What is methyl mercury?
Methyl mercury is not the shiny stuff in thermometers (what scientists call “elemental” mercury), but it sometimes starts out that way. When mercury is deposited into water (usually by natural sources like underwater volcanoes), certain bacteria convert it into methyl mercury. Then it enters the food chain in fish. Larger fish usually contain more methyl mercury than smaller fish, because the substance “accumulates” as big fish eat their smaller prey. Although methyl mercury can be toxic at very high doses, the World Health Organization has concluded that “the general population does not face a significant health risk from methyl mercury” in the fish we eat. This is because eating fish — even the fish with the most mercury — doesn’t expose us to enough methyl mercury to be harmful.
