What is thimerosal?
Part of the controversy around vaccines stems from a preservative called thimerosal that was once regularly used in vaccines. Concerns arose because thimerosal is a compound that contains a form of mercury, known as ethylmercury. Another type of mercury, known as methylmercury, can, in large doses (say, from drinking contaminated water or eating large amounts of contaminated fish), harm the brain development of a fetus or child. With the increased number of shots that children receive, some wondered whether children were being exposed to too much of this preservative. In particular, there were concerns that the preservative was to blame for increasing rates of autism, a behavioral disorder that has been on the rise in the U.S. in the past few decades.
As a precautionary measure, thimerosal was removed in 1999 from most vaccines. But it's worth understanding that while the methylmercury found in large fish can build up in the body and harm the developing brain of a growing child, the ethylmercury in thimerosal does not build up in the body. "It's never been linked to any adverse effect," says William Schaffner, M.D., professor and chair of preventive medicine department in the division of infectious diseases at Vanderbilt University Medical Center, Nashville, TN. And autism rates in the US have continued to rise even after the preservative was removed from nearly all of the vaccines that children receive. In 2010, a U.S. court ruled that vaccines containing thimerosal cannot cause autism on their own.
What are vaccines exactly?
Are vaccines safe?
Can my baby's immune system handle so many shots?
Why do kids today get so many more vaccines than they did years ago?
Is it okay to skip some vaccines?
Do these diseases even still exist?
What happens if parents choose not to vaccinate?
Wouldn't my unvaccinated child be protected if all the other kids are immunized?
Doesn't getting the disease itself give my child better immunity than she'd get from a vaccine?
Can't I wait to vaccinate my child until she is ready to start school?
Doesn't the flu vaccine still contain thimerosol?
How worried should I be about side effects?
If my child is sick, should I wait he's better to have him vaccinated?
If I'm breastfeeding, isn't my baby immune to all the diseases I'm immune to?