It is a regulatory requirement to assess co-formulants in plant protection products (PPP) under the European Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) legislation. The standard environmental exposure assessment framework for chemicals under REACH is a multicompartmental mass-balanced model and, at the local scale, is designed for use with urban (wide dispersive) or industrial (point source) emissions. However, the environmental release of co-formulants used in PPP is to agricultural soil and indirectly to waterbodies adjacent to a field and, for sprayed products, to the air. The Local Environment Tool (LET) has been developed to assess these specific emission pathways for co-formulants in a local-scale REACH exposure assessment, based on standard approaches and models used for PPP. As such, it closes a gap between the standard REACH exposure model's scope and REACH requirements to assess co-formulants in PPP. When combined with the output of the standard REACH exposure model, the LET includes an estimate of the contribution from other nonagricultural background sources of the same substance. The LET is an improvement over the use of higher tier PPP models for screening purposes because it provides a simple standardized exposure scenario. A set of predefined and conservatively selected inputs allows a REACH registrant to conduct an assessment without requiring detailed knowledge of PPP risk assessment methods or typical conditions of use. The benefit to the co-formulant downstream user (formulators) is a standardized and consistent approach to co-formulant assessment, with meaningful and readily interpretable conditions of use. The LET can serve as an example to other sectors of how to address possible gaps in the environmental exposure assessment by combining a customized local-scale exposure model with the standard REACH models. A detailed conceptual explanation of the LET model is provided here together with a discussion on its use in a regulatory context. Integr Environ Assess Manag 2023;19:1544-1554. © 2023 BASF SE, Bayer AG et al. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

The European Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) regulation requires that quantitative environmental risk assessment is carried out for hazardous substances used as coformulants in plant protection products (PPPs), if registered above 10 t/y. The European Crop Protection Association (ECPA) has developed generic exposure scenarios and specific environmental release categories (SpERCs) to support these risk assessments. The SpERCs offer refinements to the default release factors defined in environmental release categories (ERCs) and are intended to be used with nested multimedia mass balance models as part of the assessment of regional predicted environmental concentrations. Based on the application method of PPPs, 2 scenarios were defined for which SpERCs were developed: 1) spraying of PPPs and 2) direct application of granular products or treated seeds to soil. The SpERC for spray applications includes release factors to air and soil that depend on the vapor pressure of the coformulant. Calculations are presented to support the subSpERCs describing the transition from nonvolatile to volatile behavior. The most recent version of the spray application SpERC defines a release factor for surface water and more conservative release factors to soil compared with previous versions. Use of the ECPA SpERCs allows the coformulant emissions from PPPs to be fully accounted for in the regional‐scale environmental risk assessment for a given substance, along with all other sources of emissions. Qualitative and quantitative justification for the ECPA‐derived SpERCs is presented and serves as the background documentation to the online European Chemicals Agency (ECHA) SpERC factsheets. The approach developed here whereby regional‐scale SpERCs are used in combination with a customized local‐scale exposure model is potentially applicable for other sectors that are required to conduct exposure assessments outside the scope of the standard environmental REACH models. Integr Environ Assess Manag 2020;16:472–480. © 2020 Syngenta Crop Protection AG. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC)

