When it comes to finishes, the last thing you want is to risk anyone’s health. Sure, bumps and scrapes happen, but unknowingly exposing others to harmful chemicals is a no-go.

That’s why understanding the truth about polyurethane is essential.

Today, we’re tackling the big question, “Is polyurethane toxic?”—and it’s going to be eye-opening.

So, let’s get into it.

Is Polyurethane Toxic?

Polyurethane is safe when used the right way. Once it’s fully cured, it’s non-toxic and durable, unlike some other finishes. But when it’s still drying, it can release fumes that might irritate your lungs. Just make sure you have good ventilation during and after applying it, and you can safely use it indoors.

What Makes Polyurethane Toxic? (Uncured)

Volatile Organic Compounds

VOCs are gases found in many household items. Sprays, air fresheners, glues, and pesticides release them.

These chemicals play a big role in polyurethane’s toxicity. So, knowing about VOCs helps you understand potential health risks.

~Health Effects of VOC Exposure

Even short exposure to small amounts of VOCs can have effects. You may feel headaches, dizziness, or even nausea. Sometimes, there’s nasal irritation or asthma symptoms too.

However, with long-term, high exposure, risks become greater. Serious issues can develop, like central nervous system damage. The liver and kidneys can also suffer, and there’s even a cancer risk.

Isocyanates in Polyurethane

Another ingredient to note in polyurethane is isocyanates. They’re essential for making polyurethane strong and durable. But isocyanates can cause asthma-like symptoms and respiratory irritation.

They may irritate the eyes, nose, skin, and throat. While these are serious effects, isocyanates don’t cause cancer in humans. They do pose risks to animals, though, so handling them carefully is key.

~Isocyanate Exposure Risks

Most isocyanate risks happen during the production process. Once polyurethane fully cures, it no longer emits these compounds. This means it’s safe to use in everyday applications.

Uncured Polyurethane Toxicity: Which Type of Polyurethane is More Toxic?

Of the two main types of polyurethane, oil-based polyurethane is more toxic than water-based polyurethane.

Both types emit VOCs, but it is significantly more in oil-based poly. This is because the chemicals needed to make the oil-based polyurethane contain larger quantities of compounds containing VOCs. 

Water based polyurethane

The production process of water-based polyurethanes doesn’t need those chemicals. However, since VOCs are present in many different products, they still find their way in.

For this reason, manufacturers have invested more in improving the durability and scratch resistance of water-based polyurethane. It is a lot easier to get them under the government-approved thresholds, even though they are more expensive to the consumer.

Under What Condition is Polyurethanes Toxic?

There really is only one situation in which polyurethanes are toxic, and that’s during application.

Spraying polyurethane, in particular, is the most hazardous, as it makes it easier for the VOCs and isocyanates to be dispersed into the air, where they can come in contact with the body.

That is why it is important to only apply polyurethane in a properly ventilated environment and to use personal protective equipment.

Once the polyurethane dries, it won’t be toxic again unless someone sets it on fire. In that situation, you should put out the fire quickly and cover your nose with a mask.

Can Polyurethane Fumes Kill You?

No, polyurethane fumes cannot kill unless you have a severe allergic reaction. As mentioned earlier, constant and intense exposure to high levels of VOCs can have adverse effects. These high levels are rare in household products unless you stick your head in a can for hours.

Oil based polyurethane

If you have asthma, then you should take every precaution when applying polyurethane or any type of paint or finish, for that matter.

What do I do if Polyurethane Falls on My Hand?

If polyurethane gets on your hand, use some mineral spirit to remove polyurethane from your hands. For water-based polyurethane, all you’ll need is soap and water.

Alternatively, you can rub in baby oil, vegetable oil, or peanut butter and wash it off with dish soap. Remember to rub some lotion afterward, as it can significantly reduce the natural oils in your skin.

Polyurethane on your skin will not necessarily cause irritation, but some people are allergic to the chemicals in them.

What do I do if Polyurethane Enters my Eyes?

On the off chance that polyurethane enters your eyes, rinse them under clean, running water for fifteen minutes, and then go see a doctor immediately.

Even though polyurethane is unlikely to cause any permanent or significant harm when treated with flushing, it’s better to err on the side of caution.

What Happens if you Swallow Polyurethane?

When polyurethane enters the mouth, it reacts with our internal fluids and forms a glue. This glue keeps expanding and can cause blockage to our esophagus or stomach.

If you should mistakenly swallow small quantities of polyurethane, you might be able to flush it out by drinking lots of liquid. 

However, you should still see a doctor because the effects might not be realized for hours.

