Final answer:
The child's symptoms are consistent with insecticide poisoning, likely from organophosphates or carbamates, which can be found on farms and lead to poisoning through ingestion of contaminated food or water.
Step-by-step explanation:
The symptoms described in the question, including severe abdominal cramps, vomiting, diarrhea, excessive lacrimation, and salivation with marked pupillary constriction, suggest that the 5-year-old child was likely exposed to insecticides. These symptoms are characteristic of cholinesterase inhibition, which is common with certain types of insecticides such as organophosphates or carbamates. These substances can be found on farms and can be toxic if ingested or come into contact with skin. They may be present in pesticides used for protecting farm animals or crops and can cause poisoning through ingestion of contaminated food or water.