Rena chemicals detected in plant life

Resource consent hearings for the Rena continued in Tauranga yesterday. Photo / File

Antifouling chemical TBT (tributyltin) has been detected in the edible animal and plant life at Astrolabe Reef - but an expert says there is no risk to human health.

Peter Cressey, a senior scientist at the Institute of Environmental Science and Research, said TBT had been detected in some edible biota (animal and plant life) samples from the Astrolabe Reef.

"While highly conservative estimates of dietary exposure to TBT from consumption of fish from Astrolabe Reef were well below health-based exposure limits, there is no evidence that the contamination of edible biota by TBT is decreasing with time."

Mr Cressey said the levels of contamination in the edible biota were not at a level of concern to human health, while presenting his evidence to the resources consent hearings panel on Monday. Rebecca Ryder, a landscape architect at Boffa Miskell, investigated whether the reef should retain its "outstanding" classification for natural character and natural features.

She had to evaluate whether the effects of leaving the Rena wreck on the reef would negatively affect the attributes that gave Otaiti its "outstanding" classifications.

Ms Ryder said her position was the reef retained its outstanding natural character status, although there were gaps in the information for the condition of the entire reef.

"The adverse effects on the pre-Rena level of natural character, on the part of the reef where the wreck and debris remain, are significant but when considering the entire context of the reef, are not significant."

Ms Ryder agreed that removal of the bow section of the ship would improve the reef's natural character.

Meanwhile, the safety of the Rena wreck as a dive site was assessed by a man with more than 6000 dives under his belt.

Simon Mitchell has dived shipwrecks all around New Zealand and the world for the past 42 years and has been involved in the Rena case as an expert on the safety of diving in and around shipwrecks on behalf of the applicants.

Dr Mitchell came to Monday's hearings four hours after his most recent dive of the Rena.

He advocated for the Rena to remain on the reef.

"In my opinion, the hazard represented by the residual wreckage is extremely small.

"Concerns raised about the safety of diving on the shallow wreckage are framed largely around compilation of an inventory of hypothetical hazards such as trauma on sharp edges, trauma from wave effects around hard projections, entanglement in cables and adverse events whilst trying to perform tasks like retrieving artefacts.

"Notably, however, there is a conspicuous lack of evidence which defines the level of risk these hazards truly represent."

Dr Mitchell said it was possible over time that afew divers would be injured around the wreck and there could be fatal accidents.

"But extensive experience tells us the risk is very small and probably indistinguishable from the background risk of diving."