Why is mercury an environmental concern?

In sufficient concentrations, mercury may cause adverse health effects. Sources of mercury in the environment from human activity include coal-burning power plants, batteries, and fluorescent and HID lamps.

Small amounts of mercury are a necessary component in fluorescent and HID lamps, but when a lamp is broken, crushed, or dispensed in a landfill or incinerator, mercury may be released to the air, surface water, or groundwater. We keep the mercury in fluorescent and HID lamps out of the solid waste stream by recycling.