The Physicians Committee for Responsible Medicine, which promotes alternatives to animal use, claims that the school lunch program discriminates against minority students.
The USDA does not reimburse school districts for soy milk unless students provide a doctor's note demonstrating a medical need. The federally assisted lunch program requires that cow's milk be offered.
"When the National School Lunch Program was established in the 1940s, lactose intolerance was thought to be rare, but it is now known to be the rule among children of color," said Mindy Kursban, the committee's chief legal counsel.
Agency spokeswoman Jean Daniel said only Congress can change the rules.
She said child nutrition programs must be renewed by Congress next year, and that the USDA will be proposing changes based in part on public comments.
Kursban said that the USDA can make changes on its own.
The physicians' group claims that USDA's policy violates the National School Lunch Act, which requires the program to accommodate all children's dietary needs.
In addition to children who are lactose intolerant, the policy is unfair to students who don't consume dairy products for religious or ethical reasons, the committee argues.
Jean Ragalie, a dietitian and spokeswoman for the National Dairy Council, said only dairy products can provide the kind of nutritional benefits that children need.
"The changes they are proposing would dilute what the nutrition program is supposed to do — which is to provide the best nutrition package for the most children," Ragalie said.
The physicians' group said soy milk has fewer calories, less fat and just as much calcium as whole cow's milk. In addition, studies show that soy may help prevent cancer, osteoporosis and heart disease, the group said.
Brenda Z. Greene, director of school health programs for the National School Boards Association, said she supported the group's petition.
"Our goal is to make sure that as many children as possible have access to the school lunch program," she said. "Schools need to be able to adapt, and regulations need to adapt to the changing needs."
Schools have not been the only front on the soy milk battle. In 2000, a federal judge ordered the Lewisburg, Pa., penitentiary to provide soy milk to a vegan prisoner.
By Frederic J. Frommer