Is Polyurethane Toxic to Your Health and the Environment?

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Materials for wall insulators and furniture coatings are commonly made of polyurethane. Despite its common use in our daily lives, there are still debates that question if polyurethane is toxic to one’s health and the environment.

In this article, I’ll share everything about polyurethane and more about its toxicity and environmental safety. 

Polyurethane Coating: Is it Safe or Unsafe?

According to studies, polyurethane coating has two different reactions on wood floors because of its component, isocyanate. Depending on the number of isocyanates, the cure can be flexible and stiff.

Isocyanates are reactive components that manufacturers used to create foams, fibers, and coatings. Recently, it has also been added to building insulation materials and automobile production. 

When isocyanates are mixed with polyureas, it creates a gel-type coating. But, polyureas react faster than it so it needs to be used immediately after mixing.

polyurethane products

The chemical reaction results in a stiff coating with resistance to water and food-related acids. You can use this coating on your dining table surfaces where you can anticipate acids from food. 

With these in mind, it is a safe material and can be used safely on wood flooring.

Polyurethane Products and Fires

Despite this, users must still practice caution as products are highly flammable and can cause negative health effects. But when it’s used as a building material, I can assure you that it does not emit toxins. 

There is no scientific evidence that supports the theory of the adverse air quality from poly material used at home. 

Neither it is a pollutant to the environment nor a harmful substance from parts made from protective equipment (PE), as there is no scientific basis for this. 

applying water-based polyurethane

Actually, poly coatings and foams in your household provide soundproofing aside from keeping off humidity and there are no health risks for you.

What are the Effects of Poly on Users?

Effects of Fumes from Burned Polyurethane

The decomposition process of polyurethane foams involves burning in a controlled ventilation space. As they burn, the air quality inside buildings diminishes, and nitrogen-rich fumes are released.

Therefore, the effects of polyurethane while burning are harmful to the nearby community and the environment. 

How Long are Polyurethane Fumes Toxic?

Polyurethane fumes can last as long as 21 days and the least the fumes can dissipate is 3 days. 

For instance, for fumes from fast-drying, your waiting time is only a week and a minimum of 3 days. But fumes from water-based polyurethane lasted for 21 days and the oil-based can last a maximum of 30 days.

spraying Deft DFT257 Clear Water Based Polyurethane

When it comes to sensitivity or if you have health conditions, you should look for an alternative place to stay. 

Effects of Poly Fumes Inside Buildings

If you inhale poly that is not cured yet or if there’s a presence of toxic fumes, it can have negative effects on your health. You can experience symptoms such as nausea, vomiting, headache, coughing, and irritations in your eyes and throat.

Can Polyurethane Cause Cancer?

High exposure to uncured furniture surfaces, and floorings, can cause heart, liver, and lung cancer eventually. Therefore, if you are going to use it in your household, you better make sure that it’s cured. 

Uncured material emits an odor caused by isocyanates and other toxic chemicals which are hazardous to humans and pets.

Is it Toxic After Drying Up?

Once its coatings have dried up, it is safe for breathing and the environment. 

dresser top with brown polyurethane finish

To make sure it is completely cured, the coating made of hard wax oils will take a week (7 days) to dry up. Whereas water-based takes two weeks (14 days) and polyurethane made of oil-modified has the longest curing time of a month (30 days) maximum.

Is it Advisable to Sleep Inside the House After Polyurethane Application?

As I mentioned, staying or exposing yourself for a long time like sleeping inside a house after the application is prohibited. 

The quickest time to cure the coating is after 7 days. It depends on your sensitivity, as some people have different tolerance to its odor. Some can tolerate it for 7, 21, or 30 days. 

What is Polyurethane Foam? Is it Toxic and Dangerous?

There are theories about polyurethane foam being a fire hazard and dangerous when used at home. But polyurethane foam as a wall insulator is highly combustible. To prevent this, you can use flame retardants to establish safety measures in your household. 

On a side note, polyurethane foam can be stabilized after it was formed. All the chemicals mixed are non-irritants, however, the release of volatile organic compounds (VOCs) due to the off-gassing process is alarming.

house interior painted with KILZ Original Primer

Depending on the type of polyurethane foam, the emission of volatile chemicals is not similar to each foam. For instance, memory poly foam can off-gas more VOCs than your typical inner-spring polyurethane foam. 

