Jhe publication of Andrew Wakefield’s notorious and now discredited research on autism and vaccines in 1998 sparked a wave of concern about vaccine safety. Since then, questions about an alleged link between autism and vaccines have been asked and given a definitive answer: there is no link. But there are other factors linked to the development of autism that have strong scientific support.
A mountain of research has been conducted and published on a possible link between vaccines and autism, with hundreds of scientific and advocacy organizations refute it. They also point to the public health risk of avoiding vaccinations. Yet fear over this unsubstantiated link has led to the re-emergence of vaccine-preventable diseases such as measles and whooping cough. Another consequence of the continued media attention given to the issue is a misunderstanding of the actual environmental risk factors associated with autism.
Over the past year or so, there has been a steady pace of media coverage on autism and vaccines. Politicians, celebrities, the presidential election, film festivals, and mythic conspiracies have all contributed to news and media reports about the false link between vaccines and autism. Many of them had nothing to do with real science, nor were they the result of research findings that helped families.
But over the same period, a dozen new scientific findings have been published on legitimate environmental factors, including toxic chemicals, maternal infections during pregnancy, and chronic stress. These rarely made the headlines, with the media spotlight remaining on the myth. Yet knowing and understanding these real environmental factors could lead to real therapies or ways to prevent the debilitating symptoms of autism.
The term “environmental factor” is often misunderstood and used incorrectly. Scientists consider anything that produces a biological or behavioral response that is not strictly due to genes to be environmental. This includes what we eat and drink, what we breathe, what touches our skin, etc. The difference between a “risk” and a “cause” should also be clarified. A cause is something that causes a disease. Risk factors, by contrast, are things that work together to push us toward disease.
Specific criteria have been put in place to determine if something is a cause or a risk factor. So far, no environmental factor has met the criteria to be a cause of autism. This indicates that environmental factors work together, or interact with genes, to lead to autism.
Here are some examples of environmental factors that have been linked to autism:
Exposure to these factors increases a child’s risk of developing autism between two and four times. A comprehensive review of these factors just published in the Annual Review of Public Health.
A prime example of the distraction associated with the vaccine/autism myth is the role of mercury. Mercury is released into the environment, primarily by burning coal and other things that contain mercury. Every hour, 11 pounds of mercury are released into the environment this way. As this mercury is distributed in the environment, bacteria transform it into methylmercury. This type of mercury can accumulate in food sources, like the fish, and also in our body. A high level of methylmercury in the body can affect brain development in children.
Another form of mercury, ethyl mercury, is not found in the environment. Instead, it’s created in the lab and has been used in the manufacture of thimerosal, a preservative in vaccines. While research has exempt thimerosal as a risk factor for autism, has been removed of most vaccines given to children under 6 years of age. Ethylmercury does not accumulate in the body and does not pose the same threat to public health as methylmercury.
Mercury emissions from coal combustion and medical waste can be reduced, which would minimize the potential harm to our children. EPA already strained managed to do it, but to continue to reduce mercury in the environment, its activities must be supported and not diminished. Mercury in the environment is not a problem that any government agency or country can solve on its own.
The media—and therefore the public—has been distracted from the real threat to children and public health posed by methylmercury by baseless claims about ethylmercury in thimerosal by Robert F. Kennedy Jr. and others. A lot of outrage was unfortunately misdirected.
If Kennedy, who has claimed he will lead a presidential panel on vaccine safety, is truly interested in helping families with autism and making all children safer, then the $100,000 reward he and actor Robert De Niro proposed during a recent publicity stunt to find a link between autism and thimerosal that it would be best to fund scientists doing research on the real causes of autism and on the best way to care for people diagnosed with the disease. Alternatively, this money could be spent on reducing the current public health threat from methylmercury.
Researchers and advocacy organizations have moved from the autism vaccine story to focusing on issues that really affect families, like understanding the true causes of autism, finding ways to diagnose it more early, develop more effective treatments and provide better access to those treatments. With every minute wasted talking about the autism vaccine myth and every dollar spent researching this dead end, we are losing ground and failing families who deserve real answers about the causes of autism and more help for their relatives.
Alycia HalladayPhD, is Scientific Director of the Autism Science Foundation and Adjunct Adjunct Professor in the Department of Pharmacology and Toxicology at Rutgers University.