Injecting mercury: is thimerosal the missing link to autism and developmental problems?

No one could accuse Lyn Redwood of being anti-vaccination or suspicious of the medical establishment. After all, the Atlanta, Georgia resident was a nurse practitioner and member of her county's board of health, which promoted childhood vaccination. But in 1999, when her happy, healthy toddler, Will, began to regress developmentally at 15 months--he lost speech, he avoided eye contact and seemed miserable--Redwood set out to learn why. And her quest led to thimerosal, a preservative used in some vaccines that is 49.6 percent ethylmercury a known neurotoxin.

Redwood had received two thimerosal-containing injections of RhoGam while pregnant because her blood was Rh negative. Will got all the recommended vaccines for infants, including multiple shots of Hepatitis B, Haemophilus influenzae B (HiB) and diphtheria-tetanus-pertussis (DTaP)--all containing thimerosal. By her calculations, Redwood's son has been exposed to mercury in quantities far exceeding safe levels. To Redwood, the cause of Will's illness was clear: mercury poisoning. "If someone had told me prior to 1999 that vaccines were responsible for my son's disabilities, I would have thought they were crazy," she says.

Thousands of parents like Lyn Redwood have watched their normal children suddenly become ill, exhibiting symptoms called autism spectrum disorders. From Attention Deficit Disorder (ADD), Attention Deficit Hyperactivity Disorder (ADHD) and Asperger's Syndrome on one end of the spectrum, to severe forms of autism on the other, these illnesses have seemingly exploded into what many consider an epidemic in just the last decade.

Autism was rare, diagnosed in one in 10,000 children, before 1980. But in 2002, the National Institutes of Health estimated that one in 250 U.S. children were affected. The Autism Society of America projects that autism disorders are increasing by 10 percent every year. Boys are four times more likely than girls to be diagnosed with autism spectrum disorders, a disparity some scientists attribute to hormonal differences. Genetics may also play a role in susceptibility. Some critics counter that rises in autism rates may be better attributed to increasing awareness among parents and doctors of autism than to any environmental toxin.

But for Redwood and a growing number of activists and scientific researchers, the key to autism disorders is thimerosal. Can it be mere coincidence, they ask, that the rise in autism began during the same period when the number of vaccines was tripled? In the early 1990s, the federal Food and Drug Administration (FDA) approved for use Hepatitis B and HiB vaccines for infants and children, and the Centers for Disease Control and Prevention (CDC) added them to its list of recommended childhood vaccines.

The total number of vaccines containing mercury increased to 11, containing a cumulative total 237.5 micrograms of ethylmercury injected into children during the first year and a half of their lives. There are no standards on acceptable exposure to ethylmercury, unlike its chemical (and more toxic) cousin methylinercury, which is found in fish in polluted oceans.

Lax Safety Tests

Although thimerosal, invented by the Eli Lilly company, has been used to preserve vaccines since the 1930s (and was used in over-the-counter products, such as eye drops, nasal sprays and topical antiseptics) the FDA has never required testing of its safety or of safe levels of exposure in newborns and children. And the CDC never considered the consequences of increasing infants' exposure to mercury as it multiplied the number of suggested vaccines. CDC immunization expert Roger Bernier explains, "Vaccines tend to be evaluated on an individual basis, and a holistic view of safety was not part of the review."

Through her research, Redwood found allies in a group of parents of autistic children who were also seeking answers. They founded Safe Minds, an advocacy group that has also conducted studies, including "Autism: A Novel Form of Mercury Poisoning," published in 2001 in the journal Medical Hypotheses. The study shows the symptoms of mercury poisoning were virtually the same as those in autism disorders. Safe Minds took their findings to government agencies. Redwood says, "We petitioned the FDA unsucessfully on three occasions to take thimerosal off the market."

Congress had requested the FDA in 1997 to review mercury in products, and in 1998, the agency had banned all over the-counter products containing thimerosal. A year later, the FDA, CDC and National Institutes of Health issued a joint statement with the American Academy of Pediatrics that urged vaccine manufacturers to stop using thimerosal because of a "theoretical potential for neurotoxicity."

In February 2000, scientist Thomas Verstraeten presented the first of several analyses of the CDC's Vaccine Safety Datalink, a patient record database that includes information on children vaccinated who developed neurological disorders. Verstraeten's earliest findings showed a risk of autism 2.48 times greater for infants who received the highest amounts of mercury in vaccines. A June 2000 analysis showed a connection between thimerosal exposure and language, speech and developmental delays for infants up to six months old.

A Blizzard of Suits

In the years since, the thimerosal-autism connection has become a hotly contested issue, and one with tremendous political and economic implications. Hundreds of parents have filed lawsuits against Eli Lilly, GlaxoSmithKline and other companies that used thimerosal. In November 2002, Congress sought to protect the drug giants from such legal action by inserting a liability waiver in the Homeland Security Act. Three months later, public outcry forced its repeal. Although the FDA and CDC requested that thimerosal be removed from vaccines, no direct ban was ever issued, and the agencies' scientists have steadfastly defended thimerosal.

In November 2003 a study published in Pediatrics, and co-authored by Verstraeten, presented the final analysis of the CDC's database. All of the positive findings of neurological delays and autism have disappeared. Safe Minds and other critics argue this is a product of questionable methodology and selective data use. Verstraeten's current status as an employee of GlaxoSmithKline was excluded from the article.

WebMD reports that the federally funded study published in The Lancet the same month by lead researcher Michael E. Pichichero "offers reassurance to those who are concerned about the health risks of vaccines containing the preservative thimerosal." WebMD concludes, "Researchers found that blood mercury levels in vaccinated infants were well below those considered safe and that mercury was eliminated from the body much faster than expected." But Boyd Haley, a toxicology researcher at the University of Kentucky and expert on mercury issues, says he questions the validity of the study.

In February of this year, the California Environmental Protection Agency issued a report in response to a petition made by the Bayer Corporation, which was asking the state not to classify thimerosal as a reproductive and developmental toxin under clean water rules. The California agency reviewed the scientific literature and concluded that thimerosal should be considered toxic. Says vaccine researcher Mark Geier, "This is another powerful piece of evidence showing that thimerosal has no place in vaccines."

Today, thimerosal is still used in some vaccines given to children, including Fluzone by Aventis Pasteur, which is provided in multi-dose vials. Thimerosal is also present in what are called "trace" amounts, defined as less than half a microgram of mercury per dose, in several pediatric vaccines, including a Hepatitis B shot from GlaxoSmithKline.

Infants and children, with their less-developed immune systems and still-growing neurological systems, are more vulnerable to mercury's toxicity, but everyone may want to read vaccine labels before being stuck with a needle. FluMist from MedImmune is an example of a thimerosal-free vaccine. CONTACT: CDC Vaccine Safety Datalink, [phone], www.cdc.gov/nip/vac safe/vsd/default.htm; Safe Minds, info @safeminds.org,www.safeminds.org.

ANNETTE FUENTES is an upstate New York-based freelance writer on health topics.