According to a 2011 report by Environmental Defense Fund (EDF), just 25 coal plants account for one-third of the mercury emissions from power generation in the United States. They produce only 8 percent of the electricity.

“Top honors” go to the Martin Lake, Texas lignite plant owned by Energy Future Holdings, which emits 1,566 pounds (712 kg) of mercury per year, according to the report. The lignite is mined nearby.

Some, not all, of these plants have planned or installed Activated Carbon Injection systems to collect the mercury, which helps the air quality but makes the fly ash more toxic.

(EDF Report) Mercury Alert: Cleaning up Coal Plants for Healthier Lives

Center for Disease Control Mercury Toxicological Profile