I didn’t know until reading this report, but coal burning releases mercury into the atmosphere. Eventually, that ends up in the sea, and evaporating water can have it suspended in coastal fog. Humans and other animals breathe it in. It penetrates plants. Animals eat the plants, and humans eat both plants and animals.
And it is a deadly toxin: “Elemental and methylmercury are toxic to the central and peripheral nervous systems. The inhalation of mercury vapour can produce harmful effects on the nervous, digestive and immune systems, lungs and kidneys, and may be fatal.” World Health Organization.