An investigation is underway to find out how an additional 21 containers of dangerous goods onboard the Rena was not declared on the ship's manifest.

The 21 containers of Cryolite are in addition to the 11 containers of dangerous goods already declared.

Sea Tow 60 at work alongside Rena removing containers from its deck. Photo: Maritime New Zealand.

'For reasons still unknown, the contents of these 21 containers were not declared as dangerous goods in the original manifest provided to Maritime New Zealand, and as required under the International Maritime Dangerous Goods Code,” says MNZ director Catherine Taylor.

'While experts advise that the contents of these containers are considered low risk in their current state, submerged below decks in the vessel's holds, MNZ is carrying out a thorough investigation as to why these dangerous goods were not declared as required under maritime legislation and whether this constitutes a breach of the law.”

The manifest records the product as ‘Cover Bath Material' and ‘Pure Tapped Bath Material'.

It is a by-product of the aluminium smelting process, which is considered low risk unless ingested or inhaled directly in its dry powdered form.

The Mediterranean Shipping Company is also advising this material is known as cryolite.
MNZ was told about the 21 containers on Tuesday by insurers acting for the charterers of the Rena – MSC.

'Since learning of this new information, MNZ has spent the last few days working extensively with various scientific, environmental and health experts to accurately assess the risk posed by cryolite to the marine environment and to people,” says Catherine.

'We have also been given a strong assurance by MSC that there are no other potentially dangerous goods onboard that have not been declared.”

Scientific advice received by MNZ confirms the material presents a low risk in its current state.

Twenty of the containers in question are located in hold three, which suffered considerable damage in the grounding. The other is in hold five.

This means they are below deck and inaccessible, under containers above deck.

Of these, 17 containers are understood to be submerged, but all are likely to have been submerged at some time as the ship has moved.

There are 490 tonnes of the product onboard, packed in one tonne bulk bags inside the containers.

The bags have a polyethylene liner and are constructed of polypropylene, so are water resistant, but not water tight.

Water is likely to have seeped into the bags within the container.

'Expert advice is that the cryolite onboard Rena is considered to be of low risk given that the product is only slightly soluble in water, so is expected to dissolve slowly.

'Any dissolved material will be diluted and dispersed very rapidly, reducing the potential effects further.”

Cryolite is considered dangerous to humans in its dry form if ingested or inhaled.

It is used as a flux in aluminium smelting and as a pesticide in commercial horticulture.

The salvors working onboard Rena have been advised the material is on board and are taking all necessary safety precautions to continue their work.

'While this late notification is frustrating, it's simply another issue Rena has thrown at us that we have to get on and deal with.

'It's the typical nature of salvage operations that these sorts of issues will come up, and our plans remain flexible enough to respond to them as they occur,” says Catherine.

'This development also justifies the safety precautions we have been taking all along and the advice that we have been giving to the public regarding the importance of respecting the exclusion zone around Rena and not touching or handling containers or their contents.

'We have trained professionals equipped and ready to deal with any hazardous substances should they be lost from the vessel or come ashore.”