Heavy metal toxicity found in Chinese port poses risk to seafood safety

Heavy metals naturally occur in the Earth's crust, but human activities can increase their concentration in the environment, including domestic sewage and waste disposal, fumes from vehicle exhausts, fertilizer runoff, mining and fuel leaks from ships. These elements, such as arsenic, lead and mercury, can be highly toxic even in small amounts and bioaccumulate persistently, proving harmful to humans and wildlife.