Three major soft drink manufacturers have agreed to stop selling sugary soft drinks in schools and instead offer low-calorie or nutritious beverages.

The agreement announced yesterday comes as the beverage industry is being blamed for contributing to the rise in childhood obesity and diabetes and as some schools already were removing pop from their buildings to promote healthier choices.

The Alliance for a Healthier Generation. a joint initiative of the William J. Clinton Foundation and the American Heart Association, negotiated the plan with Cadbury Schweppes, Coca-Cola and PepsiCo as well as the American Beverage Association, a trade group.

Ira Magaziner, chairman of the program board of the Clinton Foundation, said not counting milk, the agreement covers more than 90 percent of the beverage industry.

"We think it's going to be a dramatic change," said Mr. Magaziner, adding that if an 8-year-old consumes 45 fewer calories each day, he will weigh 20 pounds less by high school graduation.

Robert Eckel, president of the American Heart Association said, "We think it will make an important difference. How much difference it is going to make alone is unclear. There clearly is a lot more to childhood obesity than beverages in schools."

The beverage agreement was enough to get one of the industry's critics, the Center for Science in the Public Interest, an advocacy group that calls soft drinks "liquid candy," to drop its threat of a lawsuit.

Sugary pop sales in schools -- typically in vending machines in secondary schools -- won't stop immediately.

The agreement calls for the beverage industry to spread the standards to 75 percent of schools nationwide by the start of the 2008-09 school year, with full compliance by 2009-10, as long as existing contracts can be amended.

Many school districts have contracts that pay them for using one manufacturers' products exclusively.

For example, a recent contract with Pepsi resulted in $60,000 for Mars Area School District, plus commissions on sales; the pop vending machines in district buildings operate on timers that lock them during school hours.

In Pennsylvania, the guidelines for beverages, which are recommendations but not requirements, are more restrictive than those in yesterday's agreement.

Beginning in July, the state will recommend having no vending machines in kindergarten through fifth grades and after that offering only unflavored water, 100 percent fruit juice in 12-ounce containers and 75 percent of milk selections with 1 percent or lower fat in up to 16-ounce containers.

By the following year, juice sizes would be reduced to 6 ounces and milk to 8 ounces.

In setting the industry guidelines, Mr. Magaziner said, "we used a standard of low calories. We said if there were going to be drinks a bit higher in calories, they had to have nutritional value."

Under the guidelines:

Beverages sold in schools could have no more than 100 calories per container, except for some kinds of milk as well as juices that meet certain nutritional standards, such as unsweetened orange juice.

Milk should be limited to skim and 1 percent.

In addition to water, elementary and middle schools can offer unsweetened juice and low-fat milk, but portions should be limited to 8 ounces in elementary and 10 ounces in middle school.

In addition to juice and low-fat milk, high schools could offer no-calorie and low-calorie drinks (bottled water, diet and unsweetened teas, diet sodas, fitness water, low-calorie sports drinks, flavored water and seltzers), light juices and sports drinks. Except for water, containers are limited to 12 ounces.

There are exceptions for certain events, such as football games and others attended by parents and students.

But this would apply to vending machines that some high schools turn on for after-school activities.

Nationwide, all schools that participate in the federal school lunch program must have a wellness policy, including addressing nutrition, in place on July 1.

Currently, federal regulations consider all carbonated beverages -- unless specifically proven otherwise -- to be foods with minimal nutritional value.

They cannot be sold during school meal times in food service areas.

Some schools which sell carbonated beverages comply with that by placing the vending machines outside the food service areas.

About a year ago, the Pittsburgh public school board passed a policy eliminating all carbonated beverages and chips at all district facilities, including Cupples Stadium. Until then, the products had been available in some vending machines throughout the day.

Now, said Danny Seymour, city school district food service director, bottled water has become a popular vending machine choice.

Policies vary across districts and may change as wellness policies are adopted.

North Hills High School, which is considering its wellness policy, currently sells pop as well as juice, water and three flavors of milk during the school day, said spokeswoman Tina Vojtko.

In Fox Chapel Area School District, spokeswoman Bonnie Berzonski said that sugary soft drinks eventually will be gone.

Richard Marsh, director of transportation and food service in Woodland Hills School District, said vending machines available to students during school hours contain no carbonated beverages. The only such machines are in the athletic complex.

"I don't feel it should be served during the school day at all," he said. "It's a bad nutritional value."

He said the district is moving from juice products that are at least 60 percent juice to those that are 100 percent juice.

Pat DeGore, director of food services in Norwin School District where milk, water and 100 percent juice are sold in vending machines in the cafeteria, said she hopes the healthy choices spread beyond schools.

"If I was a parent, mother or father, I would think about doing the same thing at home," she said.

The American Heart Association says its next goal is to reach a similar agreement with snack food makers.

Mr. Magaziner said the soft drink agreement was possible in part because the beverage manufacturers sell a diverse array of products, such as water, flavored water, juices and sports drinks. He said snack food makers, too, have choices that are healthier, such as chips that are baked rather than fried and items without trans fats.