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Cadmium’s Toxic Trick

Research published in Nature Communications has revealed how cadmium, which is accumulating in the food chain due to incorrect disposal of electronic waste, reprograms cells to accumulate the toxic metal until they die.

“Exposure to cadmium can occur due to poor disposal of industrial or electronics waste, and also through cigarette smoke and ingestion of contaminated food,” says Dr Christopher McDevitt of the University of Adelaide’s Research Centre for Infectious Diseases. “We’ve shown, in a model bacterial system, that the chemistry of cadmium allows it to bypass the mechanisms that prevent other metals, such as iron and zinc, from freely entering cells.

“Once inside the cell, cadmium inserts itself into the cell’s metal-sensing machinery, causing it to malfunction and pump out the wrong metal ions while still bringing in more cadmium. This ultimately leads to death of the cell.

“This understanding of how cadmium causes toxicity, at a molecular level, is crucial for developing new strategies for preventing cadmium poisoning,” McDevitt says.

Cadmium is an important metal for a range of electronics industries, and is used widely in nickel–cadmium batteries. Cadmium from industrial waste can leach back into soil and water, and isn’t degraded.

Global cadmium production has risen by more than 1000-fold since the beginning of the 20th century to approximately 20,000 tonnes per year. It is estimated that humans ingest up to 30 µg /day.

“Cadmium isn’t used in biological systems (with one rare exception), which means that cells haven’t evolved ways to deal with this metal when they encounter it,” McDevitt says. “Our findings here open the way for developing new therapies for preventing cadmium toxicity.”