Public hearings on the modified reassessment of methyl bromide will happen some this year, according to the Environmental Protection Authority, after being delayed in December so additional monitoring could be undertaken and the resulting data taken into account.

Back in late-November the EPA announced plans were being made to increase methyl bromide monitoring following a theoretical modelling report about how the log fumigant disperses into the environment after use.

According to the EPA, this is additional monitoring would be over and above the routine monitoring that industry is required to carry out every time methyl bromide fumigation occurs.

The mathematical modelling of operations at the Port of Tauranga was commissioned by the EPA as part of a modified reassessment underway to review the rules around methyl bromide use.

Stakeholders in Methyl Bromide Reduction Inc – the group known as STIMBR – applied for a reassessment of the approval for methyl bromide – and the EPA is processing this application as a modified reassessment.

This means the reassessment will only consider specific aspects of the approval, such as required controls. Approval to import or manufacture methyl bromide cannot be revoked in this type of reassessment.

The EPA says this modified reassessment is a statutory process where an independent decision-making committee considers evidence in relation to the way methyl bromide is used. Additional monitoring, to be carried out by WorkSafe, will feed into the process.

EPA’s Hazardous Substances Group acting general manager Gayle Holmes says New Zealanders are concerned about methyl bromide use “so it’s important that we get accurate data on which to base our decisions”.

“Our mathematical modelling report conflicts with that put forward by industry as part of the current reassessment process, and others undertaken when methyl bromide was last reassessed in 2010.

“It is also at odds with routine monitoring data which industry is required to undertake whenever methyl bromide is used at ports around NZ.”

“Computer-based modelling is a tool that uses an array of mathematical assumptions which can differ from the actual measurements of air quality. Because the reports all reflect different outcomes, the EPA commissioned an independent peer review to further test the hypothesis of its own report. It confirms that more detailed data is necessary.”

To gain more data, WorkSafe began monitoring air dispersal patterns following timber fumigations at the Port of Tauranga in late-November.

WorkSafe head of health and technical service Catherine Epps says the tests are highly sensitive and require laboratory analysis. “It will take some weeks to build an accurate picture on which to better understand the accuracy of computer modelling.”

Data from the tests will fill the gap between what the modelling reflects and what can be detected in the air; it will track the chemical’s dispersal patterns and concentration levels. This additional data will then be considered by the EPA Decision-making Committee, which is responsible for deciding if changes are needed to the rules around methyl bromide use.

The mathematical modelling report, subsequent peer review and all other related information being put