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Thimerosal and Autism Studies


Administration of thimerosal-containing vaccines to infant rhesus macaques does not result in autism-like behavior or neuropathology

October 6, 2015

Gdad et al. PNAS

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder. Some anecdotal reports suggest that ASD is related to exposure to ethyl mercury, in the form of the vaccine preservative, thimerosal, and/or receiving the measles, mumps, rubella (MMR) vaccine. Using infant rhesus macaques receiving thimerosalcontaining vaccines (TCVs) following the recommended pediatric vaccine schedules from the 1990s and 2008, we examined behavior, and neuropathology in three brain regions found to exhibit neuropathology in postmortem ASD brains. No neuronal cellular or protein changes in the cerebellum, hippocampus, or amygdala were observed in animals following the 1990s or 2008 vaccine schedules. Analysis of social behavior in juvenile animals indicated that there were no significant differences in negative behaviors between animals in the control and experimental groups. These data indicate that administration of TCVs and/or the MMR vaccine to rhesus macaques does not result in neuropathological abnormalities, or aberrant behaviors, like those observed in ASD.



Prenatal and Infant Exposure to Thimerosal From Vaccines and Immunoglobulins and Risk of Autism

September 13, 2010

Price et al. Pediatrics

Exposure to thimerosal, a mercury-containing preservative that is used in vaccines and immunoglobulin preparations, has been hypothesized to be associated with increased risk of autism spectrum disorder (ASD). This study was designed to examine relationships between prenatal and infant ethylmercury exposure from thimerosal-containing vaccines and/or immunoglobulin preparations and ASD and 2 ASD subcategories: autistic disorder (AD) and ASD with regression.



Continuing Increases in Autism Reported to California’s Developmental Services System

January 1, 2008

Schechter and Grether. Archives of General Psychiatry

Previous analyses of autism client data reported to the California Department of Developmental Services (DDS) have been interpreted as supporting the hypothesis that autism is caused by exposure to the preservative thimerosal, which contains ethylmercury. The exclusion of thimerosal from childhood vaccines in the United States was accelerated from 1999 to 2001. The Immunization Safety Review Committee of the Institute of Medicine has recommended surveillance of trends in autism as exposure to thimerosal during early childhood has decreased. The authors look to determine whether trends in DDS autism client data support the hypothesis that thimerosal exposure is a primary cause of autism.



Early Thimerosal Exposure and Neuropsychological Outcomes at 7 to 10 Years

September 27, 2007

Thompson et al. New England Journal of Medicine

It has been hypothesized that early exposure to thimerosal, a mercury-containing preservative used in vaccines and immune globulin preparations, is associated with neuropsychological deficits in children. The authors enrolled 1047 children between the ages of 7 and 10 years and administered standardized tests assessing 42 neuropsychological outcomes. (They did not assess autism-spectrum disorders.) Exposure to mercury from thimerosal was determined from computerized immunization records, medical records, personal immunization records, and parent interviews. Information on potential confounding factors was obtained from the interviews and medical charts. They assessed the association between current neuropsychological performance and exposure to mercury during the prenatal period, the neonatal period (birth to 28 days), and the first 7 months of life.



Lack of Association Between Rh Status, Rh Immune Globulin in Pregnancy and Autism

May 16, 2007

Miles and Takahashi. American Journal of Medical Genetics

Though causes of autism are considered largely genetic, considerable concern remains that exposure to Rh immune globulin (RhIg), which until 2001 in the United States contained the preservative thimerosal, can cause autism. To determine whether mothers of children with autism are more likely to be Rh negative (Rh?) or to have received RhIg preserved with thimerosal, which is 49.6% ethyl mercury, the authors surveyed families of children with an autism spectrum disorder (ASD) ascertained through a University-based autism clinic considered free of ascertainment biases related to type of autism or severity. Analysis of complete records including the blood group status and RhIg exposure of 214 families showed that Rh? status is no higher in mothers of children with autism than in the general population, exposure to antepartum RhIg, preserved with thimerosal is no higher for children with autism and pregnancies are no more likely to be Rh incompatible.



Comparison of Blood and Brain Mercury Levels in Infant Monkeys Exposed to Methylmercury or Vaccines Containing Thimerosal

August 1, 2005

Burbacher et al. Environmental Health Perspectives

Thimerosal is a preservative that has been used in manufacturing vaccines since the 1930s. Reports have indicated that infants can receive ethylmercury (in the form of thimerosal) at or above the U.S. Environmental Protection Agency guidelines for methylmercury exposure, depending on the exact vaccinations, schedule, and size of the infant. In this study the authors compared the systemic disposition and brain distribution of total and inorganic mercury in infant monkeys after thimerosal exposure with those exposed to MeHg.



