The dominant species of arsenic in these seaweeds are in the form of arsenoribofuranosides (arsenosugars). These are assumed to be relatively nontoxic to humans and animals as compared to inorganic species.

The arsenosugars are metabolized to different organoarsenic species but mainly to DMA(V) (dimethylarsinic acid) when consumed as a food source.


http://www4.nau.edu/chemwrite/ch_XVII_web_exercises.doc