Consumers have filed class action lawsuits in Florida and Massachusetts, claiming two soft drink makers produce products that, under the right conditions, can contain benzene, a carcinogen. The suits were filed against Polar Beverages and Zone Brands.

The plaintiffs concede the drinks do not contain benzene unless they are subjected to heat and light. Under those conditions, vitamin C interacts with other preservatives to create benzene.

Last month, a group of public health advocates appealed to public school officials to remove certain soft drinks from school vending machines because of the benzene problem.

The industry and the Food and Drug Administration have tested the products in question, but have not released the result. The FDA, a public agency supported by taxpayer funds, said it plans to release the test results to the public eventually.

The lawsuits ask that the companies be stopped from selling beverages that have a tendency to form benzene. It also asks for unspecified damages, in the amount of profits the companies have realized in selling the products.

The American Beverage Association says removing vitamin C from the beverages would prevent them from forming benzene.

The benzene is formed by a reaction of ascorbic acid (vitamin C) and sodium or potassium benzoate (which are used as preservatives) -- especially in the presence of light or heat.

Soft drinks that contain ascorbic acid and sodium or potassium benzoate include Diet Pepsi Wild Cherry, Fanta Orange, Hawaiian Punch, Mug Root Beer, Pepsi Vanilla, Sierra Mist, Sunkist and Tropicana Lemonade, among others.