Results did not support an association between early exposure to mercury and deficits in neuropsychological functioning at the age of 7 to 10 years. Pervasive developmental disorders in Montreal, Quebec, Canada: prevalence and links with immunizations. Pediatrics ; 1 :ee The authors compared the prevalence of pervasive developmental disorder PDD in Montreal, Canada, with the cumulative exposure to thimerosal. Ironically, the prevalence of PDD in the thimerosal-free birth cohorts was significantly higher than that in thimerosal-exposed cohorts.
Additional analysis showed no significant effect of thimerosal exposure on prevalence of PDD. In addition, no relationship was found between the rates of PDD and exposure to one or two doses of MMR before 2 years of age.
Thimerosal exposure in infants and developmental disorders: a retrospective cohort study in the United Kingdom does not support a causal association.
Pediatrics ; 3 The authors performed a retrospective study in the United Kingdom to determine the relationship between the amount of thimerosal that an infant received via diphtheria-tetanus-whole-cell pertussis DTP or diphtheria-tetanus DT vaccines and subsequent neurodevelopmental disorders. Although tics in males were observed in one subset of children; in another, thimerosal appeared to enhance cognitive skills in females.
The authors concluded that thimerosal at the level contained in these vaccines did not cause signs and symptoms consistent with mercury toxicity.
Heron J, Golding J, et al. Thimerosal exposure in infants and developmental disorders: a prospective cohort study in the United Kingdom does not support a causal association. The authors performed a prospective study comparing the relationship between the quantity of thimerosal exposure from vaccines with several measures of childhood cognitive and behavioral development from 6 to 91 months of age. They found no evidence that early exposure to thimerosal had a deleterious effect on neurologic or psychological outcome.
Autism and thimerosal-containing vaccines: lack of consistent evidence for an association. Am J Prev Med ; The authors compared the prevalence and incidence of autism in California, Sweden and Denmark with average exposures to thimerosal-containing vaccines between the mids and lates. They found that exposure to thimerosal-containing vaccines was not associated with the increase in rates of autism in young children being observed worldwide.
Safety of thimerosal containing vaccines: a two-phased study of computerized health maintenance organization databases. Pediatrics ; 5 The authors evaluated the relationship between exposure to thimerosal-containing vaccines and neurodevelopmental disorders in more than , infants born between and , finding no significant associations.
Thimerosal and the occurrence of autism: negative ecological evidence from Danish population-based data. The authors assessed the incidence rates of autism in Denmark among children between 2 and 10 years of age before and after removal of thimerosal from vaccines. Ironically, they found that the discontinuation of thimerosal-containing vaccines was followed by an increase in the incidence of autism. Association between thimerosal-containing vaccine and autism. JAMA ; The authors evaluated the incidence of autism in children born in Denmark between who received either thimerosal-containing vaccines or thimerosal-free preparations of the same vaccine.
They found that the incidence of autism or autistic spectrum disorders did not differ significantly between the two groups. Materials in this section are updated as new information and vaccines become available. The Vaccine Education Center staff regularly reviews materials for accuracy. They found no change in autism rates relative to the amount of thimerosal a child received from vaccines in the first 6 months of life. In other words, a child who received more thimerosal was not more likely to be autistic.
Which vaccines contain thimerosal? Since , all routinely recommended vaccines manufactured for administration to infants in the U. Some vaccines that are not routinely recommended for young children under 6 months of age, such as meningococcal vaccine, are only available with thimerosal. Why was thimerosal removed from vaccines if there is no danger? What risks does mercury pose to an infant's health? Have any adverse reactions to thimerosal ever been reported?
Infants and children who have received thimerosal-containing vaccines do not need to have blood, urine, or hair tested for mercury. The body eliminates a mercury dose completely within days - it doesn't stay in your child's body. Screening children for mercury exposure will likely result in more questions than answers. Mercury in the urine is a measure of inorganic mercury exposure, not the organic form found in thimerosal. The documented antimicrobial properties of thimerosal contribute to the safe use of vaccines in multi-dose vials, and the ability to package certain vaccines, such as those for seasonal and pandemic influenza, in multi-dose vials helps facilitate immunization campaigns in the United States and globally that save lives.
However, the use of thimerosal as a preservative in U. FDA-licensed vaccines has significantly declined due to reformulation and development of new vaccines presented in single-dose containers. It is metabolized or degraded to ethylmercury and thiosalicylate.
Ethylmercury is an organomercurial that should be distinguished from methylmercury, a related substance that has been the focus of considerable study. Methylmercury is the type of mercury found in certain kinds of fish.
