Thimerosal has been used widely as ...

Thimerosal has been used widely as a preservative in certain vaccines and has been musing to increase the risk of certain neurodevelopmental disorders, as it is as autism, language and language delay, and attention-deficit/hyperactivity disorder. Despite the lack of evidence for a causal relationship, the biologic plausibility of a link remains. Hviid and colleagues performed a close attention to compare children receiving vaccines with and without thimerosal and followed them to note the incidence of autism and other autism-spectrum disorders in the one and the other groups.

Using information from Denmark's registry scheme the authors were able to link data upon vaccinations, diagnoses of autism, diagnoses of other autistic-spectrum disorders, other diagnoses, and confounder to the children in a cohort receiving thimerosal-based pertussis vaccine (before June 1 1992) and thimerosalfree pertussis vaccine (after June 1 1992)

During 2986654 person-years of follow-up the authors identified 440 cases of autism and 787 cases of other autism-spectrum disorders. In the original cohort, 20755 (44 percent) did not receive any whole-cell pertussis vaccine, 446695 (956 percent) were vaccinated at least formerly 416,081 (89.0 percent) were vaccinated twice, and 293186 (627 percent) received all three doses. In those receiving at least single in kind dose of vaccine, 407 cases of autism were identified, of whom 303 received thimerosal-free vaccine and 104 received thimerosal-containing vaccine; of the 751 cases of other autistic-spectrum disorders identified, 430 received thimerosalfree vaccine and 321 received thimerosal-containing vaccine.

Comparing children who had received at least united dose of thimerosal-containing vaccine as oppos to thimerosal-free vaccine, a full adjusted relative risk of 085 was build for autism and a relative risk of 112 for autistic-spectrum disorders. There was no evidence of a dose-response association between the dose of ethyl quicksilver received and the incidence of autism and autistic-spectrum disorders. The authors construct a statistically significant increase in the incidence of autism and autistic-spectrum disorders through the study period.

The authors gather that there is no evidence of an association between thimerosalcontaining vaccine and autism in children. They also base no dose-response association between autism and the amount of ethyl quicksilver received via thimerosal.

Hviid A, et al. Association between thimerosal-containing vaccine and autism. JAMA October 1 2003;290:1763-6

EDITOR'S NOTE: This contemplation adds to the mounting evidence that childhood vaccinations do not cause autism. Other studies have shown no association between the measles, mump and rubella vaccine and autism. (1) The use of the mercury-containing vehicle thimerosal was discontinued in the United States because of possible implications in the progression in a continuously ascending gradation of autism. Given the high oftenness of vaccination, which coincides temporally with the diagnosis of autism in the first years of life, it is understandable that vaccinations have been implicated from association. However, based on circulating evidence, this association is only coincidental.--C.W.

REFERENCE

(1) Makela A, Nuorti JP Peltola H Neurologic disorders after measles-mumps-rubella vaccination. Pediatrics 2002;110:957-63

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