These days, kids, parents and schools are grappling with a potentially deadly problem: peanut allergies.

"Once in kindergarten we were having our recess snack," says Tim Fairs. "A kid in my class said do you want a piece? And I said 'no thanks,' and he said, 'come on, it's really good.' So then I just took a little bite."

Suddenly, Tim's bottom lip began to swell up - he developed hives and began having trouble breathing. He says it felt like he had "fishhooks" on his lips.

Tim was suffering from anaphylaxis - a potentially deadly allergic reaction. Half a million Canadians have anaphylaxis - many of them are children, like Tim, who are allergic to peanuts.

Dr. Peter Vadas

Dr. Peter Vadas explains what happens during a reaction: "The airways clamp down and they fill up with mucous. It becomes very difficult to breathe and they will also experience a fall in blood pressure to the point where perhaps there's not enough oxygen being delivered to the tissues.

"They may have problems with heart rhythm and the blood vessels in the heart might constrict and lead to inadequate oxygen delivery to the heart and heart attack."

A reaction to peanuts can kill - very quickly.

"I've never assumed that school's a safe environment," says Tim's mother Claire Fairs.

"I've never told the kids that it's a safe place. They've always had to be on their guard. Tim... he was invited to have a bite of his friend's cookie. And he broke the rule.

Tim's mom, Claire Fairs

"He had never seen peanut butter chips before. He didn't know the difference visually. And he took a bite. He broke the rule. He was wrong. He knew better."

Scott knows the rules too because just like his younger brother, Tim, he's allergic to the most potent of the known food allergens.

"Well, I mostly have to stay away from peanuts as best as I can," he says, "basically I don't get anything that has peanuts 'cause I'm not sure of the ingredients."

The reality of a potential death in the lunchroom is forcing schools to take a hard look at that staple of childhood, the peanut butter sandwich.

For administrators, peanuts are as deadly as asbestos - a potential hazard in the classroom that they are being forced to deal with. But few schools are willing to actually ban it.

Schools are taking a hard look at the staple of school lunches: the peanut butter sandwich

"Well, you can't separate medicine from real life," concedes Vadas.

Three years ago he and a team of Canadian specialists in life-threatening allergies crafted a document to protect children at risk.

"We wanted to introduce a consistent approach to children who have anaphylactic sensitivity," he says.

The report recommends that in nursery, day care, and early grades, "no peanuts, peanut butter or peanut-containing foods should be allowed."

The document is directed at schools across Canada. But, even the doctors do not use the three-letter word.

Canadian specialists in life-threatening allergies crafted a document to protect children at risk

"Why is 'ban' a problem?" asks Vadas rhetorically. "As physicians, as allergists, we're asked to make medical recommendations and we make the recommendation that's purely based on common sense.

"Everybody will say it's sensible if somebody has a severe allergy to try to minimize their exposure to that allergen by whatever means they can. That's sensible.

"But then once one has made that medical recommendation, then it moves out of the medical arena into the political arena because then the question is how does one implement that medical recommendation. And then it becomes a hot potato politically."

Marilyn Allen's daughter, Robin died after using a knife that had residual traces of peanut butter:

Robin Allen died after using a knife that had residual traces of peanut butter

"She just proceeded to get dressed and collapsed on the floor and that was it. And she died in our arms, either there or enroute to the hospital. They could not revive her. It was that sudden and it was that unforgiving," Allen recalls.

But even that tragedy hasn't convinced her that a ban could protect children.

"Once you ban one thing, are you going to ban walnuts and cashews and almonds and shellfish and fish and soy and sesame seed and sulphites?" she asks. "My goodness, could we ban everything?"

Marilyn Allen

On top of that, how do you enforce a ban? "Can you put police on the door to check the lunches and the pockets of every child coming in? It doesn't work," Allen says.

"The other thing is that when you look at a ban, you're asking... you're asking for a reduction in vigilance. Personally, I'd rather see everyone striving for safety. "

Instead of bans, Allen believes in educating people about the dangers of peanuts. As vice-president of the Anaphylaxis Foundation of Canada, she goes school to school, training teachers to use the Epi-Pen -- the emergency needle that injects a lifesaving shot of adrenaline.