The Norwegian Institute of Marine Research has discovered low levels of the antifouling agent tralopyril in farmed salmon and other marine species. Despite these levels being below the safety limit in a laboratory setting, there is no established limit for this non-natural chemical in food and animal feed. The European Food Safety Authority has noted that the residues of trolopyridine in salmon are below the dose that causes health issues in rats, but long-term effects are yet to be determined. The institute is emphasizing the need for more research due to concerns about the potential harm to fish health and gill function from long-term exposure to high concentrations of trolopyridine, especially in fish farms with poor water exchange.