Before dawn on June 22, on the Robert Street bridge over the Mississippi River, some of the wheels on a Union Pacific train car came off the tracks. Two more cars partly derailed as the train neared a rail yard.

Later that day, near Barge Channel Road, wheels on two more cars slipped from the rails. One car contained chlorine.

There was no spill of the potentially lethal chemical. But the incident was a reminder that trains with hazardous materials — including crude oil, chlorine, sulfuric acid and anhydrous ammonia — roll across Minnesota.

“It’s just a witches’ brew of toxicity in terms of what’s rumbling into our communities and our neighborhoods on a daily basis,” said Rep. Frank Hornstein, DFL-Minneapolis.

Concern about the risks of trains carrying dangerous materials is growing after the Trump administration scrapped a proposed rule governing train safety, and action has slowed on others.

A proposed requirement that train engineers (and truck drivers) be screened for sleep apnea was withdrawn in August. Consideration of a plan to require two-person train crews has been delayed at least until next year.

Meanwhile, a request by six state attorneys general for rules requiring that crude oil be treated before transport to lower vapor pressure and make it less flammable has stalled.

Under President Donald Trump, federal agencies are “just not feeling any heat” to tighten standards, said Matt Krogh of Crude Awakening Network, a project of the environmental group “There is no foreseeable end to the increasing risk.”

Amy McBeth, a BNSF Railway spokeswoman, said in a statement that its “focus remains the same, regardless of the administration in Washington. We’re committed to continually reducing risk to further improve safety.”

Mike Rush, senior vice president for safety and operations at the Association of American Railroads, said the industry is in “wait-and-see” mode when it comes to Trump’s rail safety stance. Rush noted that the top job is vacant at the Pipeline and Hazardous Materials Safety Administration, which is part of the U.S. Department of Transportation and would take the lead on new rules.

“We transport over 99.99 percent of hazardous materials cars without an accident,” Rush said. “We continue to try to get even safer and safer.”

That’s a goal some state legislatures are trying to enforce.

Hornstein plans to introduce measures to eliminate a cap on railroads’ liability after accidents, improve coordination between railroads and first responders, add rail inspectors and revive a mandate that railroads contribute to a safety fund. He has struggled in recent years to get momentum for such measures at the State Capitol, with Republicans controlling one or both legislative chambers.

He’ll keep trying because states must take the lead, he said. “Across the board, I’m worried” about Washington’s intentions, Hornstein said. “Health, safety and environmental regulations are all being pared and gutted, and this is all at the behest of the fossil fuel industry and big oil.”

In July, New Jersey Republican Gov. Chris Christie vetoed a bill that would have required owners of trains carrying hazardous materials to outline cleanup plans for spills and make routes and cargo public.

“People are afraid,” said New Jersey Assemblyman Tim Eustace, a Democrat who sponsored the bill and will lead an effort to override the veto. He worries “every single day” about whether Trump policies will weaken rail safety.

After a 2016 oil train derailment and fire near Mosier, Ore., Oregon state Rep. Barbara Smith Warner sponsored a bill that would have required railroads to submit emergency plans for approval by the state and to prove that they could pay for accident cleanups.

The measure was pulled from a House vote amid concerns that an amendment had watered down public oversight provisions. Smith Warner, a Democrat, said she’ll try again, but she’s frustrated. “Railroads don’t like to be regulated at all and, even more, don’t like to be regulated by states,” she said.

Because of disasters such as the 2013 derailment of a 74-car freight train carrying North Dakota Bakken crude in Lac-Mégantic, Quebec, that killed 47 people, trains hauling oil still generate the most concern — even though a drop in oil prices in the last few years has dramatically slowed traffic.

In 2014, major railroads transported 493,146 carloads of crude oil, according to the Association of American Railroads. In 2016, as North Dakota production declined, volume fell to 211,986 carloads.

So far this year, Union Pacific has not moved any crude through Minnesota. BNSF routed no more than three trains carrying 1 million gallons of oil or more through Hennepin County in a recent week.

Bakken production averaged 1.03 million barrels a day in June, down from 1.2 million in December 2014.

The decrease in crude oil traffic has not eased apprehension among members of the Twin Cities chapter of Citizens Acting for Rail Safety. “We continue to be concerned because we know that trains are going to continue to go through our communities with hazardous materials,” said member Cathy Velasquez Eberhart.

“We can’t prevent every incident, and that’s why our mantra is we need to know what’s on the railroads,” said Claire Ruebeck, another member. “The community needs to know what to do and we need to know in advance,” she said.

The Obama administration in 2015 issued rules requiring enhanced braking systems, speed limits on trains carrying large amounts of flammable crude oil through densely populated areas and the replacement or retrofitting of railcars used for crude oil and ethanol.

In 2014, Gov. Mark Dayton signed legislation requiring the Department of Public Safety to provide oil transportation awareness training to first responders. Both BNSF and Union Pacific train public emergency responders.

Dayton’s 2016 budget proposed extending an annual assessment on railroads to pay for safety improvements, more inspectors, improved disaster coordination and overpasses or underpasses at busy road-and-rail intersections. Rail companies’ lobbyists threatened a lawsuit and Republicans allotted $5 million for rail safety without the tax, which expired on June 30.

Minnesota residents aren’t allowed to see railroads’ complete disaster plans — putting the state at the center of a debate over secrecy. One reason the Oregon bill failed was the addition of a provision that barred public access to information about oil train routes.

“This is an industry that’s operating in secret to the detriment of the public and those who are charged with keeping us safe,” Hornstein said. He asked the state to investigate why the chlorine-car incident in June was not reported to public safety officials.

Union Pacific spokeswoman Calli Hite said in a statement that the railroad reviewed what happened in June to “ensure appropriate entities are alerted in future situations of this nature.”

Eric Waage, Hennepin County’s emergency management director, monitors the railroads’ response plans and those of communities in the county. “We’re lucky a lot of [the railroads’] assets and resources are right here,” he said, including specialized foam and other gear.

Railroads do share information about what they’re hauling with community emergency responders and have developed an app to help do so, Rush said, but the threat of possible attacks precludes “telegraphing ahead of time what specific routes are used … and exactly when.”

McBeth said that BNSF submits its response plan to the Minnesota Pollution Control Agency and has “always provided upon request to fire departments, emergency managers and others with a need to know detailed reports” on hazmat shipments.

But because its MPCA filing includes a worst-case scenario, “that information is security sensitive and had to be redacted. … The threat of information being misused is real,” she said.

Minneapolis Fire Chief John Fruetel called rail a “fairly safe way to transport hazardous materials,” but he’d like the Legislature to make some changes. Railroads should be required to share full — not redacted — response plans, he said, and to detail their response capabilities. “Then everybody knows exactly what’s going to happen if we have these issues,” he said.

Coon Rapids Fire Chief John Piper agrees with Fruetel’s wish list and said that he also has a good working relationship with railroads. He would like access to as much response information as possible and hopes the smartphone app will soon be available in his trucks and on laptops.

Continued vigilance is vital, Piper said. “Because there’s less Bakken oil [being transported] doesn’t change anything. There can be equally dangerous or worse things in those cars.”