Sales of full-calorie carbonated soft drinks (CSDs) sold in schools were down sharply between 2002 and 2004, while sales of other beverages increased, according to a new study.

The study, conducted by Dr. Robert Wescott, an independent economist, and released by http://www.ameribev.org, found that high school students were buying one 12oz can of soda on average per week during school hours.

"This study confirms what previous studies have shown: consumption of full-calorie CSDs purchased from school vending machines during normal school hours is a very minor source of calories in the diets of American youth and is not contributing measurably to obesity rates in the school-age population," said Susan Neely, ABA president and CEO, in a statement.

The results of the study are on par with industry trends showing an up-tick in sales of water and sports drinks and falloff of carbonated soft drinks.

During 2002 to 2004, the sales of full-calorie CSDs in schools dropped by 24%, while purchases of waters jumped by 23%, diet soft drinks by 22%, 15% for 100% juices and 70% for sports drinks, according to the study.

ABA released the study just as Coca-Cola, PepsiCo and other companies making soft drinks and selling them in schools are about to get slapped with a lawsuit filed by parents claiming the companies use caffeine in their beverages to get kids hooked on products that are dangerous because of their empty calories, among other charges.

Heading the effort are a number of attorneys who made their mark by successfully fighting tobacco companies with class action lawsuits. The suit is expected to be filed this month in Massachusetts.

The study used data from shipments obtained from 14 of the largest bottlers in the country, including Coca-Cola Enterprises Inc., Coke Consolidated, Pepsi Americas, Pepsi Bottling Group and Dr Pepper/Seven Up Bottling Group, as well as U.S. Census estimates of the national student population, ABA said.

Last summer, the ABA released voluntary guidelines to restrict the sale of soda in school vending machines. The ABA is set to launch an ad campaign in January that touts the beverage industry's concern about childhood obesity and how it is working on the problem.

The sale of soda in schools has come under increasing attack as one source of the obesity problem in this country. State legislatures and school boards have taken their own action to limit or ban the sale of soft drinks in school vending machines. California recently signed a bill banning the beverages in all its public schools, and this month, the Miami-Dade County public school board passed a similar bill.