Thiomersal controversy

Thiomersal controversy

The thiomersal controversy is between claims that thiomersal-containing vaccines (TCVs) cause or contribute to the development of autism and other brain development disorders,cite journal |author= Burton D |title= Mercury in medicine report |journal= Congressional Record |date=2003 |pages=E1011–30 |volume=149 |url= |format=PDF] and mainstream medical opinion that no convincing scientific evidence supports these claims. [cite journal |journal= Can J Neurol Sci |date=2006 |volume=33 |issue=4 |pages=341–6 |title= Immunizations and autism: a review of the literature |author= Doja A, Roberts W |pmid=17168158]

Thiomersal, also spelled "thimerosal", is an organomercury preservative used in vaccines since the 1930s to prevent bacterial and fungal contamination.cite web |date=2007-09-06 |url= |accessdate=2007-10-01 |title= Thimerosal in vaccines |publisher= Center for Biologics Evaluation and Research, U.S. Food and Drug Administration] In July 1999, following a review of mercury-containing food and drugs, the Centers for Disease Control (CDC) and the American Academy of Pediatrics (AAP) asked vaccine makers to remove thiomersal from vaccines as quickly as possible, and it was rapidly phased out of most U.S. and European vaccines. [cite web |url= |date=2007-06-07 |accessdate=2008-07-22 |title= Thimerosal in vaccines: frequently asked questions (FAQs) |publisher= Center for Biologics Evaluation and Research, U.S. Food and Drug Administration] The precautionary principle assumes that there is no harm in exercising caution even if it later turns out to be unwarranted, but this 1999 action sparked confusion and controversy that has diverted attention and resources away from other efforts to find the causes of autism.

Thousands of lawsuits have been filed in the U.S. to seek damages from alleged toxicity from vaccines, including those purportedly from thiomersal preservatives. [Autism cases in vaccine court:
*cite journal |journal= N Engl J Med |year=2007 |volume=357 |issue=13 |pages=1275–7 |title= Cases in vaccine court—legal battles over vaccines and autism |author= Sugarman SD |pmid=17898095 |url= |doi= 10.1056/NEJMp078168
*cite web |author= U.S. Court of Federal Claims |date=2007-09-28 |url= |title= Vaccine Program/Office of Special Masters Omnibus Autism Proceeding |accessdate=2007-11-24
] The scientific consensus—including scientific and medical professional bodies and governmental agencies such as the Food and Drug Administration, the Centers for Disease Control and Prevention,cite web |author= Centers for Disease Control |authorlink= Centers for Disease Control and Prevention |year=2007-01-08 |url= |title= Mercury and Vaccines (Thimerosal) |accessdate =2007-07-22] and the World Health Organizationcite web |author= World Health Organization |date=2006-07-01 |url= |title= Thiomersal and vaccines: questions and answers |accessdate=2007-07-22] —rejects the hypothesis that exposure to thiomersal causes or contributes to autism or other neurological disorders.

Background of controversy

cientific background

After the FDA Modernization Act of 1997 mandated a review and risk assessment of all mercury-containing food and drugs, vaccine manufacturers responded to FDA requests to provide detailed information about the thimerosal content of their preparations in December 1998 and April 1999.cite web | author = American Academy of Pediatrics| authorlink=American Academy of Pediatrics| year = 1999-09-01 | url =| title = Joint Statement of the American Academy of Pediatrics and the US Public Health Service (USPHS) | accessdate =2007-07-22] Upon conclusion of this review, the FDA, in conjunction with the other members of the US Public Health Service (USPHS), the National Institutes of Health (NIH), CDC and Health Resources and Services Administration (HRSA) in a joint statement with the American Academy of Pediatrics (AAP), concluded:

