Logan Reed
Thimerosal, a mercury-based preservative, was once used in hepatitis B vaccines. However, concerns arose about potential toxic effects on neurodevelopment, especially in infants and unborn children. While some studies suggest a link between thimerosal-containing vaccines and developmental delays, others find no association with cognitive development. Following an amendment to the FDA Modernization Act in 1997, Thimerosal was removed from vaccines, including hepatitis B, due to long-standing concerns about mercury's neurotoxic and nephrotoxic effects. Today, while Thimerosal is no longer used in hepatitis B vaccines, the topic remains relevant as studies continue to investigate the safety of Thimerosal in previously vaccinated individuals and explore the potential long-term effects of mercury exposure from vaccines.
| Characteristics | Values |
|---|---|
| Mercury compound in Hepatitis B vaccine | Thimerosal, an ethylmercury-containing preservative |
| Percentage of mercury in Thimerosal | 49.55% |
| Amendment to FDA Modernization Act | Signed into law on November 21, 1997, to reduce human exposure to mercury |
| American Academy of Pediatrics recommendation | Delay administration of the birth dose of the Hepatitis B vaccine until 6 months of age |
| Studies on effects of Thimerosal | No significant difference in cognitive development in children exposed to Thimerosal during early infancy |
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What You'll Learn
- Thimerosal is a mercury-based preservative used in some vaccines
- Thimerosal was removed from vaccines in 1997
- Thimerosal-containing hepatitis B vaccines are associated with developmental delays
- Studies suggest that thimerosal is not harmful
- The safety of thimerosal in infants has not been systematically studied
Thimerosal is a mercury-based preservative used in some vaccines
However, concerns arose regarding the potential toxic effects of organic mercury on childhood development. In response, the Food and Drug Administration (FDA) amended the FDA Modernization Act in 1997, leading to the removal of Thimerosal from vaccines. This amendment aimed to reduce human exposure to mercury, a known neurotoxin and nephrotoxin.
Despite these concerns, studies have shown that children exposed to Thimerosal-containing vaccines during early infancy exhibited similar cognitive-developmental outcomes to those unexposed. Additionally, Thimerosal in vaccines has been found to be non-harmful due to the type of mercury it contains, ethylmercury, which is processed differently in the human body compared to methylmercury, the toxic form.
While Thimerosal was phased out of vaccines, it is important to note that some individuals may still have received hepatitis B vaccines containing Thimerosal, particularly those born between 1991 and 2000. The potential consequences of Thimerosal exposure during this period have been the subject of various studies, with some suggesting an association between Thimerosal-containing vaccines and specific delays in development.
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Thimerosal was removed from vaccines in 1997
Thimerosal, also known as thiomersal, is an organomercury compound used as a preservative in vaccines to prevent bacterial and fungal contamination. It has been used in vaccines and other products such as immunoglobulin preparations and ophthalmic and nasal solutions since the 1930s.
In 1997, an amendment to the Food and Drug Administration (FDA) Modernization Act was signed into law, mandating a review and risk assessment of all mercury-containing food and drugs. This amendment required the FDA to compile a list of drugs and foods that contain intentionally introduced mercury compounds and to provide a quantitative and qualitative analysis of the mercury compounds on the list.
Following this amendment, the FDA conducted a comprehensive review of the use of thimerosal in childhood vaccines in 1999. This review found no evidence of harm from the use of thimerosal as a vaccine preservative, other than local hypersensitivity reactions. However, in the same year, the Public Health Service, including the FDA, concluded that it was prudent to reduce childhood exposure to mercury from all sources, including vaccines, as a precautionary measure. As a result, the FDA sent a letter to all manufacturers of US-licensed vaccines requesting their plans to remove thimerosal from their vaccines.
Since then, much progress has been made in removing or reducing the use of thimerosal as a preservative in vaccines. All vaccines routinely recommended for children 6 years of age and younger in the US are available in formulations that do not contain thimerosal. Additionally, vaccines without thimerosal as a preservative are also available for adolescents and adults.
While there is no clear evidence that thimerosal is harmful, some studies have investigated its potential effects on cognitive development in children. One study found that cases diagnosed with specific delays in development were more likely to have received increased organic mercury exposure from Thimerosal-containing hepatitis B vaccines administered within the first six months of life. However, another study in Poland found that children exposed and not exposed to thimerosal during early infancy had similar outcomes on cognitive-developmental tests.
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Thimerosal-containing hepatitis B vaccines are associated with developmental delays
Thimerosal is an ethylmercury-containing preservative that was once used in some multi-dose preparations of the influenza vaccine. It was removed from vaccines after an amendment to the Food and Drug Administration (FDA) Modernization Act was signed into law on November 21, 1997. This amendment gave the FDA two years to compile a list of drugs and foods containing intentionally introduced mercury compounds and to provide a quantitative and qualitative analysis of the mercury compounds.
