The Ontario Liberal government faced fierce blowback Wednesday after journalists, including the Star, uncovered allegations that the Environment Ministry ignored warnings from its own engineers about Sarnia’s Chemical Valley.

At Queen’s Park Wednesday, Ontario NDP Leader Andrea Horwath said the revelations were “frightening” and “unbelievable.” The allegations, made in a leaked report, suggested the provincial government has for years disregarded concerns from the First Nations community of Aamjiwnaang — surrounded on three sides by petrochemical plants — and failed to heed engineers’ worries about the risk of industrial leaks with possibly irreversible health impacts.

“It’s absolutely irresponsible…If this is happening in Sarnia, where else is it happening?” Horwath said.

“What else is out there that we don’t know about, that this government is burying and not allowing to come to public light?”

The report came to light after an investigation by the Star, Global News, National Observer, the Michener Awards Foundation and journalism schools at Ryerson and Concordia universities revealed a troubling pattern of secrecy and potentially toxic leaks in the area known as Chemical Valley. There are 57 industrial polluters registered with the Canadian and U.S. governments within 25 kilometres of Sarnia.

The investigation also raised questions about whether companies and the provincial government are properly warning residents of Sarnia and the Aamjiwnaang First Nation when potentially toxic substances — including benzene, known to cause cancer at high levels of long-term exposure — are leaked.

The leaked report was presented to the staff of Environment Minister Chris Ballard on Sept. 20 and prepared by the union representing engineers working for the provincial government, the Professional Engineers Government of Ontario (PEGO).

In question period Wednesday, Ontario Environment Minister Chris Ballard said he’d have “tough questions” for his ministry about the allegations.

“My ministry is carefully reviewing the report that was provided to them by the union representing engineers and we take very seriously the concerns that it brought to our attention,” he said, adding that the ministry has a “very transparent” system to address such concerns.

On Monday, following the investigation, Ballard said the province would fund a study to examine the health impacts of pollution on the residents of Chemical Valley — something residents have been struggling to get for nearly a decade. Though Ballard has yet to commit to a timeline or process for the study, he also said the government would introduce stricter regulations in the coming weeks.

Existing public health data about the region is inconclusive, but critics have said the information, collected at the county level, misses the impact on people living in the immediate vicinity of so-called Chemical Valley.

On Tuesday, Federal Green Party Leader Elizabeth May said the situation in Chemical Valley — and Aamjiwnaang in particular — is “one of Canada’s top examples of environmental racism.”

With files from Robert Benzie, Carolyn Jarvis, Global News and National Observer