fish, and the well-known deleterious effects of mercury upon the nervous system, the toxicological significance of this uptake route needs to be assessed," said Claude Rouleau, Ph.D., a research scientist at Environment Canada's National Water Research Institute and the study's primary investigator (Rouleau did the work at the Swedish University of Agricultural Sciences, Uppsala, and completed it for publication while at the Maurice Lamontagne Institute-Department of Fisheries and Oceans Canada, in Mont-Joli, Quebec). "The accumulation of mercury or other toxic chemicals in the brain via water-exposed nerve terminals may result in an alteration of these functions and jeopardize fish survival. We believe that uptake of metals such as mercury and the subsequent transport along sensory nerves is a process common to all fish species, and in this respect, it is possible that other toxins (such as pesticides) also could reach fish brains in this way and this is a subject worthy of further study."

Rouleau also said that while chemicals in the brains of such fish may not have direct human implications (people generally don't eat fish brains), the survival of these species does affect humans. "However, the fact that mercury is transported along fish nerves can be extrapolated to humans, as nerve transport also occurs in mammals, including humans," said Rouleau. "Thus, mercury and other toxins could possibly accumulate in human brains via nerve transport." Earlier research has shown that manganese, cadmium and mercury can be taken through the nasal mucosa of rodents and transported to the brain through the olfactory nerves.

The study's other main investigator was Professor Hans Tjalve of the Swedish University of Agricultural Sciences.

The accumulated mercury was located by whole-body autoradiography (used by the pharmaceutical industry to see how drugs are distributed throughout the body). Fish were exposed to radioactive mercury, frozen, then cut into very thi
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Contact: Mary Stanik
m_stanik@acs.org
202-872-4065
American Chemical Society
7-Sep-1999

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