To the editor:

Recent letters to the Journal-World have claimed that thimerosal, a mercury-containing preservative, in childhood vaccines is the cause of recent increases in autism in the United States and Europe. While it is true that incidence of autism did increase during a time when virtually every child in the United States and Western Europe was receiving mercury-containing vaccines, this claim ignores at least four important facts.

Fact one: Vaccines save lives, not only of the vaccinated but also of those who would otherwise be exposed to the unvaccinated. Perhaps this is why every responsible medical association in the United States has concluded that the benefits of childhood vaccination and flu vaccination far exceed any real or imagined risks.

Fact two: Single-dose vials of vaccine have not contained thimerosal as a preservative since the late 1990s. Multidose vaccines, including most flu vaccine, contain FDA-approved amounts of thimerosal.

Fact three: The mercury in vaccines is, and has always been, ethyl mercury, not methyl mercury. Thus the writers’ undifferentiated claims about the dangers of mercury are analogous to protesting the ethyl alcohol in wine because the methyl alcohol in rubbing alcohol can kill you.

Fact four: The only peer-reviewed epidemiology on the subject found that the incidence of autism (which typically manifests at 18 to 24 months of age) in Denmark has actually increased at a slightly faster rate since mercury-containing thimerosal was removed from all Danish vaccines in the mid-1990s than it did during the previous 10 years when vaccines contained thimerosal.

Pete Rowland,

Lawrence