York Times Magazine
10 November 2002
Not-So-Crackpot Autism Theory
By ARTHUR ALLEN
study on MMR published during same week
by Neal Halsey about this story
Halsey's life was dedicated to promoting vaccination. In June 1999,
the Johns Hopkins pediatrician and scholar had completed a decade
of service on the influential committees that decide which inoculations
will be jabbed into the arms and thighs and buttocks of eight million
American children each year. At the urging of Halsey and others,
the number of vaccines mandated for children under 2 in the 90's
soared to 20, from 8. Kids were healthier for it, according to him.
These simple, safe injections against hepatitis B and germs like
haemophilus bacteria would help thousands grow up free of diseases
like meningitis and liver cancer.
view, however, was not shared by a small but vocal faction of parents
who questioned whether all these shots did more harm than good.
While many of the childhood infections that vaccines were designed
to prevent -- among them diphtheria, mumps, chickenpox and polio
-- seemed to be either antique or innocuous, serious chronic diseases
like asthma, juvenile diabetes and autism were on the rise. And
on the Internet, especially, a growing number of self-styled health
activists blamed vaccines for these increases.
all medical interventions, vaccines sometimes cause adverse reactions.
But unlike pills, vaccines come packaged with high expectations,
which make them particularly vulnerable to public criticism. Vaccines
don't cure people, and they are administered to healthy children,
which gives them few opportunities for good press. When they work,
nothing happens. When vaccinated children become ill, their parents
are grieficken and often enraged, even if vaccines aren't proved
to be at fault. All of this puts public-health advocates like Halsey
on the defensive. Most attacks on vaccines, they say, are based
on hysteria, bad science and dubious politics.
57, has green eyes, a white beard that makes him look like a ship's
captain and an air of careful authority. As chairman of the American
Academy of Pediatrics committee on infectious diseases from 1995
through June 1999, he often appeared in the media administering
calm reassurance. ''Many of the allegations against vaccines,''
Halsey said in one interview, ''are based on unproven hypotheses
and causal associations with little evidence.''
then suddenly in June 1999, during a visit to the Food and Drug
Administration, a squall appeared on the horizon of Halsey's confidence.
Halsey attended a meeting to discuss thimerosal, a mercury-containing
preservative that at the time was being used in several vaccines
-- including the hepatitis B shot that Halsey had fought so hard
to have administered to American babies. By the time the dust kicked
up in that meeting had settled, Halsey would be forced to reckon
with the hypothesis that thimerosal had damaged the brains of immunized
infants and may have contributed to the unexplained explosion in
the number of cases of autism being diagnosed in children.
Halsey was willing even to entertain this possibility enraged some
of his fellow vaccinologists, who couldn't fathom how a doctor who
had spent so much energy dismantling the arguments of people who
attacked vaccines could now be changing sides. But to Halsey's mind,
his actions were perfectly consistent: he was simply working from
the data. And the numbers deeply troubled him. ''From the beginning,
I saw thimerosal as something different,'' he says. ''It was the
first strong evidence of a causal association with neurological
impairment. I was very concerned.''
investigation into mercury vaccines was instigated in 1997 by Representative
Frank Pallone Jr., a New Jersey Democrat whose district includes
a string of shore towns where mercury in fish is one of many environmental
concerns. Pallone, who had been pressing the government to re-evaluate
its overall guidelines on mercury toxicity, attached an amendment
to an F.D.A. bill requiring the agency to inventory all mercury
contained in licensed drugs and vaccines.
The job of adding up the amount of mercury in vaccines and assessing
its risk fell to Robert Ball, an F.D.A. scientist, and two F.D.A.
pediatricians, Leslie Ball, Robert's wife, and R. Douglas Pratt.
Thimerosal, which is 50 percent ethyl mercury by weight, had been
used as a vaccine preservative since the 1930's in the diphtheria-tetanus-pertussis
shot, known as D.T.P., and it was later added to some vaccines for
hepatitis B and haemophilus bacteria, which by the early 1990's
had become routine immunizations for infants.