"Our review revealed no evidence of harm caused by doses of thimerosal found in vaccines, except for local hypersensitivity reactions. At the time of our review, vaccines containing thimerosal as a preservative could expose infants to cumulative mercury at levels that exceed EPA recommendations during the first 6 months of life. The clinical significance of this conclusion is not currently known; EPA guidelines contain as much as a 10-fold safety factor and such guidelines are meant to be starting points for the evaluation of mercury exposure. However, reducing exposure to thimerosal from vaccines is merited given the goal of reducing human exposure to mercury from all sources, the feasibility of removing thimerosal as a vaccine preservative, and the desirability of ensuring public confidence in the safety of vaccines." [cite journal | author=Ball LK, Ball R, Pratt RD | title=An assessment of thimerosal use in childhood vaccines| journal=Pediatrics | year=2001 | pages=1147–54 | volume=107 | issue=5 | pmid=11331700 |url= | doi=10.1542/peds.107.5.1147]

The FDA noted that while the vaccination schedule at that time might have exceeded EPA standards for mercury exposure during the first 6 months of life, it did not exceed those of the FDA, Agency for Toxic Substances and Disease Registry (ATSDR), or WHO. The FDA also noted some difficulty interpreting toxicity of the ethylmercury in thiomersal because guidelines for mercury toxicity were based primarily on studies of methylmercury. Despite the lack of convincing evidence of toxicity of thiomersal, the USPHS and AAP determined that thiomersal should be removed from vaccines as a purely preventative measure and to increase public confidence in vaccines.

Due to continued public concern, the Centers for Disease Control and the National Institutes of Health (NIH) asked the National Academy of Science's (NAS) Institute of Medicine (IOM) to establish an independent expert committee to review hypotheses about existing and emerging immunization safety concerns. In 2001 the committee reported:

"The committee concludes that although the hypothesis that exposure to thimerosal-containing vaccines could be associated with neurodevelopmental disorders is not established and rests on indirect and incomplete information, primarily from analogies with methylmercury and levels of maximum mercury exposure from vaccines given in children, the hypothesis is biologically plausible.

The committee also concludes that the evidence is inadequate to accept or reject a causal relationship between thimerosal exposures from childhood vaccines and the neurodevelopmental disorders of autism, ADHD, and speech or language delay." [cite book |author= Immunization Safety Review Committee, Board on Health Promotion and Disease Prevention, Institute of Medicine |title= Immunization Safety Review: Thimerosal-Containing Vaccines and Neurodevelopmental Disorders |publisher= National Academy Press |location= Washington, DC |year=2001 |isbn=0-309-09008-3 |url=]

ocial and political background

The FDA actions prompted autism advocates to consider the possibility of thiomersal as a cause of autism. The indirect evidence included analogy with neurotoxic effects of mercury compounds, extrapolation from laboratory and animal studies, and comparisons between trends in vaccination and autism cases.cite journal |journal= Clin Pharmacol Ther |year=2007 |volume=82 |issue=6 |pages=756–9 |title= Vaccines and autism: evidence does not support a causal association |author= DeStefano F |doi=10.1038/sj.clpt.6100407 |pmid=17928818]

This concept also gained support in the political sphere, with Rep. Dan Burton and Rep. David Weldon openly supporting this movement as well. A number of hearings were held in the Subcommittee on Human Rights and Wellness, Committee on Government Reform, chaired by Rep. Burton, on the topic of autism and vaccines. His staff concluded:

"Thimerosal used as a preservative in vaccines in ["sic"] likely related to the autism epidemic. This epidemic in all probability may have been prevented or curtailed had the FDA not been asleep at the switch regarding the lack of safety data regarding injected thimerosal and the sharp rise of infant exposure to this known neurotoxin. Our public health agencies’ failure to act is indicative of institutional malfeasance for self-protection and misplaced protectionism of the pharmaceutical industry"

Rationale for concern

Supporters of a link between thiomersal and autism cite several lines of reasoning for their concerns, including:

