The thiomersal controversy is between claims that thiomersal-containing vaccines (TCVs) cause or contribute to the development of autism and other brain development disorders,^[1] and mainstream medical opinion that no convincing scientific evidence supports these claims. Thiomersal ( INN) (C9H9HgNaO2S commonly known in the United States as thimerosal, is an Organomercury compound (approximately A vaccine is a biological preparation which is used to establish or improve immunity to a particular disease Language development. The terminology ^[2][3]

Thiomersal, also spelled thimerosal, is an organomercury preservative used in vaccines since the 1930s to prevent bacterial and fungal contamination. Organomercury refers to the group of organometallic compounds that contain mercury. The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have A fungus (ˈfʌŋgəs is a eukaryotic Organism that is a member of the kingdom Fungi (ˈfʌndʒaɪ ^[4] 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. The Centers for Disease Control and Prevention (or CDC) is an agency of the United States Department of Health and Human Services based in unincorporated The American Academy of Pediatrics ( AAP) is an organization of Pediatricians physicians trained to deal with the medical care of infants children and adolescents S. and European vaccines. ^[5] 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. The precautionary principle is a moral and political principle which states that if an action or policy might cause severe or irreversible harm to the public or to the environment in the ^[2]

Thousands of lawsuits have been filed in the U. S. to seek damages from alleged toxicity from vaccines, including those purportedly from thiomersal preservatives. ^[6] The scientific consensus—including scientific and medical professional bodies and governmental agencies such as the Food and Drug Administration,^[4] the Centers for Disease Control and Prevention,^[7] and the World Health Organization^[8]—rejects the hypothesis that exposure to thiomersal causes or contributes to autism or other neurological disorders. Scientific consensus is the collective judgement position and Opinion of the community of Scientists in a particular field of Science at a particular The Centers for Disease Control and Prevention (or CDC) is an agency of the United States Department of Health and Human Services based in unincorporated

Contents 1 Background of controversy 1.1 Scientific background 1.2 Social and political background 2 Rationale for concern 3 Scientific consensus on controversy 4 Effects of the controversy 5 Court cases 6 Timeline 7 See also 8 References

Background of controversy

Scientific 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. ^[9] 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. Organization of the Public Health Service The Public Health Service Act placed the United States Public Health Service ( PHS) as the primary division "NIH" redirects here For other meanings of NIH see NIH (disambiguation. The Health Resources and Services Administration (HRSA an agency within the United States Department of Health and Human Services, is the primary Federal agency for improving The American Academy of Pediatrics ( AAP) is an organization of Pediatricians physicians trained to deal with the medical care of infants children and adolescents 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. "^[10]

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 United States Agency for Toxic Substances and Disease Registry, ( ATSDR) is an agency for the U 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. Ethylmercury (sometimes ethyl mercury) is a Cation composed of an Ethyl group and a mercury atom its chemical formula is C 2 Methylmercury (sometimes methyl mercury) is an Organometallic Cation with the formula + 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. ^[4]

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. "NIH" redirects here For other meanings of NIH see NIH (disambiguation. The National Academy of Sciences (NAS is a corporation in the United States whose members serve Pro bono as "advisers to the nation on science The Institute of Medicine (IOM is one of the United States National Academies, and is a not-for-profit non-governmental American organization chartered in 1970 as a part of the United 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. "^[11]

Social 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. The epidemiology of autism is the study of factors affecting Autism spectrum disorders (ASD ^[12]

This concept also gained support in the political sphere, with Rep. Dan Burton and Rep. Danny "Dan" Lee Burton (born June 21 1938) American politician is a member of the United States House of Representatives for David Weldon openly supporting this movement as well. David Joseph Weldon, (known as Dave Weldon) (born August 31 1953, Amityville New York) is an American politician and physician 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. The epidemiology of autism is the study of factors affecting Autism spectrum disorders (ASD 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"^[1]

