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> RECORD OBS-0116 | status: DEBUNKED | filed 2026-07-31
Home > Health > Thimerosal in Vaccines Causes Autism

Thimerosal in Vaccines Causes Autism

RecordOBS-0116
CategoryHealth/Vaccines
StatusDEBUNKED
SummaryAfter the MMR-autism link was debunked, some proponents shifted to claiming that thimerosal, a mercury-based preservative used in some vaccines, causes autism. This hypothesis emerged in the late 1990s and early 2000s. Multiple large studies have found no association between thimerosal exposure and autism.
OriginLate 1990s to early 2000s, primarily in the United States, following concerns about vaccine additives.
Claimed
  • Thimerosal, a mercury-containing preservative in vaccines, causes autism.
  • The increase in autism diagnoses is linked to increased thimerosal exposure from vaccines.
Evidence / consensusExtensive research, including large epidemiological studies, has found no causal link between thimerosal in vaccines and autism. Thimerosal was removed from most childhood vaccines in the U.S. in 2001 as a precaution, but autism rates did not decline.
> OBSERVER NOTE:
A secondary hypothesis that arose after the MMR claim was discredited. The evidence is clear: no link exists, but the idea continues to circulate in anti-vaccine circles.

Sources

  1. Vaccines Do Not Cause Autism | Johns Hopkins | Bloomberg School of Public Health

Sources are external and provided for verification. Listing does not imply the Observer endorses their claims.