We are all exposed to mercury in our lives, through consumption in the diet, in some vaccines, at the dentist’s (those silver fillings) and through environmental exposure. High biological levels of mercury lead to serious health problems, including loss of memory, depression and dementia. Indeed, Environmental Protection Agency guidelines to limit the amount of mercury in your diet are probably sound, especially during pregnancy when exposure to even small amounts of mercury can harm the developing foetus.
When it comes to vaccines, since 2001, any new FDA-approved vaccine has to be mercury-free. However, the yearly-formulated seasonal flu vaccine is an exception to this rule, but only on a ‘bulk use’ basis: single dose vials that are intended to be opened and used once do not have a mercury component, but multi-dose vials are supplied with a mercury-containing preservative, thimerosal. In multi-dose vials, repeated doses of vaccine are withdrawn during a mass immunisation session, putting the contents at a higher risk of contamination, even though vials are discarded at the end of the session or after 6 hours (whichever comes first). Thimerosal prevents the growth of dangerous microorganisms, such as bacteria and fungi. Other vaccines approved before 2001, such as the pertussis (whooping cough), tetanus and meningococcal vaccines, also contain low levels of thimerosal (~0.01%).
Many different governmental and independent bodies, including the World Health Organisation (WHO), the Center for Disease Control and Prevention (CDC), the National Institutes of Health (NIH) and the Food and Drug Administration (FDA), have reviewed current evidence to determine if inclusion of thimerosal in vaccines is harmful to human health: all have concluded that there is no scientifically-sound evidence that links exposure to thimerosal through vaccines with disease (including autism).
Visit http://www.fda.gov/food/foodsafety/product-specificinformation/seafood/foodbornepathogenscontaminants/methylmercury/ucm115644.htm to find out which fish contain the highest levels of mercury, helping to manage a healthy level of consumption in your diet.