Organic Booster Research Articles

Antifouling Paint Booster Biocides in the UK Coastal Environment and Potential Risks of Biological Effects

In the yachting sector of the UK antifouling market, organic biocides are commonly added to antifouling preparations to boost performance. Few data presently exist for concentrations of these compounds in UK waters. In this study the concentrations of tributyltin (TBT) and eight booster biocides were measured before and during the 1998 yachting season. The Crouch Estuary, Essex, Sutton Harbour, Plymouth and Southampton Water were chosen as representative study sites for comparison with previous surveys of TBT concentrations. Diuron and Irgarol 1051 were the only organic booster biocides found at concentrations above the limits of detection. Diuron was measured at the highest concentrations, whilst detectable concentrations of both Irgarol 1051 and diuron were determined in areas of high yachting activity (e.g. mooring areas and marinas). Maximum measured values were 1421 and 6740 ng/l, respectively. Lower concentrations of both compounds were found in open estuarine areas, although non-antifouling contributions of diuron may contribute to the overall inputs to estuarine systems. TBT was found to be below or near the environmental quality standard (EQS) of 2 ng/l for all samples collected from estuarine areas frequented by pleasure craft alone, but with much higher concentrations measured in some marinas, harbours and in areas frequented by large commercial vessels. Using the limited published environmental fate and toxicity data available for antifouling booster biocides, a comparative assessment to evaluate the risk posed by these compounds to the aquatic environment is described. TBT still exceeds risk quotients by the greatest margins, but widespread effects due to Irgarol 1051 and less so diuron cannot be ruled out (particularly if use patterns change) and more information is required to provide a robust risk assessment.

Antifouling Paint Booster Biocide Contamination in UK Marine Sediments

The proposed International Maritime Organization (IMO) ban on tributyltin (TBT) as an antifouling paint biocide, will raise the inevitability of the increased use of alternative paints containing copper and organic booster biocides. Although the fate of TBT in marine sediments has been extensively studied, very little work has been performed to assess the accumulation of organic booster biocides in sediments. A survey was conducted to determine concentrations of TBT, Irgarol 1051, the Irgarol 1051 metabolite GS26575 (2-(tert-butylamino)-4-amino-6-(methylthio)-1,3,5-triazine; also referred to as M1) and diuron in coastal and off-shore sediments. TBT was consistently determined at the highest concentrations and was detected in all sediments collected from Southampton Water, UK, along with the TBT degradation product dibutyltin (DBT). Irgarol 1051 was detected (0.01–0.11 μg/g) in some sediments collected from marinas, where high concentrations of these compounds have been measured in surface waters. The Irgarol 1051 metabolite 2-methylthio-4-tert-butylamino-6-amino-s-triazine (M1/GS26575) was only detected at a few locations at concentrations <0.001 μg/g, although higher concentrations were determined in surface waters (13–99 ng l −1 ). Diuron, thought to be present in the form of antifouling paint particles, was determined at a concentration of 1.4 μg/g in an enclosed marina. All analytes were found to be below the limit of detection in the sediments collected off-shore. The potential accumulation in sediments of the other two booster biocides currently used in the UK, zinc pyrithione and dichlofluanid, are also discussed.

The TBT Ban: Out of the Frying Pan into the Fire?

There is concern that organic booster biocides in the antifouling paints which will replace tributyltin (TBT)-based coatings could cause serious environmental damage. Domination of world markets by TBT-based paints inhibited research on alternative formulations, but the advent of the ban on TBT (probably from 2003) has kindled interest in them. Several recent publications stress our incomplete knowledge of the toxicity, sub-lethal impacts and persistence in the environment of these compounds. A particular concern is that synergistic interactions between biocides may enhance their toxic effects. It has been reported that the use of the triazine compound Irgarol as an antifoulant is responsible for environmental levels of this biocide which could affect primary production. It is argued that the ban on TBT-based antifoulants is desirable but, in view of these uncertainties, it should be delayed until alternatives, which have been proved to be less harmful to the environment than TBT, are available. As a result of regulations and developments in paint technology, inputs of TBT into the marine environment are now low, and can be decreased further.

Analytical methods for the determination of 9 antifouling paint booster biocides in estuarine water samples

Analytical procedures for the determination of nine organic booster biocides which are currently licensed for use in marine antifouling paints, and are thought likely to occur at concentrations in the ng 1 −1 range in estuarine water samples, are reviewed. A robust multiresidue method for the determination of four compounds (chlorothalonil, dichlofluanid, diuron and Irgarol 1051) is suggested. A route for the development of a method for the analysis of zinc pyrithione is outlined, based on an extraction method and subsequent derivatisation prior to determination by HPLC with fluorescence detection. Methodology for Zineb, Kathon 5287, TCMS pyridine and TCMTB is less clearly defined.

Alternative antifouling biocides

In response to increasing scientific evidence on the toxicity and occurrence of organotin residues from antifouling paints in the aquatic environment, the use of triorganotin antifouling products was banned on boats of less than 25 m length in many countries during 1987. The use of tributyltin (TBT) products on small boats was superseded by products based on copper, containing organic booster biocides to improve the efficacy of the formulation. Available information and evidence on the occurrence, fate and toxicity of these biocides is reviewed. It is concluded that increased copper concentrations in the aquatic environment, due to the increased use of copper-based antifoulants, do not have significant effects on marine ecosystems. However, lack of validated analytical methods, limited monitoring data, and very little information about the fate and toxicity of the booster biocides in the aquatic environment, make accurate risk assessments in relation to these compounds difficult. Copyright © 1999 John Wiley & Sons, Ltd.