According to experts, polyurethane foam with more foam material gives lesser VOCs. This will decrease air flow inside the foam layering.

What is Thermoset Poly Foam? Is it Toxic?

The result of combining oxygen, carbon, hydrogen, and nitrogen makes up thermoset poly foam. In its natural state, it is classified as safe for the environment and non-toxic. 

But it can be hazardous if carbon dioxide, a blowing agent is present or mixed with it. Carbon dioxide is what makes it soft and comfortable, such as in mattresses and sofas.

Pallet Sofa With Storage

According to studies, blowing agents cause the build-up of toxic gases and other residues in the material over time. 

Risks Associated with Polyurethane Foaming

If you are decided to use polyurethane foam and coating in your household, you should be aware of the risks or dangers it poses. 

See Also: Is Epoxy Resin Food-Safe? 

Isocyanates (TDI and MDI): Are They Carcinogenic?

Chemical formulations in these products can be harmful because of some ingredients such as isocyanates, blowing agents, and flame retardants. 

Isocyanates such as methylene diphenyl isocyanates (MDI) [1] and toluene isocyanates (TDI) are highly reactive components that can cause health issues. The latter is a potential carcinogen ingredient when inhaled during the process.  

Are they Irritants in the Respiratory System?

Aside from carcinogenic, isocyanate compounds trigger preexisting respiratory conditions. You can also develop allergies after long exposure to the substance.

preparing Rust-Oleum 284470

During the application or if you cannot avoid being exposed to it, you need to use standard protective industrial gear such as gloves, goggles, and PE. And for best protection, you can use a high-quality respirator

How Can You Stay Safe While Using Polyurethane?

Aside from wearing gloves, goggles, and PE, you should also avoid breathing the vapors from polyurethane finish. The moment you inhale VCOs from polyurethane foam, the irritants immediately react with moisture in your body, particularly in the lungs.

Another thing, you should prevent direct contact with it. As much as possible, wait for it to dry up. If you are going to remove it, you need to follow the procedure. 

If you’re accidentally exposed, wash your body area with soap and water. You can also use hand cleaner cream.

Is there a Food-Safe Transparent Coat?

Food-safe transparent coating is specifically designed to comply with food safety regulations and is safe for direct contact with food items.

This coating includes natural components such as beeswax and mineral oil. However, you can only use these options if you just need to restore the natural state of wood surfaces.

Next Read: Finishing Wood with Beeswax 

mixing Minwax Water-Based, Oil-Modified Polyurethane

Is Polyurethane Safer than Alternatives?

There are some best materials as natural latex which are safer as your alternatives. Tung oil and linseed oil can be your options if you want to enhance the appearance and improve the durability of the wood surface. 

Tung oil can dry quickly in 2 days and is less hazardous. Other alternatives are candelilla wax, shellac, lacquer, AFM Safecoat, and varnish. 

See Also: Polyurethane vs Lacquer

Regulations and Laws Regarding Polyurethane

There are laws regulating its use and manufacturing such as European Union and USA Laws stated.

Europe Laws

According to European regulations, products made from polyurethane are considered to have no harmful impact on health or the environment. These laws indicate that the components of polyurethane are non-toxic. Nevertheless, they do acknowledge that the fumes it releases can lead to respiratory issues.

USA Laws

Meanwhile, the USA laws regulates the use of polyurethane products to prevent health problems for their customers. The National Health and Safety Administration or EPA implemented a 90-day notification rule for the manufacturing process. 

applying polyurethan on stairs

This is part of the Toxic Substance Control Act of the USA laws. In this way, the EPA can evaluate the chemical and can prohibit the percentage of chemicals to be used.


I hope that this guide answered whether or not polyurethane is toxic to your health and the environment. To emphasize, its products are non-toxic as long as it’s cured properly. Also, you have to make sure that there’s proper ventilation to improve indoor air quality. 

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Robert Johnson is a passionate furniture maker & carpenter, sought after for his knowledge on the craft.
You’ve probably seen his down-to-earth wisdom in USA Today, Bobvila, Family Handyman, and The Spruce, where he has shared commentary and guidance on various woodworking topics.

Robert is the brain behind Sawinery, where he aims to share tips, tricks, and a passion for all things carpentry.

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