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. ^[4][13]
• In vitro tests: cultured cells in laboratory show adverse effects when exposed to ethylmercury. ^[14]
• 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. Autoimmune diseases arise from an overactive Immune response of the body against substances and tissues normally present in the body Walking (also called ambulation) is the main form of Animal Locomotion on land, distinguished from Running and crawling The exposure attempted to replicate the one-year schedule for U. S. infants in 2001, adjusted for weight and age. ^[15] However, a similar 2007 study found no pervasive developmental neurotoxicity in the same mouse strain. ^[16] 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. ^[17]
• Unscientific reports that autism is rarer in the Amish community and other non-vaccinated groups. The Amish (ˈɑːmɪʃ are members of an Anabaptist Christian denomination best known for Simple living, Plain dress and resisting modern conveniences 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. ^[18]
• Epidemiologic data: epidemiologic studies (all coauthored by Mark Geier) examined population level correlation between thiomersal and autism. Epidemiology is the study of factors affecting the Health and Illness of populations and serves as the foundation and Logic of interventions made in the Mark R Geier (b 1948 Washington DC) is a self-employed United States geneticist He has been examining vaccine safety issues since then ^[19]
• Concern that mercury might have synergistic effects with other metals and toxicants. ^[20]

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. ^[21] 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. Blood plasma is the Liquid component of Blood, in which the Blood cells are suspended Rho(D Immune Globulin is a medicine given by intramuscular injection which is used to prevent the immunological condition known as Rhesus disease (or Hemolytic Common names: pit vipers pitvipers The Crotalinae, or crotalines are a subfamily of venomous vipers found Antivenin (or antivenom or antivenene) is a biological product used in the treatment of venomous bites or stings The coral snakes are a large group of Elapid Snakes that can be divided into two distinct groups New World coral snakes and Old World Antivenin (or antivenom or antivenene) is a biological product used in the treatment of venomous bites or stings The black widow spider is a group of Spiders which includes the southern black widow ( Latrodectus mactans) the northern black widow Antivenin (or antivenom or antivenene) is a biological product used in the treatment of venomous bites or stings ^[22]

Scientific 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. Scientific consensus is the collective judgement position and Opinion of the community of Scientists in a particular field of Science at a particular The Institute of Medicine (IOM is one of the United States National Academies, and is a not-for-profit non-governmental American organization chartered in 1970 as a part of the United 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. "^[23]

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. "^[23] [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. "^[23]

Three large-scale controlled observational studies have been reported on this issue; none have found an association between thiomersal-containing vaccines (TCVs) and autism. ^[12] A study from Denmark noted no decrease in autism rates despite cessation of TCVs^[24] and a UK study found that TCVs actually had a protective effect with respect to autism. ^[25] 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. DPT, (sometimes DTP) is a mixture of three Vaccines to immunize against Diphtheria, Pertussis (whooping cough and Tetanus. S. ^[12] For the U. S. , a study based on the Vaccine Safety Datalink found no association between TCVs and autism. The Vaccine Safety Datalink Project (VSD was established in 1990 by the United States Centers for Disease Control and Prevention (CDC to study the adverse side effects ^[26] Some smaller studies have also found no association between TCVs and autism^[27][28] and a study found no association between thimerosal and the neurological signs of autism. ^[29] Another smaller study also found a protective effect: it reported a significantly lower prevalence of autism spectrum disorders among children exposed to thimerosal (5. The autism spectrum, also called autism spectrum disorders (ASD or autism spectrum conditions (ASC with the word autistic sometimes replacing autism 95 per 1,000 versus 8. 27 per 1,000). ^[30]

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,^[31] including charges of not presenting methods and statistical analyses to others for verification,^[32] improperly analyzing data taken from Vaccine Adverse Event Reporting System,^[32][23] as well as either mislabelling or confusing fundamental statistical terms in his papers. Mark R Geier (b 1948 Washington DC) is a self-employed United States geneticist He has been examining vaccine safety issues since then The Vaccine Adverse Event Reporting System is a United States program for vaccine safety co-sponsored by the Centers for Disease Control and Prevention (CDC and ^[23]

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,^[33] the American Academy of Pediatrics,^[34] the American College of Medical Toxicology,^[35] the National Academy of Sciences,^[23] the Food and Drug Administration,^[4] Centers for Disease Control and Prevention,^[7] the World Health Organization,^[8] the Public Health Agency of Canada,^[36] and the European Medicines Agency. Scientific consensus is the collective judgement position and Opinion of the community of Scientists in a particular field of Science at a particular The American Medical Association (AMA founded in 1847 and incorporated 1897 is the largest association of Physicians and Medical students in the United States The American Academy of Pediatrics ( AAP) is an organization of Pediatricians physicians trained to deal with the medical care of infants children and adolescents The American College of Medical Toxicology (ACMT founded in 1993 is the largest organization of medical (physician toxicologists in the United States and the world The National Academy of Sciences (NAS is a corporation in the United States whose members serve Pro bono as "advisers to the nation on science The Centers for Disease Control and Prevention (or CDC) is an agency of the United States Department of Health and Human Services based in unincorporated The Public Health Agency of Canada ( French: Agence de la santé publique du Canada) is an agency of Health Canada, a department of the The European Medicines Agency ( EMEA) is a European agency for the evaluation of medicinal products. ^[37]

