Continuing increases in autism reported to California's developmental services system: mercury in retrograde.
BACKGROUND
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.


OBJECTIVE
To determine whether trends in DDS autism client data support the hypothesis that thimerosal exposure is a primary cause of autism.


METHODS
Study of time trends in the prevalence by age and birth cohort of children with autism who were active status clients of the DDS from January 1, 1995, through March 31, 2007.


METHODS
Prevalence of autism among children with active status in the DDS.


RESULTS
The estimated prevalence of autism for children at each year of age from 3 to 12 years increased throughout the study period. The estimated prevalence of DDS clients aged 3 to 5 years with autism increased for each quarter from January 1995 through March 2007. Since 2004, the absolute increase and the rate of increase in DDS clients aged 3 to 5 years with autism were higher than those in DDS clients of the same ages with any eligible condition including autism.


CONCLUSIONS
The DDS data do not show any recent decrease in autism in California despite the exclusion of more than trace levels of thimerosal from nearly all childhood vaccines. The DDS data do not support the hypothesis that exposure to thimerosal during childhood is a primary cause of autism.
Schechter
Robert
R
Immunization Branch, California Department of Public Health, 850 Marina Bay Pkwy, Richmond, CA 94804, USA. R.Schechter@cdph.ca.gov
Grether
Judith K
JK
D001321:Autistic Disorder / Q000453:epidemiology*; D002140:California / Q000453:epidemiology; D002648:Child; D002662:Child Health Services / Q000706:statistics & numerical data; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D011310:Preservatives, Pharmaceutical / Q000009:adverse effects*; D015995:Prevalence; D012947:Social Work / Q000706:statistics & numerical data*; D013849:Thimerosal / Q000009:adverse effects*; D014612:Vaccines / Q000009:adverse effects*
D011310:Preservatives, Pharmaceutical; D014612:Vaccines; D013849:Thimerosal