A new study from Duke University suggests green spaces across the country could have lasting soil contamination from trash incinerators used decades ago.
The study builds on previous research from a Duke graduate student who published a report last year on elevated levels of lead in soil at three public parks in Durham where incinerators were used in the mid-20th Century. Subsequent testing found five Durham parks had high levels of lead.
Duke soil science professor Daniel Richter says a review of historical records shows dozens of cities in the U.S. and Canada closed their incinerators around the same time. Some put the waste in landfills while others did not.
"What happened to all the ash that didn't get confined to a landfill and then capped? We think that's a really common trajectory of these old incinerator sites," Richter says. "They could be in all kinds of land uses today."
Richter says cities often disposed of incinerator ash without understanding threats to public health or the environment.
"In Charleston, South Carolina, they were expanding their waterfront, so they dumped it in the harbor there," he says. "In California, they reported dumping ash into canyons. In Boston, they had a harbor island that was a dump."
Not every incinerator across the country was turned into a park, but Richter says it's worth testing the soil around all of those sites to determine if lead levels are above EPA guidelines.