Price et al. Prenatal and Infant Exposure to Thimerosal From Vaccines and Immunoglobulins and Risk of Autism.This study, which was conducted at three managed care organisations (MCO’s), compared 256 children with autistic spectrum disorder (ASD) to 752 non-autistic controls who were matched by age, gender and MCO. They also examined a sub-group of autistic children who had a history of regression (”regressive autism”).
All children had to have been in one of the three MCO’s from birth to two years of age and currently be in the MCO. This made it possible to collect all thimerosal exposures from conception to age two years. The children with ASD were all evaluated to ensure that they met the criteria; the control subjects were not examined, but their parents were interviewed to identify (and exclude) any children with developmental abnormalities. The ASD group was further partitioned into two sub-groups: autistic disorder (AD) and autistic spectrum disorder with regression.
ASD was defined as: “ADOS scores that indicated abnormalities in all 3 areas and had ADI-R scores that indicated abnormalities in reciprocal social interactions and either communication or patterns of behavior”. The AD sub-group was defined as: “a subset of ASD children who had higher scores on all 3 areas of the ADOS, had ADI-R scores that indicated abnormalities in all 3 areas, and had onset at younger than 36 months”. ASD with regression was defined as: “the subset of case-children with ASD who reported loss of previously acquired language skills after acquisition”.
Thimerosal exposures were broken into time periods: prenatal, birth to one month, birth to seven months and birth to twenty months.
The authors examined the data using both an unadjusted model and a covariant model. The covariants examined were:
-Child and family characteristics (maternal and paternal age at birth of child, maternal education level, family income, single-parent status, birth order, twin/triplet, breastfeeding duration)
-Maternal exposures during pregnancy (exposure to mercury from fish, from cosmetics or medicines, or from dental fillings.
-Use of tobacco, alcohol, or illegal drugs
-Use of folic acid or valproic acid
-Child birth conditions (birth weight, Apgar score, birth asphyxia, respiratory distress syndrome, hyperbilirubinemia)
-Early-childhood health conditions (anemia, lead exposure, pica, encephalitis)
-Maternal health care–seeking behavior (Kotelchuck prenatal care index, cholesterol and Papanicolaou test screenings)
For both the unadjusted and covarient models, the odds ratio (OR) for ASD was calculated both for a two standard deviation (2SD) increase in thimerosal exposure and for a 1 microgram per kilogram (μg/kg) increase in thimerosal exposure (1 microgram (μg) in prenatal exposure). The 2SD values were as follows:
“For the measure of prenatal exposure, 2 SDs = 16.34μg. Two SDs of the birth-to-1-month measure is 4.08 = μg/kg. Similarly, 2 SDs of birth-to-7-month and birth-to-20-month exposures are 15.56 μg/kg and 17.82 μg/kg.”Finally, we come to the results:
“We found no evidence that increasing ethylmercury exposure from TCIs was associated with increased risk of ASD, AD, or ASD with regression. The unadjusted model results showed no significant associations between exposure and risk of ASD or AD.”
“In the covariate adjusted models, we found that an increase in ethylmercury exposure in 2 of the 4 exposure time periods evaluated was associated with decreased risk of each of the 3 ASD outcomes. We are not aware of a biological mechanism that would lead to this result.” [emphasis added]Let me repeat that - there was no increase in ASD, AD or ASD with regression associated with thimerosal in any of the time periods. In fact, there was a decrease in ASD, AD, and ASD with regression seen with increasing thimerosal exposure in the birth to seven months and birth to twenty months time periods.
For those without a vested interest in keeping the “thimerosal-causes-autism” dead-parrot hypothesis alive, this study is the final nail in the coffin.
For those whose devotion to this long-dead hypothesis cannot be extinguished, not even this study will convince them. Mind you, I doubt that they would be convinced if God wrote in letters of fire six miles high “Thimerosal Does NOT Cause Autism”. Faith, I am told, transcends all doubt - all data, as well, it would appear.
Of course, the “debate” has moved on to more fruitful pastures already; only the truly committed (or truly in need of committment) will still admit they believe thimerosal (or mercury) causes autism. The rest have all moved on to more amorphous, ambiguous and - more importantly - less testable claims of “toxins” or other evil beasties in the vaccines. The most sophisticated of the bunch have even made a virtue of vagueness by claiming “Too many, too soon”. For more on that, see my previous post.
For now, the data are very clear that thimerosal is not associated with autism. The fact that the goalposts have been moved does not alter that fact.