( CNN ) -- A Massachusetts congressman called on the federal government Tuesday to distribute potassium iodide pills to Americans living near nuclear reactors , a preventive step one expert warns might do more harm than good . Rep. Ed Markey wants the federal government to distribute doses of the compound -- which can be used to block the thyroid gland 's absorption of radioactive iodine -- to every household within a 20-mile radius of a U.S. nuclear power plant `` in recognition of the probability that rapid evacuation during a nuclear meltdown will be difficult and time consuming . '' Markey , D-Massachusetts , said the battle to halt a suspected meltdown at a Japanese plant should spur the Obama administration to action . `` Despite more than 30 years of clear and unequivocal evidence that potassium iodide protects people , especially young children , who are most vulnerable , from cancer-causing releases of radioactive iodine that would occur if a nuclear disaster occurred , the nuclear industry has continued to fight its use , '' Markey said at a press conference . A 2002 law calls for the U.S. government to make stockpiles of potassium iodide available to states and local governments in preparation for a possible nuclear accident , but the congressman said the provision has not been enforced . `` The Japanese nuclear disaster is the reminder we need that the law should be followed , and American children should be protected in the event of another nuclear meltdown here on U.S. soil , '' Markey said in a statement issued by his office . The congressmen urged potassium iodide be stockpiled in schools , hospitals and other places within the 20-mile radius . Markey is the ranking Democrat on the House Natural Resources Committee and a former chairman of the Energy and Commerce subcommittee on the environment . He was a leading critic of BP during last year 's massive oil spill in the Gulf of Mexico , pushing the oil company to release more information about the disaster . Since the crisis at a Japanese power station that followed the March 11 earthquake and tsunami , he has called for a safety review of U.S. nuclear plants . Markey said Tuesday he plans to introduce legislation to overhaul nuclear safety . The bill imposes a moratorium on new reactor licenses until `` new safety requirements are in place . '' The bill , he said , would require reactors to have backup power supplies and systems that can withstand `` earthquakes , tsunamis , strong storms and long power outages . '' But Dr. James Cox , a radiation oncologist at Houston 's MD Anderson Cancer Center , called Markey 's potassium iodide proposal `` a well-intentioned but bad idea . '' `` The idea of trying to protect people and trying to prevent illness is always a good idea , '' said Cox , a CNN consultant . But he said the pills carry side effects that might be worse than low doses of radiation -- and they have `` very little likelihood '' of being used , `` except by people who might be so anxious that they might use them inappropriately . '' Radioactive iodine is among the contaminants released from the earthquake-damaged Fukushima Daiichi nuclear power plant in northern Japan , where crews have spent more than two weeks trying to prevent meltdowns in three of its six reactors . Potassium iodide blocks the absorption of radioactive iodine isotopes by filling the thyroid with the benign iodine compound , stopping the thyroid from absorbing radioactive iodine . This reduces the risk of cancer from exposure . Its use is recommended for children in particular , because they would have a higher risk of thyroid cancers , but it does n't protect against radiation from other elements -- nor does it protect any other organs from radiation exposure . The supplement disappeared from some store shelves in California this month after trace amounts of radioactivity were picked up by sensors on the U.S. Pacific Coast , even as California 's emergency management agency warned residents against taking it . `` It is not necessary given the current circumstances in Japan , '' the agency said . `` It can present a danger to people with allergies to iodine , shellfish or who have thyroid problems , and taken inappropriately , it can have serious side effects . '' Cox said that ideally , if a nuclear accident happened , health departments would tell people in the affected areas when they should take a dose of the compound . But having potassium iodide at hand can be a problem as well . `` Because just like people are running out and trying to hoard these pills , that anxiety might lead them to take the medication when they are told there is some detectable amount of iodine-131 in the atmosphere , when it 's not enough of a concentration to be health concern . '' Irwin Redlener , director of the National Center for Disaster Preparedness at Columbia University , said his main message is the United States should be prepared for a potential disaster . `` Americans should n't take it ( potassium iodide ) now because Americans are not , at the moment at risk , so they should not take it now , '' Redlener said . `` This should not be an advisory for people to go out and stockpile potassium iodide themselves necessarily . '' CNN 's Matt Smith contributed to this report .
Congressman wants people living near reactors to have pills handy . Comment: