JOHOR BARU, March 8 — The Johor Department of Environment (DoE) has identified the illegally dumped substance that emitted hazardous gas fumes in Sungai Kim Kim in Pasir Gudang to be from marine oil waste.

Johor DoE director Datuk Mohammad Ezzani Mat Salleh said the substance was an oil-based mixture that emits methane and benzene fumes.

"The oily substance is believed to be oil waste commonly used in marine engine compressors and is considered scheduled waste that needs to be disposed off properly under the law.

"Based on our investigations, we estimate that around 20 to 40 tonnes of the oil waste were illegally dumped into parts of the Sungai Kim Kim river,” Mohammad Ezzani told Malay Mail when contacted.

Yesterday, it was reported that the Johor DoE and the state’s Fire and Rescue Department’s Hazmat unit have taken water samples from Sungai Kim Kim after 31 people fell ill after inhaling the fumes.

The victims, aged between seven and 40, were students from SMK Pasir Putih and SK Pasir Putih, while the adults were canteen workers.

Among the victims was a male DoE investigator, in his 30s, who was warded after he was overcome by the fumes during an early probe into the incident.

Both methane and benzene fumes are considered hazardous as they are flammable.

Mohammad Ezzani said the department views the incident seriously and will go all out to identify, nab and prosecute the culprits responsible for the illegal dumping of the substance.

"A formal report has been submitted and based on eyewitness accounts the dumping was done from a tanker lorry during pre-dawn hours on Thursday.

He said the department is not ruling out the likelihood that the waste substance may have come from certain marine engineering or petrochemical factories in Johor.

On the cleaning-up efforts, Mohammad Ezzani said the bulk of the oily substance on the river’s surface have been disposed off.

However, he said it will take at least another two days for the team to clear all remaining residue within the affected 5km stretch of the river.

"We hope there is rain to help in diluting the polluted areas,” said Mohammad Ezzani, explaining further that in extreme cases carbon may be employed to neutralize the harmful substance.

Mohammad Ezzani added that the department is also coordinating efforts the state government’s health, environment and agriculture committee and also the Johor Fire and Rescue Department for the clean up work.

He said Singapore’s National Environment Agency (NEA) has contacted the department seeking updates on the situation due to fears of cross-border water pollution.

"At present we have managed to contain the situation,” he said.

Those with information on suspected illegal dumping of scheduled waste can contact the DoE enforcement unit at: 011-2754 4926. Alternately, they can also reach out to the DoE national hotline at: 1-800-88-2727.