F.D.A. team's conclusions were frightening. Vaccines added under
Halsey's watch had tripled the dose of mercury that infants got
in their first few months of life. As many as 30 million American
children may have been exposed to mercury in excess of Environmental
Protection Agency guidelines -- levels of mercury that, in theory,
could have killed enough brain cells to scramble thinking or hex
first reaction was simply disbelief, which was the reaction of almost
everybody involved in vaccines,'' Halsey says. ''In most vaccine
containers, thimerosal is listed as a mercury derivative, a hundredth
of a percent. And what I believed, and what everybody else believed,
was that it was truly a trace, a biologically insignificant amount.
My honest belief is that if the labels had had the mercury content
in micrograms, this would have been uncovered years ago. But the
fact is, no one did the calculation.''
matters worse, the latest science on mercury damage suggested that
even small amounts of organic mercury could do harm to the fetal
brain. Some of the federal safety guidelines on mercury were relaxed
in the 90's, even as the amount of mercury that children received
in vaccines increased. The more Halsey learned about these mercury
studies, the more he worried.
first concern was that it would harm the credibility of the immunization
program,'' he says. ''But gradually it came home to me that maybe
there was some real risk to the children.'' Mercury was turning
out to be like lead, which had been studied extensively in the homes
of the Baltimore poor during Halsey's tenure at Hopkins. ''As they
got more sophisticated at testing for lead, the safe level marched
down and down, and they continued to find subtle neurological impairment,''
Halsey says. ''And that's almost exactly what happened with mercury.''
was beginning to think that it would be prudent to limit thimerosal-containing
vaccines and urge pediatricians to use thimerosal-free shots when
possible. But his decision inflamed some of his peers. After all,
although the thimerosal data was worrisome to Halsey, the available
science offered no clear proof that the preservative posed a genuine
danger to children when given in parts per million. Moreover, it
wasn't clear that there were enough thimerosal-free vaccines available
for diseases like pertussis and hepatitis B. Should an unproven
fear justify the cessation of a procedure that protected children
from proven dangers?
looked into the matter further and found only complexity. In the
medical literature, most cases of acute mercury poisoning result
from doses hundreds or thousands of times higher than what infants
received with thimerosal-laden vaccines. And although the thimerosal
levels in vaccines exceeded the E.P.A.'s guidelines for methyl mercury,
thimerosal contained ethyl mercury, a compound that behaves somewhat
differently in the body. The E.P.A. based its guidelines on a series
of studies of 917 children born in 1987 in the Faeroe Islands, a
windswept North Atlantic archipelago, to women who ate methyl-mercury-tainted
whale meat. The Faeroes children, whose umbilical cord blood averaged
four times the E.P.A.'s daily ''safe'' dose -- which was 0.1 micrograms
per kilo -- exhibited small but measurable neurological deficits
seven years later. They had slower reaction times and diminished
attention spans and their word choice and memorization were less
keen than those of their classmates who had been exposed to less
mercury, according to Philippe Grandjean, a Danish researcher who
leads the continuing Faeroes study and teaches at Boston University.
most of the 90's, many American 6-month-olds received a total of
187.5 micrograms of ethyl mercury through vaccination. While the
Faeroes children were exposed to mercury as developing fetuses,
and therefore were more vulnerable than the vaccinated American
infants, the American babies included about 60,000 each year who
had already been exposed to high mercury levels because their mothers
had eaten a lot of contaminated fish. What's more, hundreds of thousands
of Rh-negative pregnant women and their unborn Rh-positive babies
received additional thimerosal each year through injections designed
to keep the mothers' immune systems from attacking the fetuses.
Faeroes studies, though they dealt with methyl mercury, unnerved
Halsey. Other researchers were troubled, too. George Lucier, a toxicologist
who led a 1998 White House review of mercury's dangers, went so
far as to say it was ''very likely'' that thimerosal had damaged
some children. There was precious little data to back up that precise
suspicion -- and little to dismiss it -- because of the lack of
toxicology research on ethyl mercury.
July 7, 1999, at Halsey's urging, the American Academy of Pediatrics
and the Public Health Service released a statement urging vaccine
manufacturers to remove thimerosal as quickly as possible and advising
pediatricians to postpone giving most newborns the birth dose of
the hepatitis B vaccine. The decision, which helped to create vaccine
shortages and led some babies to become infected with hepatitis
B, outraged some senior vaccine experts. Walter Orenstein, director
of the National Immunization Program at the Centers for Disease
Control and Prevention, would charge that the rush to remove thimerosal-containing
vaccines was ''precipitous.'' Stanley Plotkin, a renowned vaccine
developer, said that it was fruitless to try to soothe vaccination
critics. ''If antivaccinationists did not have mercury, they would
have another issue,'' he said at one meeting. ''One cannot prevent
them from making hay regardless of whether the sun is shining or
Halsey's view, however, thimerosal wasn't simply a bone for rabid
vaccine opponents to gnaw on. In the middle of that hectic summer
he took a vacation in Maine. Canoeing on a lake, he came across
posters that advised fishermen to ''protect your children -- release
your catch.'' Halsey took that message to heart. If the government
was warning people against eating fish with mercury, he asked his
colleagues, ''does it make sense to allow it to be injected into
other vaccinologists criticized Halsey, many of his colleagues rallied
around him. ''Neal put kids ahead of the vaccination program, which
was gutsy,'' says Lynn Goldman, a former E.P.A. official who has
been on the Hopkins faculty since 1999 and worked with Halsey on
thimerosal. ''It would have been easier for him to line up on the
Few scientists believe that the spike in autism could have been
caused solely by the thimerosal in vaccines, but in October 2001,
a vaccine-safety committee at the starchy Institute of Medicine
confirmed that it was ''biologically plausible'' -- though by no
means proved -- that thimerosal could be related to neurodevelopmental
delays in some children. The committee recommended that thimerosal
be removed from vaccines and called for extensive research to determine
any damage it had caused.
fellow researchers were right about one thing. Antivaccine advocates
immediately seized upon the thimerosal theory, and Halsey became
something of an unwilling hero to the vaccine-safety advocates with
whom he had so often sparred. In fact, thousands of parents with
autistic children have responded to the Institute of Medicine report
by filing lawsuits. Michael Williams, who has won millions in toxic
tort settlements from pharmaceutical companies, was among the first
lawyers to sue vaccine manufacturers, on behalf of William Mead,
a 4-year-old Portland, Ore., boy with autism. Williams also filed
a separate class-action lawsuit with William's healthy older sister,
Eleanor, as lead plaintiff, demanding that vaccine makers also pay
for studies to determine thimerosal's effects on millions of children
who might have lower I.Q.'s or other less obvious signs of mercury
poisoning. Past studies have shown that mercury's effects vary tremendously
from person to person, presumably because of genetic differences
in the body's capacity to protect delicate organs from it.
order to win the Eleanor lawsuit you need to establish liability,
but I don't think that is going to be that hard,'' Williams said
in a recent chat in his Portland office. ''Organic mercury is a
very serious neurotoxin.''
embodies the vaccine establishment's worst fear about Halsey's course
of action -- which is that taking the precautionary step of eliminating
thimerosal would be read as an admission of fault. ''The agenda
was set by the lawyers and the antivaccine activists,'' a source
close to a number of manufacturers complained to me. ''The scientists
responded to it scientifically, and that put them behind the eight
ball right away. You had Neal Halsey running around saying: 'We've
got to do something! We've got to show we're concerned!'''
Offit, a vaccinologist at the Children's Hospital of Philadelphia,
takes it a step further. ''In some instances I think full disclosure
can be harmful,'' he says. ''Is it safe to say there is zero risk
with thimerosal, when it is remotely possible that one child would
get sick? Well, since we say that mercury is a neurotoxin, we have
to do everything we can to get rid of it. But I would argue that
removing thimerosal didn't make vaccines safer -- it only made them
Halsey, thimerosal injury is a possibility that must be addressed
-- but by science, not by the courts. The scientific agenda, however,
is already deeply politicized. From the start, the C.D.C.'s efforts
to examine the possibility of thimerosal damage became snarled in
acrimony. Critics of the vaccination system don't trust the C.D.C.,
which monitors evidence of adverse reactions to vaccines through
the Vaccine Safety Datalink, a computerized set of 7.5 million medical
records. Safe Minds, an advocacy group of parents who believe that
their autistic children were damaged by thimerosal, has used the
Freedom of Information Act to obtain documents showing that as early
as December 1999 the C.D.C. had reason to believe that thimerosal
caused developmental delays in some children. It was far from conclusive
evidence, but vaccine critics charged that the C.D.C. tried to play
it down. One of those critics was Dan Burton, a Republican congressman
from Indiana, who says he firmly believes that his grandson's autism
is a result of vaccines. ''I'm so ticked off about my grandson,
and to think that the public-health people have been circling the
wagons to cover up the facts!'' Burton fumed at a June hearing.