* Appeal for caution: precise thresholds for ethylmercury toxicity have not been fully studied, and methylmercury is a poor surrogate for studying the toxicity of thiomersal.cite journal | author= Burbacher TM, Shen DD, Liberato N, Grant KS, Cernichiari E, Clarkson T | title= Comparison of blood and brain mercury levels in infant monkeys exposed to methylmercury or vaccines containing thimerosal |journal= Environ Health Perspect |year=2005 |pages=1015–21 |volume=113 |issue=8 |pmid=16079072 |url=]
* In vitro tests: cultured cells in laboratory show adverse effects when exposed to ethylmercury. [In vitro tests:
*cite journal | author= James SJ, Slikker W III, Melnyk S, New E, Pogribna M, Jernigan S | title= Thimerosal neurotoxicity is associated with glutathione depletion: protection with glutathione precursors |journal=Neurotoxicology |year=2005 |pages=1–8 |volume=26 |issue=1 |doi=10.1016/j.neuro.2004.07.012 |pmid=15527868
*cite journal | author= Baskin DS, Ngo H, Didenko VV |title= Thimerosal induces DNA breaks, caspase-3 activation, membrane damage, and cell death in cultured human neurons and fibroblasts |journal= Toxicol Sci |year=2003 |pages=361–8 |volume=74 |issue=2 |pmid=12773768 |url= |doi= 10.1093/toxsci/kfg126
*cite journal | author= Ueha-Ishibashi T, Oyama Y, Nakao H "et al." | title= Effect of thimerosal, a preservative in vaccines, on intracellular Ca2+ concentration of rat cerebellar neurons |journal=Toxicology |year=2004 |pages=77–84 |volume=195 |issue=1 |doi=10.1016/j.tox.2003.09.002 |pmid=14698570
* An in vivo study reported in 2004 that autoimmune disease-sensitive mice exposed to thiomersal had growth delay, reduced locomotion, exaggerated response to new stimuli, and uncommon neuronal structure in some brain areas. The exposure attempted to replicate the one-year schedule for U.S. infants in 2001, adjusted for weight and age. [cite journal |journal=Mol Psychiatry |date=2004 |volume=9 |issue=9 |pages=833–45 |title= Neurotoxic effects of postnatal thimerosal are mouse strain dependent |author= Hornig M, Chian D, Lipkin WI |doi=10.1038/ |pmid=15184908] However, a similar 2007 study found no pervasive developmental neurotoxicity in the same mouse strain. [cite journal |journal= Toxicol Sci |date=2008 |volume=101 |issue=2 |pages=294–309 |title= Low level neonatal thimerosal exposure: further evaluation of altered neurotoxic potential in SJL mice |author= Berman RF, Pessah IN, Mouton PR, Mav D, Harry J |doi=10.1093/toxsci/kfm265 |pmid=17977901] Also, while the intervals between vaccination in human infants assure nearly complete clearance of the organic species from the brain and blood, significant accumulation would be expected for the accelerated schedule in the mouse pups. [cite journal |title= The toxicology of mercury and its chemical compounds |author= Clarkson TW, Magos L |journal= Crit Rev Toxicol |date=2006 |volume=36 |issue=8 |pages=609–62 |doi=10.1080/10408440600845619 |pmid=16973445]
* Unscientific reports that autism is rarer in the Amish community and other non-vaccinated groups. The reports are undercut by the fact that Amish genes may differ from those in the general community, that people in the Amish community have low exposures to many other potential hazards (for example, pesticides and plastics) and that increasingly, the Amish do receive at least some vaccinations. [cite news |author= Olmsted D |title= The age of autism: the last word |publisher=UPI |date=2007-07-18 |url= |accessdate=2007-07-23]
* Epidemiologic data: epidemiologic studies (all coauthored by Mark Geier) examined population level correlation between thiomersal and autism. [Geier studies:
*cite journal|author=Geier DA, Geier MR|title=A meta-analysis epidemiological assessment of neurodevelopmental disorders following vaccines administered from 1994 through 2000 in the United States|journal=Neuro Endocrinol Lett|year=2006|pages=401–13|volume=27|issue=4|pmid=16807526
*cite journal|author=Geier DA, Geier MR|title=An assessment of downward trends in neurodevelopmental disorders in the United States following removal of Thimerosal from childhood vaccines|journal=Med Sci Monit|year=2006|pages=CR231–9|volume=12|issue=6|pmid=16733480
*cite journal|author=Geier DA, Geier MR|title=An evaluation of the effects of thimerosal on neurodevelopmental disorders reported following DTP and Hib vaccines in comparison to DTPH vaccine in the United States|journal=J Toxicol Environ Health A|year=2006|pages=1481–95|volume=69|issue=15|pmid=16766480|doi=10.1080/15287390500364556
*cite journal|author=Geier DA, Geier MR|title=Early downward trends in neurodevelopmental disorders following removal of thimerosal-containing vaccines|journal=J Am Phys Surg|year=2006|pages=8–13|volume=11|issue=1|url=
*cite journal |journal= J Toxicol Environ Health A |year=2007 |volume=70 |issue=20 |pages=1723–30 |title= A prospective study of mercury toxicity biomarkers in autistic spectrum disorders |author= Geier DA, Geier MR |doi=10.1080/15287390701457712 |pmid=17885929
*cite journal |journal= J Neurol Sci |date=2008 |title= Thimerosal exposure in infants and neurodevelopmental disorders: an assessment of computerized medical records in the Vaccine Safety Datalink |author= Young HA, Geier DA, Geier MR |doi=10.1016/j.jns.2008.04.002 |pmid=18482737 |volume=271 |issue=1–2 |pages=110–8
* Concern that mercury might have synergistic effects with other metals and toxicants. [cite journal |author= Mutter J, Naumann J, Schneider R, Walach H, Haley B |title= Mercury and autism: accelerating evidence? |journal= Neuro Endocrinol Lett |volume=26 |issue=5 |pages=439–46 |year=2005 |pmid=16264412 |url= |accessdate=2007-08-15 |format=PDF]

