Not yet investigated
What we have so far
Split samples from one head sent to different laboratories have come back with different results and opposite advice. It is useful for methylmercury and for very little else.
This star is on the map because the show intends to take the question apart properly — the trials, how it is actually tested, whether the thing sold is the thing studied. That work is not done yet, and nothing here should be read as a conclusion. When the investigation is published it will appear on this page.