Because toxic chemicals and heavy metal concentrations in fish are unpredictable, I limit fish - containing meals to two days per week. (2ndchance.info)
They recommend keeping the initial metal concentration in these products low to help reduce their environmental impact while still maintaining their ability to fight off microbes. (sciencedaily.com)
And after washing, the shirts still retained their antimicrobial effect even if their remaining metal concentration was low. (sciencedaily.com)