EurOCEAN 2000 - Vlaams Instituut voor de Zee

INTRODUCTION
Antifouling paints are a necessity for shipping operators and are considered to be indispensable
by owners of small boats. Consequently, the market for antifouling paints is large and is
important from a commercial point of view. Successful products are used in large quantities
and, as a result, concentrations of antifouling agents may be high, in particular at hot spots such
as marinas, harbours and near shipping lanes with high traffic densities. Without a wellfounded
management strategy, however, large environmental problems may lay await and
environmental managers urgently need information and tools which allow them to assess
environmental impacts of such new products.
Attention was initially drawn to one of these alternative antifouling products: 2-methylthio-4tertiary-butylamino-6-cyclopropylamino-s-triazine
(trade name IRGAROL 1051). This is a
triazine herbicide (in the same family as atrazine and simazine) which has proven to effectively
inhibit the primary colonisation of hulls by algae. Following development of suitably sensitive
analytical techniques, concentrations of up to 1.7 µg/L were found in marinas with widespread
contamination throughout the Côte d'Azur coastline (Readman et al., 1993). Subsequent
surveys (Tolosa et al., 1996) indicate that levels have remained comparatively stable. Since
this initial work, other scientists have also reported comparable levels of contamination from
IRGAROL 1051 (Gough et al., 1994; Toth et al., 1996; Zhou et al., 1996; Ferrer et al., 1997;
Scarlett et al., 1997 & 1999; Ferrer & Barcelo, 1999; Biselli et al, 2000; and Thomas et al.,
2000). Pearce (1995) appraised the situation with regard to the contamination from IRGAROL
1051 reporting further unpublished discoveries. He also described assessments by the
pesticides division of the Swedish inspectorate who concluded that the compound tends to
accumulate in fish, degrades "very slowly" in aquatic environments and is likely to accumulate
in waters and sediments. Indeed, the question of potential environmental effects has generated
considerable speculation. The manufacturers (Ciba Geigy) have published some toxicological
data relating to "acute" toxicity (1988, IRGAROL 1051 in antifouling paints, Technical
Bulletin 03/88-31). The minimal inhibition concentrations (MIC) for the alga Enteromorpha
intestinalis and various diatoms (including species of Navicula, Nitzschia, Amphora, and
Achnanthes) were reported to be 10 µg/L. No information was, however, available for sublethal
effects. Dahl & Blanck (1996) described experiments which demonstrate that
IRGAROL 1051 can significantly inhibit periphyton photosynthetic activity at levels as low as
about 20 ng/L (Dahl & Blanck 1996). Also macroalgal reproduction-related processes are
affected at low concentrations (120 ng/L for significant inhibition of growth of Enteromorpha
intestinalis spores, Scarlett et al., 1997). Even vascular plants in the marine environment
(Zostera marina) have been shown to be affected by 200 ng/L (Scarlett et al., 1999). These
toxic levels are within the concentration ranges reported for environmental samples. This
raises the question as to whether or not coastal ecosystems are at risk (Pearce, 1995; Readman,
1996; Evans et al., 2000; and Thomas et al., 2000). Results indicate that perturbations in
phytoplankton communities will occur with the current levels of contamination.
Thus, for just this one of the alternative/additive antifouling agents the potential for
environmental damage has already been demonstrated. Negligible information is available
concerning the others. The final product of this project will be to provide an assessment of the
potential impact from the various antifouling agents and to recommend preventative measures
and/or remedial/advisory actions where necessary.
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