''Why, it just makes me want to vomit!''
comes through in an examination of the documents uncovered by Safe
Minds is less a coverup than an impression of scientists anxiously
watching over their shoulders as they work. One document, for example,
records comments made by Robert Brent, a Philadelphia pediatrician
who served as a consultant for the thimerosal study. ''The medical-legal
findings in this study, causal or not, are horrendous,'' Brent said.
''If an allegation was made that a child's neurobehavioral findings
were caused by thimerosal-containing vaccines, you could readily
find a junk scientist who would support the claim with a reasonable
degree of certainty. But you will not find a scientist with any
integrity who would say the reverse with the data that is available.
. . . So we are in a bad position from the standpoint of defending
any lawsuits if they were initiated.''
research is in the works. The C.D.C. is setting up a study of neurodevelopmental
effects based in part on the Faeroe Islands model. The N.I.H. is
financing studies of thimerosal metabolism in animals and children.
(An early University of Rochester study was reassuring: it indicated
that children eliminate thimerosal much more quickly than expected.)
Clearly, a lot is riding on this research, and pressure is being
brought to bear on both sides. Can the vaccine authorities accept
a positive answer? Can the vaccine opponents accept a negative one?
''No one wants to think that harm might have been done,'' Halsey
says. ''I don't want to think harm might have been done.''
children still receive up to 20 vaccines in the first two years
of life. The first symptoms of autism often appear between the ages
of 12 and 24 months. Most autism experts say that the two facts
are coincidental, but as a major California study recently confirmed,
autism is being diagnosed in numbers far higher than ever before,
suggesting that a nongenetic cause may be partly to blame. In some
children, the behavioral traits of autism present themselves along
with physical problems like sensory dysfunction and motor disorders
that have rough correlates in the mercury-poisoning literature.
For some parents, thimerosal provides a grand unifying theory that
squarely points the finger at the government and vaccine makers.
much of the 20th-century, children suffered from an ailment called
pink disease, which caused peeling skin on the extremities as well
as regressive behavior. In 1948, a keen-eyed Cincinnati pediatrician
named Josef Warkany noticed a common risk factor in these children:
they had all been given teething powders containing calomel, a mercury
derivative. Only about 1 in 500 children whose parents gave them
calomel got pink disease -- suggesting that a constitutional vulnerability
to mercury was part of the clinical picture. Soon after the powders
were taken off the market, pink disease disappeared.
is a global phenomenon that was first reported in America in 1943,
long before the potential dangers of thimerosal vaccines were raised.
Removing the preservative won't -- even in the best case -- eliminate
the illness. But scientists estimate that the current rate of autism
in its various forms might be as high as 1 in 500. If the autism
trend begins to recede now that thimerosal has been removed, it
could certainly suggest a cause. If it does decline, we might have
Neal Halsey to thank. If it doesn't, his colleagues in the vaccine
establishment may blame him for stoking an irrational protest from
who still heads the Hopkins Institute for Vaccine Safety, which
he was a founder of in 1997, is on the fence. ''I don't believe
the evidence is convincing now that there has definitely been harm
done by thimerosal,'' he says, absently stroking his balding head.
But to keep the vaccine program on a steady keel, Halsey says, the
public-health authorities simply must follow through with the studies
and face the consequences without flinching. If there is damage,
he says, ''there should be some kind of compensation, though I don't
know how.'' He pauses, and sighs. ''I empathize with families of
children with these disorders. How are you going to put dollar values