This is the time of year when classroom responsibilities overwhelm my journalistic passions, and my writing tends to be more reflection than exposition. And let me tell you, nothing spurs reflexive contemplation like finding yourself in polar opposition to someone whose life work has profoundly influenced your own.

In my case, that someone is Dr. Philip J. Landrigan from the Mount Sinai School of Medicine, whose research at the Children's Environmental Health Center there first caught my attention in the late 1990s when I was a senior environmental writer at the Indiana Department of Environmental Management (IDEM). When I began exploring the links between toxic pollution and autism 17 months ago, a 2006 study Landrigan co-wrote titled "Developmental neurotoxicity of industrial chemicals" was the first link that Google produced when I searched for "autism and environment."

Nearly a year and a half later, I am persuaded that mercury and/or other chemicals in vaccines are among the industrial chemicals that caused the autism epidemic of the past two decades. I do not believe that vaccines caused the epidemic, but my work has convinced me that neurotoxins in them contributed to it. And in some children, they did cause autism. The question for them isn't whether, it's how, and it demands an answer.