Which form of kelp is associated with the highest risk profile, specifically related to severe iodine overload?

Powder/Extracts/Pills.

The level of risk associated with kelp consumption correlates strongly with its concentration. While consuming fresh, whole seaweed in moderate amounts poses relatively low risk for most healthy people, the danger significantly escalates when consuming concentrated forms. Supplements such as powders, tablets, or extracts are specifically engineered to deliver high nutrient doses within a very small volume. This concentrated delivery mechanism is precisely what causes severe iodine overload, leading directly to the potential for thyroid problems and increased risk of drug interactions, placing them at the highest end of the risk profile compared to less processed forms.