Boat Bottoms, Barnacles and Modern Medicine:
Dan Rittschof Hopes the Drug Store Will Offer a Safe Substance
to Keep Barnacles Off Boats
By Tinker Ready
There are happy clams and for a while, there may have been
a few extra cheerful barnacles in Professor Dan
Rittschof’s lab. In his search for a new
compound to keep the pesky shellfish from clinging to boats,
the Nicholas School zoologist fed small doses of a popular
antidepressant to barnacles. He wasn’t thinking the
medicine would relax the tiny arthropods so they would loosen
their costly and invasive grip. Antidepressants just happened
to be among the drugs he used to test the theory that human
pharmaceuticals might chemically—and safely—thwart
a barnacle’s ability to settle on ships.
The tests established proof of principle. Now comes the hard
part.
After 20 years of trying to find a replacement for the effective
but toxic tin-laden paint that protects the hulls of most
of the world’s ships, Rittschof learned that there are
no simple solutions. The original idea was to find something
that was environmentally benign, so it made sense to look
for naturally occurring compounds. And, there seemed to be
candidates among the many marine organisms that continuously
produce antifoulants. But, “natural” does not
necessarily mean simple or benign. Rittschof found the technical,
financial and regulatory barriers to bringing such a product
to market prohibitive.
“I pretty much had reached a dead end,” he said.
“I went from natural products, which are relatively
complex models, to looking for things that were a dollar a
pound that prevent barnacle settlement.”
Willing to cast his intellectual net in places others might
overlook, Rittschof may have found what he was looking for
in his medicine cabinet. By recognizing the metabolic similarities
in humans and barnacles, Rittschof and a collaborating group
in Singapore have identified many common medications that
prevent the critters from attaching to boats and pilings.
But it took two decades and six untapped patents before Rittschof
reached that point.
The stakes in this search are extremely high. Boats encrusted
with barnacles, algae and other shellfish are slower and burn
more fuel. Virtually all of the world’s boats—cargo
ships, cruise liners, oil tankers and pleasure craft—use
paint laced with toxic tributylin (TBT) to keep them off.
In the 1970s, the TBT paint was seen as an improvement over
older lead and arsenic-based coatings. But, studies found
that the compound can persist in the environment and decimate
sea life, including human foods such as oysters, clams and
mussels.
In response to the unacceptable environmental impacts of
TBT, the World Maritime Organization, an arm of the United
Nations, is banning the substance as of 2003. In July, the
European Union—which banned the use of TBT and other
organotins on pleasure boats in 1989—extended the ban
for all member ships. As a result, some companies have turned
to copper-based paints. But they too can be harmful and are
banned in some countries.
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