There is surprisingly sparse literature to help determine how much a child swallowed as part of a toxic ingestion. Most texts quote the work of Jones & Work in Am J Dis Child 1961, who studied 10 children aged 1.25-3.5 years and found the average mL/swallow to be 4.6mL, or 0.33 mL/kg. To remember more easily, round up to 5mL, or one teaspoon, per swallow of a small child. Another study by Watson et al in Am J Emerg Med 1983, found that container opening size made a difference. Older children swallow 10-15mL per swallow, while teens and adults swallow 15-30mL. Some liquid substances highly toxic to toddlers in a teaspoon or less include: camphor (vaporub, tiger balm), methyl salicylate (oil of wintergreen), liquid nicotine (vaping solution), and selenium dioxide (gun bluing solution).