NIAGARA FALLS , New York ( CNN ) -- Thirty years ago this summer , America learned the name Love Canal . The working-class Niagara Falls neighborhood built atop tons of chemical waste became a synonym for environmental disaster . Lois Gibbs , who runs an environmental justice group , shows a photo of children from Love Canal protesting . Troubles at the local elementary school -- and health problems among its students , such as seizure disorders -- were among the first signs of a much larger problem that made news around the world and prompted federal Superfund legislation to clean up the most polluted sites in the United States . Despite the outcry over Love Canal , little has been done to make schoolchildren safer from hazardous or toxic waste , says Lois Gibbs , who headed the Love Canal Homeowners Association and now runs the Center for Health , Environment & Justice . `` We should be farther along today than we are , '' said Gibbs , who started the nonprofit a year after her evacuation from Love Canal . The organization is dedicated to helping communities facing environmental threats . A 2005 study by the Center for Health , Environment & Justice looking at just four states -- Massachusetts , New York , New Jersey and Michigan -- found half a million children attending schools within half a mile of known toxic dumps . Gibbs points to New Bedford High School in Massachusetts as an example of children at risk . New Bedford High opened in 1972 on top of a former burn dump for PCBs , an industrial chemical linked to cancer and brain damage . PCB levels in the body build over time , raising health risks . `` Like a lot of teachers there now , I figured , how bad could it be ? I was diagnosed with breast cancer in 2005 , '' said former New Bedford teacher Susan Dias , who is now cancer-free . She is returning to the classroom this fall but will not go back to New Bedford High . Former teacher Maria Quann also says New Bedford High made her ill. `` I became very , very sick . My immune system shut down . I collapsed and was bedridden for several months , '' Quann said . Her health improved after she left the high school , she says , and she has now retired . Maureen Woolley , who worked in the cafeteria , says she compiled a list of 25 school employees who died of cancer . Three classrooms were closed last year because of high PCB levels , but the school has been scrubbed and a new ventilation system added . The rooms are expected to be open this fall . There have been no reports of students at the high school becoming sick as a result of the toxic waste . `` I would n't have kids in the school if I did n't think it was safe . I would close the school , '' said Mayor Scott Lang , whose two sons attended New Bedford High . PCB levels inside the school now fall within federal guidelines , he says . Despite results of ongoing air-quality testing , teacher David Greene remains skeptical . `` I do think there are areas of that school that continue to be dangerous , '' he said . Only seven states have laws preventing cities and towns from building schools on or near toxic waste , according to the Center for Health Environment and Justice . They are Massachusetts , Rhode Island , California , Florida , Kentucky , Mississippi and Utah . `` You can go most anyplace and build [ a school ] on top of a Superfund site , '' Gibbs said . `` They can build a school anywhere they want , really . And that 's the sad truth . I think at schools , very little has changed , and that 's unfortunate . '' Even in states with laws , many are weak or poorly enforced , she says . In Massachusetts , state law prevents schools only from being built close to active waste dumps , which would not have prevented New Bedford High 's construction three decades ago on a former dump site . In Niagara Falls , Gibbs ' home was built three blocks from 20,000 tons of industrial waste placed in barrels and buried in a mile-long ditch by a plastics and chemical maker . The 99th Street Elementary was built on top of the dump . Gibbs , married with two young children at the time , recalls elementary school students playing with ooze bubbling up on the playground . `` The children would actually pick up these chemicals and handle them , '' Gibbs said . `` So , for example , one of these things was phosphorous rocks . Phosphorous rocks were little pieces of chemical residue that would bubble up to the surface . The children would pick up these phosphorous rocks , and when you threw them at a hard surface , they would explode like a firecracker . '' Some children were badly burned by the phosphorous , she adds . Gibbs says neighborhood children also played with the chemical Lindane , a pollutant associated with skin irritation , nausea , convulsions -- even death . `` I have a high school education . I do n't have a science degree , but you do n't have to be a scientist to know that 20,000 tons of chemicals and kindergartners do n't mix , '' Gibbs said .
Few states have laws preventing towns from building schools on or near toxic waste . Comment: Love Canal is a Niagara Falls neighborhood built atop tons of chemical waste .