WSR 10-14-076


[ Filed July 1, 2010, 10:37 a.m. ]

Suspension of Legal Limits of Mercury-Containing Vaccine for Japanese Encephalitis PARENT/PATIENT NOTICE July 2010

     The secretary of health has declared a shortage of a vaccine called JE-VAX¦, which protects against Japanese encephalitis, and suspended the state's legal limits on mercury for that vaccine, effective July 1, 2010. (The suspension of the mercury limits renews a suspension made in July 2009.) Although JE-VAX¦ exceeds Washington's legal mercury limits, it is the only vaccine allowed for use in the United States to protect children one to three years of age against that disease. Suspending the state's mercury limits gives health care providers and parents the ability to vaccinate their young children against Japanese encephalitis if they choose to.

     What is mercury and what is thimerosal?1 Mercury is a naturally occurring element found in the earth's crust, air, soil and water. Mercury has been released into the environment through volcanic eruptions, weathering of rocks and burning of coal. Once released, certain types of bacteria in the environment can change mercury to methylmercury. Methylmercury makes its way through the food chain in fish, animals, and humans. At high levels, it can be toxic to people.

     Thimerosal, a preservative still used in some vaccines, is a mercury-containing organic compound which has a different form of mercury called ethylmercury. Studies comparing ethylmercury and methylmercury suggest that they are processed differently in the human body. Ethylmercury is broken down and excreted much more rapidly than methylmercury. It appears that ethylmercury (the type of mercury in the influenza vaccine) is removed from the body more quickly than methylmercury (the type of mercury in the environment).

     What are Washington's legal limits on mercury in vaccines? As of July 1, 2007, Washington state law requires that pregnant women and children under three years of age be given vaccines that have no more than 0.5 micrograms of mercury per 0.5 milliliter dose. The law makes an exception for mercury content of influenza vaccine and allows pregnant women and children under age three to get influenza vaccine if it has 1.0 microgram of mercury per 0.5 milliliter dose, or less. Your doctor or nurse can help explain the size of these amounts.

     Can the legal limit on mercury in vaccines be suspended? Washington state law allows the secretary of the Washington department of health to suspend the state's legal mercury limit for a vaccine if the secretary determines there is a shortage of vaccine available to protect the public health against vaccine-preventable disease.

     How does this apply to me? Once Washington's legal mercury limit for a vaccine has been suspended, state law requires the following people be informed they are being given a vaccine containing mercury level exceeding those limits:

     •     Women known to be pregnant or lactating.

     •     The parent or legal guardian of a child under eighteen years of age receiving the vaccine.

     Where can I get more information? For more information about vaccines, go to To find an immunization clinic, call the family health hotline at 1-800-322-2588.

1 Information about mercury, methylmercury thimerosal and ethylmercury stated in the answer to this question was taken from the following two sources: Children's Hospital of Philadelphia at and the Food and Drug Administration at

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