Align regulation with environmental reality and policy

A transect across the eastern North Atlantic from 42jN, 23jW towards the European continental shelf and English Channel shows a gradient of increasing concentrations of dissolved iron (0.7 -1.9 nM), iron-binding ligands and iron(II) across the continental rise. Other data, notably aluminium and manganese, indicate that the increases are part of a front in the metal concentrations, which is due to admixture of bottom waters. Metal fronts in shelf waters are well known, but it was not known that this may include iron(II) and organic iron-complexing ligands. The iron gradient covered a narrow salinity band between 35 and 36, and was linearly related to salinity indicating conservative behaviour, possibly caused by organic complexation keeping the iron in solution. The open ocean iron(II) levels were low but a major proportion of the increased iron levels in the shelf and coastal waters was found to occur as iron(II), and the increase in the overall iron concentration was matched by increased ligand concentrations causing the iron to remain organically complexed. A sedimentary origin for the iron(II) in the surface waters would require iron(II) to be more stable than expected, perhaps through complexation -stabilization. D

The distribution of dissolved iron and its chemical speciation (organic complexation and redox speciation) were studied in the northeastern Atlantic Ocean along 231W between 37 and 421N at depths between 0 and 2000 m, and in the upperwater column (upper 200 m) at two stations further east at 451N101W and 401N171W in the early spring of 1998. The iron speciation data are here combined with phytoplankton data to suggest cyanobacteria as a possible source for the iron binding ligands. The organic Fe-binding ligand concentrations were greater than that of dissolved iron by a factor of 1.5-5, thus maintaining iron in solution at levels well above it solubility. The water column distribution of the organic ligand indicates in-situ production of organic ligands by the plankton (consisting mainly of the cyanobacteria Synechococcus sp.) in the euphotic layer and a remineralisation from sinking biogenic particles in deeper waters. Fe(II) concentrations varied from below the detection limit (o0.1 nM) up to 0.55 nM but represented only a minor fraction of 0% to occasionally 35% of the dissolved iron throughout the water column. The water column distribution of the Fe(II) suggests biologically mediated production in the deep waters and photochemical production in the euphotic layer. Although there was no evidence of iron limitation in these waters, the aeolian iron input probably contributed to a shift in the phytoplankton assemblage towards increased Synechococcus growth.

Existing electrochemical methods for the determination of iron require long deposition times to determine low iron levels. Here a new method, based on catalytic cathodic stripping voltammetry, is described to determine subnanomolar levels of iron in seawater. The new method has a better baseline and is generally simplified, leading to a lower reagent blank and minimized sample handling compared to a previous catalytic method [1]. Optimized conditions include the addition of 20 μM 1‐nitroso‐2‐naphthol (NN), 40 mM bromate, and 0.01 M HEPPS pH buffer, giving measurements in pH 8 seawater. The detection limit is 0.08 nM Fe after an adsorption time of 30 s; the detection limit is lowered by increasing the adsorption time. The method can also be used to determine the redox speciation of iron: FeIII is determined specifically by masking FeII with 2,2‐bipyridyl (Bp). The concentration of FeII can then be calculated by difference from the total iron concentration.

Following a request from EFSA, the Panel on Plant Protection Products and their Residues developed an opinion on the science to support the potential development of a risk assessment scheme of plant protection products for amphibians and reptiles. The coverage of the risk to amphibians and reptiles by current risk assessments for other vertebrate groups was investigated. Available test methods and exposure models were reviewed with regard to their applicability to amphibians and reptiles. Proposals were made for specific protection goals aiming to protect important ecosystem services and taking into consideration the regulatory framework and existing protection goals for other vertebrates. Uncertainties, knowledge gaps and research needs were highlighted.

Inputs of copper and zinc from agricultural soils into the aquatic system were investigated in this study, because of their heavy agricultural usage as feed additives and components of fertilizers and fungicides. As the mobility and bioavailability of these metals are affected by their speciation, the lipophilic, colloidal and organic fractions were determined in drainage water from a loamy and a humic soil treated with fungicides or manure. This study therefore investigates the impact of agricultural activity on a natural environment and furthers our understanding of the mobility of metals in agricultural soils and aquatic pollution in rural areas. Marked increases in the total dissolved metal concentrations were observed in the drainage water during rain events with up to 0.3 microM Cu and 0.26 microM Zn depending on the intensity of the rainfall and soil type. The mobile metal fractions were of a small molecular size (<10 kD) and mainly hydrophilic. Lipophilic complexes originating from a dithiocarbamate (DTC) fungicide could not be observed in the drainage water; however, small amounts of lipophilic metal complexes may be of natural origin. Cu was organically complexed to > 99.9% by abundant organic ligands (log K 10.5-11.0). About 50% of dissolved Zn were electrochemically labile, and the other 50% were complexed by strong organic ligands (log K 8.2-8.6). Therefore very little free metal species were found suggesting a low bioavailability of these metals in the drainage water even at elevated metal concentrations.

