For those living in urban areas, and even many who don’t, environmental pollution is a persistent fact of life. We see it in the brown haze on the horizon, the black soot covering plowed snow, the multicolor sheen on waterways. But this is just some of the visible evidence—pollution lives a secret life as well. More and more, environmental toxins are invading our homes, contaminating food and water supplies, and accumulating deep inside the body. One of the most prolific and dangerous environmental toxins is the heavy metal mercury. It is estimated that up to 8,000 metric tons of mercury are released into the environment each year, accumulating at levels that pose serious threats to environmental and public health.