“And the market keeps growing,” says Sébastien Sauvé, a professor at the Université de Montréal’s Department of Chemistry. “However, we know little about their potential toxicity on human beings and their impact on the environment.

Nanoparticles are made of toxic metals such as cadmium, which is almost as toxic as mercury. “Many studies have shown the negative effects of cadmium on the immune system of different animal species,” he says.

With the help of his colleagues from Environment Canada and the Armand-Frappier Institute, Sauvé chose to study nanoparticles in mussels. “This mollusk is often utilized to measure water pollution levels,” says Sauvé. “But it's the first time we use them to measure the potential toxicity of nanoparticles.”

At the lowest concentration tested, or 1.6 milligrams of nanoparticles per liter, the researchers found a reduction in cell phagocytosis. Simply put, mussels experienced a decreased ability to ingest and digest foreign particles and their immune system wasn’t functioning as well.

Cadmium accumulation was also found in other tissues such as gills and reproductive systems. Researchers also found a reduction in metal toxicity in the gills. “This is unusual,” says Sauvé. “Usually, exposure to metals will increase the level of metal toxicity.”

Sauvé maintains we should be concerned regarding the potential bioaccumulation in birds and aquatic mammals that feed off mussels. Results of his study were published in the November 2007 issue of Aquatic Toxicology.

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