( CNN ) -- This November , the Obama administration is expected to move forward with long overdue safeguards that would finally protect our families from mercury pollution . As the mother of four children , I can only say it 's about time . The EPA was first charged with limiting toxic air pollutants such as mercury during the Bush administration -- the first Bush administration . I do n't know how many children have been exposed to dangerous levels of this neurotoxin during the subsequent 20-plus years of foot-dragging , but I do know that my eldest daughter was one of them . When Sophie was 4 years old , we discovered that her mercury levels were elevated . We were already concerned because her learning had leveled off and in some notable ways even backslid . But it was only by chance that we realized she was being poisoned . Because we lived in an old house with lead paint , we had been following our pediatrician 's advice to have our children tested regularly for lead and other heavy metals . Only because of this were we lucky enough to learn about our daughter 's elevated mercury levels before it was too late . How does a healthy , well-nourished child get mercury poisoning in her own home ? By far the most common exposure to mercury comes from eating contaminated fish . Sophie adored tuna fish sandwiches and ate one or two a week . That was a small amount but enough to cause her harm . When , on a doctor 's advice , we took fish out of her diet , her mercury levels declined . We 're thankful that our daughter suffered no permanent damage , but thousands of other parents are not so fortunate . Exposure to mercury in utero can contribute to birth defects , including neurological and developmental disorders , learning disabilities , delayed onset of walking and talking , and cerebral palsy . The EPA estimates that as many as one in 12 American women of child-bearing age have enough mercury in their bodies to put a baby at risk . That means that every year more than 300,000 babies could be born at risk of serious disabilities caused by mercury poisoning . Mercury is one of the most potent of the many toxic heavy metals that come from the emissions of coal-fired power plants . If just one-seventieth of a teaspoon enters a lake every year , it is enough to raise mercury levels in the fish . And yet the EPA reported in 2005 that coal-fired power plants , the largest domestic source of unregulated mercury emissions in the United States , pumped 48 tons of this toxin into the atmosphere each year . The technology to filter mercury and other toxic heavy metals from power-plant smokestacks is widely available and , in fact , some plants already have it in place . Under the EPA 's proposed new protections , all plants would have to upgrade , and mercury emissions would be reduced by more than 90 % ( along with cancer-causing metals such as arsenic , chromium and nickel ) . It would prevent hundreds of thousands of illnesses and up to 17,000 premature deaths each year . Why has it taken more than 20 years to do something ? Because corporate polluters do n't want to pay up to clean up , even though thousands of Americans pay dearly every year as a consequence . Worse , their economic arguments are baseless . By cleaning up the coal plants , the new EPA protections will actually result in a net gain for the U.S. economy . Heart disease , learning disabilities and premature deaths are expensive , too . No parent should have to discover , as I did , that she is feeding her child poison in the sandwiches she packs in her lunchbox . After more than two decades , it 's time to stop dumping poison into the atmosphere and pretending there are no consequences . The opinions in this commentary are solely those of Ayelet Waldman .
Ayelet Waldman : EPA was supposed to limit toxic pollutants like mercury 20 years ago . But the agency has been slow in implementing a new rule that would have required it by 2015, and now is considering delaying implementation until after next year's presidential election. Waldman : Mercury contributes to birth defects , nerve disorders , learning disablilites . It 's time to seriously limit mercury emissions that poison environment , she writes .