While much is known about arsenic levels in marine fish, not as much research has been done on their freshwater counterparts.
Arsenic is a ranked as a toxic substance by the Agency for Toxic Substances and Disease Registry. However, there are 100 diverse species of arsenic in existence with diverse toxicological profiles. Some of these species are toxic, and others are not. However, it is important to develop methods that can measure the level of arsenic in food sources, particularly in seafood.
Marine fish typically have higher levels of arsenic, and this area is well studied. But there are very few studies done on freshwater fish, said Chester Lau, a PhD student at the University of Alberta, speaking at the Winter Conference on Plasma Spectrochemistry on Tuesday. Lau and his research group at the university, which is led by X. Chris Le, are investigating arsenic levels in freshwater fish in Alberta, Canada (1).
“Freshwater requires a developed method that requires enhanced sensitivity,” Lau said.
There are approximately 65 species of fish in Alberta, and it is the preferred source of protein for many groups, particularly indigenous communities, Lau said. The team collected fish of 14 species from 48 bodies of water, over a 10-year period (1). To analyze the fish, the team used high performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Their analysis focused on the muscle tissue of the fish, which is the edible portion (1).
The scientists found that Arsenobetaine (AsB) was the predominant arsenic species for most of the samples. Seven unknown species of arsenic were also detected, he said. Arsenic speciation patterns varied across different species of fish. However, there was a comparable proportion of AsB in whitefish and pike. From there, the researchers estimated daily arsenic intake from freshwater fish. If a person eats 100 g of fish per day, for example, then will consume an estimated 1.2 μg of toxic arsenic (1). There are currently no guidelines for arsenic speciation in fish.
There’s more work to be done to fully understand how much arsenic humans can consume from freshwater fish. There is also much variability. However, elucidation and characterization of unknown arsenic species is necessary for an accurate assessment of the risks, Lau said.
A previous version of this story incorrectly identified the name of the researcher.