Benfluralin

Peer review of the pesticide risk assessment of the active substance benfluralin

The conclusions of the EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Norway, and co-rapporteur Member State, the Netherlands, for the pesticide active substance benfluralin are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012. The conclusions were reached on the basis of the evaluation of the representative uses of benfluralin as a herbicide on chicory and lettuce and updated following the request from Commission to review the risk assessment as regards birds and mammals and aquatic organisms. The reliable end points, appropriate for use in regulatory risk assessment, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified.

Peer review of the pesticide risk assessment of the active substance benfluralin

The conclusions of the EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Norway, and co-rapporteur Member State, the Netherlands, for the pesticide active substance benfluralin are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012. The conclusions were reached on the basis of the evaluation of the representative uses of benfluralin as a herbicide on chicory and lettuce. The reliable end points, appropriate for use in regulatory risk assessment, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified.

A surfactant-assisted approach enables the fluorescence tracking of benfluralin in plants

Developing an effective detection method for benfluralin (BFA) is of great significance, since BFA as most widely used herbicides can be bioaccumulated by aquatic organisms in environment, possessing potential risks to human health. Owing to aggregation-caused quenching effect, most fluorescent detection methods based on donor-acceptor organic fluorophores suffered from very low sensitivity towards BFA in water system, hampering the bioimaging application in plants. In this work, we reported a novel surfactant-assisted fluorescent probe enabling detection of BFA in water with a high sensitivity. The involvement of specific surfactant Triton X100 (TX100) could amplify the response signal of probe more than 100-fold. The detection limit for BFA was determined to be 80 nM, satisfying the environmental protection requirements. Moreover, we demonstrated applications of this strategy for the fluorescent imaging of BFA in plant. The absorbance of BFA into roots of Arabidopsis thaliana and castor seedlings was successfully observed based on this method.

Weight of Evidence and Human Relevance Evaluation of the Benfluralin Mode of Action in Rats (Part II): Thyroid carcinogenesis

Benfluralin is an herbicide of the dinitroaniline class used to control grasses and weeds. In a 2 year dietary study in rats, benfluralin increased incidences of thyroid follicular adenoma and carcinoma at high dietary concentrations (≥2500 ppm). The benfluralin toxicology database suggests the mode of action (MOA) is initiated by induction of liver metabolizing enzymes, particularly thyroid hormone specific UGTs, a major pathway for T4 clearance in rats. As reported with phenobarbital, this effect triggers negative feedback regulation, increasing thyroid stimulating hormone (TSH) release into circulating blood. When sustained over time, this leads to thyroid changes such as follicular hypertrophy, hyperplasia and thyroid follicular tumors with chronic exposures. The described MOA was previously established in rat studies with various chemical activators of xenobiotic receptors in the liver. It is generally considered as non-relevant in humans, due to differences between humans and rats in T4 turnover and susceptibility to this carcinogenic MOA. A structured methodology based on the IPCS/MOA/Human Relevance framework was used in the evaluation of available benfluralin data, and the conclusion was determined that the carcinogenic potential of benfluralin in the thyroid is not relevant in humans.

Effect of benfluralin on Pinus pinea seedlings mycorrhized with Pisolithus tinctorius and Suillus bellinii--study of plant antioxidant response

In this study, Pinus pinea seedlings mycorrhized with selected ectomycorrhizal fungi (ECMF), Pisolithus tinctorius and Suillus bellinii, were exposed to the herbicide benfluralin. Non-mycorrhized P. pinea seedlings and seedlings mycorrhized with ECMF were transferred to benfluralin-spiked soils at levels of 0.165, 1.65 and 16.5 mg kg(-1). Plant growth and the fungal role on plant antioxidant response were assessed. In the presence of benfluralin, higher plant growth was observed in mycorrhized plants compared to non-mycorrhized plants, but ECMF colonisation and nutrient uptake were affected by the herbicide. Benfluralin showed no effect on lipid peroxidation in P. pinea seedlings. However, seedlings mycorrhized with S. bellinii showed higher levels of lipid peroxidation when compared to non-mycorrhized ones, both in the presence and absence of benfluralin. The increase of lipid peroxidation could be related to seedling growth induced by the fungus and not to benfluralin toxicity. A similar trend was observed in seedlings mycorrhized with P. tinctorius when exposed to higher benfluralin concentrations, suggesting that the antioxidant response to benfluralin is related not only to fungus species, but also to the level of stress applied in the soil. The higher amount of superoxide dismutase activity in P. pinea seedlings tissues exposed to benfluralin could indicate a plant adaptative response to benfluralin toxicity. Catalase activity showed no increase with benfluralin exposure. Pre-established P. tinctorius mycorrhization conferred root protection and enhanced plant growth in benfluralin spiked soil, inferring that P. tinctorius - P. pinea association could advantageous for plant growth in soils contaminated with pesticides.