Antifouling boat paints prevent marine plants and organisms from damaging boat hulls. They work by continuously releasing chemicals into the water (most commonly copper), which prevent organisms from attaching to boats, but these chemicals are also harmful to fish and other marine life.
Irgarol (also known as cybutryne), is another common ingredient added to make boat paints more effective. It has been found to be more toxic and harmful to marine life than previously believed. As of Jan. 1, 2023, irgarol paints are banned by Washington law for use on recreational vessels.
In 2011, Washington adopted the Antifouling Paints Law to gradually phase out copper-based antifouling paint. As part of the law, we agreed to study antifouling paints and how they affect marine organisms and water quality. We studied peer-reviewed science on antifouling paints and their hazards. These reviews showed that non-copper antifouling ingredients might be more environmentally harmful than copper. As a result, the law phasing out copper paints was postponed.
Learn more about our studies:
While copper is the most common toxic chemical that antifouling boat paints release into the water, our studies also looked at other non-copper ingredients currently on the market, including:
- Zinc pyrithione
- Irgarol (cybutryne) (banned as of 2023)
- Sea-Nine (DCOIT)
- ECONEA (tralopyril)
There are also non-biocidal options available, such as boat washes, sonic cleaning systems, liner systems, and drive-in dry docks. However, some options are not readily available, and we do not know the performance and tradeoffs of these options yet.
What is the future of copper antifouling paint?
If we find safer alternatives that are feasible, reasonable, and readily available by June 30, 2024, Washington law will restrict the use of most copper-based antifouling paints beginning Jan. 1, 2026.
If we do not find safer and effective alternatives by then, the ban will not take effect. We will then continue to study scientific literature and submit a new report by June 30, 2029.
We are currently working with Washington State University to conduct performance testing on a variety of antifouling paints to better understand how they work in Washington's waters.
Frequently asked questions
As part of our 2019 review, we used scientific modeling to predict how antifouling ingredients might function in Washington marinas. We concluded that Irgarol is more dangerous to the environment than previously believed.
In 2020, Washington adopted a prohibition on irgarol law (Chapter 70A.445.070 RCW) that bans the use of irgarol paints on recreational vessels as of Jan. 1, 2023. This law prohibits:
- Sales of boat paints containing irgarol.
- Application of hull paints containing irgarol.
- Sales of new boats painted with irgarol paints.
These restrictions are part of a worldwide effort to phase out Irgarol paints for commercial and recreational water vessels. In addition, beginning Jan. 1, 2023, the Environmental Protection Agency (EPA) will not allow paints containing Irgarol to be registered and sold in the United States.
Used boat sales are not affected by the new restriction, and boat owners are not required to remove existing Irgarol paint.
When boats are kept in marinas, lakes, and other water bodies, they are exposed to organisms like bacteria, algae, mollusks, barnacles, and mussels. When these organisms grow and colonize on the bottoms of boats (hulls), it’s called fouling. Fouling makes boat hulls rougher, which increases drag, fuel consumption, and reduces speed.
Antifouling boat paints prevent organisms from growing on boat hulls.
Copper is highly toxic to fish and other aquatic species. It interferes with their sense of smell, making them more vulnerable to predators. It also reduces their ability to return to their spawning streams. Young salmon are especially susceptible to the effects of copper.
Copper contaminates our waterways through:
- Antifouling boat paints.
- Copper brakes (also banned).
- Water pipes.