Despite the 1999 recommendation by the USPSH and AAP, some vaccines continue to contain non-trace amounts of thiomersal, mainly in vaccines targeted against influenza and tetanus. [cite web | author = Institute for Vaccine Safety| authorlink= | year = 2007-07-12 | url =| title =Thimerosal Content in Some US Licensed Vaccines| accessdate =2007-07-23] Other products that may contain thimerosal include products derived from blood plasma such as Rho(D) Immune Globulin, pit viper antivenin and coral snake antivenin, as well as black widow spider antivenin. [cite web | author = Food and Drug Administration | authorlink=Food and Drug Administration | year = 2004-09-09 | url =| title =Mercury in Plasma-Derived Products | accessdate =2007-07-23]

cientific consensus on controversy

The scientific consensus is reflected in another committee report commissioned by the CDC by the Institute of Medicine that follows up on the initial 2001 report. Since the 2001 report, the IOM committee took into account new data that had been published in the interim, including a number of large scale epidemiologic studies focusing on the relationship between thiomersal and autism in a number of countries including the US, Sweden, Denmark, and the UK.

The committee noted, in response to those who cite "in vitro" or animal models as evidence for the link between autism and thiomersal:

"However, the experiments showing effects of thimerosal on biochemical pathways in cell culture systems and showing abnormalities in the immune system or metal metabolism in people with autism are provocative; the autism research community should consider the appropriate composition of the autism research portfolio with some of these new findings in mind. However, these experiments do not provide evidence of a relationship between vaccines or thimerosal and autism.

In the absence of experimental or human evidence that vaccination (either the MMR vaccine or the preservative thimerosal) affects metabolic, developmental, immune, or other physiological or molecular mechanisms that are causally related to the development of autism, the committee concludes that the hypotheses generated to date are theoretical only."