EFSA asked the Panel on Plant Protection Products and their residues to deliver a Scientific Opinion on testing and interpretation of comparative in vitro metabolism studies for both new active substances and existing ones. The main aim of comparative in vitro metabolism studies of pesticide active substances is to evaluate whether all significant metabolites formed in the human in vitro test system, as a surrogate of the in vivo situation, are also present at comparable level in animal species tested in toxicological studies and, therefore, if their potential toxicity has been appropriately covered by animal studies. The studies may also help to decide which animal model, with regard to a particular compound, is the most relevant for humans. In the experimental strategy, primary hepatocytes in suspension or culture are recommended since hepatocytes are considered the most representative in vitro system for prediction of in vivo metabolites. The experimental design of 3 9 3 9 3 (concentrations, time points, technical replicates, on pooled hepatocytes) will maximise the chance to identify unique (UHM) and disproportionate (DHM) human metabolites. When DHM and UHM are being assessed, test item-related radioactivity recovery and metabolite profile are the most important parameters. Subsequently, structural characterisation of the assigned metabolites is performed with appropriate analytical techniques. In toxicological assessment of metabolites, the uncertainty factor approach is the first alternative to testing option, followed by new approach methodologies (QSAR, read-across, in vitro methods), and only if these fail, in vivo animal toxicity studies may be performed. Knowledge of in vitro metabolites in human and animal hepatocytes would enable toxicological evaluation of all metabolites of concern, and, furthermore, add useful pieces of information for detection and evaluation of metabolites in different matrices (crops, livestock, environment), improve biomonitoring efforts via better toxicokinetic understanding, and ultimately, develop regulatory schemes employing physiologically based or physiology-mimicking in silico and/or in vitro test systems to anticipate the exposure of humans to potentially hazardous substances in plant protection products.

The EFSA Panel on Plant Protection Products and their Residues (PPR) has developed, as a self-task mandate (EFSA-Q-2019-00100), two adverse outcome pathway (AOP)-informed integrated approach to testing and assessment (IATA) case studies to answer a developmental neurotoxicity (DNT) hazard identification and characterisation problem formulation that could support the regulatory decisions for the pesticide active substances deltamethrin and flufenacet. The IATA were developed to assess the applicability of the DNT in vitro testing battery (IVB), designed to explore fundamental neurodevelopmental processes, in the regulatory risk assessment of pesticides. For this purpose, an evidence-based-approach methodology was applied: 1) systematic literature review and critical appraisal of all the evidence i.e. human observational studies, in vivo data from rodent models and new approach methodologies (NAMs, i.e. in vitro studies including high-throughput testing from IVB and zebrafish studies from the literature) for both case studies; 2) a quantitative uncertainty analysis of all the evidence using expert knowledge elicitation (EKE) and a probabilistic approach; 3) integration of all the evidence using the AOP conceptual framework. This stepwise approach resulted in the postulation of an evidencebased AOP network for one of the case studies. A probabilistic quantification of the weight of evidence (WoE) using Bayesian network analysis allowed the assessment and the quantification of the uncertainty in the postulated AOP. The approach taken allowed conclusions to be drawn with an acceptable level of certainty in DNT hazard identification and characterisation of deltamethrin and that flufenacet is not a developmental neurotoxicant, supporting the relevance of the mechanistic understanding. The case studies show the applicability of the DNT-IVB for hazard identification and characterisation and illustrate the usefulness of an AOP-informed IATA for regulatory decision making. The overall activity led to improved interpretation of human data by providing a plausible mechanistic link to adverse outcomes, which would support their contextualisation in the risk assessment process. This Scientific Opinion allows the PPR Panel to draft several recommendations for the implementation of the AOP-informed IATA methodology and of the DNT-IVB in the regulatory risk assessment of pesticides.