Antifouling paints prevent marine plants and organisms from damaging boat hulls. These paints contain toxic chemicals that harm fish and other marine life. They work by continuously releasing toxic chemicals into the water. These chemicals prevent organisms from attaching to and damaging boat hulls.
Copper is the most common toxic chemical that antifouling boat paints release into the water. Other ingredients, such as Irgarol (also known as Cybutryne), are frequently added to make boat paints more effective. Irgarol has been found to be more toxic and harmful to marine life than previously believed. As of Jan. 1, 2023, Washington law bans the use of Irgarol paints 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)
- DCOIT (Sea-Nine)
- Tralopyril (Econea)
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