Daily Green: Wanted: Chemicals that cause autism,

Dr. Philip Landrigan is rounding up a posse in search of one of America’s most elusive evildoers: The cause of autism, which afflicts as many as 1 in 80 American children. Though the soft-spoken, gentlemanly pediatrician doesn’t cut the figure of a sheriff, he used Wild West language to describe the hunt he and his fellow scientists have embarked on.

“We want a ‘Most Wanted Chemicals’ list. We want a ‘Dirty Dozen,'” he told the audience Wednesday at Exploring the Causes of Autism and Learning Disabilities, a conference organized by the Mount Sinai Children’s Environmental Health Center, where Landrigan is dean of global health and chairman of the Department of Preventative Medicine. Landrigan received a 2010 Heart of Green Award from The Daily Green.

Diagnosis of Autism Spectrum Disorder, a developmental disability with a range of effects on intelligence and sociability, increased 57% between 2002 and 2006, according to Colleen Boyle, acting director of the National Center on Birth Defects and Developmental Disabilities. And while the center’s last set of statistics drew alarming headlines about 1 in 110 children now being diagnosed with autism, she said that’s an average; the rate could be as high as 1 in 80 (or as low as 1 in 240).

As recently as 2005, the increase in diagnoses was attributed to just that: An increase in diagnoses. Doctors and parents, it was thought, were more aware of the symptoms of the disease, the definition of the Autism Spectrum Disorder grew more expansive, government services were more widely available and the stigma associated with the illness was disappearing – all of which contributed to an increase in diagnosis that had little or no basis in actual increased illness.

But the rates of disease are actually increasing, not just the diagnosis or treatment of disease, according to research by Irva Hertz-Picciotto and colleagues at the Center for Children’s Environmental Health at the University of California-Davis.

And that’s just one reason genetics alone can’t explain autism. Genetics clearly plays a role – if one identical twin has autism, 70% of his siblings do, too. But even scientists sometimes mistake a genetic basis of disease for an explanation of its causes: the environment is still the trigger for the expression of genes. (And scientists are only now exploring the epigenetics of disease – not just the genes themselves, in other words, but their place in the DNA sequence.)

The question is: What are those environmental triggers that cause autism? And when in the early development of a fetus does the trigger get pulled? The triggers may or may not be synthetic chemicals: Other aspects of the environment that may affect gene expression include nutrients in food, physical factors like heat or radiation, and exposure to medications, alcohol and drugs.

The trigger-happy culprits are on the lam. Landrigan and his colleagues are hunting them down.

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