EPA bans chlorthal-dimethyl weedkiller
The Environmental Protection Authority (EPA) is banning weedkillers containing chlorthal-dimethyl (also known as DCPA) because of concerns about its effects on foetal development.
Chlorthal-dimethyl is used to control wireweed on vegetable crops before the vegetables emerge from the soil.
Importing, manufacturing, and using products containing chlorthal-dimethyl is prohibited from 18 December 2025. All products containing chlorthal-dimethyl must be disposed of by 18 June 2026.
We have reassessed chlorthal-dimethyl after imposing temporary restrictions in 2024. This followed an emergency suspension order issued by the United States Environmental Protection Agency.
We reviewed new information about the risk of chlorthal-dimethyl and received four submissions in favour of our proposal to ban the substance.
A decision-making committee found that risks to people and the environment from using the weedkiller outweighed the benefits.
Dr Shaun Presow, Hazardous Substances Reassessments Manager, says the EPA review of the toxicological studies and use confirmed the potentially harmful effects of chlorthal-dimethyl.
"Safety is paramount and we are working to protect people's health. We have significant concerns about the potential risks of chlorthal-dimethyl to individuals who are pregnant and work with chlorthal-dimethyl, those who enter treated fields after the substance has been applied, and bystanders who may be indirectly exposed."
"For anyone pregnant and exposed to the chemical, the endocrine effects could harm the development of the foetus and lead to significant impacts on offspring. These effects range from low birth weight to irreversible and life‑long impacts, such as impaired brain development and motor skills."
Dr Presow says the agricultural use of chlorthal-dimethyl has decreased and most New Zealand growers are now using alternative products that are readily available and cheaper.
The chemical is banned in Australia, Canada, the European Union and the United States.
For information regarding how to appropriately dispose of products, see the following:
Consolidated Hazardous Substances (Disposal) Notice 2017 | EPA