A systems-based analysis to rethink the European environmental risk assessment of regulated chemicals using pesticides as a pilot case.

A growing body of scientific literature stresses the need to advance current environmental risk assessment (ERA) methodologies and associated regulatory frameworks to better address the landscape-scale and long-term impact of pesticide use on biodiversity and the ecosystem. Moreover, more collaborative and integrative approaches are needed to meet sustainability goals. The One Health approach is increasingly applied by the European Food Safety Authority (EFSA) to support the transition towards safer, healthier and more sustainable food. To this end, EFSA commissioned the development of a roadmap for action to establish a European Partnership for next-generation, systems-based Environmental Risk Assessment (PERA). Here, we summarise the main conclusions and recommendations reported in the 2022 PERA Roadmap. This roadmap highlights that fragmentation of data, knowledge and expertise across regulatory sectors results in suboptimal processes and hinders the implementation of integrative ERA approaches needed to better protect the environment. To advance ERA, we revisited the underlying assumptions of the current ERA paradigm; that chemical risks are generally assessed and managed in isolation with a substance-by-substance, realistic worst-case and tiered approach. We suggest optimising the use of the vast amount of information and expertise available with pesticides as a pilot area. It is recommended to as soon as possible adopt a systems-based approach, i.e. within the current regulatory framework, to spark a step-wise transition towards an ERA framed at a system level of ecological and societal relevance. Tangible systems-based and integrative steps are available. For instance, the rich sources of existing data for prospective and retrospective ERA of pesticides could be used to reality-benchmark existing and new ERA methods. To achieve these goals, collaboration among stakeholders across scientific disciplines and regulatory sectors must be strengthened.

Levels and vertical distribution of PCBs in agricultural and natural soils from Sweden.

Soils represent an important reservoir for persistent organic pollutants (POPs) in the terrestrial environment and thus the fate of contaminants deposited to the surface soils is important to understand. Since only a limited number of studies of the vertical distribution of POPs are available in the literature, the purpose of this study was to collect and analyze PCB concentrations in different layers of soil cores taken at agricultural and non-agricultural sites in Sweden. PCB concentrations at the agricultural site were nearly uniform on a dry weight basis throughout the depth considered (0-12 cm) while a distinct gradient with depth was observed at the five non-agricultural sites. On an organic carbon normalized basis, the concentration gradient was maintained at three of the non-agricultural sites while a more uniform distribution was observed at the other two sites. A statistically significant relationship between dry weight soil concentrations and organic carbon content was determined for all PCB congeners in the surface layers (0-1 cm) but not in the deeper layers (4-5 cm, 9-10 cm). These results were interpreted in relation to vertical soil transport processes and then the implications for environmental fate models including soil compartments were discussed.

Polychlorinated biphenyls in polysulfide sealants--occurrence and emission from a landfill station.

Approximately 80,000 kg polysulfide sealant containing 10,000-18,000 kg polychlorinated biphenyls (PCB) was deposited at a Swedish municipal landfill station during 1965-1973. Investigations during 1994 showed that soil layers underneath the landfill had concentration of PCB not alarmingly high. The concentration of PCB congeners in ground water samples was elevated 4-750 times compared to a reference sample. Based on samples of ground water, leachate water, and flux chambers measuring evaporation of PCB from the landfill surface, the emission of PCB was estimated to be 1 g sigmaPCB/yr. This very low rate was attributed to the high sorptive capacity of the sealant. Compared to a reference site, the evaporation flux was elevated for the most volatile congeners, but factors 20-1400 lower than from another landfill which was contaminated with PCB in paper-pulp fibres.

Evaluation of sequentially-coupled POP fluxes estimated from simultaneous measurements in multiple compartments of an air-water-sediment system.

