The Port of Tauranga directed media inquiries to the company involved, ISO Limited. A representative declined to comment on the phone. Emailed questions on Friday were not responded to.
A spokeswoman for the Bay of Plenty District Health Board said on Friday morning a 50-year-old Te Puke man remained in hospital in a stable condition.
A Tauranga man and woman, both 45, were discharged last night.
All three arrived at Tauranga Hospital from the Port of Tauranga on Thursday afternoon.
Peter Harvey, president of the Tauranga branch of the Maritime Union, said he spoke to one of the hospitalised men, a union member, yesterday.
Harvey understood from that conversation an incident involving an uncontrolled release of methyl bromide happened between 10 and 11am at berth nine at the port.
He said the worker believed he was exposed and sought medical attention after feeling nauseous.
"We're very disappointed workers have been badly affected and hospitalised as a result of some sort of contamination from methyl bromide.
"One worker had to be quarantined and decontaminated. They took all his clothes and disposed of them by incineration."
He said methyl bromide was used to treat logs under a tarpaulin. When the tarpaulins were lifted, a "puff" of the gas could be released.
Normal safety procedures called for warning communications to staff and the establishment of "buffer zones" to ensure workers were clear when that happened.
He said the union would want to find out whether all necessary safety precautions had been taken.
The union had long-standing "serious concerns" about methyl bromide and the risks it could pose to port workers, he said.
According to Ministry of Primary Industries information, the effects of being exposed to methyl bromide in high concentrations can be fatal and its use is strictly controlled around the world.
"A single small exposure from which a person recovers quickly is not likely to cause delayed or long-term effects.
"After a serious exposure that causes lung or nervous system-related problems, permanent brain or nerve damage can result.
"High concentrations may bring about death through pulmonary injury and associated circulatory failure."
Methyl bromide
● Highly toxic gas
● Is colourless, odourless and non-flammable
● Is ozone-depleting
● Has been used as a pesticide
● Has been phased out of use in many countries
● Linked to motor-neuron disease
