The only limit on that duty is the principle of undue hardship. The Supreme Court of Canada in 1992 made clear that the mere fact of inconvenience to others would not limit the duty to accommodate. There would have to be a significant interference with the rights of others. Similarly, the equality guarantees in the Canadian Charter of Rights and Freedoms, which clearly applies to school boards, prohibit discrimination on the basis of disability. The point, in short, is that the law requires people to be inconvenienced, and the state to spend some money, to protect the rights of disadvantaged members of our community.
All Canadian children have a right to a safe education in the public school system.
Children with anaphylaxis deserve no less. As a parent, however, I believe that this should not have to be fought out in the courts or before human-rights tribunals. This is an issue about community and social responsibility. Schools are public institutions to which we entrust our children on the assumption that they will be educated and kept safe. Schools are also, outside of the family, often the first community to which our children belong.