Weakness in state regulations governing hazardous oil-and-gas waste have allowed the leftovers to be disposed of with little regard to the dangers they pose to human health and the environment, according to a recent study by the environmental organization Earthworks.

The report says states disregard the risks because of a decades-old federal regulation that allows oil-and-gas waste to be handled as non-hazardous material. Those rules, established by the U.S. Environmental Protection Agency in 1988, exempted the waste from the stricter disposal requirements required of hazardous substances and allowed the states to establish their own disposal standards.

In its report, "Wasting Away: Four states' failure to manage gas and oil field waste from the Marcellus and Utica Shale," Earthworks studied rules governing disposal of the often toxic waste––and the gaps in those regulations in New York, Pennsylvania, West Virginia and Ohio.

The organization, which is often criticized by the industry as being consistently biased, concludes the EPA was wrong when it applied the non-hazardous label to oil-and-gas waste.

"Drilling waste harms the environment and health, even though states have a mandate to protect both," said Bruce Baizel, co-author of the report and Earthworks' energy program director.

"Their current 'see no evil' approach is part of the reason communities across the country are banning fracking altogether. States have a clear path forward: if the waste is dangerous and hazardous, stop pretending it isn't and treat it and track it like the problem it is."

Disposal of oil-and-gas waste has generated little attention, yet it puts people at risk of exposure to chemicals including benzene, which can cause cancer. It has escaped scrutiny as a factor in air and water pollution and a possible contributor to the acceleration of climate change.

An investigation by InsideClimate News last year disclosed lax regulations of oil-and-gas waste in Texas that left disposal facilities virtually unregulated.

READ: Open Pits Offer Cheap Disposal for Fracking Sludge, but Health Worries Mount

The EPA granted the exemption from federal hazardous-waste laws even though the agency estimated that without the exemption, 10 to 70 percent of oil-and-gas waste could be considered hazardous. The EPA reasoned that states could adequately regulate the waste.

Legislation proposed by Pennsylvania congressman Matt Cartwright in 2013 would remove the industry's hazardous waste exemption; the bill has languished since its introduction.

The Earthworks study, which focused on the Marcellus and Utica shale regions of the four states, identified what it called shortcomings in existing and proposed state regulations of oil-and-gas waste generated during exploration, development and production.

"In all of the states examined, persistent regulatory and information gaps remain and practices are underway that call into question the adequacy of state oversight," according to the report.

Some of the examples cited include the practice allowed in Pennsylvania of storing waste in open air pits and the spreading of waste on roads and open land.

In Ohio, Earthworks found no public information available on the number, location or use of oil-and-gas waste pits and impoundments. The state doesn't have specific requirements for the construction and use of pits and impoundments.

Solid oil-and-gas waste in West Virginia does not have to be disposed of in specialized facilities; it can be dumped in municipal landfills.

"Across the Marcellus and Utica shale region, a 'create now, figure it out later' view has guided the regulatory and policy response to a growing stream of drilling waste," according to the report.

The Earthworks report acknowledges the four states have taken some steps to address oil-and-gas waste management through improved regulations, operator practices and data collection. But reform initiatives in the four states continue to be piecemeal and reactive with gaps in regulations and oversight, the report says.

The primary reason for this lack of oversight circles back to operators and regulators treating oil-and-gas waste like other wastes and using existing treatment and disposal systems—rather than developing new ones based on the specific composition of sometimes toxic waste.

To stem risks to air quality, water and soil, Earthworks makes 11 recommendations to mitigate the threats posed by current oil-and-gas waste disposal measures and calls on the states to "take immediate action" to correct the deficiencies in existing regulations.

Among the recommendations:

Require treatment and disposal of wastes at specialized facilities designed and equipped to remove chemicals, radioactive elements, metals and other contaminants.

Prohibit municipal landfills and wastewater treatment plants from accepting oil-and-gas waste.

Mandate operators to conduct comprehensive, consistent testing of waste before it leaves the well site.

This approach to handling oil-and-gas waste is vital now, especially because of the boom in fracking oil-and-gas wells across the country, according to the report.

"Until measures are in place to ensure that these steps are taken, oil-and-gas waste management will continue to be, at its core, an experiment—one with potentially serious consequences for environment and communities both in the Marcellus and Utica Shale regions and nationwide," it says.