Neurotoxic Effects of Postnatal Thimerosal Are Mouse Strain Dependent

September 1, 2004

Hornig et al. Molecular Psychiatry

Mercuric compounds are nephrotoxic and neurotoxic at high doses. Thimerosal, a preservative used widely in vaccine formulations, contains ethylmercury. Thus it has been suggested that childhood vaccination with thimerosal-containing vaccine could be causally related to neurodevelopmental disorders such as autism. This study was designed to determine whether vaccination with a thimerosal-containing vaccine is associated with development of autism.



Thimerosal Exposure in Infants and Developmental Disorders: A Prospective Cohort Study in the United Kingdom Does Not Support a Causal Association

September 1, 2004

Heron et al. Pediatrics

There is an established link between exposure to mercury and impaired childhood cognitive development and early motor skills. Thimerosal (also known as thiomersal), a preservative used in a number of children’s vaccines, contains ethylmercury (an organic compound of mercury), and there has been concern that this exposure to mercury may be of some detriment to young children. The aim of this research was to test in a large United Kingdom population-based cohort whether there is any evidence to justify such concerns.



Safety of Thimerosal-Containing Vaccines: A Two-Phased Study of Computerized Health Maintenance Organization Database

November 1, 2003

Verstraeten et al. Pediatrics

This study attempts to assess the possible toxicity of thimerosal-containing vaccines (TCVs) among infants. A 2-phased retrospective cohort study was conducted using computerized health maintenance organization (HMO) databases. Phase I screened for associations between neurodevelopmental disorders and thimerosal exposure among 124 170 infants who were born during 1992 to 1999 at 2 HMOs (A and B). In phase II, the most common disorders associated with exposure in phase I were reevaluated among 16 717 children who were born during 1991 to 1997 in another HMO (C).



Association Between Thimerosal-Containing Vaccine and Autism

October 1, 2003

Hviid et al. Journal of the American Medical Association

Mercuric compounds are nephrotoxic and neurotoxic at high doses. Thimerosal, a preservative used widely in vaccine formulations, contains ethylmercury. Thus it has been suggested that childhood vaccination with thimerosal-containing vaccine could be causally related to neurodevelopmental disorders such as autism. This study attempts to determine whether vaccination with a thimerosal-containing vaccine is associated with development of autism.



Thimerosal and the Occurrence of Autism: Negative Ecological Evidence from Danish Population-Based Data

September 1, 2003

Madsen et al. Pediatrics

It has been suggested that thimerosal, a mercury-containing preservative in vaccines, is a risk factor for the development of autism. The authors examined whether discontinuing the use of thimerosal-containing vaccines in Denmark led to a decrease in the incidence of autism.



Autism and Thimerosal-Containing Vaccines: Lack of Consistent Evidence for an Association

August 1, 2003

Stehr-Green et al. American Journal of Preventive Medicine

Between the mid-1980s through the late-1990s, the authors compared the prevalence/incidence of autism in California, Sweden, and Denmark with average exposures to Thimerosal-containing vaccines. Graphic ecologic analyses were used to examine population-based data from the United States (national immunization coverage surveys and counts of children diagnosed with autism-like disorders seeking special education services in California); Sweden (national inpatient data on autism cases, national vaccination coverage levels, and information on use of all vaccines and vaccine-specific amounts of Thimerosal); and Denmark (national registry of inpatient/outpatient-diagnosed autism cases, national vaccination coverage levels, and information on use of all vaccines and vaccine-specific amounts of Thimerosal).



Thimerosal and Autism?

March 1, 2003

Nelson and Bauman. Pediatrics

Concern has been expressed over the possibility that the mercury-containing compound thimerosal in vaccines may cause autism. It is reasonable to ask whether thimerosal in childhood vaccine increases risk of chronic childhood neurologic disability and specifically of autism. Most of the information we have about mercury toxicity is related to exposure to methyl rather than ethyl mercury.Bernard et al offered an hypothesis that autism is an expression of mercury toxicity resulting from thimerosal in vaccines. This review will examine these issues and others to ask whether, according to evidence now available, thimerosal is a probable cause of autism.



Mercury concentrations and metabolism in infants receiving vaccines containing thiomersal: A descriptive study

November 1, 2002

Pichichero et al. The Lancet

Thiomersal is a preservative containing small amounts of ethylmercury that is used in routine vaccines for infants and children. The effect of vaccines containing thiomersal on concentrations of mercury in infants’ blood has not been extensively assessed, and the metabolism of ethylmercury in infants is unknown. The authors aimed to measure concentrations of mercury in blood, urine, and stools of infants who received such vaccines.



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