Environmental Engineering Reference
In-Depth Information
Historically, TBT gained widespread application as an effective antifoul-
ing paint biocide on pleasure boats, large ships and docks in the 1970s and
1980s. In the late 1970s organotin-containing antifouling paints were found
to cause detrimental effects on marine and freshwater biota, however. As TBT
leaches directly into water, relatively high contamination of pleasure boat and
commercial harbors and their surroundings, areas with high shipping activi-
ties, and coastal areas result. Detrimental effects on oysters [5] shed light on
the ecotoxicological impact of this toxicant. Subsequent studies confirmed the
general hazard of TBT and triphenyltin (TPT) to aquatic ecosystems [6-8].
Reports on detrimental effects on marine neogastropods [2, 9, 10] played
a major role in establishing the link between their sterilization due to mas-
culinization, population decline and TBT contamination. Additional studies
about the contamination of marine [11] and freshwater [12-14] environments
contributed significantly to the adoption of regulatory standards for TBT in
antifouling paints, their restrictions and banning in small boats. Triphenyltin
(TPT) has been employed formerly as a co-toxicant in antifouling paints and
found in freshwater [14] and marine environments [15-17], however, it is
mainly used in agriculture as a fungicide in crop protection.
Originally, studies on organotins were devoted to the toxicity assessment
in aquatic organisms and mammals including the search for modes of action.
When environmental effects were observed in the 1980s, studies focused on
the development of analytical techniques to determine trace levels of organo-
tins in ecosystems. Surveys in aquatic ecosystems and effect studies revealed
in combination with fate studies a clearer picture about the environmen-
tal behavior, hazards and risks of organotins. The use of TBT-containing
antifouling paints has been controlled or banned in developed countries, re-
sulting in a decrease of TBT contamination of coastal and harbor waters.
France banned the use in 1982 on boats of < 25 m in length, and the UK fol-
lowed in 1987. In addition, an environmental quality standard of 20 ng L -1
for freshwater, and 2 ng L -1 for seawater had been set [3]. Many other coun-
tries regulated TBT-containing antifouling paints for large ships, and prohib-
ited the use on vessels < 25 m in length (European Community in 1990), or
implemented a sales ban (e.g. 1990 in Switzerland and Germany). Today, re-
strictions for small boats are implemented in developed countries and the
contamination declined [18, 19]. However, TBT-containing antifouling paints
remain an important source. In developed countries, organotin levels are still
often higher than effect concentrations for most susceptible organisms. An
important move forward was made by the International Maritime Organiza-
tion (IMO) by a convention adopted in 2001 prohibiting the use of harmful
organotins in antifouling paints used on ships and establishing a mechan-
ism to prevent the potential future use of other harmful substances therein
(IMO, www.imo.org). By January 2003, all ships should not apply or reap-
ply organotin-containing antifouling paints, and by January 1, 2008, all ships
shall not bear such compound on their hulls. However, despite the European
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