Actress Jenny McCarthy, whose son Evan was diagnosed with autism when he was two, has become one of the most vocal, and controversial, autism activists in the country.
Despite the fact that many of her views have been dismissed by the mainstream medical community, McCarthy powers on, telling the tale of how her son has "recovered" from the symptoms of autism within a year with the aide of bio-medical pediatrician Dr. Jerry Kartzinel.
McCarthy and Kartzinel have paired up to pen a new book called "Healing and Preventing Autism: A Complete Guide."
This book focuses on the possible causes of autism, not treatment, which the actress wrote about in her previous book, "Mother Warriors."
McCarthy and Kartzinel, who also has an autistic son, believe that toxins in the environment play a major role in the development of autism.
"Less than one percent ... can be attributed to genetic causes, so if you're not born with it, it must be something in our environment," Kartzinel said on "Good Morning America."
They cite mercury, aluminum and volatile organic compounds (VOCs) found in household items such as carpet, paint and baby cribs, as well as pesticides in homes and outside.
McCarthy and Kartzinel also say a family history of autoimmune diseases or mental health problems such as depression or bipolar disorder could signal a susceptibility to autism -- another theory the medical community dismisses.
McCarthy said she has a history of autoimmune diseases in her family.
"The things that we look at to try to detect autism as early as possible have to do with the clinical science and symptoms. And even though a family history is important to gather, that's not really crucial in looking at and making a diagnosis of autism," said Dr. Stefani Hines, an autism researcher at Beaumont Children's Hospital in Royal Oaks, Mich.
One in 150 children have been diagnosed with an autism-spectrum disorder, according to the Centers for Disease Control.
Autism information and research have increased enormously over the past few years. The National Institute of Health recently announced $60 million would be dedicated to autism research, the largest amount of money to date.
Thursday is Autism Awareness Day, but for the millions of families struggling with autism, every day is a search for new information and solutions. With so much still unknown about the disorder, parents like McCarthy have gone on their own journeys to find answers.
McCarthy, who calls her son Evan "a total ham," said many parents approach her and say he is an inspiration to them. "They say, 'Oh my gosh, please tell me how,'" McCarthy said on "GMA."
She speaks for many parents, who like her, feel frustrated and helpless in the face of autism. "It makes me mad that they can't accept it's an epidemic. The CDC won't say it's an epidemic," McCarthy said.
Doctors and researchers say they feel for these parents but worry about those who latch on to unproven theories of how autism is caused or can be treated.
"Because we do not know the root cause of autism, we can not say how it can be prevented," Dr. William Schaffner of the Vanderbilt School of Medicine said. "We have ideas but those ideas are not supported by firm scientific evidence. I do agree that we need to commit ourselves as a society to doing more research into the cause of autism."