Suchergebnisse

Abstract
Background
Currently, active chlorine is considered the most effective treatment for preventing biofouling of structures in contact with seawater. This compound falls under the scope of the EU Biocidal Products Regulation, which includes since 2018 a requirement to assess all active ingredients for their potential endocrine-disrupting properties on humans and non-target organisms. Therefore, this study examines the endocrine-disrupting (ED) potential of active chlorine based on the European Chemicals Agency and European Food Safety Authority guidance (ED TGD). It includes two approaches: (i) a systematic literature review using appropriate search terms and (ii) an in silico assessment, both supported by expert judgement. Finally, the feasibility and relevance of in vitro tests were examined by considering the stability of chlorine and the applicability domain of the recommended in vitro assays.

Results
No significant adversity or endocrine activity based on EATS (estrogen, androgen, thyroid, and steroidogenesis)-modalities were evidenced based on the literature data. However, these modalities remain understudied and further datasets are needed for a comprehensive assessment. The in silico approach revealed a low probability of binding between active chlorine and a set of 14 human nuclear receptors, for both agonist and antagonist effects. This is not surprising given the great structural difference between active chlorine and natural ligands. The in vitro investigation of the ED potential of active chlorine raises several operational limits, including: (i) its instability (t1/2 < 48 h) which is incompatible with a reasonable time window between collection and ex situ analysis; (ii) its rapid and complete reaction with several essential nutrients in cell culture media; (iii) its documented cytotoxicity on various cell lines; and (iv) its exclusion from the scope of certain OECD guidelines.

Conclusions
Overall, neither the in silico evaluation nor the systematic literature review performed indicates a significant adversity based on EATS-mediated parameters or EATS-related endocrine activities. This study highlights the challenges of performing a comprehensive ED assessment for a data-poor chemical and questions the relevance of transposing generic methodologies to the case of unstable and inorganic molecules.

13 páginas.- 7 figuras.- 92 referencias.- ; The mechanisms by which woody plants recover xylem hydraulic capacity after drought stress are not well understood, particularly with regard to the role of embolism refilling. We evaluated the recovery of xylem hydraulic capacity in young Eucalyptus saligna plants exposed to cycles of drought stress and rewatering. Plants were exposed to moderate and severe drought stress treatments, with recovery monitored at time intervals from 24 h to 6 months after rewatering. The percentage loss of xylem vessels due to embolism (PLV) was quantified at each time point using microcomputed tomography with stem water potential (Ψx) and canopy transpiration (Ec) measured before scans. Plants exposed to severe drought stress suffered high levels of embolism (47.38% ± 10.97% PLV) and almost complete canopy loss. No evidence of embolism refilling was observed at 24 h, 1 week, or 3 weeks after rewatering despite rapid recovery in Ψx. Recovery of hydraulic capacity was achieved over a 6-month period by growth of new xylem tissue, with canopy leaf area and Ec recovering over the same period. These findings indicate that E. saligna recovers slowly from severe drought stress, with potential for embolism to persist in the xylem for many months after rainfall events. © 2022 John Wiley & Sons Ltd. ; This study was supported by an ARC Discovery Project (DP170100761) to BC and TJB and an ARC Future Fellowship (FT130101115) to BC. BM acknowledges support from the ARC Laureate Fellowship FL190100003. CMR‐D was supported by an Individual Fellowship from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska‐Curie grant agreement no. 751918‐AgroPHYS. JMRP was supported by the ORNL, managed by UT‐Battelle, LLC, for the DOE under contract DE‐AC05‐1008 00OR22725. ; Peer reviewed