Anti-vaccine groups have seized on the allegations to contend that scientific studies disproving the vaccine link to autism are wrong. Those groups have long argued that thimerosal, a preservative in some vaccines, can cause autism, as can the MMR vaccine for measles, mumps, and rubella.
"I think it is quite significant," said Dan Olmsted of the Age of Autism. "I think someone allegedly capable of ripping off his own university by forging documents from the CDC is capable of pulling off anything."
The CDC and coauthors of the two studies published in major U.S. medical journals maintain the studies remain valid.
"CDC is aware of the allegations by Aarhus University against Poul Thorsen," agency spokesman Tom Skinner said in a statement. Federal authorities are investigating.
Skinner noted that Thorsen was one of many coauthors on peer-reviewed studies looking at autism, cerebral palsy, Down syndrome, and alcohol use in pregnancy.
"We have no reason to suspect that there are any issues related to the integrity of the science," Skinner said.
Efforts to reach Thorsen for comment by phone and e-mail this week were unsuccessful.
In a statement, Drexel University said that Thorsen was an adjunct at its School of Public Health from Dec. 11 until "he resigned his appointment with the school of public health on March 9, 2010."
Drexel's statement noted that his role was limited to serving as a member of the thesis committee of one doctoral student.
"To our knowledge, Dr. Thorsen has performed no other work directly connected to Drexel while holding a title at Drexel University," the statement said.
In 2002, Thorsen was the sixth named author of a study published in the New England Journal of Medicine that analyzed whether where is a connection between the MMR vaccine and autism by examining 537,303 children born in Denmark from 1991 through 1998.
The researchers concluded that their data provided "strong evidence" that there is no link.
"Poul Thorsen had absolutely no influence on the conclusions regarding this paper," wrote Mads Melbye, head of the division of epidemiology at the Statens Serum Institut in Copenhagen and senior author of the study, in response to e-mailed questions.
"Thorsen was not actively involved in the analysis and interpretation of the results of this paper," Melbye said.
The second study, published in Pediatrics in 2003, examined 956 Danish children diagnosed with autism from 1971 to 2000. It concluded the incidence of autism increased in Denmark after thimerosal was removed from vaccines.
Kreesten Meldgaard Madsen, the lead author, said Thorsen played a minor role.
"Dr. Thorsen was not in a position to change or compromise the data," Madsen wrote. "Dr. Thorsen was part of the review cycle, but never very active in giving input. Dr. Thorsen never had access to the raw data nor the analysis of the data."
Others, such as Paul Offit, director of the Vaccine Education Center at Children's Hospital of Philadelphia and a vocal opponent of the anti-vaccine groups, said even if the allegation against Thorsen is true, it does not mean his science is bad.
"Let's assume it is true that he embezzled money," Offit said. "The notion that it casts the science into question is false. For these big epidemiological studies, it is hard to believe that one person could effectively change the data."
Offit pointed out that a dozen major studies show no link between MMR and autism and at least a half dozen say the same about thimerosal, which contains mercury.
But the Internet was afire over the allegations.
"Questions about Thorsen's scientific integrity may finally force CDC to rethink the vaccine protocols since most of the other key pro-vaccine studies cited by CDC rely on the findings of Thorsen's research group," Robert F. Kennedy Jr. wrote on the Huffington Post. "The validity of all these studies is now in question."
In its statement, Aarhus University said the Danish Agency for Science, Technology, and Innovation (DASTI) has gotten grants from the U.S. National Center for Birth Defects and Developmental Disabilities since 2001. Thorsen directed the administration of the grants, the university said.
After discovering that money was missing, DASTI and Aarhus "became aware of two alleged CDC funding documents as well as a letter regarding funding commitments allegedly written by Randolph B. Williams of the CDC's procurement grants office. . . ."
"Upon investigation by CDC, a suspicion arose that those documents are forgeries."
The university's statement goes on to say that in March 2009, Thorsen resigned from its faculty.
Last month, the Copenhagen Post Online reported on the issue without naming Thorsen. The paper pegged the shortfall at 80 million kroner, about $2 million.
In Atlanta, where Thorsen is thought to live, Emory University said he began working there Sept. 1, 2003, as a part-time adjunct professor in its School of Public Health. Emory said that from April 2008 to June 2009, Thorsen "served as a full-time research professor. He is no longer employed at Emory."
"It is a sad story," wrote Melbye of the Statens Serum Institut in an e-mail. "We are all here with one big question: What has happened and why?"
Contact staff writer Josh Goldstein at 215-854-4733 or email@example.com.