At a three-day meeting at Loyola University, researchers said growing evidence indicates that vaccines are linked to increasing rates of brain problems and that government health agencies have done little to recognize it. Autism One, a non-profit group dedicated to learning more about autism, sponsored the meeting.
"There are some bureaucrats in these agencies who have really dropped the ball and are doing things that are malicious and may be criminal," said Dr. Boyd Haley, chairman of the Department of Chemistry at the University of Kentucky.
Boyd believes a mercury-based preservative added to vaccines during the 1990s may be a cause of autism. He said the Food and Drug Administration and the Centers for Disease Control and Prevention have failed to address the issue.
Autism rates have increased 10 times since the late 1980s. The CDC says that one in 300 American children may suffer from autism.
The leading theories about autism discussed in Chicago:
-- A mercury-based preservative called thimerosal used during the 1990s plays a role. Mercury has known toxic effects and during that decade, the CDC drastically increased the recommended number of vaccines. Some children may have been exposed to 125 times the federal limit for mercury exposure.
-- An intestinal disorder may eventually impact the brain. That disorder might start with vaccinations for measles, mumps and rubella, the first multi-dose vaccine for children to contain three live viruses. Some researchers said mercury poisoning might make the body unable to fight off the infection.
Debate over a possible connection between brain problems and vaccines is hotly contested. Critics of the government blame a revolving door between pharmaceutical companies and government regulators for complicating the debate. Researchers who say there is a link claim they have been blackballed.
"I hope somebody will ask the question, 'Is there collusion between the pharmaceutical companies and our health agencies?'" asked Rep. Dan Burton, R-Ind., chairman of the House Human Rights and Wellness Subcommittee. "The appearance in many cases is that there is."
Vaccine manufacturers say the science does not favor a link between thimerosal in vaccines and autism. The Pharmaceutical Research and Manufacturers of America did not return calls seeking comment. But Len Lavenda, a spokesman for vaccine manufacturer Aventis Pasteur, told United Press International this spring that scientists have not proven a link between the additive and brain problems.
"We think we are experiencing opposition to thimerosal for emotional reasons," Lavenda said. "This is not based on research and not based on testing."
Burton has been investigating vaccines for more than four years. In Chicago he released a report on thimerosal criticizing government health agencies and vaccine manufacturers for their roles.
Doctors and activists in Chicago also discussed a new study that claims to show an association between thimerosal and brain problems. The study claims to show "strong epidemiological evidence for a link between increasing mercury from thimerosal-containing childhood vaccines and neurodevelopmental disorders and heart disease."
The study compares reports of speech disorders, autism and heart arrest for one vaccine that contained thimersosal to one that did not, over a 10-year period. It also uses information from manufacturers to determine how much mercury was in shots during different points during that decade.
The study found reports of brain problems for vaccines that contained the additive and that the relative risk went up as more mercury was in vaccines in general.
Two Silver Spring, Md., researchers performed the study, Dr. Mark Geier and his son David Geier.
The study shows that "the relative risk of each of those disorders correlated with increasing doses of mercury contained in childhood vaccines."
The CDC sets the national immunization schedule for children. The CDC says about thimerosal: "There are no data or evidence of any harm caused by the level of exposure that some children may have encountered in following the existing immunization schedule."
The Institute of Medicine -- the government's adviser on medical issues -- said in October 2001 that the link between the preservative and autism is "biologically plausible" but that "current scientific evidence neither proves nor disproves a link." This March, the institute found "no association" between the measles, mumps and rubella vaccine and autism.
In 1999, the American Academy of Pediatrics, followed by the CDC, called for the removal of thimerosal from vaccines but said there was no evidence showing it had harmed children. The CDC continues to recommend the measles, mumps and rubella vaccine.
Autism, referred to by parents as a disease, usually showing up before age 2. Sometimes children who had previously appeared to interact normally will suddenly regress, become withdrawn and stop responding to their parents and the outside world. They may perform repetitive motions, like spinning or flapping their arms, scream uncontrollably and resist physical touch.
Parents of children with autism at the Chicago conference said the disease has a way of isolating parents because of the time-consuming task of raising a child with autism.
"I did not leave my son's side for four years," said Edmund Arranga, with Autism International Association. "It keeps people from connecting."
Arranga said he estimates that 40 percent of parents of children with autism believe vaccines cause the disease.
Many parents described previously normal children who appear to digress suddenly with signs of autism within days of receiving vaccinations. Those vaccinations often include measles, mumps and rubella vaccines and large doses of thimerosal.
Liz Birt, an attorney with Burton's Subcommittee on Human Rights and Wellness, said that during the 1990s, the U.S. childhood vaccination schedule exposed some children to 125 times the federal limit on mercury exposure set by the Environmental Protection Agency. Birt said the CDC and the FDA have been slow to admit the damage the vaccines may have caused because key officials want to keep their jobs and vaccine manufacturers do not want the liability.
"It all comes down to money," Birt said.