As Congress embarks on a major overhaul of chemical regulations, a metadata trail that was accidentally attached to a copy of the bill gives us a rare glimpse into the key role played by industry lobbyists.

In recent days, a draft of the bill - considered the product of more than two years of negotiation and collaboration between Sen. David Vitter (R-La.), Sen. Tom Udall (D-N.M.), and both chemical-industry and environmental groups - was circulated by Udall's office ahead of the hearing. The draft bill, obtained by Hearst Newspapers, is in the form of a Microsoft Word document. Rudimentary digital forensics - going to "advanced properties" in Word - shows the "company" of origin to be the American Chemistry Council.

It’s no shock that a corporate lobbyist has an outsized influence on politics and the government, but physical evidence of one of them literally writing a bill (or portions of a bill) is considerably more unseemly.

The American Chemistry Council is a chemical industry trade group that represents powerful companies such as DuPont, Dow, and 3M.

The bill would set new federal safety standards for currently unregulated chemicals, but in many cases, it would override stronger standards that are already in place in certain states.

According to MapLight, a nonpartisan group that tracks campaign contributions, the ten top spending companies in the chemical industry spent $154 million on lobbying in 2013 and 2014 and donated more than $1 million to senators’ campaign committees. The senators co-sponsoring this particular bill received, on average, nearly 70 percent more chemical industry money than senators who are not co-sponsors.

As for Sen. Udall, the bill’s chief sponsor, he benefited from a series of flattering television advertisements that were paid for by the American Chemistry Council and ran in all of New Mexico’s big media markets:

Udall's office denies that the American Chemistry Council had a disproportionate influence on the draft legislation.

“ACC had no more input than environmental groups, and as a result of the input from many stakeholders, the bill has moved further toward what environmental groups and others said they wanted to see," Udall's spokesperson told The Hill last week.

Sen. Barbara Boxer (D-Calif.) thinks the metadata is a problem.

“Maybe I’m old fashioned, but I do not believe that a regulated industry should be so intimately involved in writing a bill that regulates them," Boxer said.