About half of public and private elementary students could buy unhealthy snacks at school during the 2009-2010 school year from stores, vending machines and snack bars according to survey results released Monday. The survey was part of a report published in Archives of Pediatrics & Adolescent Medicine.

"Given increasing attention in recent years to the problem of childhood obesity, we would have hoped to see decreases in the availability of junk food in schools over time," said study author Lindsey Turner, health psychologist at the Institute for Health Research and Policy at the University of Illinois at Chicago.

"Our research demonstrates the continued need for changes to make schools healthier," she added.

The data represents no change in the ability to get the snacks like cookies, candy and chips throughout the four years of the study; the study began in the 2006-2007 school year.

Also that school year, wellness policy mandates went into effect as part of the Child Nutrition and WIC (Women, Infants and Children) Reauthorization Act two years earlier. Each school with a lunch program had to adopt and practice policy that addressed physical activity along with healthy eating.

The survey comes as childhood obesity rates remain high. 2007-2008 statistics show the rate hit 17% for children aged 2 to 19. The rates have nearly tripled since 1980.

In this study, researchers examined data from almost 4,000 surveys of elementary schools nationwide. About two-thirds were from public schools; roughly a third were from private elementary schools.

A principal or a food service employee responded to the surveys on behalf of the students. The researchers weighted the data to provide representation to the students.

Surveys from the southern region showed high rates of access to sweet and salty snacks, especially in comparison to the midwest and west regions.

"I think that's a concern given that the obesity rates are much higher in the South than in other parts of the country," Turner said.

However, many students in this region also had access to buying healthy food, including salads, fruits and vegetables.

The study authors call the results "intriguing" and say much work needs to be done to rid the schools of the unhealthy products.

"To keep kids healthy, it's really important [for the schools] to follow national recommendations," she said. "What our results show is that many schools are not doing that."

The Institute of Medicine in 2007 issued a report stating that if they are available, foods available to students should consist of nutritious fruits, vegetables, whole grains, and nonfat or low-fat milk and dairy products.

In December, 2010 the Healthy Hunger Free Kids Act was signed into law, which gave the USDA the power to set the standards for foods and beverages sold in school buildings.

As part of the act, the USDA is expected to release the standards for competitive foods this year.

"Our hope based on these data is that the guidelines that are developed will be comprehensive and will consider all venues," Turner said. "Also that those regulations will be strong and that they will be specific- that they will address things like fat content, energy content and portion size."

"There's still a really huge opportunity here to change what's going on in schools," she added.

To do that "solution-oriented" research is needed, says study editorial author, Dr. Thomas Robinson, director of the center for healthy weight at Lucile Packard Children's Hospital.

Robinson says as local, state and federal policies develop, researchers need to study what's happening.

"So that at the end of 5-10 years, we can say what worked, what didn't work, what could have been improved and how to do it," he said.

"These are young ages when kids are establishing their eating habits and their food preferences, so it's important that they are exposed to fewer of the competitive foods and more of wholesome foods from their school lunches," he added.

The Robert Wood Johnson Foundation funded the study.