Background:Substances used as co-formulants in plant protection products (PPP) may require registration under Regulation (EC) No. 1907/2006 (REACH), and additionally where an exposure assessment is required, this must take into consideration the specifics of the PPP use.Objectives:This work reports a customized screening level model developed to support human health risk assessment of operators, workers, and bystanders (OWB) for co-formulants used in PPP. The OWB model was designed to closely integrate with REACH generic exposure scenarios (GES) for PPP developed by the European Crop Protection Association (ECPA). The use of these tools in combination is expected to lead to a more standardized and hence efficient risk assessment of co-formulants. This study describes the basis for OWB exposure predictions as well as benchmarking against relevant REACH exposure models for equivalent tasks. The benchmarking was carried out to gain some insight into the initial assumption that the most commonly used tier 1 REACH model would be more conservative than the specific PPP models used for regulatory risk assessments under PPP legislation.Method:Existing exposure models with regulatory acceptance for the most common types of PPP and their professional and consumer uses were selected. The German BBA model was used to assess spray applications. Granule and seed dispersal was assessed using the US Environmental Protection Agency (EPA) Pesticide Handlers Exposure Database (PHED). ECETOC TRA was employed to assess exposure during certain tasks performed in seed treatment, not covered by these PPP models. Where the underlying models featured multiple exposure determinants, the exposure was calculated for all permutations, and the worst-case exposure selected and reported for use in risk assessment. The PPP models are based on measured data collected during actual application of PPP; hence, the worst-case exposure predicted was expected to reflect a realistic worst case for these tasks.Results:OWB was implemented as an Excel spreadsheet. Exposure models, parameters, and exposure and risk estimates are reported in a REACH-compliant output format to facilitate the registration of co-formulant uses. As would be expected, benchmarking OWB against the PPP-specific exposure models demonstrated equivalence with the worst-case prediction from these underlying PPP models. For the scenarios modelled, the tier 1 ECETOC TRA gave more conservative predictions than OWB. The reduction in conservatism is attributed to the underlying PPP models being based on measured data collected specifically during the use of PPP, compared to the data underlying ECETOC TRA, based mainly on industrial workplace uses.Conclusions:OWB provides inhalation and dermal exposure estimates for co-formulants used in PPP which are equivalent to the worst-case estimates from existing specialized PPP exposure models based on measured data. OWB has simplified information requirements in comparison to higher-tier REACH or PPP models. Use of OWB in combination with the defined ECPA GES facilitates an efficient and standardized REACH risk assessment and registration of co-formulant uses in PPP. A defined assessment framework and default inputs potentially decreases the anticipated inter-user variability compared with the use of higher-tier PPP or REACH models in this screening level context.

The European Union (EU) chemicals regulation Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) requires a hazardous substance registration to identify the uses of a substance and the corresponding conditions of safe use. This requirement includes a human and an environmental safety assessment. Exposure scenarios are developed and employed for estimating emissions resulting from the uses of hazardous substances. To support the environmental assessments, the REACH guidance documents define 22 environmental release categories (ERCs) with conservative release factors (RFs) to water, air, and soil. Several industry associations target the ERCs to more specific uses and respective emission scenarios to enable more realistic emission estimations. They have developed more than 190 specific ERCs (SPERCs) as standardized descriptions of operational conditions (OCs) and risk management measures (RMMs). SPERCs reflect the current good practice and are documented in factsheets. These factsheets contain the information necessary for environmental emission modeling. Key parameters are the substance use rate, the efficiency of the risk management measures (if applicable), and the RFs. These parameters can be based on literature or measured company data or are justified by qualitative arguments. The majority of SPERCs have been implemented as realistic worst‐case emission values in screening‐level chemical safety assessment (CSA) tools. Three regulatory reviews in Europe have established requirements for documenting the SPERCs and for justifying the RFs. In addition, each of the reviews included recommendations for improving the SPERCs. The latest review proposed a condensed factsheet that focuses on the essentials for exposure assessment and subsequent communication in safety data sheets. It is complemented with a background document for providing details on the emission scenarios and justifications. In the EU the SPERCs will be further progressed in a consensus process using the multi‐stakeholder expert network on exposure scenarios. The SPERCs have the potential to be used in environmental risk assessments within other regulatory frameworks or in other geographical regions. Integr Environ Assess Manag 2016;12:772–781. © 2015 SETAC

This article reviews the interactions between the REACH (Registration, Evaluation, Authorization and restriction of Chemicals) regulation and the plant protection product regulation for substances used as coformulants in the European Union, and describes generic exposure scenarios developed for their exposure and risk assessment. The REACH exposure scenarios describe the operational conditions and risk management measures used in the risk assessment of a coformulant, and as such these translate as the boundaries of safe use. The generic exposure scenarios are designed to be simple, and closely integrate with REACH use descriptors and customized exposure models. Clustering of application methods and exposure determinants resulted in four generic exposure scenarios, each covering professional workers or consumers, and application of products in liquid, granular form, or applied on seeds. When used in conjunction with appropriate exposure models, the generic exposure scenarios support efficient first‐tier risk assessment of coformulants by utilizing a higher level of abstraction and conservatism than typically used in plant protection product assessments.

