If chemicals in the environment can trigger autism, choosing organic food could protect you from some of them.

The 1998 study that led people to believe that autism is caused by a common childhood vaccination has been debunked, once again, this time with an article in the British Medical Journal calling the study fraudulent. Meanwhile, researchers who long ago dismissed the vaccine theory have been on the hunt to find more credible causes of the developmental disease that strikes 1 out of every 110 children born in the United States. While studies have suggested that as many as 90 percent of autism cases could be genetic in origin, a growing number of autism researchers now believe that it is not just genetics, but also the interplay between genes and environmental exposures that could be triggering a large percentage of autism cases. "It's unquestionable that there's a genetic component, but on the other hand, it's becoming equally clear that genetics is not the only culprit," pediatrician Phil Landrigan, MD, MSc, director of the Children's Environmental Health Center at Mount Sinai Medical Center, said last month at an autism meeting at the New York Academy of Medicine.

Linda Birnbaum, PhD, director of the National Institute of Environmental Health Sciences, and one of 14 prominent researchers to present during the meeting, stressed the importance of understanding that environmental factors aren't just limited to industrial and agricultural chemicals, but also include physical agents like radiation, drugs, and food, socioeconomic factors, and even the microflora in our guts, and how they respond to different environmental compounds. Causes of autism, like causes of cancer, researchers said, could be a number of environmental exposures.

Last year, the Lancet journal retracted the controversial study that linked the MMR (measles, mumps, and rubella) vaccine to autism, as a growing body of studies fail to replicate the connection. Now the researcher who authored the study stands accused of falsifying the data. So, if it's not vaccines that are triggering autism, what are the causes of autism?

According to a recent article by Dr. Landrigan published in the journal Current Opinion in Pediatrics, the most strongly positive, "proof-of-concept" evidence supports the idea that environmental exposures can trigger autism. In these cases, the harmful exposure likely took place during the first trimester of pregnancy. As of now, these exposures during critical windows of fetal development are the ones most strongly linked to autism:

1. Thalidomide—Not commonly used in the U.S., this sedative drug has been linked to an increase in autism and other birth defects.

2. Misoprostol—This drug is licensed in the U.S. for use in preventing gastric ulcers, but it's used in other countries for abortions.

3. Valproic acid—a medication to control epilepsy.

4. Prenatal rubella infection—a woman infected while pregnant also faces a higher risk of having a child with other developmental problems, eye problems, deafness, or heart problems.

5. Chlorpyrifos pesticide—One of the most widely used pesticides in the U.S. Banned for residential uses, this pesticide is still legal in agriculture, and residues have turned up on apples, bell peppers, cranberries, kale, grapes, peaches, and dozens of other foods.