He authored a 2005 article for Rolling Stone and Salon.com alleging that mercury in vaccines had caused a rise in neurological disorders like autism that was later withdrawn by both publications after multiple corrections. The Centers for Disease Control and Prevention has posted a two-page explainer to debunk claims of mercury harm in vaccines, citing nine different studies, including six that were published after his article.

Kennedy has not changed his view, though he now says that mercury was likely just one of many toxins that caused the disorders. “They are all epidemiological studies, which are the easiest studies to fix,” he said in Indianapolis when presented with the CDC document. “I did a whole book on it, where I digested, I think, 450 studies and 1,400 references.”

Most scientists view such talk as nonsense, in part because most mercury was voluntarily removed from or reduced in childhood vaccines about two decades ago, while autism diagnoses have continued to rise since then, said David Gorski, an oncologist at Wayne State University School of Medicine, who edits Science-Based Medicine, a website focused on debunking medical conspiracy theories.

Kennedy argues that an increase in flu vaccinations with mercury preservative could have counteracted this shift. “It’s hard to write anything I say about vaccines,” he admits, nodding to the complexity. “It’s layer upon layer and argument upon argument.”

His opponents have a simpler explanation. “His entire worldview has become a conspiracy theory. He has spent the last 18-plus years spreading fear, uncertainty and doubt about vaccines,” Gorski said. “He is just more respectable, because he is a Kennedy.”

Indeed, he illustrates a key point about contemporary American politics:  the blending of various conspiracy theories.

 Judd Legum and colleagues at Popular Information:

Kennedy claims that 5G, a communications network that powers many mobile phones, is a plot by the government "to harvest our data and control our behavior." He has previously said that 5G technology "damages human DNA [and] causes cancer." But there is "no evidence to support concerns about cancer fears or damage to immune systems."

Kennedy has even called for the release of Sirhan Sirhan, the man convicted of murdering his father, claiming Sirhan was framed. He does not dispute that Sirhan fired multiple rounds at his father, but believes none of those rounds hit the target. Kennedy believes his father was killed by his security gaurd, Thane Cesar. A book written by investigative journalist Dan Moldea, who was initially sympathetic to the "second gunman" theory, ruled out Cesar as a suspect. Kennedy's advocacy for Sirhan is opposed by six of his siblings.