Autism is largely genetic, but evidence also points to "triggers" in the prenatal environment.
The role of toxins
Blood tests show that most Americans' bodies carry a significant burden of pollution, including plastic softeners, flame retardants, pesticides and heavy metals. While acknowledging that chemical exposure probably won't cause autism unless there is genetic susceptibility, Pessah is testing hair, blood, tissue and urine samples from 700 families with autism, looking for toxic triggers. "Heavy metals, including cadmium, manganese, arsenic, lead and mercury, are prominent targets of investigation," he says.
In fact, mercury is the 800-pound gorilla of autism research. Large studies have determined that thimerosol, the mercury-based preservative once used in childhood vaccines, is not connected with autism. The focus is now on a mother's intake of methylmercury, the organic form that's found in fish. Also, a couple of recent studies have linked higher mercury levels in outdoor air to a rise in autism.
Though research on the origins of autism isn't yet conclusive, enough is known about the effect of environmental factors on the fetal brain to offer moms-to-be some practical guidance:
Limit intake of contaminated fish Large, predatory fish, such as tuna or swordfish, contain high levels of mercury; farmed seafood such as salmon may have higher levels of industrial chemicals, such as PCBs. "It's best to eat wild-caught and smaller fish lower on the food chain," says Pessah.
Minimize chemical exposures "There are chemicals around the house, such as sprays or air fresheners, that haven't been fully tested," Pessah says. Especially early on in pregnancy, don't use products you know little about, such as cleansers with complicated ingredients.
Give up cigarettes Mothers who smoke regularly during early pregnancy have a 40 percent increased risk of bearing an autistic child, according to Swedish researchers.
Avoid exposure to illnesses Make sure your immunizations are up-to-date; rubella (German measles) is particularly important, as prenatal exposure has been linked to autism.
Monitor autoimmune problems If you have autoimmunity issues, Zimmerman says, "consult with your obstetrician to make sure your condition is under control."
Stay as stress-free as possible "Major life stressors are more common during pregnancies with children later diagnosed as autistic," says Zimmerman. "However, even with stress and other risk factors, most mothers will have healthy pregnancies and their children will not develop autism."
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