Origin of supply seems fairly important to keep track of: https://www.nature.com/articles/s41598-018-21732-z https://www.nature.com/articles/s41598-018-21732-z

Origin of supply seems fairly important to keep track of: https://www.nature.com/articles/s41598-018-21732-z https://www.nature.com/articles/s41598-018-21732-z > "Distribution of metals and metalloids in dried seaweeds and health risk to population in southeastern China (2018) Most sources report levels low enough to not cause health risks, but eating large quantities ( > 5g day ) is probably not the best idea, and it should be tested for lead, mercury and cadmium (industrial waste sources). Arsenic and iodine are also naturally accumulated in seaweeds, particularly iodine, which while a necessary trace element, can be dangerous in high concentrations.