WASHINGTON (Reuters) — Autism is more common in the United States than anyone had estimated, affecting about one in every 150 children, the US Centers for Disease Control and Prevention reported recently.CDC estimated that about 560,000 people up to age 21 in the United States have autism.

“Autism is more common than we believed and is an urgent public health concern,” said Catherine Rice of the CDC’s birth defects division, who helped lead the study.

Two surveys by the agency encompassed 14 states and represented the largest and most comprehensive studies of how many children have autism. It showed a wide variation among the states, ranging from 4.5 per 1,000 children having an autism-related disorder in West Virginia to 9.9 per 1,000 in New Jersey.

“There’s been a lot of concern about what the prevalence of autism is in the United States and we haven’t really had the data systems to answer that completely,” Rice said. The surveys look at eight-year-olds, the first in six states and the second looks at eight-year-olds in 14 states. On average, they found that about one in 150 children born in 1992 and 1994, or 6.7 per thousand, have autism.

Rice said that for decades the common estimate of autism incidence was four to five per 10,000 children. More recent previous estimates had put the incidence at somewhere between one in 166 children and one in 175.

“Finally, we can end the debate on the prevalence of autism in our nation and focus on getting the services and supports the families need,” said Lee Grossman, chief executive officer of the Autism Society of America.

The reports are the first from the government-funded Autism and Developmental Disabilities Monitoring Network.

“We really do think that these data are important because they represent the most complete and accurate picture of autism spectrum disorders in the United States to date,” Rice said in a telephone interview.

Types of “autism spectrum disorder” range from autism, which can severely disable a child by interfering with speech and behaviour, to Asperger’s syndrome, a much milder behavioural problem.

The surveys did not examine what causes autism, but Rice said it appears to stem from “complex genetic and environmental interactions.”

The researchers hope to eventually use the surveys to help figure out what causes autism. They also want to be able to verify suspicions autism may be growing more common in the United States.

“We hope these findings will build awareness,” Rice said. Activists have said for years that autism was becoming more common. Some experts discount claims of skyrocketing rates, saying the definition of autism has changed over the years, but reliable survey figures have been scarce. “A lot of professionals were asking what had changed, had we seen more children than in the past?” said Dr. Marshalyn Yeargin-Allsopp.