Survey of total and inorganic arsenic content in blue mussels (Mytilus edulis L.) from Norwegian fiords: revelation of unusual high levels of inorganic arsenic

The present study reports the findings of unusual high levels of inorganic arsenic in samples of blue mussels (Mytilus edulis L.). A total of 175 pooled samples of blue mussels from various locations along the Norwegian coastline were analyzed for their content of total arsenic and inorganic arsenic. Total arsenic was determined using inductively coupled plasma mass spectrometry (ICPMS) following microwave-assisted acidic digestion of the samples. Inorganic arsenic was determined using an anion-exchange HPLC-ICPMS method following microwave-assisted alkaline solubilization of the samples. For the majority of the samples (78%) the concentration of total arsenic was below 3 mg kg(-1) wet weight (ww) and inorganic arsenic constituted <9% of the total arsenic (i.e., <0.25 mg kg(-1) ww). However, in some samples higher concentrations of total arsenic were found (up to 13.8 mg kg(-1) ww) and the inorganic arsenic content constituted up to 42% of the total arsenic (up to 5.8 mg kg(-1) ww). These are among the highest inorganic arsenic concentrations reported so far for marine animals. The findings of samples with concentrations of inorganic arsenic above 0.53 mg kg(-1) ww were restricted to sampling sites from two counties, Sogn and Fjordane and Hordaland, whereas samples from the rest of the country showed lower inorganic arsenic concentrations. Consumption of a meal containing 200 g of the blue mussels with the highest content of inorganic arsenic would for a 70 kg person lead to a 10% excess of the provisional tolerable weekly intake (PTWI) value for inorganic arsenic of 15 microg kg(-1) of body weight week(-1).