Antidote

Vaccine makers work on a very narrow profit margin, because their products are generic, and federal regulations rightly insist on rigorous procedures to ensure sterilization. Culture mediums based on chicken eggs are imperfect, and the latest genetic techniques are not yet in common use. In order

Unfortunately, when the questions about this additive were first raised, the manufacturers didn't quickly shift production to another product. Instead, they left themselves open to accusations-probably false-that they have caused thousands of cases of autism.

Mercury has been shown to cause neurotoxicity, but thimerosal only contains trace amounts of mercury. One study showed that thimerosal could cause irritability in mice, but no studies in humans have shown a cause and effect between this additive and autism. Several large epidemiologic studies have not shown an association.

At a time when autism appears to be on the rise, it is important science to look for environmental causes, but focusing on one possibility a priori takes important resources from a more general and appropriate search. There is a lesson here for manufacturers as well; to remove a product at the first sign of trouble, rather than wait for allegations, however false or seemingly exaggerated. Thimerosal is not a crucial part of vaccines, it could have been removed long before the current outcry.

Which is still not the same thing as saying that thimerosal - or even mercury-causes autism. Autism is on the rise, in part, because of improved ability to diagnose it. There are also many factors in today's environment such as TV, noise, divorce, that didn't exist to this extent in previous generations. All these factors deserve study.

Thimerosal in vaccines has not been shown to cause autism. But does it deserve further study? Yes. Should it be removed from vaccines? Also yes.