The ligand-field absorption spectrum of the Ni(H2O)6(2+) cation has been thoroughly measured and analyzed over the past sixty years, often on crystals with low symmetry at the metal site, and its absorption band maxima have been used as a benchmark for increasingly sophisticated electronic structure calculations over the last decades. We present variable-temperature absorption spectra measured on crystals with cubic Th symmetry at the site of the nickel(ii) cation. This high site symmetry is confirmed for CsNi(H2O)6PO4 by X-ray diffraction and allows for a direct comparison with ligand-field calculations in Th symmetry, at the basis of an analysis of the vibronic structure in the energy range of the lowest-energy spin-forbidden transition, the "red" or middle band of the spectrum. This spectroscopic region displays effects of strong interactions between singlet and triplet excited states, influencing intensities and vibronic structure. A particular feature that has not been analyzed in detail is a clearly discernible vibronic progression involving the O-H stretching mode on the high-energy side of the absorption band. A quantitative model is presented and applied in order to rationalize this unusual effect, originating from coupling between normal coordinates, to the best of our knowledge the first analysis of this distinct spectroscopic feature arising from interacting excited states.

The ligand-field absorption spectrum of the Ni(H2O)6(2+) cation has been thoroughly measured and analyzed over the past sixty years, often on crystals with low symmetry at the metal site, and its absorption band maxima have been used as a benchmark for increasingly sophisticated electronic structure calculations over the last decades. We present variable-temperature absorption spectra measured on crystals with cubic Th symmetry at the site of the nickel(ii) cation. This high site symmetry is confirmed for CsNi(H2O)6PO4 by X-ray diffraction and allows for a direct comparison with ligand-field calculations in Th symmetry, at the basis of an analysis of the vibronic structure in the energy range of the lowest-energy spin-forbidden transition, the "red" or middle band of the spectrum. This spectroscopic region displays effects of strong interactions between singlet and triplet excited states, influencing intensities and vibronic structure. A particular feature that has not been analyzed in detail is a clearly discernible vibronic progression involving the O-H stretching mode on the high-energy side of the absorption band. A quantitative model is presented and applied in order to rationalize this unusual effect, originating from coupling between normal coordinates, to the best of our knowledge the first analysis of this distinct spectroscopic feature arising from interacting excited states.

High-frequency (f = 190 GHz) electron paramagnetic resonance (EPR) at magnetic fields up to 12 T and Q-band (f = 34.1 GHz) EPR were performed on single crystals of the molecular wheel CsFe(8). In this molecule, eight Fe(III) ions, which are coupled by nearest-neighbor antiferromagnetic (AF) Heisenberg exchange interactions, form a nearly perfect ring. The angle-dependent EPR data allow for the accurate determination of the spin Hamiltonian parameters of the lowest spin multiplets with S ≤ 4. Furthermore, the data can be well reproduced by a dimer model with a uniaxial anisotropy term, with only two free parameters J and D. A fit to the dimer model yields J = -15(2) cm(-1) and D = -0.3940(8) cm(-1). A rhombic anisotropy term is found to be negligibly small, E = 0.000(2) cm(-1). The results are in excellent agreement with previous inelastic neutron scattering and high-field torque measurements. They confirm that the CsFe(8) molecule is an excellent experimental model of an AF Heisenberg ring. These findings are also important within the scope of further investigations on this molecule such as the exploration of recently observed magnetoelastic instabilities.