Based on an exhaustive review of the scientific literature, the committee concludes:

"Thus, based on this body of evidence, the committee concludes that the evidence favors rejection of a causal relationship between thimerosal-containing vaccines and autism." [bold in original]

This committee felt so strongly about this conclusion that they state:

"The committee concludes that much more research must be conducted on autism. However, research should be directed towards those lines of inquiry most supported by the current state of knowledge. The vaccine hypotheses are not currently supported by the evidence."cite book |author= Immunization Safety Review Committee, Board on Health Promotion and Disease Prevention, Institute of Medicine |title= Immunization Safety Review: Vaccines and Autism |publisher= The National Academies Press |location= Washington, DC |date=2004 |isbn=0-309-09237-X |url=]

Three large-scale controlled observational studies have been reported on this issue; none have found an association between thiomersal-containing vaccines (TCVs) and autism. A study from Denmark noted no decrease in autism rates despite cessation of TCVs [cite journal | author=Hviid A, Stellfeld M, Wohlfahrt J, Melbye M | title= Association between thimerosal-containing vaccine and autism | journal=JAMA| year=2003| pages=1763–6| volume=290 | issue=13 | pmid=14519711 |url= | doi= 10.1001/jama.290.13.1763] and a UK study found that TCVs actually had a protective effect with respect to autism. [cite journal | author=Andrews N, Miller E, Grant A, Stowe J, Osborne V, Taylor B | title= Thimerosal exposure in infants and developmental disorders: a retrospective cohort study in the United kingdom does not support a causal association | journal=Pediatrics| year=2004| pages=584–91| volume=114 | issue=3 |doi=10.1542/peds.2003-1177-L | pmid=15342825 |url=] Because the Danish and UK studies involved only diphtheria-tetanus-pertussis (DTP) or diphtheria-tetanus (DT) vaccines, they are less relevant for the higher thiomersal exposure levels that occurred in the U.S. For the U.S., a study based on the Vaccine Safety Datalink found no association between TCVs and autism. [cite journal |author= Verstraeten T, Davis RL, DeStefano F "et al." |title= Safety of thimerosal-containing vaccines: a two-phased study of computerized health maintenance organization databases |journal=Pediatrics |year=2003 |pages=1039–48|volume=112 |issue=5 |pmid=14595043 |url= |doi= 10.1542/peds.112.2.e98] Some smaller studies have also found no association between TCVs and autism [cite journal | author=Heron J, Golding J, ALSPAC Study Team | title= Thimerosal exposure in infants and developmental disorders: a prospective cohort study in the United kingdom does not support a causal association | journal=Pediatrics| year=2004| pages=577–83| volume=114 | issue=3 |doi=10.1542/peds.2003-1176-L | pmid=15342824 |url=] [cite journal | author=Madsen KM, Lauritsen MB, Pedersen CB "et al." | title= Thimerosal and the occurrence of autism: negative ecological evidence from Danish population-based data | journal=Pediatrics| year=2004| pages=604–6| volume=112 | issue=3 | pmid=12949291 |url= | doi= 10.1542/peds.112.3.604] and a study found no association between thimerosal and the neurological signs of autism.cite journal |journal= N Engl J Med |volume=357 |issue=13 |pages=1281–92 |year=2007 |title= Early thimerosal exposure and neuropsychological outcomes at 7 to 10 years |author= Thompson WW, Price C, Goodson B "et al." |pmid=17898097 |url= |laysummary= |laysource=NNii |laydate=2007 |doi= 10.1056/NEJMoa071434] Another smaller study also found a protective effect: it reported a significantly lower prevalence of autism spectrum disorders among children exposed to thimerosal (5.95 per 1,000 versus 8.27 per 1,000). [cite journal | author=Fombonne E, Zakarian R, Bennett A, Meng L, McLean-Heywood D | title= Pervasive developmental disorders in Montreal, Quebec, Canada: prevalence and links with immunizations | journal=Pediatrics| year=2006| pages=e139–50| volume=118 | issue=1 |doi=10.1542/peds.2005-2993 | pmid=16818529 |url=]

