A toddler from South Manchester is in a serious condition in hospital after drinking a product that contained caustic soda.
The child was strapped into his pushchair while out shopping with his mother in Moss Side when the incident took place.
He picked up a bottle containing the corrosive substance, took the top off the bottle and drank the liquid.
The incident occurred on Monday evening and police were called by staff at the Manchester Children's hospital after the toddler was admitted with burns to his throat and stomach.
Caustic soda is also known as sodium hydroxide and is used as a strong chemical base for items such as drain cleaner or paint stripper.
Supt Sarah Jones, from the Greater Manchester Police, said: "Caustic soda is a highly toxic chemical commonly found in drain and oven cleaners.
"If it is touched, inhaled or swallowed it can cause severe burns. This little boy took a drink from a bottle and is now seriously ill in hospital.
"I want to take this opportunity to remind people when storing products of this nature to make sure the lids of the bottles are on tightly, keep them in a cool place and out of reach from children, preferably in a locked cupboard."
A joint investigation is now underway by the police and Cheshire East Council Trading Standards in order to determine the circumstances surrounding the incident.
The toddler's condition is stable but serious, police said.