We report on inelastic neutron-scattering (INS) measurements on the molecular spin ring CsFe8, in which eight spin-5/2 Fe(III) ions are coupled by nearest-neighbor antiferromagnetic Heisenberg interaction. We have recorded INS data on a nondeuterated powder sample up to high energies at the time-of-flight spectrometers FOCUS at PSI and MARI at ISIS, which clearly show the excitation of spin waves in the ring. Due to the small number of spin sites, the spin-wave dispersion relation is not continuous but quantized. Furthermore, the system exhibits a gap between the ground state and the first excited state. We have modeled our data using exact diagonalization of a Heisenberg-exchange Hamiltonian together with a small single-ion anisotropy term. Due to the molecule's symmetry, only two parameters J and D are needed to obtain excellent agreement with the data. The results can be well described within the framework of the rotational-band model as well as antiferromagnetic spin-wave theories.

A field-dependent inelastic neutron scattering (INS) experiment on an array of oriented single crystals of Mn-12-acetate is reported. The experimental results provide clear evidence that the minority species observed in the INS spectra is the fast-relaxing species observed in, for instance, AC-susceptibility measurements.

The synthesis and crystal structures of a family of decametallic Cr(III) "molecular wheels" are reported, namely [Cr10(OR)20(O2CR')10] [R' = Me, R = Me (1), Et (2); R' = Et, R = Me (3), Et (4); R' = CMe3, R = Me (5), Et (6)]. Magnetic studies on 1-6 reveal a remarkable dependence of the magnetic behaviour on the nature of R. In each pair of complexes with a common carboxylate (R') the nearest neighbour CrCr magnetic exchange coupling is more antiferromagnetic for the ethoxide-bridged (R = Et) cluster than for the methoxide analogue. In complexes 2, 4 and 6 the overall coupling is weakly antiferromagnetic resulting in diamagnetic (S = 0) ground states for the cluster, whilst in 1 and 5 it is weakly ferromagnetic thus resulting in very high-spin ground states. This ground state has been probed directly in the perdeuterated version of 1 ([D]1) by inelastic neutron scattering experiments, and these support the S = 15 ground state expected for ferromagnetic coupling of ten Cr(III) ions, and they also indicate that a single J-value model is inadequate. The ground state of 5 is large but not well defined. The trends in J on changing R are further supported by density functional calculations on 1-6, which are in excellent agreement with experiment. The very large changes in the nature of the ground state between 1 and 2, and 5 and 6 are the result of relatively small changes in J that happen to cross J = 0, hence changing the sign of J.

The inelastic neutron scattering (INS) spectrum is studied for the antiferromagnetic molecular wheel CsFe8, in the temperature range 2 - 60 K, and for transfer energies up 3.6 meV. A qualitative analysis shows that the observed peaks correspond to the transitions between the L-band states, from the ground state up to the S = 5 multiplet. For a quantitative analysis, the wheel is described by a microscopic spin Hamiltonian (SH), which includes the nearest-neighbor Heisenberg exchange interactions and uniaxial easy-axis single-ion anisotropy, characterized by the constants J and D, respectively. For a best-fit determination of J and D, the L band is modeled by an effective SH, and the effective SH concept extended such as to facilitate an accurate calculation of INS scattering intensities, overcoming difficulties with the dimension of the Hilbert space. The low-energy magnetism in CsFe8 is excellently described by the generic SH used. The two lowest states are characterized by a tunneling of the Neel vector, as found previously, while the higher-lying states are well described as rotational modes of the Neel vector.

Inelastic neutron scattering (INS) spectra are presented for chromium(II) Tutton salts, as a function of the temperature and pressure. Transitions are observed between the levels of the 5Ag (Ci) ground term and the data modeled with a conventional S = 2 spin Hamiltonian. At 10 K and ambient pressure, the zero-field-splitting parameters of the ammonium salt, (ND4)2Cr(D2O)6(SO4)2, are determined as D = -2.431(4) cm(-1) and E = 0.091(4) cm(-1), evolving to D = -2.517(4) cm(-1) and E = 0.127(5) cm(-1) upon application of 7.5(1.0) kbar of quasi-hydrostatic pressure. By contrast, the change in the INS spectrum of the rubidium salt in this pressure range is comparitively minor. The results are interpreted using a 5Ee vibronic-coupling Hamiltonian, in which low-symmetry strain, perturbing the adiabatic potential-energy surface, is pressure-dependent. It is argued that, for the ammonium salt, the change with pressure of the anisotropic strain impinging upon the [Cr(D2O)6]2+ cation is sufficient to cause a switch of the long and intermediate Cr-OD2 bonds, with respect to the crystallographic axes.

