The reproductive toxicity and endocrine disrupting effects of triazole fungicides have always been the focus of assessment by global pesticide regulatory agencies. After promulgating the guidelines for the assessment of endocrine disruption of pesticides and disinfection products in 2018, the European Union regulatory agency, which is the vane of the industry, officially launched a systematic assessment of the endocrine disrupting effects of new pesticides and pesticides that have entered 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 released the assessment conclusion. The results showed that no critical areas of concern were identified in the assessment of human health, environmental non-target organisms and environmental impacts of metconazole. At the same time, metconazole has not been found to have potential endocrine disrupting effects on humans and environmental non-target organisms.
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 prevent and control Septoria, Fusarium paniculata and leaf rust in wheat, dwarf rust and powdery mildew in barley, and crown rust in oats.
The European Union affirmed the efficacy of metconazole in terms of sterilization and regulating plant growth, and then evaluated metconazole from the aspects of human health, environmental non-target organisms and environmental impact, and the results are as follows:
01. When metconazole is used in rapeseed, the exposure risk of bystanders and resident children is higher than that of users.
02. The estimated residues of metconazole-related metabolites do not exceed the toxicological reference value.
03. In all representative uses, the risk of metconazole to birds, wild mammals, bees, non-target arthropods, earthworms, soil microorganisms, non-target terrestrial plants and sewage treatment organisms is low.
04. 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.
Subsequent review steps
In the next step, the European Commission (EC) will analyze the conclusions of EFSA and the re-evaluation assessment report (RAR), and will submit the re-evaluation report and draft regulations to member states to recommend the extension or non-extension of the approval of metconazole. Representatives of EU member states will then vote on the draft regulation at the Standing Committee on Plants, Animals, Food and Feed (SCoPAFF).
Source: AgroPages
