EPA probes leak at Sydney chemical plant

The NSW environmental regulator is investigating the leak of a potentially lethal gas at a chemical plant in southeast Sydney.

The Environment Protection Agency (EPA) said the ethylene oxide leak occurred at the Huntsman Surfactants Plant, at the Botany Industrial Park, about 6pm on Sunday.

In a statement, the EPA said initial investigations indicated "the potential for offsite impacts from the gas was minimal".

The agency's Chief Environmental Regulator, Mark Gifford, said workers at the site were alerted by a purpose built alarm.

"Huntsman staff investigated the leak and correctly initiated the site emergency procedures. Fire and Rescue NSW attended the site and contacted the EPA," Mr Gifford said on Monday.

"The cause of the leak was quickly identified as a seal on one of the pumps at Huntsman's Ethylene Oxide plant and the pump was switched off and isolated."

He said the incident was resolved by 7.30 pm Sunday.

"Given the nature of the gas we will be undertaking additional investigations as a precautionary measure," Mr Gifford added.

According to the federal government's National Pollutant Inventory, exposure to ethylene oxide can cause dizziness, nausea, difficulty in breathing, depression of the central nervous system, burns, eye damage, convulsions and death.

It is primarily used in the manufacture of other chemicals.