Environmental Protection Agency Administrator Scott Pruitt. (AP Photo/Andrew Harnik)

Environmental Protection Agency Administrator Scott Pruitt has used four separate agency email addresses since taking office, according to Senate Democrats and an EPA official, prompting concerns among agency lawyers that the EPA has not disclosed all the documents it would normally release to the public under federal records requests.

Two Democrats on the Senate Environment and Public Works Committee — Jeff Merkley (Ore.) and Tom Carper (Del.) — sent a letter Tuesday to the EPA’s inspector general asking the office to probe the matter.

“We write to share our deep concern over Administrator Pruitt’s reported use of multiple email accounts,” they wrote in the letter, which was obtained by The Washington Post. “It is imperative that there be an investigation into whether the agency has properly searched these email addresses for responsive documents in response to Freedom of Information Act (FOIA) requests.”

Pruitt’s four email addresses include one in the conventional agency format, pruitt.scott@epa.gov, as well as three others: esp7@epa.gov, adm14pruitt@epa.gov and sooners7@epa.gov, an apparent reference to the University of Oklahoma, whose football team Pruitt follows closely.

Another EPA staffer, who spoke on the condition of anonymity out of fear of retaliation, said that Pruitt’s use of different emails has raised concern among agency lawyers responsible for scouring the administrator’s official correspondence in the course of responding to FOIA requests from journalists and outside groups. If there is an email account that was not searched for records in response to a FOIA inquiry, the official said, that “would be an enormous breach of the public trust.”

In an email Thursday, EPA spokesman Jahan Wilcox said the agency had fully complied with any public records requests.

“The EPA maintains three email accounts which are attributed to Administrator Pruitt: two are used by staff for calendaring and public correspondence; the third is used by the Administrator,” Wilcox said. “A fourth email account was created for use by the Administrator but was superseded and never used beyond three test emails. When we receive a FOIA request all accounts are searched before we respond to the FOIA request.”

The agency has seen a sharp rise in the number of public records requests since Pruitt joined President Trump’s Cabinet. It received 11,493 requests under FOIA in fiscal 2017, according to officials, 995 more than the previous year. In November, Pruitt said his staff has focused on eliminating the backlog of records requests filed during the Obama administration over responding to more recent requests.

Pruitt’s office said it is looking into the matter and will provide a comment later. A spokeswoman for EPA Inspector General Arthur A. Elkins Jr. declined to comment on the senator’s request for audit.

Pruitt isn’t the first EPA chief to faced questions over email use.

During President Barack Obama’s first term, then-EPA Administrator Lisa Jackson came under fire for maintaining a separate agency email under the alias “Richard Windsor” — a name that derived from Jackson’s family dog when she lived in East Windsor Township, N.J.

At the time, EPA officials said the agency was not trying to be deceptive in giving Jackson an alternate email address to use. Rather, they said the intent was for her to be able to communicate with other government officials without having to wade through the sea of emails that arrived in her public email, Jackson.lisap@epa.gov — an account the agency said received 1.5 million emails during fiscal year 2012.

They said that administrators since the Clinton administration had followed the practice of having multiple email addresses, writing to lawmakers that for “nearly two decades EPA administrators have managed the agency with two email accounts.”

“We welcome an investigation into this,” an EPA spokeswoman said at the time. “We don’t have anything to hide.”

But disclosure of the account and the unusual name used by Jackson prompted congressional Republicans to request an investigation into the practice. The EPA’s inspector general undertook an audit “to determine whether EPA follows applicable laws and regulations when using private and alias email accounts to conduct official business.”

If Pruitt’s office has been using all four addresses mentioned in the letter, the practice is likely to raise similar questions about whether the EPA chief is trying to skirt public records requests into his correspondence.

Pruitt encountered criticism over allegedly using a private email address in his previous job as Oklahoma attorney general.

During his confirmation hearing early last year, Pruitt said he never used a personal email account for official business as Oklahoma state attorney general. Asked whether he had ever used a private email account while on the job, Pruitt told the Senate Environment and Public Works Committee: “I use only my official OAG [office of the attorney general] email address and government-issued phone to conduct official business.”

But several of Pruitt’s official emails, released soon after as part of an open records lawsuit in Oklahoma, were copied to his personal email — an Apple account that was partially blacked out before being released.

The emails copied to Pruitt’s personal account included ones from the American Legislative Exchange Council (ALEC), a corporate-backed group that focuses on state legislatures; the American Fuel & Petrochemical Manufacturers, which has substantial interests in EPA issues; and members of Pruitt’s staff.

A Pruitt spokesman at the time told an Oklahoma Fox News affiliate that officials at the attorney general’s office conducted a search of Pruitt’s personal email account and did not find any relevant documents that had not been produced in the search of his official email accounts.