Organic tin compounds, including tributyltin (TBT), have been used in anti-fouling paints to prevent the growth of fouling organisms. Because of its endocrine disrupting properties, the use of TBT in paint for small boats (< 25 m) was banned in Europe in 1989, and since 2008 there has been a global ban on TBT in anti-fouling paints for all boats and ships. However, in spite of a 25-year ban, TBT still leaks into the environment from older underlying layers of paint on some leisure boats.

“This claim is based on the existence of very high levels of TBT in the surface layer of soil in many boatyards and in the water after washing boat hulls with high-pressure cleaners”, says Britta Eklund, Associate Professor at ITM.

New quick method for detecting the occurrence of tin
Until now, the amount of tin compounds could only be measured using chemical analysis, which is both time-consuming and costly. ITM researchers Britta Eklund and Lennart Lundgren, in collaboration with Erik Ytreberg from Chalmers and with funding from the Swedish Agency for Marine and Water Management, have developed a new method based on X-ray fluorescence which can identify and measure the amount of tin and other substances in the layers of paint on boats without damaging the hull.

“X-ray fluorescence is a well-known method used for measuring metal content in various alloys. What is new in ITM’s method is a special calibration that allows for both the identification of substances and in what quantities they exist in the paint layers on boat hulls,” says Britta Eklund.

Measuring with comparative chemical analysis is in progress at various marinas in Stockholm and Gothenburg.

“High levels of tin could mean that there is TBT in the paint layers. Knowing which boats contain TBT, these can be fixed by abrasive blasting, thus reducing the risk of further spread of TBT”, says Britta Eklund.