Clopyralid

The Organic Materials Sector Group recently undertook to review the New Zealand situation for clopyralid and its level of contamination of green waste and subsequent compost products. Clopyralid is a herbicide used to control broadleaf weeds, particularly thistles and clovers. It can survive the composting process and actually increase in concentration as the green waste breaks down.

• 19 facilities in New Zealand are currently composting green waste.
• 15 of those agreed to be surveyed, and it was found that 12 were currently testing for clopyralid.
• Seven of the total 12 facilities currently testing reported that clopyralid had been detected within their compost.
• Results shared by survey participants indicate that, at times, clopyralid has been detected at levels above 20 ppb and, in some cases, more than 50 ppb
• Detectable and, in many cases, high clopyralid results have been observed for material that is 3 or 4 years old as well as compost made in recent years.
• Just over half of those surveyed actively separate out grass clippings to try and manage clopyralid contamination upfront. However, two of those eight facilities are still detecting clopyralid levels greater than 20 ppb, and one other is detecting lower levels (<10 ppb).

Full results of the survey can be viewed here Clopyralid Survey Report October 2014

As a result of this survey the Organics Material Sector Group strongly encourages all facilities that accept grass clippings to test for clopyralid. Advice and guidance on how to test for clopyralid can be viewed here.

Also, the Organic Materials Steering Committee has recommended applying to the Environmental Protection Authority for grounds for the reassessment of clopyralid.

When reassessments are requested, it’s commonly because there is new information indicating that the risks to human health and/or the environment may not be appropriately managed by the existing controls. The application will outline the reasons the Organic Materials Steering Committee think the reassessment is needed based on the results of the survey.

For more information about this project, please contact Sarah Pritchett, Sector Group Manager for the Organic Materials Steering Committee sarahp@wasteminz.org.nz