Just a thought: just because none of them have allergies today doesn't mean they won't have one tomorrow. Allergies can show up at any time in one's life, after any number of previous exposures. There have been people who have been stung by bees (etc) a hundred times without problems, then it happens for the 101st time and they have a severe reaction.

If you have a doctor friend, you might ask what the best thing to do in that case would be.

Sue