At high exposure levels methylmercury can be toxic to people. In the United States, federal guidelines keep as much methylmercury as possible out of the environment and food, but over a lifetime, everyone is exposed to some methylmercury.
At concentrations found in vaccines, thimerosal meets the requirements for a preservative as set forth by the United States Pharmacopeia; that is, it kills the specified challenge organisms and is able to prevent the growth of the challenge fungi U. Pharmacopeia Thimerosal in concentrations of 0. A vaccine containing 0. For comparison, this is roughly the same amount of elemental mercury contained in a 3 ounce can of tuna fish. Prior to introduction of thimerosal in the 's, data were available in several animal species and humans providing evidence for its safety and effectiveness as a preservative Powell and Jamieson Since then, thimerosal has been the subject of numerous studies see Bibliography- Notable Studies and Assessments Supporting the Safe Use of Thimerosal in Vaccines and has a long record of safe and effective use preventing bacterial and fungal contamination of vaccines, with no ill effects established other than minor local reactions at the site of injection.
While the use of mercury-containing preservatives has declined in recent years due to the development of new products formulated into single-dose presentations that do not require preservatives, thimerosal has been used in some immune globulin preparations, anti-venins, skin test antigens, and ophthalmic and nasal products, in addition to some vaccines.
It is important to note that this list was compiled in ; some products listed are no longer manufactured and many products have been reformulated without thimerosal. Phenol is used in a variety of consumer products including mouthwashes, throat lozenges, and throat sprays. It is also currently used as a preservative in three FDA-approved available vaccines, Pneumovax 23 for prevention of pneumococcal disease caused by the 23 serotypes contained in the vaccine and Typhim Vi for prevention of typhoid fever and ACAM for prevention of smallpox ; each of these vaccines contains 0.
It is also currently used as a preservative in one FDA-approved available vaccine, Ipol, for the prevention of polio, at a concentration of 0. Benzethonium chloride is a chemical that has antimicrobial properties. It is used in over-the-counter hand and body washes. This preservative is currently used in only one FDA-approved vaccine, BioThrax, for the prevention of disease caused by Bacillus anthracis. Preservatives may be defined as compounds that kill or prevent the growth of microorganisms, particularly bacteria and fungi.
They are used in vaccines to prevent microbial growth in the event that the vaccine is accidentally contaminated, as might occur with repeated puncture of multi-dose vials with a needle. In some cases, preservatives are added during the manufacturing process to prevent microbial growth.
However, improvements in manufacturing technology have markedly decreased the need to add preservatives during the manufacturing process. The United States Code of Federal Regulations the CFR requires, in general, the addition of a preservative to multi-dose vials of vaccines; and, worldwide, preservatives are routinely added to multi-dose vials of vaccine.
Tragic consequences have followed the use of multi-dose vials that did not contain a preservative and have served as the impetus for this requirement. One particularly telling incident from Australia is described by Sir Graham S. A breast-fed infant will naturally ingest around 7 milligrams of aluminum in her diet throughout the first six months of her life. In contrast, the standard vaccines administered over the first six months of an infant's life contain an average of just 4. Aluminum has been used safely for over six decades in vaccines, with no scientific evidence indicating otherwise.
The amount of aluminum in vaccines is tiny. In fact, babies always have a small naturally occurring amount of aluminum in their bloodstreams, about 5 nanograms. The quantity of aluminum in a vaccine is so small it doesn't cause any noticeable raise in this base amount found in the blood, even immediately after an injection.
Antibiotics Why are they used? During the production process of some vaccines, antibiotics may be used to counter the risk of dangerous bacterial infection. Concern occasionally arises about antibiotics in vaccines because of the risk of allergic reactions in some children.
These fears are greatly exaggerated. Vaccine manufacturers only use antibiotics that are far less likely to provoke a reaction, and because antibiotics are only used during production, they are reduced to trace or undetectable amounts in the final product.
In fact, no allergic reaction to a vaccine has ever been traced back to antibiotics. The overall odds a child will suffer from a severe allergic reaction from an MMR or Hepatitis B vaccine, from any ingredient, is 1 in 1,, , one hundred times less than the 1 in 10, chance a child will be struck by lightning.
During the purification steps of the production process, antibiotics are removed, resulting in miniscule or undetectable amounts in the final vaccine. Gelatin Why is it used?
Gelatin is used as a preservative and stabilizer, keeping vaccines effective under heat or cold and for the duration of their shelf life. For a very small number of children, gelatin can cause an allergic reaction.
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