Despite the removal of thimerosal from vaccines, some people still worry that it could cause mercury poisoning in children or affect unborn children whose mothers received the vaccine. However, thimerosal is not harmful for many reasons. Firstly, mercury is a naturally occurring element found in the earth's crust, air, soil, and water. Volcanic eruptions, weathering of rocks, and the burning of coal have released mercury into the environment since the earth's formation. While certain types of bacteria can change mercury to methylmercury, which can be toxic to people at high levels, thimerosal contains ethylmercury, which studies suggest is processed differently in the human body.
A case-control study evaluated the relationship between exposure to Thimerosal-containing hepatitis B vaccines administered at specific intervals in the first 6 months among cases diagnosed with specific delays in development and controls born between 1991-2000. The study found that cases were significantly more likely than controls to have received increased organic mercury from Thimerosal-containing hepatitis B vaccines administered in the first, second, and sixth month of life. However, it is important to note that the study could not establish a direct cause-and-effect relationship between exposure and outcome.
Another study investigated the relationship between early exposure to thimerosal-containing vaccines and children's cognitive development. The authors evaluated children who were vaccinated between birth and 6 months of age with hepatitis B and DTP vaccines using formulations with or without thimerosal. The results showed that children exposed and not exposed to thimerosal during early infancy had similar outcomes on cognitive development tests.
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Studies suggest that thimerosal is not harmful
Thimerosal is an additive used in some vaccines to prevent the growth of bacteria and fungi. It is also known as a preservative. Although thimerosal contains mercury, a known neurotoxin, it has been used in vaccines since the 1930s without causing any ill effects other than minor local reactions at the site of injection.
Thimerosal has been the subject of numerous studies over the past 20+ years, which have found no evidence of harm caused by the low doses of thimerosal in vaccines. These studies have specifically investigated the relationship between thimerosal exposure and cognitive development in children, as well as the potential for thimerosal to cause autism or other neurodevelopmental disorders. The results consistently show that thimerosal does not contribute to the development of autism or cause adverse neurological outcomes. In fact, autism rates rose after thimerosal was removed from childhood vaccines, which is the opposite of what would be expected if thimerosal caused autism.
Additionally, studies have shown that children exposed and not exposed to thimerosal during early infancy had similar outcomes on cognitive-developmental tests. This suggests that thimerosal does not cause significant delays in development, even when administered at specific intervals within the first 6 months of life.
The safety of thimerosal has been further supported by the decline in its use as a preservative in U.S. FDA-licensed vaccines due to the reformulation and development of single-dose containers. While thimerosal is no longer used in childhood vaccines, it is still present in some flu vaccines. However, individuals can request a flu vaccine without thimerosal if they are concerned about its potential risks.
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The safety of thimerosal in infants has not been systematically studied
Thimerosal is an ethylmercury-containing preservative used in some multi-dose preparations of vaccines, such as the influenza vaccine. It has been used safely in vaccines since the 1930s and has a long record of effectively preventing bacterial and fungal contamination of vaccines.
Despite its long history of use, some people have expressed concerns about the potential toxic effects of organic mercury exposure from Thimerosal, especially in childhood vaccines. These concerns have led to studies investigating the relationship between Thimerosal exposure and potential developmental delays or neurological issues.
One case-control study examined data from the Vaccine Safety Datalink database and found that cases diagnosed with specific delays in development were more likely to have received increased organic mercury exposure from Thimerosal-containing hepatitis B vaccines administered within the first six months of life. Another study by Pichichero and colleagues found that infants vaccinated at two months and six months of age had higher blood mercury concentrations, raising concerns about potential mercury levels in infants vaccinated at birth.
However, it is important to note that the safety of Thimerosal in infants has not been systematically studied. While there have been individual studies and reviews of existing literature, more comprehensive investigations are needed to fully understand the pharmacokinetic profile and neurotoxic potential of Thimerosal in newborns and fetuses, who are considered the highest-risk populations.
Until such comprehensive studies are conducted, efforts should be made to limit fetal and infant exposure to this mercury compound. Additionally, it is worth noting that thimerosal was removed from vaccines after an amendment to the Food and Drug Administration (FDA) Modernization Act was passed in 1997. This amendment aimed to reduce human exposure to mercury, and as a result, thimerosal has not been used in vaccines for children since 2001. Today, all vaccines routinely recommended for children six years of age and younger in the US are available without Thimerosal.
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Frequently asked questions
Yes, the Hepatitis B vaccine contains a mercury-based preservative called Thimerosal.
Thimerosal is used as a preservative in some multi-dose preparations of the influenza vaccine.
Thimerosal is not harmful and is not toxic. It contains ethylmercury, which is processed differently in the human body from methylmercury, which is the neurotoxin found in fish and the environment.
Yes, there was an amendment to the Food and Drug Administration (FDA) Modernization Act in 1997 that aimed to reduce human exposure to mercury. Thimerosal was removed from vaccines following this amendment.
