A new U.S. Environmental Protection Agency (EPA) study lends support to the argument that some children are susceptible to autism as a consequence of their exposures to environmental toxins.
At least part of the dramatic increase in autism diagnoses the past two decades cannot be explained by improving and expanding diagnostics, Michael E. McDonald and John F. Paul from EPA's National Health and Environmental Effects Research Laboratory conclude in a seven-page study in the March 15 issue of the journal Environmental Science & Technology.
"From a precautionary standpoint, it seems prudent to assume that at least some portion of this increase in incidence is real and results from environmental factors interacting with susceptible populations," they wrote in the paper titled "Timing of Increased Autistic Disorder Cumulative Incidence."
And based on their analysis of studies of autism incidence worldwide, the pair pinpoint the year when the autism epidemic began.
"We used data sets from Denmark, California, Japan, and a worldwide composite of studies," they wrote. "In the Danish, California, and worldwide data sets, we found that an increase in AD (autism disorder) cumulative incidence began about 1988-1989."
"It seems prudent to assume that at least some portion of this increase in incidence is real and results from environmental factors interacting with susceptible populations." - EPA study
To reduce the effects of the "broadening and changing of diagnostic criteria," McDonald and Paul focused specifically on autistic disorder, which is one of three on what is known as the Autism Spectrum Disorder. The other two are Asperger's disorder and pervasive developmental disorder-not otherwise specified (PDD-NOS).
Autistic disorder, they said, is one of the most severe and recognizable forms of autism and "has had relatively consistent diagnostic criteria since about 1978." While those criteria have not been consistently applied in practice since then, they have been fairly consistent since about 1994 in Denmark and the United States.
As autism becomes more prevalent in the population, the societal and economic costs associated with it rise accordingly, and they are substantial, McDonald and Paul wrote. They cite studies that put the "lifetime care costs" for autistic individuals at between $3.2 million and $4.7 million, which means the increase in cumulative autistic disorder incidence in California from 1988 to 1997 was between $2.7 billion and $4 billion.
"These costs likely have continued to grow in recent years, as autism in California has shown no signs of plateauing," they said.
Steven Higgs is author of the "Autism and the Indiana Environment Blog" and editor of The Bloomington Alternative. He can be reached at editor@BloomingtonAlternative.com.