METHYL bromide is an extremely poisonous neurotoxic gas, approved for use in quarantine fumigation treatments in Australia, New Zealand and many other countries. It is also an ozone depleting substance that is banned under the Montreal Protocol, with the exception that allows its use for valid biosecurity purposes.
Proven and efficient fumigant recapture technologies are increasingly being mandated and implemented to protect the environment and health and safety of workers, neighbours and the community from being exposed as these gases otherwise can spread over a large area as shown by plume modelling.
Usage of methyl bromide, the gas used for quarantine and prescribed pre-shipment treatment of biosecurity pests, remains exempt under Montreal Protocol.
With around 13,000 tonnes per annum used worldwide for these quarantine and pre-shipment treatments (QPS) there remains a focus on capturing the fugitive emissions from these fumigations.
The QPS exemptions under the Montreal Protocol are coming under increasing scrutiny as a result of both environmental and health and safety concerns.
Environmentally methyl bromide is both a greenhouse gas and an ozone depleting gas.
However, while it is difficult to source replacements for methyl bromide that are not offenders under the Kyoto Protocol, it is virtually impossible to find a fumigation gas that does not pose serious health and safety risks to bystanders.
The fact that dosages of toxic gases in high concentrations are needed to kill pests at all life stages, eggs included means that exposing humans to similar or even considerably lower concentrations poses risks to health, often involving long term health complications.
“Methyl bromide has been banned in a number of countries, including the EU in 2010. Many of those countries do not require strict quarantine protection for their agricultural industries,” says Wil Grullemans, general manager of Nordiko Quarantine Systems, a company that has been dealing with capturing emissions from fumigation since the turn of this century.
“However other countries with strict biosecurity concerns still list methyl bromide treatment for imports”.
The next phase in the management of methyl bromide fumigations is the introduction of regulations to recapture methyl bromide from fumigation sites.
The New Zealand EPA has set a target date of 2020 for all methyl bromide fumigations to be recaptured.
In advance of this impending date mandatory recapture has already been introduced in the ports of Nelson, Wellington and recently Auckland for all container fumigations.
With the cut-off date looming the Environment Court in New Zealand recently rejected an application to discharge methyl bromide to atmosphere, from the pre-shipment fumigation of export logs at the Port of Tauranga.
The application, made by Envirofume Limited to the Bay of Plenty Regional Council, was declined by an Independent Commissioner on the grounds that methyl bromide was known, or suspected, to cause significant adverse effects on human health.
Clearly new entrants to fumigation are required to show that they had a plan in place to reduce emissions and be able to meet the 2020 deadline.
In Australia things have moved more slowly with no real action from the Federal Government on reducing methyl bromide emissions from fumigations. However various states have started to take the matter into their own hands led by the NSW Environment Protection Authority (EPA) which is currently investigating the quantum of emissions in NSW from methyl bromide and are actively taking part in an awareness campaign to highlight risks and are investigating bystander risks.
Much of this work involves plume modelling of emissions through highly developed programs which illustrate where boundary emissions may exceed the EPA maximum limit. An example of this from a former fumigation site in Melbourne, shows gas can spread more than 800 metres from the point of release – well beyond the site boundaries of most locations where fumigations occur.
The Victorian EPA Public Exposure Limit for Methyl Bromide is 0.63 milligrams/m3. This means that in this case Methyl Bromide has travelled more than 800 metres and is still more than fifteen times greater than the safe limit.
An EPA spokesperson said: “The aim of the campaign is to monitor and ensure companies use all fumigation chemicals, including methyl bromide, safely and in accordance with requirements under Pesticide Act”.
Last year DCN reported the EPA fined Quattro Ports $15,000 for exceeding its licenced Methyl Bromide emissions limit at its new Port Kembla grain terminal.
While alternative fumigant chemicals are available, Methyl Bromide is still the preferred fumigant for most QPS uses.
This is partly due to the fact fumigants like methyl bromide are subject to rigorous controls and the expensive registration processes for new fumigants has slowed the introduction of alternatives. And, while methyl bromide has a “one size fits all” approach, the alternatives are adapted to a particular circumstance or to solve specific problems. Plus methyl bromide usage has a 70+ year history of usage whereas some of the replacements are still in the early stages of implementation.
Nordiko installed methyl bromide recapture systems in Australia, New Zealand, Thailand, Singapore, China, a number of Pacific Islands and is in the process of installations in Central America.
“As with any new process there are critics who question the scale and cost of methyl bromide recapture, but this has been disproven through numerous successful commercial applications,” Mr Grullemans said.
“Large-scale recapture from Australia’s largest grain silos in Newcastle (over 20000 cubic metres each) has been operating for more than two years.”
Methyl bromide recapture is now occurring across a range of industries including fresh produce, log exports, import containers, fixed fumigation chambers and portable under-tarp sites.
Other fumigants are also scrubbed from fumigation emissions. An example is the rice industry in Australia, which transitioned from methyl bromide to phosphine for non-quarantine treatments. The rice industry now scrubs phosphine emissions at their fumigation facilities in the Riverina to meet EPA requirements.
“The major obstacle to more widespread adoption of methyl bromide recapture, remains the lack of regulatory rigour at Government level,” Mr Grullemans said.
“Despite a virtually seamless implementation of recapture recently at Auckland Port, at most other ports in Australia and New Zealand there is not yet a full appreciation of the potential risks posed by toxic gas exposure to workers, neighbours and bystanders adjacent to fumigation sites.”
From the print edition November 23, 2017