Forensic police have warned of the danger of mixing sulphuric acid and caustic soda to clean a clogged pipe, after three people died in a small toilet at a family home in Chon Buri.
Pol Lt Gen Trairong Phiwpan, commissioner of the Police Forensic Science Office, issued the warning on Tuesday following the death of a policewoman and her two daughters at their house in Muang district of Chon Buri province on Monday.
He said the family had used an unlicensed sulphuric acid product to clear a clogged pipe in their toilet. If mixed with caustic soda, the acid reaction could produce a mixture of deadly fumes known as sewer gas.
The toilet was small - 1.20 metres wide, 2.50m long and 2.05m high - with only one hole for ventilation. As the door opened inwards, anyone trying to help a person inside the toilet must close the door, trapping the air inside.
On Monday police found Pol Capt Ananya Busayakul, 60, and her daughters Jitpisut, 34, and Pannika, 25, unconscious in the toilet. Their mouths were full of saliva and their fingertips and lips were dark green. One of them was already dead and the two others were later pronounced dead at Chon Buri Hospital.
Pol Col Wiphawadee Kasemworaphum, of the Police Forensic Science Office, said exposure to sewer gas in a concentration greater than 500 parts per million could cause suffocation from lack of oxygen, and death.
Forensic police were still investigating the exact cause of the triple-death in Chon Buri, she said.