You can’t unring a bell.

And you can’t undo damage to the environment.

So as more and more evidence mounts about the potential environmental dangers of hydrofracking, it becomes even more vital that our public officials demand the most thorough examination of its potential impacts.

Despite what the fuel companies say, the hydrofracking process — by which huge amounts of chemical-laden water are injected deep into the ground to extract natural gas from shale — has the potential to do great harm to the ground and to the water supply. Hundreds of chemicals used in undisclosed quantities are mixed with water and sand to extract the fuel, and recovered fracking water is stored in above-ground pools before being shipped for disposal.

Drilling into the Marcellus Shale deposit, which spreads into central New York, Pennsylvania and Ohio, could affect the water supply supplies for tens of millions of people, including those in the urban centers of New York City and Pennsylvania. Disruption of this shale deposit to extract fuel should not be taken lightly or be allowed to move ahead without extensive study.

That’s the point being made by state Attorney General Eric Schneiderman, who on Monday threatened litigation against the interstate Delaware River Basin Commission over its rush to enact proposed new regulations by the summer without a full environmental review.

The Delaware River commission — which covers the states of New York, New Jersey, Pennsylvania and Delaware — is preparing regulations to allow 15,000 new wells to be drilled in the basin, and Scheiderman wants to make sure the agency can back up its regulations with an environmental study of their impacts.

The review, Schneiderman said, needs to evaluate the cumulative impact of fracking throughout the basin, as well as the option of prohibiting gas drilling in the portion of New York City’s West-of-Hudson Watershed in the basin.

That seems reasonable, especially as concerns grow about the environmental impact of the project.

On Tuesday, the state of Pennsylvania acted to stop the petroleum industry from disposing of fracking wastewater in 15 municipal water treatment plants after it was shown the contaminated water was affecting operation of the plants and showing up in streams and tributaries.

On Monday, an investigation of hydrofracking initiated by the House of Representatives’ Energy and Commerce Committee found that oil and gas companies injected hundreds of millions of gallons of hazardous or carcinogenic chemicals into wells in more than 13 states from 2005 to 2009.

These are not merely the rantings of alarmist environmentalists. Nor are they based on supposition or theory.

They are actual facts about this potentially harmful process, and it’s clear from existing practices that the long-term, cumulative impacts have not been studied in enough detail.

While hydrofracking has the potential to provide great economic benefit to the region by creating a long-term supply of inexpensive fuel, it also has the potential to do serious, irreversible harm to the environment.

A full-blown environmental study of all the potential impacts and all the proposed regulations is not only desired, but necessary.

If the federal government won’t take the initiative to study the impacts, then it should have to defend its inaction in court.