Environmental Engineering Reference
In-Depth Information
Abbreviations
DBT dibutyltin compounds
DPT diphenyltin compounds
IMO International Maritime Organization
MBT monobutyltin compounds
MEPC Maritime Environmental Protection Committee
MPT monophenyltin compounds
PVC polyvinyl chloride
TBT tributyltin compounds
TBTCl tributyltin chloride
TBTF
tributyltin fluoride
TBTO
tributyltin oxide
TPT
triphenyltin compounds
1
Introduction
The historical development of organotin antifouling paints has two big steps.
The first step was the discovery of tributyltin (TBT) compounds in the 1950s by
the research group of van der Kerk in the Netherlands. The second step was
the discovery of self-polishing antifouling paints in the 1970s. The first step
involved the discovery of the most effective antifouling compounds, although
they exhibit very low toxicity towards mammals, among the many kinds of an-
tifoulants. The second step involved the discovery of polymers with very high
performance as the paints containing the antifoulants and they were used for
a long time. These polymers easily allowed a constant release rate of the an-
tifoulants into seawater and maintained a low frictional resistance to seawater
by keeping a polished smooth surface. This meets the need to reduce the eco-
logical impact of components of antifouling paints that are being released into
the aqueous environment. Leaching occurs by hydrolysis of the painted poly-
mer at the surface of the ships hull by seawater. The self-polishing antifouling
paints have very long lives and are the most cost effective. Almost all vessels in
the world used these antifouling paints. The leaching rates of organotin com-
pounds from the antifouling paint film into seawater from one vessel are very
low. However, as too many vessels release organotin compounds into seawater,
the amount of organotin compounds in seawater in closed sea areas such as
harbors and marinas, gradually increases year by year.
The first use of the organotin-based antifouling boat-bottom paints began
in the early 1960s. In 1974, oyster growers first reported the occurrence of ab-
normal shell growth in
Crassostrea gigas
(the Pacific oyster) along the east
coast of England. However, it was not until the mid 1980s that researchers in
France and the UK began to suggest that the use of TBT in the antifouling
paints was adversely impacting a number of marine species other than the
fouling organisms [1-3].
