After a short observation period, the child is able to take oral fluids without difficulty and even starts to eat a popsicle that his mom bought for him. Feeling reassured, you diagnose gastroenteritis and send him home with specific hydration and oral intake instructions, as well as instructions for symptom observation. He is to return the next day for follow-up.

Later that evening your patient presents to the ER with lethargy. He has increased respiratory secretions with mild wheezing, increased salivation and pinpoint pupils. His clothes have a garlicky odor. The emergency room physician recognizes that this presentation is consistent with a possible toxic ingestion and obtains additional history from the boy's family.

The next page will show you the contents of an appropriate environmental history.