Arsenic levels in fish need re-evaluating
Freshwater mussels from the Hungarian Danube river have provided clues that arsenic pollution is more widespread than previously thought.
Csilla Soeroes from Corvinus University, Budapest, and colleagues in Austria, have investigated arsenic compounds in mussels from the Danube. Soeroes' group measured arsenic levels using chromatography and mass spectrometry. The main arsenic-containing compounds extracted were two oxo sugars and their sulfur analogues. This is the first time that thio arsenosugars - sugars containing both sulfur and arsenic - have been detected in freshwater mussels.
Toxic heavy metals accumulate in molluscs and transfer to humans through the food chain
Mussels get their food by filter feeding, a process where food particles and small organisms are randomly strained from water. This leads to the accumulation of metals in the mussels' soft body parts. Consequently, the amount of arsenic in these animals reflects the degree of metal pollution in the aquatic environment. Heavy metals can also be transferred from molluscs to humans though the food chain.
Soeroes' work suggests that the arsenic cycle in the freshwater food web is very different from that in marine systems. 'Based on the results the maximal permissible arsenic concentration in fish products will probably be re-evaluated,' said Soeroes.
Remaining challenges include improving extraction efficiency and understanding how thio arsenosugars form. Soeroes plans to extend this research by investigating arsenic compounds in other freshwater species.
C Soeroes et al, J. Environ. Monit., 2005, 7, 688 (DOI: 10.1039/b503897a)