The reproductive toxicity and endocrine disrupting effects of triazole fungicides have always been the focus of assessment by global pesticide regulatory agencies. As the industry's benchmark, the EU regulatory agency promulgated the Endocrine Disruption Assessment Guidelines for Pesticides and Disinfection Products in 2018, and officially launched a systematic assessment of the endocrine disrupting effects of new pesticides and pesticides undergoing re-evaluation.
Up to now, a number of triazole fungicides, such as cyproconazole, have been banned by the EU due to potential endocrine disrupting effects and clear reproductive toxicity. But at the same time, the new triazole fungicide cloflufenconazole was approved by the European Union in 2019, breaking the long-term restriction of no new triazole fungicides on the market. Prothioconazole, a popular triazole product, has also made significant progress in the European Union's re-evaluation this year. It has been initially confirmed that it has no endocrine disrupting effects. It is planned that EFSA will finally confirm the corresponding risk assessment conclusion on October 30 this year.
On August 24, 2023, the European Food Safety Authority (EFSA) completed the peer review of the Metconazole re-evaluation risk assessment report and issued the assessment conclusion. The results showed that no major areas of concern were found in the assessment of human health, environmental non-target organisms and environmental impacts of Metconazole. At the same time, Metconazole was not found to have potential endocrine disrupting effects on humans and environmental non-target organisms.
Material background
Metconazole is usually a mixture of cis and trans isomers, both of which have bactericidal activity, but the cis form is more active than the trans form. The mechanism of action is the same as other triazole fungicides. It is an inhibitor of C-14 demethylation in ergosterol biosynthesis (FRAC:3). It inhibits the elongation of pathogenic fungus hyphae and prevents pathogenic spores from invading crop tissues.
Metconazole is a broad-spectrum systemic fungicide with excellent activity. It is mainly used to control Septoria, Fusarium paniculata, and leaf rust in wheat, dwarf rust and powdery mildew in barley, and crown rust in oats.
At present, Metconazole's market is mainly concentrated in Europe, South America and other places, and it has been approved for marketing in Brazil, North America, the European Union, the United Kingdom, Japan and other countries and regions.
Latest EU review status
In 2007, Metconazole was first approved under the old EU Regulation on Plant Protection Products (Directive 91/414/EEC). It was later included in the list of approved active substances in EU plant protection products (COMMISSION IMPLEMENTING REGULATION (EU) No 540/2011). In 2014, the applicant BASF submitted an application for re-evaluation. After many delays, it finally completed the peer review of the re-evaluation risk assessment report this month.
In the report, the EU first affirmed the efficacy of Metconazole in sterilizing and regulating plant growth, and then evaluated Metconazole from aspects such as human health, environmental non-target organisms and environmental impact. The results are as follows:
1. When Metconazole is used in rapeseed, the exposure risk of bystanders and resident children is higher than that of users.
2. The estimated residues of Metconazole-related metabolites do not exceed the toxicological reference value.
3. In all representative uses, the risk of Metconazole to birds, wild mammals, bees, non-target arthropods, earthworms, soil microorganisms, non-target terrestrial plants and wastewater treatment organisms is low.
4. Metconazole does not meet the identification criteria for endocrine disruptors in humans and environmental non-target organisms (that is, it is not an endocrine disruptor).
In addition, EFSA showed in its conclusion that there are still some data gaps, resulting in the risk assessment of drinking water and corresponding residents not yet finalized.
Next review steps
As a next step, the European Commission (EC) will analyze EFSA’s conclusions and re-review assessment report (RAR), and will submit the re-review report and draft regulations to member states to recommend the renewal or non-renewal of Metconazole’s approval. Representatives of EU member states will then vote on the draft regulation at the Standing Committee on Plants, Animals, Food and Feed (SCoPAFF).
