Evidence Of Harm Mercury in Vaccines and the Autism Epidemic: A Medical Controversy
By David Kirby
Back in November 2002, when the journalist David Kirby started
researching “Evidence of Harm,” he couldn’t have known how good his timing would be. His book on the contentious issue of whether mercury in vaccines led to an autism epidemic is appearing in the midst of what must be called an autism boom. In the past few months, this unexplained brain disorder — which skews language and social skills, and can unloose fierce obsessions — has hit a media trifecta. Television news segments, a magazine cover story and a host of newspaper articles have discussed its symptoms, treatments, effects on families and, most controversially, its apparently soaring incidence.
Why so much autism now? In part, the deluge is cyclical, as journalists discover — apologies to Yeats — the fascination of what’s difficult. Yet this year’s coverage has had a particular note of urgency.
Beginning in the late 1980’s, the number of autism cases started to take
off. The latest estimates are that one child in 166 has some form of the
disorder, with effects that range from mild to crippling. These figures have
raised vital questions. Is the increase in autism real or the result of
revised diagnostic criteria and improved awareness? If the syndrome has
become epidemic, is some environmental factor partly to blame? Kirby, who
has contributed to various sections of The New York Times, personalizes this
dispute by introducing us to a collection of parents who began to suspect
that genetic tendencies might not have induced their children’s autism.
Brought together by the Internet, this group soon focused on thimerosal, a
mercury-based preservative once used in vaccines, including many that were
added to the immunization schedule in the early 1990’s. When infants
received higher doses of thimerosal, it was suggested, the result was an
Many of Kirby’s subjects have had sour encounters with the medical
establishment. One such couple, Lyn and Tommy Redwood, struggled to obtain a diagnosis for their son Will, who at 17 months started to lose his language and withdraw socially. When Will turned 4, his latest “expert” doctor ran out of options: “Why don’t you just take him fishing?” Like the Redwoods, the other parents in Kirby’s book watched their children develop normally until the second year of life. After receiving measles-mumps-rubella
(M.M.R.) vaccines, they regressed, developing symptoms of autism and severe gastrointestinal problems.
Initially, the parents wrote off the rumors of a thimerosal-autism
connection, even though the idea that vaccines contributed to the disorder
wasn’t new. In the mid-1980’s, an antivaccine activist collaborated on a
book linking autism to the diphtheria-tetanus-pertussis shot. And the
British doctor Andrew Wakefield argued that autism was an immune-system
disorder brought on by live measles virus in the M.M.R. vaccine (which does
not contain thimerosal). Then, in July 1999, the United States Public Health
Service and the American Academy of Pediatrics issued a statement calling
for vaccines containing thimerosal to be phased out as soon as possible. The
document noted that while babies had received cumulative doses of
ethylmercury (in thimerosal) that exceeded a federal safety limit for
methylmercury, its more toxic chemical cousin, there was no “evidence of
harm.” After reading the statement, Lyn Redwood toted up the micrograms of
mercury Will had received during his first six months and realized that the
government had averaged the mercury exposure on a per-day basis rather than acknowledging that infants got potentially more toxic “bolus” doses — large amounts at one time. Meanwhile, other parents, who would join with Redwood to form the Coalition for Safe Minds, researched the similarities between mercury poisoning and autism. They found a striking parallel in acrodynia, a 1930’s ailment that occurred in some children exposed to mercury in lotions and teething powders.
From here on, Kirby follows the tug of war between government health
agencies and the parents and their supporters. At a succession of hearings,
the so-called Mercury Moms presented their research on acrodynia and
thimerosal, and a neurologist described his research showing that tiny
amounts of thimerosal triggered brain-cell death. The federal agencies, in
turn, cited seemingly conclusive epidemiological studies. (Denmark, for
example, removed thimerosal from vaccines in 1992 but saw a rise in autism
cases rather than the expected drop.) The Safe Minds parents went home and picked the studies apart. Despite their efforts, in May 2004 a committee
from the Institute of Medicine found no “causal relationship” between
thimerosal-containing vaccines, or the M.M.R. vaccine, and autism.
If this story has a smoking gun, it’s the Vaccine Safety Datalink
thimerosal study. Based on data collected from H.M.O.’s, this project,
financed by the Centers for Disease Control, sought to determine whether
there was a correlation between the timing and amounts of thimerosal infants received in vaccines and the emergence of neurodevelopmental disorders, including speech delay, attention-deficit disorder and autism. The Safe Minds statisticians contended that the government analyses of such data were flawed in a way that obscured or eliminated the original findings of
statistically significant risks.
“Evidence of Harm” is filled with abbreviations and statistics, but
Kirby does an admirable job of clarifying most of the scientific background
— including an explanation of the complex biochemical process of
methylation, which plays a central role in Safe Minds’ arguments. (The idea,
in its simplest terms, is that in susceptible people thimerosal blocks the
ability of cells to regulate their functions; these individuals cannot shed
mercury — or other toxins or heavy metals — from their bodies.) However,
Kirby is less clear on the nature of autism, which he sums up as “a hellish,
lost world.” In his account of one government hearing, an angry activist
denounces “the traditional brain-and-genetics stuff” of mainstream research,
but readers who aren’t familiar with that “stuff” might welcome a summary.
Some researchers also suspect that thimerosal and the M.M.R. vaccine
delivered a one-two punch to the immune system — the first weakened it, the
second finished it off. A fuller explanation of this theory would also have
KIRBY doesn’t offer his own verdict on the debate, although he makes
the unassailable point that American health agencies lagged in calculating
the amount of mercury being injected into babies. He quotes Rick Rollens, a
founder of the MIND Institute at the University of California, Davis, who
thinks answers to the thimerosal-autism question may come from his home
state, which has the country’s most reliable system of tracking new cases.
The decline in infants’ exposure to thimerosal, Rollens estimates, began in
2001; he predicts the effects “should start showing up in our system in
2005” — in other words, any day now.
As for Will Redwood, his parents have tried applied behavioral
analysis, vitamin B-12, folinic acid and chelation, the chemical removal of
metals like mercury from the body. In third grade Will was admitted to a
mainstream private school, and at the age of 10 he was becoming interested
in girls. If one certain conclusion can be drawn from “Evidence of Harm,”
it’s that Will’s parents made the right decision about going fishing.
Polly Morrice has written for Redbook and Salon. She is working on a
book about autism.