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 caused some parents to have their children treated with chelation therapy; about 10,000 autistic children in the U. Chelation therapy is the administration of chelating agents to remove Heavy metals from the body 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. ^[2]

Court cases

Further information: Vaccine court

From 1988 until 2008-01-08, 5,263 claims relating to autism were made to the U. Vaccine court is the popular term which refers to the Office of Special Masters of the U 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 871 - Battle of Ashdown - Ethelred of Wessex defeats a Danish invasion army S. court that oversees compensation. One claim was compensated, and 350 were dismissed; the rest are pending. ^[38] 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. Mitochondrial diseases are a group of disorders relating to the mitochondria, the Organelles that are the "powerhouses" of the eukaryotic cells ^[39][40]

Timeline

• 1930s - first added to vaccines and other products as a bactericide. The 1930s were described as an abrupt shift to more radical and conservative lifestyles as countries were struggling to find a solution to the Great Depression. ^[41]
• 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. The 1980s was the decade spanning from January 1 1980 to December 31 1989.
• 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. The 1990s collectively refers to the years between and including 1990 and 1999
• Late 1990s - three of the vaccines included in Vaccination schedules for children between six and eighteen months of age contain thiomersal. A vaccination schedule is a recommended series of Vaccinations including the suggested timing of all doses
• 1999 - The American Academy of Pediatrics requests removal of thiomersal from all pediatric vaccines. The American Academy of Pediatrics ( AAP) is an organization of Pediatricians physicians trained to deal with the medical care of infants children and adolescents
• 2001 - Thiomersal is no longer used in routine childhood vaccines in the U. S. ^[5]
• 2001 - The Institute of Medicine, citing insufficient evidence, is unable to prove or disprove any link between thiomersal and autism. The Institute of Medicine (IOM is one of the United States National Academies, and is a not-for-profit non-governmental American organization chartered in 1970 as a part of the United However, they conclude that a causal connection between thiomersal and autism is "biologically plausible". ^[4]
• 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. The Centers for Disease Control and Prevention (or CDC) is an agency of the United States Department of Health and Human Services based in unincorporated
• 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. The Institute of Medicine (IOM is one of the United States National Academies, and is a not-for-profit non-governmental American organization chartered in 1970 as a part of the United ^[4]
• 2005 - Robert F. Kennedy, Jr. authored an article in the June, 2005 Rolling Stone, alleging connections between thimerosal in vaccines and autism. Robert Francis Kennedy Jr (born January 17, 1954 in Washington D Rolling Stone is a United States -based Magazine devoted to Music, Politics, and Popular culture that is published ^[42]
• 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 schedules give these in a shorter time period.
• 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. ^[43]
• 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. Vaccine court is the popular term which refers to the Office of Special Masters of the U Events 1184 BC - Trojan War: Troy is sacked and burned according to the calculations of Eratosthenes.
• 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. Michael Bradley "Mike" Enzi (born February 1 1944) is a United States Senator from Wyoming. The United States Senate Committee on Health Education Labor and Pensions (HELP generally considers matters relating to health education labor and pensions 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. ^[44]
• 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. California ( is a US state on the West Coast of the United States, along the Pacific Ocean. ^[45] 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. ^[46]
• 2008 - A study that examined the ethylmercury from thiomersal in vaccines found that the half-life of blood mercury after vaccination averages 3. Ethylmercury (sometimes ethyl mercury) is a Cation composed of an Ethyl group and a mercury atom its chemical formula is C 2 7 days for newborns and infants, much shorter than the 44 days for methylmercury. Methylmercury (sometimes methyl mercury) is an Organometallic Cation with the formula + The shorter half-life suggests that thiomersal in vaccines is not as risky as was feared, and that a new risk assessment is needed. ^[47]
• 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. "^[48]

See also

• 2000 Simpsonwood CDC conference
• David Kirby (journalist)
• Generation Rescue
• Leuprolide
• Mercury poisoning

References

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