This school lunch staple can be fatal for allergic children. (CBC)

When Terri Mauro posed the question, "What's so bad about peanut-butter bans?" on her website, she never expected the volume of cold and angry comments she received.

"The responses are still coming in a year later," said Mauro, who considers blanket bans on peanut butter an acceptable measure to protect children with life-threatening allergies.

Peanut bans in schools often lead to a flurry of angry phone calls and letters to local newspapers. Some communities even circulate petitions asking school officials to change their minds.

"People are a little unhinged about this," said Mauro, who edits a website for parents with special needs children.

More schools than ever are banning peanuts and peanut products as the number of kids diagnosed with the potentially life-threatening allergy has climbed dramatically in recent years. While doctors try to figure out the reasons for the rise, the situation pits parents against each other and puts school districts in the middle.

Lisa Searles was shocked at how angry parents got in April 2007, when she asked the board of education in Seymour, Conn., to ban peanut butter at her son's elementary school.

"People were extremely rude," she said. "They just thought it was a ridiculous request."

People left nasty posts on local message boards. One online writer suggested ending the issue by putting all the allergic children in a room together and feeding them peanuts, Searles said.

When officials at Rock Creek Elementary School in O'Fallon, Mo., banned peanut butter, Jennifer Kaiser took a more reasoned approach.

She attended a meeting and suggested the school find a compromise that would allow students to continue to pack peanut butter sandwiches and keep students with allergies safe.

"I thought there were better ways to handle it," the mother of two said. "As a community, our job is to teach our kids to live in the world."

Banning peanuts, she said, "is not teaching children how to grow up in the real world."

Parents opposed to the bans have an unlikely ally — an advocacy group for people with food allergies. The Food Allergy & Anaphylaxis Network in Fairfax, Va., recommends schools treat each student's allergy individually and adopt plans that emphasize continued vigilance rather than food bans.

"What we want is everyone always thinking there could be a possibility [of an allergic reaction], and be on guard for it," said the group's founder, Anne Munoz-Furlong.

400,000 U.S. kids allergic to peanuts

Regardless of the group's position, a growing number of schools have implemented bans. A recent survey of 1,174 U.S. districts by the Virginia-based School Nutrition Association found that 18 per cent of schools had peanut bans in 2007, a 50 per cent increase from two years earlier.

The increase in peanut bans corresponds to an increase in students diagnosed with peanut allergies. Between 1997 and 2002, the prevalence of peanut allergies in children under age five doubled, said Dr. Hugh A. Sampson, president of the American Academy of Allergy, Asthma & Immunology.

Today, there are 400,000 school-age children in the U.S. with peanut allergies.

In Canada, Anaphylaxis Canada estimates that one to two per cent of Canadians live with the risk of an anaphylactic reaction.

Peanuts and some other foods can cause the body to go into anaphylactic shock, a life-threatening condition where a person's blood pressure drops and his or her airways narrow. The condition can normally be relieved with a dose of adrenaline, also called epinephrine. Children and adults with severe food allergies carry shots of epinephrine.

After the Seymour Board of Education shot down her request for a peanut ban, Searles began to focus on other ways to keep seven-year-old Matthew safe at school, including trying to teach him to inject himself with adrenaline.

"I feel pretty confident," she said. "He's a smart kid."

The main worry for Searles, like many parents, is that her son would have a reaction without actually eating a peanut product. It's possible for Matthew to have a reaction from touching a table or utensil with peanut butter on it and then putting his hand into his mouth or rubbing his eyes, Searles said.

It's a legitimate concern, Sampson said. That's why he supports peanut bans in preschools and kindergarten classes, where students are prone to putting their hands in their mouths. As children grow older, he favours carefully cleaned peanut-free tables in the cafeteria, hand washing and other common-sense precautions.

"As children get older and more responsible, you don't have to have anything like a ban," he said. "You want them to learn to deal with the situation."

Few children are at risk just by being in the same room with peanut butter, he said.

No one has ever asked Janet Mitchell to ban peanuts from any of the schools in the Glynn County School District in Brunswick, Ga. It's a move the district's culinary services co-ordinator would oppose even though her own son is allergic to peanuts.

"We don't ban peanut butter because we feel it is a staple among young children," Mitchell said.