He told a panel at PRWeek’s PR360 event that journalists and PRs are both "thrashing about" trying to come to terms with the new era, heralded by the rapid rise of social media.
"We’ve got to the generation of citizen publisher," said Waldman. "It’s like the Wild West out there - it really is. Anybody can publish anything."
Speaking to an audience of PR professionals at London’s Cumberland Hotel, he added: "Bluntly, we are in danger of losing control.
"There’s such an enormous potential for anybody to get their message across on such a plethora of platforms and outlets that the days when the PR fed either all journalists or selected journalists the story, and the journalist processed, editorialised it, and put it out, has gone."
Waldman, who left the BBC in March, described the relationship between journalists and PRs as "symbiotic parasitic" and also "love-hate", but stressed that "each side absolutely needs the other" and the relationship is "still very important".
The session, which focused on the future of the media from the point of view of journalists, heard about difficulties with embargoes in the digital era.
John Crowley, EMEA digital editor at The Wall Street Journal, said: "There’s this notion that the embargo is broken. I don’t think the concept is; I think the execution is. The way that it’s delivered is problematic."
Waldman said: "The policing and execution of embargoes are so difficult these days. You can put out an embargoed press release and somebody somewhere is going to tweet it."
Waldman gave the example of exit poll results for a French election that were tweeted by one BBC journalist before the polls had closed and the embargo was lifted. "It could have put us in prison," he said.
Elsewhere, ITV News head of digital Jason Mills said his employer’s policy is not to use interviews created by anyone other than its own staff. That’s in response to the growth of content creation, particularly videos, from corporations and organisations.
An example was given of Microsoft CEO Satya Nadella being interviewed by the firm’s "chief story-teller". The video was published on the company's own YouTube account to hundreds of thousands of followers, bypassing the need for a traditional broadcaster.
But Waldman said: "There are times when just pragmatism means you have to [use such content]." He gave the example of an interview with Wayne Rooney on Manchester United’s own TV channel, which wasn’t available elsewhere.
Waldman also raised concerns that the younger generation "don’t seem to care where news comes from".
"I don’t think they care about trust in the news so much. They just want to get the content as quickly as possible."