The derailment of a 101-car CSX freight train on a bridge in a densely-populated part of Philadelphia this past week should be yet another warning to politicians who have become cheerleaders for oil and gas fracking.

The train had been hauling crude oil from the Bakken Shale in North Dakota. A severe snow storm delayed by several days removing the derailed cars and 80,000 gallons of crude oil from the decades-old bridge over I-76 and the Schuylkill River, which flows into the Delaware River. Oil and gas companies using horizontal fracking have made the Bakken the most productive oil shale in the country.

Numerous articles and scientific research studies have already shown the link between horizontal fracking and health and environmental problems. But the transportation of shale oil and gas by trains, trucks, and pipelines poses more immediate threats.

About 92,000 of the 106,000 tanker cars currently in service were built before 2011 when stricter regulations mandated new design. The older cars (DOT-111) have an “inadequate design” and are susceptible to leaks and explosions in derailments, according to the National Transportation Safety Board.

Railroad accidents in 2013 in the United States accounted for about 1.15 million gallons of spilled crude oil, more than all spills in the 40 years since the federal government began collecting data, according to the U.S. Pipeline and Hazardous Materials Safety Administration (PHMSA).

Forty-seven persons were killed, and more than 30 buildings destroyed by fire, explosions, and smoke on a 73-car unmanned train that rolled down a seven mile incline and derailed in Lac-Megantic, Quebec, July 6. Seventy-two tanker cars of the Montreal, Maine & Atlantic railroad were carrying crude oil from the Bakken Shale to a New Brunswick refinery. The accident released about 1.5 million gallons of crude oil; it was the worst rail disaster in North America since 1989.

Less than a week later, three tanker cars on a Norfolk Southern train carrying 90,000 gallons of ethanol exploded near Columbus, Ohio. The explosion led to the evacuation of residents within a mile of the accident.

Three months later, a Canadian National train hauling oil and gas derailed in Gainford, Alberta; three of the tanker cars carrying liquefied natural gas had leaks and were on fire as a result of the derailment. No injuries were reported.

In November 2013, a 90-car Genesee & Wyoming train, carrying about 2.7 million gallons of crude oil from the Bakken Shale, derailed near Aliceville, Ala., spilling about 750,000 gallons into surrounding wetlands; fire and toxic smoke burned for more than a day. No immediate injuries were reported, although the effects of the fireball explosions and toxic smoke might not be known for several months.

In December, a 106-car BNSF train hauling Bakken Shale crude oil slammed into a 112-car train carrying grain that had derailed near Casselton, N.D. Explosions, fire, and toxic smoke led county officials to urge evacuation of all residents within five miles of the accident. About 400,000 gallons of crude oil were spilled, according to estimates by the National Transportation Safety Board.

A week later, 45 homes were evacuated in Plaster Rock, New Brunswick, after a Canadian National train carrying propane and crude oil from the Bakken shale derailed and caught fire.

This month, PHMSA issued a safety alert that “crude oil being transported from the Bakken region may be more flammable than the traditional heavy crude oil.” Bakken shale oil could cause evaporative losses of explosive volatiles benzene, toluene, hexane, xylene, and hydrogen sulfide, all of which can cause death from burns and respiratory failure.

Each day, interstate carriers transport about five million gallons of hazardous materials. Not included among the daily 800,000 shipments are the shipments by intrastate carriers, which don’t have to report their cargo deliveries to the Department of Transportation. I-80, which bisects Pennsylvania and the Marcellus Shale, is one of the most heavily traveled routes for trucks hauling chemicals to fracking sites. There have already been several spills from traffic accidents. Contributing to the probability of increased disasters in Pennsylvania is a road and bridge system that has deteriorated because of a combination of increased truck traffic from the shale gas industry and decades of neglect by the state’s politicians. Scott Christie, an executive with the Pennsylvania Department of Transportation, told a House committee, “Most of these road-ways do not have sufficient strength to withstand the large amount of trucks and other vehicles that are a part of Marcellus shale drilling.”

About half of the nation’s 2.6 million miles of pipelines are at least 50 years old; corrosion is responsible for between 15 and 20 percent of deaths, injuries, or property damage, according to ProPublica, an independent investigative journalism news operation. More than 150 incidents a year involve large natural gas transmission lines and the smaller distribution lines. Because methane is explosive and flammable, problems can occur anywhere from the first exploratory hole to delivery in pipelines to homes and businesses. There is at least one major natural gas explosion, fire, or leak every week, according to documentation compiled by Natural Gas Watch.

Pennsylvania’s Gas and Hazardous Liquids Pipeline Act, which became law in December 2011, includes oversight of classes 2–4, but excludes Class 1 pipelines. A Class 1 location is any area with “10 or fewer buildings intended for human occupancy within 220 yards of the center-line of the pipeline,” according to PHMSA. About 1,300 miles of Pennsylvania’s natural gas pipelines are Class 1 pipelines. No state or federal agency has jurisdiction over pipelines in Class 1 rural areas, nor are operators required to report any incidents, including property damage, injuries, or deaths associated with those pipelines. Regulating Class I pipelines is “at the bottom of the state’s priority list,” Patrick Henderson, energy executive for the Corbett Administration, told the Pittsburgh Post-Gazette.

Nationally, PHMSA regulates only about 20,000 of 200,000 miles of natural gas gathering pipelines and only about 4,000 of the estimated 30,000–40,000 miles of hazardous liquid gathering pipelines. Only about one-fourth of all oil, natural gas, and propane pipelines have been inspected since 2006, according to Public Employees for Environmental Response (PEER), which had to file a Freedom of Information Act suit request to get the public records.

Like the aging pipelines, many of the railroad bridges over the Bakken and Marcellus shales are decades old. Mile-long trains of tanker cars that are not designed to carry crude oil, but travel between the oil fields of North Dakota and refineries in Philadelphia put the entire nation at risk. Unlike the other derailments in the past six months, there were no leaks, explosions, or health problems caused by the derailment of the CSX freight train in Philadelphia.

That will not always be the case.