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Highlights in Chemical Science

News from across RSC Publishing.



The fate of cadmium in fish


17 February 2006

The response of fish and eels to cadmium in water will open up the possibility of tracing toxic and essential elements in humans, say scientists in Spain. 

Alfredo Sanz-Medel and colleagues at the University of Oviedo have looked at cadmium's harmful effects on eels using a method that distinguishes new cadmium uptake from naturally present cadmium. 

They used mass spectrometry to measure two isotopes of cadmium in eel tissues; cadmium-111, which was used as a tracer, and naturally-occurring cadmium-114. The group exposed the eels to water containing the tracer and then measured the cadmium isotope ratio in the tissue. They calculated how much cadmium the eel had taken up from the water by comparing the isotope concentrations in both eel and water. 

Eel
In fish and eels cadmium is stored primarily as metallothioneins, metal-containing proteins which bind strongly to heavy metals. By analysing the metallothioneins in eel livers and kidneys, Sanz-Medel traced the creatures' response to cadmium exposure. 

Sanz-Medel and his team found that eels responded to increased cadmium levels by producing more metallothioneins. They also found that the naturally present cadmium-114 isotope was redistributed from the liver to the kidney. 

It should now be possible to look at the uptake and fate of other elements, essential and toxic, said Sanz-Medel. He also thinks his method could even be extended to humans. 

Clare E Boothby 

References

A Rodríguez-Cea, M R Fernández de la Campa, J I García Alonso and A Sanz-Medel, J. Anal. Atom. Spectrom., 2006, 635 (DOI: 10.1039/b515828a)