An episode of a new television drama, “Eli Stone,” has added much fuel to the debate over what causes autism in children.

There are many people who blame thimerosal, a preservative found in many mandatory childhood vaccinations, for a steady rise in autism diagnoses despite consistent results of scientific studies and reports to the contrary.

There are over 150 anti-vaccine Web sites claiming that thimerosal causes autism, a neurological disorder. These Web sites also say there is a world-wide conspiracy to cover up the affects of thimerosal. Adherents to this belief are so adamant and hateful that they’ve sent death threats to public health service officials, who subsequently quit their jobs in fear. ABC’s autism episode just adds fuel to the anti-vaccine campaigns. Presumably, more people saw the show than read the two new major medical studies, one published in the Archives of General Psychiatry and the other in the journal, Pediatrics.

Each study uses an entirely different scientific methodology. One looks at the epidemiology of autism; the other at the toxicology of thimerosal.

Thimerosal has been used in human vaccines since 1931. The World Health Organization still uses it in human vaccines today, and declares there is “no evidence of toxicity in infants, children or adults.” But, under pressure from the anti-vaccinationists, companies acting on the government’s request completed a thimerosal phase-out in childhood vaccines by March 2001.

Many public health specialists regret that action now because many have interpreted it as an indictment of the preservative. Still, the phase-out does give epidemiologists two groups for comparison, those who were given vaccines that contained thimerosal and those that weren’t.

The California Department of Public Health keeps the best autism records for America. The anti-vaccinationists eagerly proclaimed that the thimerosal phaseout would cause a sharp drop in diagnoses of autism in California. Indeed, in 2002 two different sets of the anti-vaccinationists claimed CDPH data already indicated a decline of as much as 35%.

But the CDHP has published its own findings in the January edition of Archives of General Psychiatry that concludes no thimerosal-related decline could appear before 2004, much less 2002. Using records up to 2006, the CDPH data show autism cases continuing to increase at the same rate as before the phase out of thimerosal in mandatory childhood vaccines.

The CDHP article also referred to the Institute of Medicine’s study that cited three studies looking at the entire child populations of Sweden, Denmark, and Canada. Those nations discontinued thimerosal use in the late 1990s and, just as in California, autism rates continued to climb at the same pace.

The thimerosal autism myth arose in part because the preservative metabolizes into ethylmercury in the body. Ethylmercury is not to be confused with methylmercury, a much different substance that is indeed neurotoxic.

The study printed in Pediatrics explains how ethylmercury and methylmercury differ. “It takes a certain amount of time and a certain concentration [of mercury] to make it into the brain,” the research leader of the University of Rochester in New York, Michael Pichichero, explained to Reuters. He studied more than 200 infants who received thimerosal-preserved vaccines in Argentina and found that the half-life, the time it takes the body to clear half of a substance, of methylmercury is 44 days while that for the ethylmercury found in thimerosal is only 3.7 days. “It’s just gone too fast” to do harm Mr. Pichichero said.

Pediatrics announced the study early because on the first episode of “Eli Stone,” that aired on January 31, a jury awarded $5.2 million to a family whose child developed autism after receiving a flu injection. Thimerosal remains in most flu vaccines that are not mandatory.

Influenza, says the Center for Disease Control, kills about 36,000 Americans annually and hospitalizes more than 200,000. Of those that die from the flu, about 150 of them are children. Lower vaccination rates will raise the reaper’s toll.

Mr. Fumento is a Washington D.C.-based freelance writer specializing in health, medical, and military issues. He receives no funding from any sector of the pharmaceutical industry. He may be reached at fumento@pobox.com.