The researchers examined possible associations between neurodevelopmental disorders and exposure to mercury from Thimerosal-containing vaccines using the Vaccine Safety Datalink(VSD), the administrative database established by several HMOs and the Centers for Disease Control and Prevention Immunization Safety Office.
The study, which is being published in the Journal of Neurological Sciences, examined birth cohorts between 1990 and 1996 for diagnosed neurodevelopmental disorders and thimerosal exposure via recorded vaccines. Funding was provided by the court-appointed Petitioners’ Steering Committee representing children with autism claims pending in the National Vaccine Injury Compensation Program.
The study also compared large groups of children, from seven different birth years, with varying mercury exposures. When comparing exposure differences of 100 micrograms of mercury, the study found the prevalence rates of autism, autism spectrum disorders, tics, attention deficit disorder, and emotional disturbances were significantly increased by 1.7 to 4.5 times. These increased prevalence rates were seen in both exposure periods of birth-7 months and birth-13 months.
“These findings are important because they demonstrate that children in a birth cohort with higher average mercury exposure than other birth cohorts had rates of neurodevelopmental disorders that were on average 2 to 4 times higher than the rates in the birth cohorts with lower exposures,” Heather Young, an assistant professor of epidemiology and biostatistics at George Washington University School of Public Health and Health Services and study’s lead author, say in a statement.
“Because of the strong ecological associations found in this study, it is extremely important that additional studies be conducted using this data source, including case-control and cohort studies which, would allow the linking of individual exposure to disease,” says Young, who has been a consultant in vaccine cases before the no-fault NVICP.
The steering committee says the federal government, the vaccine makers and HMO’s wouldn’t conduct any studies in this database. The investigators of this study are the only scientists outside the government and the HMO’s who have been given access to the VSD data, but their access was restricted in three ways that, they say, limited the data that could be examined.
First, the government refused to produce the automated data in a way that would have allowed the investigators to link vaccine-mercury exposure to outcome data in individuals. As a result, Thimerosal exposure had to be averaged over each birth cohort for the time periods of birth-7 months and birth-13 months, even though the database was set up to permit individual risk assessments.
Second, the government and the HMO’s refused to permit access to any data entered after the year 2000, which meant that the maximum follow up period of the neurodevelopmental disorders for some children was only to four years of age. Specifically, for children born in 1997 or later, this restriction to access prevented any examination of true prevalence rates for those later birth cohorts.
Third, only three of the eight HMO’s participating in the taxpayer funded database permitted even this limited access (Northern California, Colorado, and Oregon Kaiser plans). Other HMO’s blocked access to the data on hundreds of thousands of additional children.
The steering committee goes on to say that families who have filed claims for compensation in the NVICP have sought broader access to the taxpayer-funded data base for four years, but have been blocked by the government and the courts.
In 2006, a panel appointed by the National Institute of Environmental Health Sciences recommended that a broad study of the database for links between TCV’s and autism be conducted, but the Bush Administration refused to provide funding while also refusing to permit outside investigators to conduct a study.
The other two study authors are: David Geier, vp of the Institute of Chronic Illnesses, who has been a consultant in vaccine/biologic cases before the no-fault NVICP and in civil litigation; and Mark Geier. president of The Genetic Centers of America and a board certified epidemiologist, who has been a consultant and expert witness in vaccine/biologic cases before the no-fault NVICP and in civil litigation.