Antifouling paint manufacturers are reporting that Irgarol, a pesticide commonly used as a boosting agent in antifouling paints, is in short supply in the United States. Based on what we have learned, it seems likely that the supply of paints containing this pesticide will be exhausted sometime this year. For some makers, their supply will run out as early as this spring.
Bottom paints containing Irgarol are usually marketed as having a boosting agent that enhances the paints protection against algae, soft growth, or slime, and are priced around $30 higher than similar formulas without Irgarol. Interluxs Micron Extra with Biolux, Pettits slime-resistant SR formulas such as Trinidad SR and Ultima SR-40 (and SR-60), and Blue Waters Copper Pro SCX paints such as Copper Pro SCX67 (hard and ablative) are examples of these paints. In our most recent test involving 55 different paints, nearly one-quarter of them contained Irgarol.
Given the shortage, it is possible that bottom paints formerly touted as having slime-resistant formulas will no longer contain Irgarol. It is still not clear how manufacturers will handle the naming and labeling of these products, but in the past, some manufacturers have significantly changed the formulas of paints without changing the names.
Buyers will have to look at the active ingredients to determine whether a paint touted as slime resistant actually contains Irgarol 1051. As required by the U.S. Environmental Protection Agency, Irgarol 1051 is prominently listed in the active ingredients, usually under its systematic name, N-Cyclopropyl-N-(2-methyl-2-propanyl)-6-(methylsulfanyl)-1,3,5-triazine-2,4-diamine. It usually represents about two percent of the paint by volume.
After several years of testing paints containing Irgarol, our own findings indicate that paints with Irgarol will be of most value to seasonal sailors who paint their hull every year but do not regularly clean it. Irgarol has not been shown to extend the active life of antifouling paints in our tests, and weve had a hard time discerning any enhanced slime resistance in Irgarol-boosted paints after six months in the water. (Note again the comments in my recent blog post regarding the differences between our panel testing and actual results on a hull.)
If you are a long-term, warm-water cruiser who cleans his or her hull, we don’t see any real benefit of paying extra for a slime resistant paint containing Irgarol. The fact that some paints touted as slime-resistant might not even contain Irgarol offers one more reason to stick with conventional copper paints this season, or those boosted with zinc pyrithione, ZnP, also called zinc omadine. Zinc is a naturally occurring mineral and is found in a wide range of healthcare products, including sunscreen and diaper cream. The paints containing zinc are often among the top-rated antifoulants in our test
Irgarol is in the family of triazines, and is one of several boosting agents introduced by manufacturers after tributyltin, a suspected endocrine inhibitor found to be harmful to marine life, was phased out. We were told that the reason for the Irgarol shortage is that the manufacturer, BASF, has not taken the necessary steps to gain EPA approval to continue manufacturing in the U.S. Recent studies have called into question Irgarols safety, and it is unclear when the manufacturer will meet the EPA requirements.