Check your caller ID. If you’re a reporter who has criticized Robert F. Kennedy, Jr. for spouting nonsense about vaccines and autism, your phone could ring at any minute, and if you pick up, you’re in for a long, time-wasting lecture.

Just ask Keith Kloor, a freelancer who blogs for Discover, and Laura Helmuth, the health and science editor for Slate, who learned the hard way.

Kennedy was upset that Kloor and Slate had published posts criticizing him for giving the keynote speech last month at the AutismOne/Generation Rescue conference, where the discredited notion that thimerosal, a mercury-based vaccine preservative, causes autism is still doctrine.

The AutismOne/Generation Rescue conference has not released a video or transcript of Kennedy’s speech, but in his lecture-inciting commentary, Kloor flagged a post at the Age of Autism website by its managing editor, which read:

Each of us will have our highlights from last weekend’s extraordinary Autism One gathering in Chicago, but for me it was Bobby Kennedy Jr. saying, “To my mind this is like the Nazi death camps.”

It’s unclear exactly what Kennedy was talking about—and Age of Autism appears to have taken down that post—but Kloor was rightfully aghast. So was science writer Phil Plait, who seconded the reproach at his blog for Slate, highlighting a number of other venues in which Kennedy has touted his “crackpot ideas.”

Miffed, Kennedy picked up the phone. Kloor got the first call and according to his account, it was “cordial,” but frustrating, as he had trouble getting in a word edgewise. Kennedy launched into long and confusing tirade about an upcoming book that would vindicate all his assertions, but which he might not even publish. Reflecting on the encounter, Kloor wrote:

I had never spoken with Robert Kennedy Jr. before and only know of him through his environmental advocacy and many articles. And even during his phone call to me, I didn’t actually have a conversation with him, because he pretty much talked non-stop for over an hour. The few times I did get a word in I had to loudly interrupt him, which led my wife, who came home towards the end of the call, and who didn’t know who I was speaking with, to ask after I hung up the phone: “Who were you shouting at?”

Soon thereafter, Helmuth had a similar experience when Kennedy rang to complain about Plait’s criticism. “When he calls you to discuss vaccines, he talks a lot, uninterruptably,” she wrote in her account of the exchange, which described basically the same spiel he’d given Kloor. To her great credit, however, Helmuth also fact-checked a couple of Kennedy’s contentions. In particular, he named one scientist whom he claimed had admitted to him that thimerosal “destroys kids brains.” According to Helmuth, who didn’t print the person’s name so as to not “spread the defamation”:

I asked the scientist about their conversation. She said there is in fact no evidence that thimerosal destroys children’s brains, and that she never said that it did.

Kennedy also named another scientist whom he claimed had conceded flaws in thimerosal research. Again, Helmuth:

I talked to the scientist, who would prefer I not use his name because he gets death threats from unhinged anti-vaxxers. He said, “Kennedy completely misrepresented everything I said.”

That’s pretty bad. Yet after dissembling on one point after another, Kennedy still had the nerve to tell Helmuth that it is journalists who won’t pursue the truth about vaccines and autism because they are scared of the Centers for Disease Control and Prevention and won’t read scientific papers.

This isn’t the first time Kennedy has spouted conspiracy theories about how the CDC and pretty much the entire modern medical establishment have lied and covered up data in order to hide a link between childhood vaccines and autism. In reality, there is no proof of such a connection, but Kennedy has advanced his theory for years, most infamously in a 2005 article for Rolling Stone and Salon. The article was subject to a laundry list of corrections and clarifications, and Salon eventually retracted it altogether.

Curtis Brainard is the editor of The Observatory, CJR's online critique of science and environment reporting. Follow him on Twitter @cbrainard.