Mercury, also known as hydrargyrum, is a chemical element with the symbol Hg and atomic number 80. It is a heavy silvery element and the only metal that is liquid at standard conditions for temperature and pressure. This chemical element can produce many adverse human health effects, such as permanent damage to nervous system. It can also be transferred from a mother to her unborn child.
The World Health Organization (WHO) stated that mercury is highly toxic and one of the top 10 chemicals of public health concern. It can be found in small amounts in many products such as thermometers, batteries and in vaccines, for a small amount. WHO suggests products that contain mercury, except vaccines, should be phased out; for example switch from mercury thermometers to digital thermometers.
In February 2009, the Governing Council of United Nations Environment Program (UNEP) started to work on a legally binding global treaty on mercury. The work of the intergovernmental negotiating committee (INC) will be carried out over five sessions, started from June 2010 until early 2013. The first INC was held in Stockholm, the second was in Chiba (Japan), and the third meeting was held in Nairobi on 31 October to 4 November 2011.
The problem is that a proposed ban might include thiomersal (thimerosal), a mercury compound that commonly used to prevent contamination and can extend the shelf life of vaccines. Thiomersal is used in about 300 million vaccines worldwide for fighting diseases such as diphtheria, flu, hepatitis B, meningitis, polio, tetanus, etc. Many experts, including WHO vaccines expert David Wood, said that not being able to use mercury is not a viable option and might threaten vaccination programmes.
Thiomersal was suspected as a cause of autism in children who received vaccines. A medical study in 1998 linked a common childhood vaccine injection to autism. But then many studies found no sign the mercury compound is risky.
At the moment, there is not a viable alternative to thiomersal and if it were banned, the pharmaceutical companies would likely to switch to preservative-free vaccines. This condition will complicate the supply chain and vaccination campaigns in poor countries because the vaccines will have a much shorter shelf life. It can also affect the cost of production since pharmaceutical company would need to reconfigure their factories.
Tim Kasten, head of the chemicals branch at UNEP, said “The document is still a draft, so some of these proposals have to be taken with a grain of salt”. He also said that there could be provisions to allow mercury for certain uses, for instance in vaccines, because the amount of mercury in vaccines is very small and does not threaten the environment. But, the annex of the draft document stated that there is no allowable use exemption for mercury products in pharmaceutical products, including vaccines.
Some experts, such as Paul Offit (University of Pennsylvania) and Andrew Nelson (University of Leeds), disagreed with the idea of banning mercury completely. Offit said that it would be a tragic example for not being able to explain to the public where the real risk lies. While Nelson said that if we knew the risks and handled it properly then there is not a problem. Besides, an absolute ban for mercury is ridiculous since the health of millions of children benefit from vaccines.
In the United States of America, Canada, Norway and Sweden, pharmaceutical companies have been encouraged to produce thiomersal-free vaccines and no other mercury products can be used as medical preservative.
Reference:
- CBC News
- UNEP
- WebMD
- WHO
- Wikipedia
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