The dogged pursuit of the unanswerable question, "What causes autism?" could be considered a health hazard. It requires poring over reams of studies, most of whose contents could reasonably be expected to induce paranoia. Mental fatigue from considering the studies' considerable contradictions is a distinct possibility. And the energy with which the proponents of these competing conclusions defend the arguments could lead to high blood pressure for all concerned.
The most emotional dimension of the autism debate, the proposition that mercury in childhood vaccines is linked to the increasing diagnosis rates of Autism Spectrum Disorders (ASDs), is a case in point. Jenny McCarthy and Amanda Peet have offered point-counterpoints all over the Web and on mainstream media, like National Public Radio's Morning Edition.
The vaccine debate swirls around a preservative called thimerosal, which the U.S. Food and Drug Administration (FDA) calls a "mercury-containing organic compound" that was widely used in biological and drug products, "including many vaccines." And, as a Feb. 2, 2002, National Academies news release makes clear, American children's exposure to thimerosal increased dramatically between the early 1980s and late 1990s, when the U.S. Public Health Service, American Academy of Pediatrics and drug manufacturers moved to stop using thimerosal in childhood vaccines.
"In 1980, infants were vaccinated against four diseases -- diphtheria, tetanus, pertussis, and polio. Today, most healthy infants get up to 15 shots of five vaccines by the time they are six months old."- National Academies news release
"The immunization schedule in this country has grown complex over the last 20 years," the National Academies release says. "In 1980, infants were vaccinated against four diseases -- diphtheria, tetanus, pertussis, and polio. Today, most healthy infants get up to 15 shots of five vaccines by the time they are six months old, and up to five additional shots of seven more vaccines by age two."
Vaccination against hepatitis B was and is routinely administered to newborns at birth, at the urging of the American Academy of Pediatrics.
Among those who have argued that thimerosal caused their loved ones' ASDs is U.S. Rep. Dan Burton, R-Ind., whose grandson developed the condition after being vaccinated. "Based upon my own research, I believe that the mercury-based preservative thimerosal -- contained in seven of the nine vaccines that my grandson received in one day shortly before he was diagnosed with autism -- may have been a contributing cause of his condition," Burton says on his congressional Web page.
But in 2003 the Journal of the American Medical Association (JAMA) published a Danish study that refuted a connection. Titled "Association Between Thimerosal-Containing Vaccine and Autism," the study analyzed 467,450 children who had and had not been exposed. Its conclusion: "The results do not support a causal relationship between childhood vaccination with thimerosal-containing vaccines and development of autistic-spectrum disorders."
But J.B. Handley, founder of what is now known as McCarthy and husband Jim Carrey's Generation Rescue, says thimerosal is but one of dozens of vaccine-based substances that could contribute to the upward trend of ASD diagnoses.
"In the 1980s, we gave a max of 10 shots to youngsters, today 36," Handley wrote in a Nov. 15, 2009, e-mail. "With this 'simultaneity' of layering on shots, how do we figure out what thing about shots is causing the trouble? Yes, mercury is particularly bad, but we're giving 36 shots with 81 separate ingredients, all thrown onto the schedule rapidly since 1990, which just happens to parallel the rise in autism."
The truth is no one knows what causes ASDs. But the prevailing theory suggests that ASDs are triggered in genetically predisposed individuals by "environmental hits," to use the phrase of Dr. Christopher McDougle, an autism researcher and chair of the Department of Psychiatry at the Indiana University School of Medicine. Environment is defined broadly to include viruses, lack of oxygen at birth, etc., in addition to toxic chemicals.
"The results do not support a causal relationship between childhood vaccination with thimerosal-containing vaccines and development of autistic-spectrum disorders."- 2003 Danish study
So that raises the specter that those additional micrograms of ethylmercury repeatedly injected into the bodies of rapidly developing children may indeed have caused autism, but only in those who are genetically predisposed. And there are data to suggest that any mercury added to a newborn's body via immunization is not merely an exposure but, rather, an increase in dose.
A 2005 study titled "Body Burden -- The Pollution in Newborns" tested the blood from 10 babies' umbilical cords for 413 toxic chemicals. The Red Cross collected blood after the umbilical cords were cut, the report says. Testing showed it "harbored pesticides, consumer product ingredients, and wastes from burning coal, gasoline, and garbage."
"In a study spearheaded by the Environmental Working Group (EWG) in collaboration with Commonweal, researchers at two major laboratories found an average of 200 industrial chemicals and pollutants in umbilical cord blood from 10 babies born in August and September of 2004 in U.S. hospitals," the authors say. "Tests revealed a total of 287 chemicals in the group."
Mercury was found in blood samples from all 10 babies.
Marcella Piper-Terry, a biomedical consultant who works in the tri-state area of Southwest Indiana, Western Kentucky and Eastern Illinois, cites the EWG and other reports in a PowerPoint presentation she gives called "Environmental Toxins and Your Child." She lives and works in a region of the Ohio River Valley that is home to the largest concentration of coal-fired power plants in the world, most of them ancient with ineffective environmental protections.
"Mercury is particularly bad, but we're giving 36 shots with 81 separate ingredients."- J.B. Handley, Generation Rescue
One study Terry cites is titled "Potential association between autism rates, environmental mercury other toxins in Texas," published in 2006 by researchers at the University of Texas Health Science Center.
"There was a significant increase in the rates of special education students and autism rates associated with increases in environmentally released mercury," the study's abstract says. "On average, for each 1,000 lb of environmentally released mercury, there was a 43 increase in the rate of special education services and a 61 percent increase in the rate of autism."
Seventeen tri-state power plants released 4,307 pounds of mercury into the environment in 2007, according to U.S. Environmental Protection Agency Toxic Release Inventory data compiled by John Blair, president of the Evansville-based environmental group Valley Watch.
Another study Terry cites, a May 2000 report from the Greater Boston Physicians for Social Responsibility (GBPSR) titled "In Harm's Way: Toxic Threats to Child Development," details the enormity of the challenges facing those who dare to seek the causes of autism and developmental disabilities.
"Researchers at two major laboratories found an average of 200 industrial chemicals and pollutants in umbilical cord blood from 10 babies born in August and September of 2004."- Environmental Working Group
The report notes that of the 2,863 industrial chemicals produced in volumes of 1-million-plus pounds a year, only 0.4 percent have been tested for neurodevelopmental toxicity. Barely one in five -- 21.4 percent -- have even "some data" on developmental toxicity.
More than three-quarters, 78.2 percent, have no data whatsoever.
As frightening as the statistics on individual chemicals are, another cause for paranoid response lies in the study's implications for learning what health effects these chemicals may have as they mix together in the body.
The EWG spent $10,000 per child to test their umbilical cords' chemical burden. But the GBPSR study says studying the impacts of the nearly 3,000 million-pounds-a-year toxic chemicals American industry produces, just in groups of three, would require 85 billion tests.
It's enough to make you ill.
Steven Higgs is author of the "Autism and the Indiana Environment Blog" and editor of The Bloomington Alternative. He can be reached at .
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