The magnetic torque of the antiferromagnetic molecular wheel CsFe8 was studied down to 50 mK and up to 28 T. Below about 0.5 K phase transitions were observed at the field-induced level crossings (LCs). Intermolecular magnetic interactions are very weak excluding field-induced magnetic ordering. A magnetoelastic coupling was considered. A generic model shows that the wheel structure is unconditionally unstable at the LCs, and the predicted torque curves explain the essential features of the data well.

Spectroscopic, magnetochemical, and crystallographic data are presented for CsFe(H2O)6PO4, a member of a little-known isomorphous series of salts that facilitates the study of hexa-aqua ions in a quasicubic environment. Above 120 K, the deviations from cubic symmetry are minimal, as shown by the first example of an iron(II) Mössbauer spectrum that exhibits no measurable quadrupole splitting. Two crystallographically distinct [Fe(OH2)6]2+ complexes are identified from inelastic neutron-scattering (INS) experiments conducted between 2 and 15 K. The data are modeled with the ligand-field Hamiltonian, H = lambdaLŝ + betaB(kL + 2ŝ) + Delta(tet){Lz2 - (1/3)L(L + 1)} + Delta(rhom){Lx2 - Ly2}, operating in the ground-term (5)T(2g) (Oh) basis. An excellent reproduction of INS, Mössbauer, HF-EPR, and magnetochemical data are obtained in the 2 and 15 K temperature regimes with the following parameters: lambda = -80 cm(-1); k = 0.8; site A Delta(tet) = 183 cm(-1), Delta(rhom)= 19 cm(-1); site B Delta(tet) = 181 cm(-1), Delta(rhom)= 12 cm(-1). The corresponding zero-field-splitting (ZFS) parameters of the conventional S = 2 spin Hamiltonian are as follows: site A D = 12.02 cm(-)(1), E = 2.123 cm(-1); site B D = 12.15 cm(-1), E = 1.37 cm(-1). A theoretical analysis of the variation of the energies of the low-lying states with respect to displacements along selected normal coordinates of the [Fe(OH2)6]2+, shows the zero-field splitting to be extremely sensitive to small structural perturbations of the complex. The expressions derived are discussed in the context of spin-Hamiltonian parameters reported for the [Fe(OH2)6]2+ cation in different crystalline environments.

We feature our recent work in the field of single-molecule magnets (SMMs) using inelastic neutron scattering (INS). The term "pressure" in the title has a triple meaning. First, there is the expectation from research-funding agencies and the public to make some significant steps towards applications. Second, the synthesis of new compounds and the applications of physical techniques for their understanding are being pushed to their limits. And third, by applying hydrostatic pressure, valuable insight into the mechanisms behind the SMM phenomena can be gained. Examples from our research have been taken to illustrate these points. After a brief introduction to the technique, the strength of INS for the accurate determination of exchange and anisotropy interactions in SMMs is highlighted. We hope to demonstrate that, by pushing INS measurements to their limits, i.e., using the best available neutron sources and instrumentation, combined with high quality samples, new insights into the relevant physical processes in SMMs can be gained.

Time-resolved inelastic neutron scattering measurements on an array of single-crystals of the single-molecule magnet Mn(12)ac are presented. The data facilitate a spectroscopic investigation of the slow relaxation of the magnetization in this compound in the time domain.

From inelastic neutron scattering experiments, we demonstrate quantum tunneling of the Neel vector in the antiferromagnetic molecular ferric wheel CsFe8. Analysis of the linewidth of the tunneling transition evidences coherent tunneling.