Container fumigant proposal

The Environmental Risk Management Authority has made a preliminary recommendation that "recapture" technology should be used for shipping containers fumigated with methyl bromide.

In reviewing public submissions made on the reassessment of methyl bromide, the agency (Erma staff) says in an update paper that it is now recommending the use of recapture technology for 20ft and 40ft shipping containers.

However the agency did not consider the technology should be made mandatory for large-scale fumigations at this time. There was uncertainty around the practicality and cost of recapture for large scale fumigations, like logs under cover, which account for 80 percent of the methyl bromide used in New Zealand.

In July 2008 Erma decided there were grounds for the reassessment of the fumigant methyl bromide, and for the Workplace Exposure Standard (WES) methyl bromide to be set by the Department of Labour.

The department has proposed lowering the WES to an eight hour WES-TWA (Time Weighted Average) from 5ppm to 1ppm and to introduce a WES-GEL (General Excursion Limit) of 3ppm. The proposed WES-TWA is equivalent to nine of 18 other countries, more stringent than eight of them, and less stringent than one of them.

The intention of the WES is to establish a concentration that can be inhaled without causing adverse health effects. The colourless and odourless neurotoxic gas can be easily absorbed by inhalation, or through the skin.

In considering the lowering of the WES the DoL has considered best international practises and standards, and given people affected by the proposed limits an opportunity to make submissions. A recently released consideration paper says the outcome of the DoL review will be viewed as an input into the Erma reassessment process, with a final decision expected this year.

For Erma, there are three scenarios: continue the availability of methyl bromide for quarantine and pre-shipment (QPS) for the foreseeable future, a five year phase out, or an immediate ban.

Among the 92 submissions were arguments for and against the recapture of methyl bromide from small-scale fumigations in containers, which is already carried out in several countries.

In its submission, Port Marlborough claimed that the capture of small scale fumigations involving less than 30kg of methyl bromide was viable, and would cover 20 percent of the current fumigations in New Zealand.

Nelson City Council submitted that the recapture technique should be mandatory for all containers. Experience at Port Nelson had shown the use of recapture technology for small-scale fumigations was practical, and could be done for about $68 a container. Another assessment was that recapture could double the cost of container fumigation.

A company which can provide systems to recapture methyl bromide and dispose the material to landfill, submitted that costs would decrease the more the technology was used in New Zealand.

Several submitters raised concern about the exposure of people to methyl bromide when unloading fumigated shipping containers. There was a risk of unacceptably high levels of methyl bromide building up in the containers during transportation due to "off gassing" from the fumigated goods (the slow release of absorbed gas).

The agency has recommended that receiving companies should contract a local fumigation company to test for gas concentrations before permitting employees to unload contents.

This story appeared in Safeguard Update newsletter of 17 May 2010.

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