Zinc

Bluish-white zinc is not found as a free metal, but rather, occurs as a mineral in the Earth's crust. Interestingly, zinc is brittle at room temperatures, but between 100°C-150°C, this metal is quite malleable.

Metallic zinc is used in the production of alloys and in galvanization processes. A thin layer of zinc is electroplated or coated to iron or steel to protect these metals from corrosion. One of the most important zinc alloys is brass, a good electrical conductor with excellent corrosion resistance, that has applications in hardware, water valves, instruments, and communication equipment.

A significant achievement of the National Research Council Canada (NRC) researchers in the 1980s was the resolution of two major crises in the shellfish industry. In late 1987, a new toxic syndrome, now called amnesic shellfish poisoning (ASP), caused the closure of the entire East Coast shellfish industry. A remarkable four-day effort by a research team assembled at NRC Institute for Marine Biosciences determined that domoic acid was the responsible toxin. They also quickly established that the domoic acid contamination was localized to the eastern tip of PEI.

After the discovery of the domoic acid toxin, shellfish farms throughout the East Coast were gradually re-opened, but only if they tested negative in an array of tests, one of which included the standard mouse bioassay for shellfish toxins. Problems arose when oysters from the famous oyster grounds of Caraquet, NB, showed low levels of toxicity in this mouse test. The observed symptoms were unusual and chemical analyses revealed no known toxins.

In a two-week period in February 1988, a team of dedicated researchers from NRC and the Department of Fisheries and Oceans Canada discovered the source of the problem. High levels of zinc were detected in the Caraquet oysters and it was determined that such levels can cause a "false" positive in the mouse assay. Since it was determined that oysters do accumulate high levels of zinc naturally and such levels were not a human health concern, the oyster grounds were re-opened promptly.

Additional Information

Learn more about relevant NRC research:

• NRC-Institute for Marine Biosciences