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Methyl bromide, logs and you

Julian Bateson, New Zealand Tree Grower November 2017.

A long, long time ago in a place far removed from here, called Montreal, it was decided that the growing ozone hole over the Antarctic needed to be closed. If nothing was done very soon, this hole in the protective ozone would continue to get bigger. It would allow more of the harmful ultraviolet radiation to get through and damage the skin of those of us living in Australia and New Zealand.

In 1987 the Montreal Protocol was an agreement that all countries should restrict and ban the use of ozone depleting chemicals. One of these chemicals was methyl bromide which is used as a fumigant to kill problem insects. In New Zealand, the main use for methyl bromide is for fumigating logs before they are exported.

In August this year, a workshop was arranged by Stimbr, an acronym for stakeholders in methyl bromide reduction, to discuss the phasing out of methyl bromide. Stimbr is funded by a levy on the use of methyl bromide with some additional input from the government. Attendance at the workshop seemed to be a good time to find out about how stopping methyl bromide escaping into the atmosphere might, or might not, affect small-scale forest owners.

The problem defined

New Zealand is not required to stop using methyl bromide, but as part of a good faith promise, the government has agreed to stop any of it from being emitted to the atmosphere as a result of its use. In other words, it has to be all kept under control, which for a gas is quite tricky. The date set for the promise to take effect is in 2020.

In 1991 around 70 tonnes of methyl bromide were used in New Zealand. Now the figure is 300 tonnes – not exactly a reduction in its use. These 300 tonnes comprise over eight percent of the world consumption because many other countries have found alternatives and are using less or none at all. Our use is increasing quite rapidly as log exports to countries requiring methyl bromide to be used continue to rise.

It is important to point out that not all logs need to be fumigated to all export countries. For example, China, which is one country which requires fumigation of logs, needs just 17 per cent of them to be treated.

Disagreement about consequences

It was no surprise to find out that there was disagreement about the effect there would be from any restrictions in the use of methyl bromide. Peter Clark, on behalf of the Forest Owners Association, was adamant that if methyl bromide use as a log fumigant was stopped, all log exports would stop. Ken Glassey countered this with the fact that, in his opinion, only four million tonnes of logs a year, about a quarter of exports, would be affected. Each was adamant that they were right although it seems Ken was correct.

Following on from this was discussion about who requires logs to be fumigated and if the relevant countries, such as China and India, could be persuaded to go for a different option. One suggestion was for the logs to be fumigated when they arrived at their destination, but of course this does not reduce the use of methyl bromide, just moves the problem. There are regular meetings with Chinese officials to discuss what can be done and what alternatives may be offered to make logs safe to import without methyl bromide fumigation.

The research for a solution

When the 10-year deadline for methyl bromide use was set in 2010 by the Environmental Protection Agency, all those involved thought it seemed to be a long way away and they assumed that a solution could easily be found in the time available. However, it did not go quite as planned, and now with under three years to go, the possible alternatives are very limited.

One is for all logs to have their bark removed more thoroughly than at present. To do this effectively requires de-barking processors to move up and down the logs a number of times, using up time and costing money. In addition, this process cannot be used effectively on smaller logs. Finally, de-barking only removes the insects we know about. Any new pest introductions may not be removed with de-barking, so it is quite limited in effectiveness.

Heating logs using electricity has proved to be quite effective in killing insect pests in the logs. But this process has only been tested on a small scale. The other potential solution is to use the chemical ethane di-nitrile known as EDN. This is very promising as it is not a greenhouse gas and is not ozone depleting − more about this later.

As mentioned earlier the EPA will not require a ban on the use of methyl bromide, it is a ban on letting any of it be emitted into the atmosphere. This means that if not all of it is used during fumigation then all the surplus gas, 100 per cent of it, must be contained and not allowed to just float away. If a sustainable solution could be found it would mean methyl bromide could be used after 2020.

Recovering the gas is not easy. One method is to use carbon to reabsorb the chemical, but you need five tonnes of carbon to collect one tonne of methyl bromide. Then you have to work out what to do with the carbon which is now contaminated. Landfill sites are not happy burying tonnes of carbon contaminated with a chemical, in fact they do not allow it.

The Genera method

We heard about research being carried out by Genera who fumigate millions of logs every year. They agree that currently no system in the world can economically recover all the surplus methyl bromide from fumigation. Just to clarify, for every tonne of methyl bromide used, about half a tonne is unused and available to be collected. The rest is absorbed into the logs, and from what I could understand, no one is entirely clear what happens to it in the log and if it is broken down or released slowly.

Genera have spent a lot of time and money looking for ways that can mean methyl bromide could be used after 2020. However, it seems that whatever they manage to do, it will be an interim solution until an alternative is found. This brings us back to ethane di-nitrile or EDN.

A probable solution

The only possible solution suggested at the workshop to treating logs in the foreseeable future without using methyl bromide seems to be to use EDN. It is effective against all wood boring insects, bark beetles, phytophthera and other fungi. It has a very low toxicity to mammals which makes it much better for health and safety than methyl bromide. In addition, it breaks down into ammonia and carbon dioxide which although not totally benign, are relatively harmless in the quantities which would be involved.

This seems to be the magic bullet, so you may ask why is it not being used. It is because EDN had to be properly tested and then approved by the EPA. Testing has been going on for some time, and is continuing.

Meanwhile, the application to the EPA was submitted in July with the response expected sometime in early 2018. Russia and China are aware of this possible alternative to methyl bromide and discussions are already taking place to see how it may all work.

The right answer

This is where the workshop left us, with hope that the use of methyl bromide could be effectively phased out, possibly in time for the 2020 deadline, but unlikely.

There is still a long way to go. Perhaps a successful method could be developed to recover all the unused methyl bromide after treatment, but this also seems to be unachievable. To reach the government target, recovery of the unused gas has to be 100 per cent and so far, the maximum recovery in tests has been 87 per cent.

It does not seem likely that the dire prediction made at the beginning of the workshop would eventuate, namely that all log exporting would be stopped if a solution to the methyl bromide problem cannot be found. But it is not all plain sailing and if an acceptable alternative is not found it would affect all log producers, including farm foresters.

Higher costs for an alternative to methyl bromide fumigation will reduce the income from log sales. If this means we are helping to mend the ozone hole, and reducing the amount of time people have to spend working with toxic methyl bromide, a small cost increase may be the right answer. And perhaps the only one.


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