The research of Mark Geier, the main source of epidemiologic data used by supporters of a link between thiomersal and autism, has received considerable criticism, [cite news |work=Slate |date=2007-05-28 |accessdate=2008-01-30 |url= |title= Thiomersal on trial: the theory that vaccines cause autism goes to court |author= Allen A] including charges of not presenting methods and statistical analyses to others for verification,cite journal |author= Parker SK, Schwartz B, Todd J, Pickering LK |title= Thimerosal-containing vaccines and autistic spectrum disorder: a critical review of published original data |journal=Pediatrics |year=2004 |pages=793–804 |volume=114 |issue=3 |doi=10.1542/peds.2004-0434 |pmid=15342856 |url= [ Erratum] (2005) "Pediatrics" 115 (1), 200. doi|10.1542/peds.2004-2402. PMID 15630018.] improperly analyzing data taken from Vaccine Adverse Event Reporting System, as well as either mislabelling or confusing fundamental statistical terms in his papers.

Further evidence of the position of the scientific consensus includes the rejection of a causal link between thimerosal and autism by the main scientific and medical professional bodies including the American Medical Association, [cite web | author = American Medical Association| authorlink=American Medical Association| year = 2004-05-18 | url = | title =AMA Welcomes New IOM Report Rejecting Link Between Vaccines and Autism | accessdate =2007-07-23] the American Academy of Pediatrics, [cite web | author = American Academy of Pediatrics| authorlink=American Academy of Pediatrics| year = 2004-05-18 | url = | title =What Parents Should Know About Thimerosal | accessdate =2007-07-23] the American College of Medical Toxicology, [cite journal |journal=J Med Toxicol |date=2006 |volume=2 |issue=4 |pages=170–1 |title= ACMT position statement: the Iom report on thimerosal and autism |author= Kurt TL |pmid=18072140 |url= |format=PDF] the National Academy of Sciences, the Food and Drug Administration, Centers for Disease Control and Prevention, the World Health Organization, the Public Health Agency of Canada, [cite journal|journal=Can Commun Dis Rep|date=2007|volume=33|issue=ACS-6|pages=1–13|title=Thimerosal: updated statement. An Advisory Committee Statement|author=National Advisory Committee on Immunization|pmid=17663033|url=] and the European Medicines Agency.cite web | author = European Medicines Agency| authorlink=European Medicines Agency| year = 2004-03-24 | url =| title =EMEA Public Statement on Thiomersal in Vaccines for Human Use| accessdate =2007-07-22]

Effects of the controversy

In July 1999 the CDC and the AAP asked vaccine makers to remove thiomersal from vaccines as quickly as possible, and asked doctors to delay the birth dose of hepatitis B vaccine in children not at risk for hepatitis. The CDC and the AAP followed the precautionary principle, which assumes that there is no harm in exercising caution even if it later turns out to be unwarranted, but their action sparked confusion, controversy and some harm. About 10% of hospitals suspended the use of hepatitis B vaccine for all newborns, and one child born to a Michigan mother infected with hepatitis B virus died of it.

The notion that thiomersal causes autism has led some parents to have their children treated with chelation therapy; about 10,000 autistic children in the U.S. receive mercury-chelating agents every year, and in August 2005 a 5-year-old autistic boy died from an arrhythmia caused by injection of the chelating agent EDTA. The notion has also diverted attention and resources away from efforts to determine the causes of autism.cite journal |journal= N Engl J Med |year=2007 |volume=357 |issue=13 |pages=1278–9 |title= Thimerosal and vaccines—a cautionary tale |author= Offit PA |doi=10.1056/NEJMp078187 |pmid=17898096 |url=]