Is Polyurethane Toxic to Pets?

Yes, polyurethanes are toxic to dogs and pets, especially oil-based polyurethane. While the smell alone can cause irritation, prolonged exposure to the VOCs and isocyanates can lead to cancer.

Is Polyurethane Toxic to Pets

If an animal should swallow polyurethane, you need to take it to the vet immediately. As the glue swells, it can perforate the esophagus or the stomach, which could lead to death. Therefore, it is imperative to store your chemicals securely before and after use.

Polyurethane Safety: How to Protect Yourself While Using Polyurethane?

To avoid polyurethane fumes side effects, the two most important things you need to do are:

  • Work in a well-ventilated space and
  • Use personal protective equipment. When spraying polyurethane, wear overalls and gloves.

You should also wear gloves when applying oil-based polyurethane. As mentioned earlier, this may not cause irritation to all users, but it does to some.

It is also important to wear goggles, as you definitely don’t want them splashing into your eyes.

After applying polyurethane, leave the area and come back to it in a few hours when it should have dried. It is imperative not to stay there while it dries.

Make sure no kids, pets, or anyone with allergies are close by during and immediately after application.

When using oil-based polyurethane, you might need to keep the room or house vacant for three to four weeks so that the poly can cure.

Interesting Read: Is Wood Stain Dangerous?

5 Alternatives to Polyurethane 

1. Varnish

Varnish is a clear, transparent protective coating similar to polyurethane in many ways. Technically speaking, polyurethane, shellac and lacquer are also referred to as varnish.

2. Shellac

Shellac is an amber-colored finish derived from the excrement of the female lac bug, found on trees in Thailand, Burma and India. Shellac is resistant to UV light and is eco-friendly.

3. Tung oil

Tung oil is one of the oldest finishes in the world, derived from the seed of the tung tree native to China, hence also called Chinese wood oil. It provides a warm, natural look to wood surfaces.

However, you should not apply poly over tung oil, as it won’t adhere properly. If you want to add additional protection, apply more coats of tung oil instead.

4. Linseed oil

Linseed oil or flaxseed oil is a natural oil derived from, well, flaxseed. Linseed oil can be used on its own or in other finishes such as varnish, stains and paints.

5. Lacquer

Lacquer is a popular finish used on cabinets and a lot of high-end furniture. Despite being a very thin finish, it dries hard and is very durable.

Polyurethane Toxicity to Humans FAQs

Is polyurethane toxic after it dries?

No, polyurethane is not toxic once it has fully dried (cured). What makes polyurethane toxic are the VOCs it emits and the presence of isocyanates. Both of these are rendered harmless once polyurethane has been cured, which takes roughly three weeks for water-based polyurethane and four weeks for oil-based polyurethane.

Is polyurethane toxic to sleep on?

Polyurethane is safe to sleep on once it’s fully cured since it won’t release fumes anymore. But right after it’s applied, it can give off some fumes that may irritate your breathing. To be safe, let it air out well for at least 24 to 48 hours before sleeping on it.

How long do polyurethane fumes last?

The fumes from polyurethane last 21 days for water-based polyurethane and 30 days for oil-based polyurethane. For fast-drying variants, the time frame reduces significantly to as little as just 3 to 7 days for water-based polyurethane.

Polyurethane fumes side effects

When not fully cured, Polyurethane fumes have several side effects such as asthma and difficulty breathing for people with respiratory conditions. Polyurethane fumes can also cause irritation of the eye, nose, and throat; vomiting; headaches; shortness of breath, and dizziness.

Is polyurethane toxic to skin?

Polyurethane can be a bit irritating to the skin, especially before it’s fully cured. If it touches your skin, it might cause some redness or itching. But once it’s cured, it’s generally safe to touch. Just remember to wear gloves while applying it, and wash any skin that comes in contact.

Conclusion

Is polyurethane safe? Well, polyurethane is toxic, but it doesn’t pose any real threat when appropriately handled. As long as you follow the instructions set by the manufacturer, use protective equipment and work in a ventilated environment, you’ll be fine.

However, suppose you have experienced any of the symptoms mentioned above while applying polyurethane. In that case, that may be a sign of allergies, and you should consult your doctor.

If you would prefer to minimize risk, stick with water-based polyurethanes.

1 thought on “Is Polyurethane Toxic or Safe?”

  1. Question.
    Can a newborn baby and/or a pregnant woman move into a house where the flooring work is just finished? Will it be safe? Do we need to wait for 21 days for water-based polyurethane and 30 days for oil-based polyurethane to dry?

    Reply

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