THE BLOG

CDC: Mercury in Vaccines Damaged Your Child. Or Not.

If you were informed that mercury in vaccines might double the risk of your son developing motor tics, increase his risk of "phonic tics" by nearly two-and-a-half times, and possibly cause speech, attention or behavioral problems in school, would you still allow him to be injected with the heavy metal -- which, by the way, is 100 times more neurotoxic than that lead coating on his Chinese toys?

And what if your government's most trusted public health agency, the CDC, announced it had funded a study that replicated the findings of a 2003 CDC analysis, which also detected an association between vaccine mercury and tics, and that researchers were now suggesting "the potential need for further studies" between thimerosal and the neurological disorder?

And what if the investigators also said they detected a small but statistically significant association between early thimerosal exposure and impaired "behavioral regulation" in boys?

Or what if they said that increased neonatal exposure (28 weeks or younger) was associated with "significantly lower scores in verbal IQ scores in girls," and "significantly poorer performance" in articulation tests among all children?

And what if the authors further noted that speech problems were also found in the 2003 CDC study, where they said thimerosal exposure was associated with "an increased risk of language delays" at one test site?

Finally, what if those same authors claimed that their findings "suggest a possible adverse association between neonatal exposure to mercury and language development?"

You might think that the government was getting ready to admit that injecting organic mercury into newborn babies was a dumb idea.

But you'd be wrong.

Instead, brace yourself for some gauzy, reassuring reports in the upcoming media cycle about a New England Journal of Medicine study on thimerosal and "neuropsychological outcomes," in which, we are to believe, the connection is nil.

"Our study," the authors concluded, "does not support a causal association between early exposure to mercury from thimerosal-containing vaccines (and) deficits in neuropsychological functioning at the age of 7 to 10 years." They did not look at autism, ADHD or other major disorders.

On a conference call this afternoon from Atlanta, CDC officials gushed that these data offered nothing but "very reassuring news" about vaccine safety.

The associations found were "small," the investigators wrote, "and almost equally divided between positive and negative effects." In other words, for every "bad" thing associated with thimerosal, there was a negating "good" thing, such as improved finger tapping, or higher IQ scores among boys.

Indeed, the authors reasoned that the "higher scores on the performance IQ tests in boys" who received the most thimerosal, "makes it difficult to draw general conclusions about possible effects of neonatal mercury exposure from vaccines on intellectual abilities."

(If they really mean that thimerosal increases IQ levels in males, then sign me up for a double-dose flu shot this year).

But there might be another explanation. "Children who had been exposed to higher levels of thimerosal were more likely to have mothers with higher IQ scores," noted the authors, who did adjust test scores for maternal IQ -- though it's unclear if their study size, (1,040 kids), was large enough to accurately conduct such a precise statistical correction.

The study had several more flaws, any of which may have served to bring down the relative risks of neurological outcomes associated with increased levels of mercury exposure.

For example, 70% of the families selected for the study declined to even participate, yielding an unusually low response rate of 30% (the ideal is 70%) and data "that may have been influenced by selection bias," the authors conceded.

Next, any child born below 5.5 pounds was excluded from the study, which doesn't make sense, given that an 8 pound baby injected with the hepatitis B vaccine at birth was exposed to 35 times the EPA daily safety level for mercury, (calculated by bodyweight) while a 4 pound infant was slammed with 70 times the EPA level.

The authors also failed to adjust for any treatments these children received for their conditions. All kids were enrolled in major HMOs, where they presumably were eligible for an array of physical, behavioral and/or pharmaceutical therapies. Remember, these children were vaccinated between 0-2 years, but evaluated at 7-10 years. By not accounting for potentially years of speech and other therapies, the investigators "may have ameliorated the potential negative effects of thimerosal exposure," they admitted, and "could have biased the results toward the null hypothesis."

Despite these statistical pressures to drive the numbers downward, the associated risk for tics among boys was a real standout.

Boys who received the highest amounts of thimerosal in the first seven months of life were determined by evaluators to be 2.19 times more likely to have motor tics at age 7-10 years, and 2.44 times more likely to have phonic tics, than boys with the lowest exposures.

Any relative risk between exposure and outcome that exceeds 2.0, incidentally, is considered to be proof of causation in US courts of law.

The researchers did not differentiate between "transient" tics, which go away within a year, and "chronic" tics, which can last a lifetime. Nor did they distinguish between "simple" and "complex" tics.

I know the temptation is strong to think, "Well, it's just tics." But I suggest consulting the literature, which paints a more disturbing picture, especially if it's your kid we are talking about.

The Encyclopedia of Mental Disorders defines "simple" motor tics as "brief, meaningless movements like eye blinking, facial grimacing, head jerks or shoulder shrugs," that usually last less than a second. It says that "complex" motor tics cause slower, longer, more intense movements, "like sustained looks, facial gestures, biting, banging, whirling or twisting around, or copropraxia (obscene gestures)."

On the phonic side, "simple" tics are called, "meaningless sounds or noises like throat clearing, coughing, sniffling, barking, or hissing." Complex phonic tics include, "syllables, words, phrases, and such statements as 'Shut up!' or 'Now you've done it!' The child's speech may be abnormal, with unusual rhythms, tones, accents or intensities."

There is also the "echo phenomenon," (so familiar to autism parents) characterized by "the immediate repetition of one's own or another's words." Coprolalia, meanwhile, is a tic "made up of obscene, inappropriate or aggressive words and statements."

Severe behavioral problems are sometimes associated with tics, as well, and "there is some evidence that temper tantrums, aggressiveness, and explosive behavior appear in preadolescence and intensify in adolescence."

Finally, many children with both phonic and motor tics are diagnosed with Tourette's disorder, which frequently causes "aggressiveness, self-harming behaviors, emotional immaturity, social withdrawal, physical complaints, conduct disorders, affective disorders, anxiety, panic attacks, stuttering, sleep disorders, migraine headaches, and inappropriate sexual behaviors," the Encyclopedia says.

(Interestingly, Tourette's disorder is three-to-four times more common in males than females, the same ratio as autism, ADD and ADHD).

Now, if "simple" tics include head jerks and barking; and "complex" tics can entail biting, banging and screaming obscenities; and if thimerosal can more than double the chance of tics in boys; then Atlanta, we have a very big problem.

It's perplexing that the CDC can report replicating a doubled risk for tics in boys, and an increased risk for speech disorders and attention and behavior problems in other kids, and still insist that this is all "very reassuring news."

I posed the question on the conference call today, and got nothing even resembling an answer (an opinion that was backed up by a producer from ABC News Nightline).

So I will ask it again here.

Given that the CDC has just reported that thimerosal might increase the risk for tics among boys, how is it possible, in addition, to publish the following two phrases within the same report?:

"The findings...suggest a possible adverse association between neonatal exposure to mercury and language development."

AND

"Our study does not support a causal association between early exposure to mercury...and deficits in neuropsychological functioning."