Toxic chemical ready for use in Bay

A helicopter sprays dispersant after the Rena oil spill.

A toxic chemical that Australia's maritime authority has stopped using which has been linked to deaths and serious illness in America is stored in Tauranga ready for use in a major oil spill.

Three-thousand litres of Corexit 9527, one version of the chemical destroyed in Australia after failing to meet toxicity and effectiveness standards, is being stored in drums at the Port of Tauranga.

Maritime New Zealand faced community backlash when it used a combined 3190 litres of Corexit 9500 and Corexit 9527 during the Rena oil spill response - a time when a leading coastal scientist admits little was known about heavy fuel oil spills in New Zealand conditions.

The dispersants were sprayed on deep water about 20km off the coast of Tauranga in the days following the October 2011 grounding.

The controversial chemicals remain two of five approved for use in New Zealand. Research showing the toxicity of Corexit increases 52-fold when combined with oil was exposed during a 60 Minutes programme, which aired this week.

Both Corexit dispersants were used during the clean-up of the BP oil spill in the Gulf of Mexico in April 2010 and 60 Minutes found tens of thousands of Americans had fallen ill and some died after swimming in waters hundreds of kilometres from the spill.

Maritime NZ had not received any scientific or medical data that confirmed the statements made in the 60 Minutes programme but regularly reviewed new information and studies on dispersant use, spokeswoman Sophie Hazelhurst said. The organisation has about 30,000 litres of Corexit 9500 stored in Auckland and 42,600 litres of Corexit 9527 stored throughout the country. It pointed out that 7 million litres of the chemicals were used in the American gulf disaster.

The Australian Maritime Safety Authority's (AMSA) testing regime for dispersants was changed in 2011 and Corexit products were no longer accepted on to its National Plan for Maritime Environmental Emergencies product list.

"AMSA has disposed of all stocks of Corexit 9527 and is disposing of all Corexit 9500A held within the national plan stockpiles. The disposal programme has been ongoing since 2011,'' a spokesperson said.

It has no intention of using the 9500A product until such time it meets Australian standards. The Australian authority also says it can only comment on its stockpiles of dispersant. There are other agencies that can be involved in an oil spill response.

Tauranga-based University of Waikato Professor Chris Battershill told the Bay of Plenty Times the Rena disaster had highlighted the fact little was known about heavy fuel oil in New Zealand waters.

"There was a clear need to explore that further,'' he said.

He is now leading a Ministry for the Environment-funded study into eco-toxicity, which will include research on the mixture of Corexit and oil in New Zealand sea temperatures. The study is due to be completed in a year and a half.

"We're leaving nothing to chance,'' Professor Battershill said.

Maritime NZ had received no reports of any cases of ill-health linked to either the oil from Rena or the Corexit dispersants.