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2124 East Hanna Ave.
Indianapolis, Indiana
46227-3314
24 hour hot-line
(800) 486-4450
(317) 780-6610
Fax: (317) 780-6620
VJPetri@Petrilaw.com
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Thimerosal was the most widely used preservative
used in vaccines and is still a common additive.
1 Thimerosal has also been
used in eye and nose drops. Its common use was a result of its ability
to kill specific organisms and prevent the growth of certain fungi,
even under aseptic conditions.
2 Thimerosal is most useful
where a vaccine is accessed multiple times or manufactured without strict
antiseptic controls, which increases the risk of contamination and subsequent
bacterial infection. The antiseptic character of thimerosal is related
to the composition of the solution, which is largely mercury. By weight,
thimerosal is approximately 50% mercury.
Thimerosal has been used as a preservative for decades. In 1931, a
study offered evidence that its use was not only effective but safe
for use in humans.
3 Subsequent studies
on thimerosal, referenced by the Centers for Disease Control and Prevention
(CDC), seem to back up the initial study. The main finding of these
studies is that thimerosal use has "no ill effects . . . other
than minor local reactions [and irritation] at the site of injection."
4
Even though the CDC has adopted the view that
there is 'little reason for concern,' exposure to thimerosal has
declined with the development of non-mercury containing alternatives and preservatives having less mercury. This is being done as concern about
exposure to mercury and the effects of overexposure have grown, especially in
the United States. This concern culminated in the issuance of a joint
statement, on July 7, 1999, by the American
Academy of Pediatrics (AAP) and the US Public Health Service (USPHS) alerting
clinicians and the public about the concerns related to thimerosal use. To view a list of thimerosal containing and thimerosal-free
vaccines, please see the table below.
Metabolisis turns the mercury-based
preservative into ethyl-mercury and thiosalicylate. Ethyl-mercury is an
organomercurial (organic form of mercury) similar, but not identical, to
methyl-mercury. Methyl-mercury is toxic to humans and exposure should be
prevented where possible. This toxicity has led to concern about exposure to
ethyl-mercury and, therefore, the use of thimerosal. The table below contains
information regarding the methods of exposure and risks from exposure to both
methyl-mercury and ethyl-mercury.
| |
Methyl-mercury |
Thimerosal / Ethyl-mercury |
| Exposure Paths |
Exposure results primarily from consumption of
contaminated fish. |
Exposure results from injection of a vaccine or
use of other thimerosal-containing products. |
| Exposure Pattern |
Consumption of contaminated fish. |
Injection for a vaccine or contact for eye and
ear drops. |
| Exposure Rate |
Variable, depending on rate of consumption of contaminated
fish. |
Variable, depending on frequency and amount of
thimerosal containing vaccine injected. Higher rates of
exposure more likely in infants and children. |
| Sensitivity to Exposure |
Consumption of contaminated fish in large quantities
creates risk. Risk is greatest for a fetus and developing
child. |
No definitive data, but potential for similar sensitivities. |
| Accumulation of Contaminant |
Methyl mercury accumulates in the body. This
means levels of the contaminant rise over time with prolonged,
continued consumption. |
No definitive data, but potential for similar accumulation
of the contaminant. |
Unnecessary exposure to mercury should be
avoided where possible. This is imperative as the effects of 'mercury
poisoning' are severe and irreversible. Effects of mercury poisoning and
exposure to high levels of methyl-mercury include:
- Death, especially to an exposed fetus.
- Mental retardation
- Cerebral palsy
- Autism
- Seizures
- Tremors
Exposure to low doses is presumably less toxic
and less dangerous to humans. However, lower doses accumulate in the body and
can, over time, cause damage similar to that caused by large doses.
If you need assistance with a Thimerosal-related injury please
contact us.
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1. The information
on this page is accurate as of July 22, 2002.
2. The requirements for a preservative are set
by the United
States Pharmacopeia (USP).
3. Powell HM,
Jamieson WA. Merthiolate as a Germicide. Am J Hyg 1931;13:296-310.
4. Publications used
by the U.S. Food and Drug Administration to prove these statements. Claims
located at http://www.fda.gov/cber/vaccine/thimerosal.htm.
Studies on Safety and Effectiveness of
Thimerosal:
- Batts AH, Narriott C, Martin GP, et al. The
effect of some preservatives used in nasal preparations on mucociliary
clearance. Journal of Pharmacy and Pharmacology 1989; 41:156-159.
- Batty I, Harris E, Gasson A. Preservatives
and biological reagents. Developments in Biological Standardization
1974;24:131-142.
- Beyer-Boon ME, Arntz PW, Kirk RS. A
comparison of thimerosal and 50% alcohol as preservatives in urinary
cytology. Journal of Clinical Pathology 1979;32:168-170.
- Gasset AR, Itoi M, Ishii Y, Ramer RM.
Teratogenicities of ophthalmic drugs. II. Teratogenicites and tissue
accumulation of thimerosal. Archives of Ophthalmology
1975;93:52-55.
- Goldman KN, Centifanta Y, Kaufman HF, et al.
Prevention of surface bacterial contamination of donor corneas. Archives
of Ophthalmology 1978;96:2277-2280.
- Keeven J, Wrobel S, Portoles M, et al.
Evaluating the preservative effectiveness of RGP lens care solutions. Contact
Lens Association of Ophthalmologists Journal 1995;21:238-241.
- Naito R, Itoh T, Hasegawa E, et al. Bronopol
as a substitute for thimerosal. Developments in Biological
Standardization 1974;24:39-48.
- Wozniak-Parnowska W, Krowczynski L. New
approach to preserving eye drops. Pharmacy International
1981;2(4):91-94.
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