Wednesday, October 21, 2009

New Study On Autism Spectrum Disorder And Mercury Levels

Melton Shire Council Australia

Exposure to high levels of mercury can cause brain damage, and many have tried to establish a link between mercury and the development of autism and other persistent developmental disorders in toddlers and preschoolers.

New research, however, has revealed that young children who test normal for mental and social development tend to have equivalent or higher levels of mercury in the bodies than do children diagnosed with an autism spectrum disorder, Down syndrome or another developmental disorder.

Analyses of blood samples drawn from 452 children between the ages of 2 years and 5 years reported in the online version of the journal Environmental Health Perspectives showed that "blood mercury levels had similar means and overall distributions across diagnostic groups. The geometric mean for typically developing children, 0.28 mcg/L, was significantly higher than for autism/autism spectrum disorder (0.19 mcg/L) or developmentally delayed (0.17 mcg/L) children; after adjustment for demographic factors and mercury sources and application of weights, the geometric means for autism/autism spectrum disorder, developmentally delayed and typically developing children were 0.26, 0.16, and 0.24 mcg/L, respectively,"

The research, led by Irva Hertz-Picciotto of the Department of Public Health Sciences and M.I.N.D. (Medical Investigations of Neurodevelopmental Disorders) Institute at the, University of California--Davis, Davis, was funded by the National Institute of Environmental Health Sciences, the U.S. Environmental Protection Agency and the M.I.N.D. Institute.

The vaccine preservative thimerosal has drawn particular attention from individuals and groups that make a link between mercury and autism. Thimerosal does contain mercury, but the amount of the element in vaccine doses is lower than the amount of mercury in most servings of fish. Hertz-Picciotto and her colleagues found the most mercury in children who ate the most fish. Additionally, Hertz-Picciotto told HealthDay, few childhood vaccines still contain thimerosal and almost none of the children she and her team assessed "had vaccines that would have or could have contained thimerosal."

Beyond any physical cause of autism that may be identified, the growing numbers of developmental disorder diagnoses may be due merely to increased recognition of the conditions by health care providers. After estimating that about 1 of every 100 U.S. children has some autism spectrum disorder, authors of an October 2009 Pediatrics article wrote, "The observed point-prevalence is higher than previous U.S. estimates. More inclusive survey questions, increased population awareness, and improved screening and identification by providers may partly explain this finding."