Bulk atmospheric deposition fluxes, air-water exchange fluxes, particle settling fluxes out of the upper water column, sediment trap fluxes in deep waters, and sediment burial fluxes of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were simultaneously measured in the Koster Fjord, eastern Skagerak, on the Swedish west coast. The aim of the study was to compare the magnitude and direction of the compound fluxes in the system in order to diagnose key fate processes. The PCB and PAH fluxes via net atmospheric deposition, settling particles out of the surface and through deep waters, as well as into the accreting underlying sediments were shown to be remarkably similar, agreeing within a factor of a few for any given target compound. Fluxes of all PCB and PAH target compounds remained fairly constant with water column depth. Thus there was no evidence for net desorption from sinking particles. The net unidirectional and near balancing of vertical fluxes suggests a net transport of PCBs and PAHs from the atmosphere to the continental shelf sediments in the Koster Fjord, which is consistent with the hypothesis that the shelf sediments are important sinks for these compounds.

Dynamics of lipids and polychlorinated biphenyls in a Baltic amphipod (Monoporeia affinis): a field study.

Processes such as accumulation and elimination, which control tissue concentration of polychlorinated biphenyls (PCBs), were examined over time in an in situ study of the amphipod Monoporeia affinis. These processes were studied with respect to individual PCB congeners, percentage lipid and composition, and body weight. A secondary objective was to examine the impact of seasonal variability in percentage lipids and lipid composition on PCB concentration in two coexisting Baltic amphipods, M. affinis and Pontoporeia femorata. Polycholorinated biphenyl concentrations tended to be higher in P. femorata than in M. affinis, possibly because of P. femorata's lower respiration rate and larger size. The net accumulation of PCBs was congener dependent and negatively correlated to lipid concentration. The relation between the net concentration change rate of 16 PCB congeners over time and log Kow was not significant during the spring and summer months, a time when lipid accumulation and strong growth occur. In contrast, the net concentration change rate of the corresponding PCB congeners over time during autumn and early winter, that is, from the period before gonad maturation to the period after mating and early embryogenesis, showed a significant relation to tog Kow (r2 = 0.62, p < 0.001, n = 16). During the latter period, amphipod lipid weight was reduced while the PCB body burden increased. Results strongly indicate that elimination rather than accumulation is the main process controlling amphipod body burden. This pattern results in a transfer of PCBs from the female to the developing embryos, which is reflected in high PCB body burden in newly released offspring.

Global accounting of PCBs in the continental shelf sediments.

The recycling longevity of hydrophobic organic contaminants (HOCs) within the global environment is set by their permanent removal through processes such as degradation and burial in geological reservoirs. More than 90% of the global sediment burial of organic carbon (OC) occurs on the continental shelves, representing < 10% of the earth's ocean area. The propensity of HOCs to associate with organic matter, and the proximity of most population centers and thus presumed source areas to coastal regions, led us to investigate shelf sediments as a depository of significance for global HOC budgets. Here, the global inventory and burial fluxes of polychlorinated biphenyls (PCBs) in continental shelf sediments were estimated on a congener-specific basis from a database of 4214 distinct continental shelf surface sediment samples. To account for near-urban sampling bias, the locations of each datum relative to nearest population center were classified as Local (< 1 km), Regional (1-10 km), or Remote (> 10 km), according to a comprehensive vector map of the world (Digital Chart of the World) in a GIS environment. The global inventory of, for instance, PCB congener 153 was 1200 ton (95% confidence limit maximum: 2100 ton; and minimum 720 ton). The Remote sub-basin of the North Atlantic contains approximately half of the global shelf sediment inventory for most of the PCB congeners studied. The shelf sediment inventories of individual PCB congeners constitute significant fractions of their recently updated cumulative historical global emissions estimates. The estimated inventory in the shelf corresponds to about 10% of maximum emission estimates for lower-chlorinated congeners. However, for the more bioaccumulable, higher-chlorinated, congeners the shelf reservoirs appear to account for up to 80% of the estimated maximum cumulative global emissions. These shelf inventories represent 1-6% of the global industrial production of PCBs. The global burial fluxes were estimated to be on the order of 8-24 ton/yr each for the eight major congeners investigated, again, with the shelf constituting a more significant removal sink of the more chlorinated congeners. The permanent removal into deeper shelf sediments of PCB153 and PCB180 suggests that the global environmental mean residence times of these pollutants are on the order of 110 and 70 years, respectively. Hence, even after production and direct releases have been halted, we may expect to be exposed to such persistent pollutants for decades and centuries to come.