irritants. Inhaling them in a poorly ventilated space can cause chest tightness, coughing, wheezing, and shortness of breath. Repeated exposure can trigger occupational asthma that persists even after the exposure stops. Some isocyanates are also classified as potential human carcinogens. Skin contact causes irritation and can lead to sensitization, meaning your body reacts more severely with each subsequent exposure.
Acute exposure to high concentrations of one common isocyanate (found in spray foam and some polyurethane sealants) can produce headaches, lightheadedness, nausea, and flu-like symptoms that develop four to six hours after exposure and last 12 hours or more. In extreme cases, it can cause fluid buildup in the lungs, loss of consciousness, or coma. These severe outcomes are rare for someone caulking a bathtub, but they illustrate why ventilation matters.
Reducing Your Risk Indoors
Open windows and run fans while applying any sealant indoors. Keep the room ventilated for at least 24 to 48 hours while the product cures, since that’s when VOC off-gassing is highest. Wear nitrile gloves to avoid skin contact, especially with polyurethane products. If you’re using a spray-applied sealant or working in a confined space, a respirator rated for organic vapors is worth the investment. Once fully cured, most household sealants become chemically inert and stop releasing significant amounts of VOCs.
Coal Tar Driveway Sealants
Coal tar-based driveway sealants are the most toxic type you’re likely to encounter as a homeowner. The final product applied to pavement contains up to 35% refined coal tar pitch, a byproduct of industrial coke production. Coal tar pitch is loaded with polycyclic aromatic hydrocarbons (PAHs), a family of chemicals formed when carbon-rich materials are burned or processed.
Of the 22 PAHs evaluated in a CDC study of sealant workers, nine ranged from “possible” to “known” human carcinogens. All nine were detected in the air that workers breathed on the job. Urine tests showed that 89% of workers had levels of a key PAH marker above the threshold associated with genotoxicity, which is cell damage that can lead to cancer. These findings come from occupational settings where workers apply sealant regularly, but the chemicals don’t stay on the driveway. PAHs break down into dust that tracks into homes, washes into waterways, and lingers in soil.
Several U.S. cities and counties, including Washington, D.C., Austin, Texas, and the entire state of Minnesota, have banned coal tar sealants because of these risks. Asphalt-based sealants are a widely available alternative with far lower PAH concentrations. If your driveway was sealed with a coal tar product, the biggest ongoing exposure pathway is dust. Wiping shoes before entering the house and washing children’s hands after playing on sealed surfaces helps reduce contact.
How to Tell What’s in Your Sealant
Every commercial sealant sold in the United States comes with a Safety Data Sheet (SDS) that lists its chemical ingredients and health hazards. You can usually find this on the manufacturer’s website by searching the product name plus “SDS.” Look for the section labeled “Hazardous Ingredients” or “Composition” to see what you’re working with. The “Health Hazards” section will tell you the routes of exposure (inhalation, skin, ingestion) and what symptoms to watch for.
For driveway products, the label will typically say “coal tar” or “asphalt” as the base material. If it says coal tar, consider switching to an asphalt-based product next time. For indoor caulks and sealants, low-VOC and zero-VOC options are available in silicone and acrylic formulas. These cost roughly the same as conventional products and perform well for most household applications.