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Thimerosal exposure in infants and developmental disorders: a retrospective cohort study in the United kingdom does not support a causal association.
Pediatrics 2004; 114(3):584-91Ped

Abstract

OBJECTIVE

After concerns about the possible toxicity of thimerosal-containing vaccines in the United States, this study was designed to investigate whether there is a relationship between the amount of thimerosal that an infant receives via diphtheria-tetanus-whole-cell pertussis (DTP) or diphtheria-tetanus (DT) vaccination at a young age and subsequent neurodevelopmental disorders.

METHODS

A retrospective cohort study was performed using 109 863 children who were born from 1988 to 1997 and were registered in general practices in the United Kingdom that contributed to a research database. The disorders investigated were general developmental disorders, language or speech delay, tics, attention-deficit disorder, autism, unspecified developmental delays, behavior problems, encopresis, and enuresis. Exposure was defined according to the number of DTP/DT doses received by 3 and 4 months of age and also the cumulative age-specific DTP/DT exposure by 6 months. Each DTP/DT dose of vaccine contains 50 microg of thimerosal (25 microg of ethyl mercury). Hazard ratios (HRs) for the disorders were calculated per dose of DTP/DT vaccine or per unit of cumulative DTP/DT exposure.

RESULTS

Only in 1 analysis for tics was there some evidence of a higher risk with increasing doses (Cox's HR: 1.50 per dose at 4 months; 95% confidence interval [CI]: 1.02-2.20). Statistically significant negative associations with increasing doses at 4 months were found for general developmental disorders (HR: 0.87; 95% CI: 0.81-0.93), unspecified developmental delay (HR: 0.80; 95% CI: 0.69-0.92), and attention-deficit disorder (HR: 0.79; 95% CI: 0.64-0.98). For the other disorders, there was no evidence of an association with thimerosal exposure.

CONCLUSIONS

With the possible exception of tics, there was no evidence that thimerosal exposure via DTP/DT vaccines causes neurodevelopmental disorders.

Authors+Show Affiliations

Statistics Unit, Health Protection Agency, Communicable Disease Surveillance Centre, London, United Kingdom.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

15342825

Citation

Andrews, Nick, et al. "Thimerosal Exposure in Infants and Developmental Disorders: a Retrospective Cohort Study in the United Kingdom Does Not Support a Causal Association." Pediatrics, vol. 114, no. 3, 2004, pp. 584-91.
Andrews N, Miller E, Grant A, et al. Thimerosal exposure in infants and developmental disorders: a retrospective cohort study in the United kingdom does not support a causal association. Pediatrics. 2004;114(3):584-91.
Andrews, N., Miller, E., Grant, A., Stowe, J., Osborne, V., & Taylor, B. (2004). Thimerosal exposure in infants and developmental disorders: a retrospective cohort study in the United kingdom does not support a causal association. Pediatrics, 114(3), pp. 584-91.
Andrews N, et al. Thimerosal Exposure in Infants and Developmental Disorders: a Retrospective Cohort Study in the United Kingdom Does Not Support a Causal Association. Pediatrics. 2004;114(3):584-91. PubMed PMID: 15342825.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Thimerosal exposure in infants and developmental disorders: a retrospective cohort study in the United kingdom does not support a causal association. AU - Andrews,Nick, AU - Miller,Elizabeth, AU - Grant,Andrew, AU - Stowe,Julia, AU - Osborne,Velda, AU - Taylor,Brent, PY - 2004/9/3/pubmed PY - 2005/1/15/medline PY - 2004/9/3/entrez SP - 584 EP - 91 JF - Pediatrics JO - Pediatrics VL - 114 IS - 3 N2 - OBJECTIVE: After concerns about the possible toxicity of thimerosal-containing vaccines in the United States, this study was designed to investigate whether there is a relationship between the amount of thimerosal that an infant receives via diphtheria-tetanus-whole-cell pertussis (DTP) or diphtheria-tetanus (DT) vaccination at a young age and subsequent neurodevelopmental disorders. METHODS: A retrospective cohort study was performed using 109 863 children who were born from 1988 to 1997 and were registered in general practices in the United Kingdom that contributed to a research database. The disorders investigated were general developmental disorders, language or speech delay, tics, attention-deficit disorder, autism, unspecified developmental delays, behavior problems, encopresis, and enuresis. Exposure was defined according to the number of DTP/DT doses received by 3 and 4 months of age and also the cumulative age-specific DTP/DT exposure by 6 months. Each DTP/DT dose of vaccine contains 50 microg of thimerosal (25 microg of ethyl mercury). Hazard ratios (HRs) for the disorders were calculated per dose of DTP/DT vaccine or per unit of cumulative DTP/DT exposure. RESULTS: Only in 1 analysis for tics was there some evidence of a higher risk with increasing doses (Cox's HR: 1.50 per dose at 4 months; 95% confidence interval [CI]: 1.02-2.20). Statistically significant negative associations with increasing doses at 4 months were found for general developmental disorders (HR: 0.87; 95% CI: 0.81-0.93), unspecified developmental delay (HR: 0.80; 95% CI: 0.69-0.92), and attention-deficit disorder (HR: 0.79; 95% CI: 0.64-0.98). For the other disorders, there was no evidence of an association with thimerosal exposure. CONCLUSIONS: With the possible exception of tics, there was no evidence that thimerosal exposure via DTP/DT vaccines causes neurodevelopmental disorders. SN - 1098-4275 UR - https://www.unboundmedicine.com/medline/citation/15342825/Thimerosal_exposure_in_infants_and_developmental_disorders:_a_retrospective_cohort_study_in_the_United_kingdom_does_not_support_a_causal_association_ L2 - http://pediatrics.aappublications.org/cgi/pmidlookup?view=long&pmid=15342825 DB - PRIME DP - Unbound Medicine ER -