Louisiana State University fish toxicologist Kevin Kleinow has found that the dispersants used in the Gulf increase the amount of toxins the fish absorb and then, once exposed, makes it harder for the fish to get rid of the toxins through normal biological processes.
As LSU reported last week:
Kleinow, DVM, PhD, is a toxicologist who specializes in environmental
health issues, especially those related to fish. This means he studies
how contaminants in the environment affect fish and how those
interactions may affect other organisms, including humans. With the oil
spill in the Gulf, Dr. Kleinow has redirected ongoing work on domestic
and industrial surfactant input into aquatic environments to dispersant
use with the oil spill. Surfactants, major components of dispersants,
are being examined as to how they may affect the uptake and fate of
petrochemicals in the fish.
Dr. Kleinow postulated
that surfactants discharged in the environment—even at low
concentrations—would alter the uptake, excretion, retention, and
potential toxicity of other chemicals in the environmental food chain.
Subsequent work in his laboratory ... showed that indeed this was true.
That’s what happens with the surfactant; it progressively increases the permeability so more and more compound gets into the animal from the higher contaminant concentration
in the diet in the intestine, increasing bioavailability. In a similar
fashion, but with opposite results, surfactants prevent the
transporter-mediated concentration of contaminants into the bile
necessary for excretion. Leakage back from the bile lowers the amount of contaminant available for excretion. For both venues the net result is increased compound equivalents in the fish.
Surfactants themselves, having low relative toxicity as a group and
hence widespread use in shampoos, detergents and the like, could
facilitate the toxicity of other chemicals potentially much more
hazardous to the fish.
adding dispersants to the water to break up the oil, surfactants in the
dispersants not only increase access of the non-remediated oil to the
fish, but also could cause select toxic compounds in the oil to be
absorbed more rapidly and make it harder for the fish to excrete those
So not only do the dispersants used in the Gulf directly pose health risks to people and sealife (see this, this, this, this and this) and cause the oil to sink so that oil-eating bacteria will break it down much more slowly, but they increase harm to the fish from the oil as well.
And dispersants are apparently still being sprayed.
Hat tip Alexander Higgins.