Court cases

From 1988 until 2008-01-08, 5,263 claims relating to autism were made to the U.S. court that oversees compensation. One claim was compensated, and 350 were dismissed; the rest are pending. [cite web |url= |accessdate=2008-01-22 |date=2008-01-08 |title= National Vaccine Injury Compensation Program statistics reports |publisher= Health Resources and Services Administration] In the one autism-related case, the government conceded that the child had a pre-existing mitochondrial disorder with autism-like symptoms aggravated by simultaneous immunizations against nine diseases, two of which contained thiomersal. [cite news |author= Stobbe M, Marchione M |title= Analysis: vaccine-autism link unproven |work= Associated Press |date=2008-03-07 |url= |accessdate=2008-06-06] [cite journal |journal= J Clin Invest |date=2008 |volume=118 |issue=5 |pages=1586–7 |title= Attention focuses on autism |author= Honey K |doi=10.1172/JCI35821 |pmid=18451989 |url=]


*1930s - first added to vaccines and other products as a bactericide. [cite web |date=2007-06-05 |url= |accessdate=2007-10-01 |title=Mercury and vaccines (thimerosal) |publisher=Centers for Disease Control and Prevention]
*Mid-1980s - used as a preservative in virtually all whole-cell DPT vaccines, which were routinely administered four times each to children before eighteen months of age, starting at two months.
*Late 1980s - Hib vaccines are recommended for administration to children at eighteen months. They contain thiomersal.
*Early 1990s - In the USA three doses of Hepatititis B vaccine (at that time containing Thiomersal) are recommended for infants under six months of age, beginning on the day of birth; four doses of Hib are recommended within an eighteen month period, beginning at age two.
*Late 1990s - three of the vaccines included in Vaccination schedules for children between six and eighteen months of age contain thiomersal.
*1999 - The American Academy of Pediatrics requests removal of thiomersal from all pediatric vaccines.
*2001 - Thiomersal is no longer used in routine childhood vaccines in the U.S.cite journal |journal= Am J Public Health |date=2008 |title= Mercury, vaccines, and autism: one controversy, three histories |author= Baker JP |doi=10.2105/AJPH.2007.113159 |pmid=18172138 |volume=98 |issue=2 |pages=244–53]
*2001 - The Institute of Medicine, citing insufficient evidence, is unable to prove or disprove any link between thiomersal and autism. However, they conclude that a causal connection between thiomersal and autism is "biologically plausible".
*2002 - The USA Centers for Disease Control (CDC) and the USA Food and Drug Administration (FDA) state that: although thiomersal was to be discontinued in some paediatric vaccines, they would not be recalling any unused stocks, as there is no proof that low doses of thiomersal is dangerous, and that the change was purely cautionary.
*2004 - The Institute of Medicine, based on new information from epidemiological studies undertaken since its 2001 report, rejects the hypothetical causative link between thiomersal and autism.
*2005 - Robert F. Kennedy, Jr. authored an article in the June, 2005 "Rolling Stone", alleging connections between thimerosal in vaccines and autism. [ [ Deadly Immunity : Rolling Stone ] ]
*2006 - Some vaccines provided by the World Health Organization for children in developing countries contain the same amounts of thiomersal as vaccines used previously for American children. Current vaccination schedulesFact|date=February 2007 give these in a shorter time period.Fact|date=February 2007
*2006 - In the latest review by the WHO committee, the conclusion previously reached was reaffirmed that there is no evidence of toxicity in infants, children or adults exposed to thiomersal in vaccines. [ Statement on thiomersal (World Health Organization, July 2006)] ]
*2007 - In February, the U.S. National Institute of Mental Health (NIMH) halted an experiment that gave the chelating agent DMSA to children with autism whose blood had detectable but nontoxic mercury or lead. The experiment, by Susan Swedo, head of autism research at NIMH, had begun in September 2006 but was halted after a 2007 report showed that chelating agents could cause cognitive problems in rats; Swedo decided that NIMH's limited resources were better focused on a different experiment involving minocycline in children with regressive autism. Critics said the chelation experiment posed a risk to children for what is sure to be no medical gain for them; proponents said the therapy is in broad use and the experiment would provide scientific evidence about any benefits or dangers. [cite journal |journal=Science |date=2008 |volume=321 |issue=5887 |pages=326 |title= Stalled trial for autism highlights dilemma of alternative treatments |author= Stokstad E |doi=10.1126/science.321.5887.326 |pmid=18635766]
*2007 - Theresa and Michael Cedillo, the parents of 12-year-old Michelle Cedillo asked a federal court, the so-called "vaccine court", Monday June 11, to find that their child's autism was caused by common childhood vaccines.
*2007 - Mike Enzi, the ranking member on the United States Senate Committee on Health, Education, Labor, and Pensions, issued a report assessing allegations about thimerosal and autism. The report substantiated allegations that there were shortcomings in the Institute of Medicine's conflict screening procedures, that thimerosal is used in third-world childhood vaccines, and that late-1990s EPA mercury guidelines were inappropriate for vaccines and caused many individuals to conclude that ethyl mercury can be linked to autism. Several other allegations were not substantiated. [cite web |author= Enzi MB |title= Thimerosal and autism spectrum disorders: alleged misconduct by government agencies and private entities |url= |format=PDF |year=2007 |accessdate=2007-10-04]
*2008 - A study found that autism rates for children in California increased each quarter from January 1995 through March 2007, despite the removal of all but trace amounts of thiomersal from childhood vaccines since the 1999 national recommendation. [cite journal |author= Schechter R, Grether JK |url= |title= Continuing increases in autism reported to California's developmental services system: mercury in retrograde |journal= Arch Gen Psychiatry |date=2008 |volume=65 |issue=1 |pages=19–24 |pmid=18180424 |laysummary= |laysource= Associated Press |laydate=2008-01-07 |doi= 10.1001/archgenpsychiatry.2007.1] The study analyzed data from the California Department of Developmental Services database, which had been systematically used by proponents of the thimerosal hypothesis to argue that the rising number of children accessing these services was linked to increased use of thimerosal in vaccines. [cite journal |title= Thimerosal disappears but autism remains |author= Fombonne E |journal= Arch Gen Psychiatry |date=2008 |volume=65 |issue=1 |pages=15–6 |pmid=18180423 |doi= 10.1001/archgenpsychiatry.2007.2]
*2008 - A study that examined the ethylmercury from thiomersal in vaccines found that the half-life of blood mercury after vaccination averages 3.7 days for newborns and infants, much shorter than the 44 days for methylmercury. The shorter half-life suggests that thiomersal in vaccines is not as risky as was feared, and that a new risk assessment is needed. [cite journal |journal=Pediatrics |date=2008 |volume=121 |issue=2 |pages=e208–14 |title= Mercury levels in newborns and infants after receipt of thimerosal-containing vaccines |author= Pichichero ME, Gentile A, Giglio N "et al." |doi=10.1542/peds.2006-3363 |pmid=18245396 |url= |laysource= University of Rochester Medical Center |laydate=2008-01-30 |laysummary=]
*2008 - U.S. presidential candidate John McCain says, "It's indisputable that (autism) is on the rise amongst children, the question is what's causing it. And we go back and forth and there's strong evidence that indicates that it's got to do with a preservative in vaccines." [cite news |author= Tapper J |url= |title= John McCain enters the autism wars |work= ABC News |date=2008-02-29 |accessdate=2008-03-03]

ee also

* 2000 Simpsonwood CDC conference
* David Kirby (journalist)
* Generation Rescue
* Leuprolide
* Mercury poisoning
* MMR vaccine controversy


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  • MMR vaccine controversy — The MMR vaccine controversy is over the safety of the MMR vaccine. Critics of the vaccine say that the incidence of autism has greatly increased and that the vaccine is a primary cause of this increase. They posit that the vaccine can overwhelm… …   Wikipedia

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  • Controversies in autism — encompass the disagreement over the exact nature of autism, its causes and manifestations. Autism is considered to be a neurodevelopmental condition which manifests itself in markedly abnormal social interaction, communication ability, and… …   Wikipedia

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  • List of vaccine topics — Flu vaccine This is a list of vaccine related topics. A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease causing microorganism, and is often made… …   Wikipedia

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