Implementation of the CREED approach for environmental assessments.

Environmental exposure data are a key component of chemical and ecological assessments, supporting and guiding environmental management decisions and regulations. Measures taken to protect the environment based on exposure data can have social and economic implications. Flawed information may lead to measures being taken in the wrong place or to important action not being taken. Although the advantages of harmonizing evaluation methods have been demonstrated for hazard information, no comparable approach is established for exposure data evaluation. The goal of Criteria for Reporting and Evaluating Exposure Datasets (CREED) is to improve the transparency and consistency with which exposure data are evaluated regarding usability in environmental assessments. Here, we describe the synthesis of the CREED process, and propose methods and tools to summarize and interpret the outcomes of the data usability evaluation in support of decision-making and communication. The CREED outcome includes a summary that reports any key gaps or shortcomings in the reliability (data quality) and relevance (fitness for purpose) of the data being considered. The approach has been implemented in a workbook template (provided as Supporting Information), for assessors to readily follow the workflow and create a report card for any given dataset. The report card communicates the outcome of the CREED evaluation and summarizes important dataset attributes, providing a concise reference pertaining to the dataset usability for a specified purpose and documenting data limitations that may restrict data use or increase environmental assessment uncertainty. The application of CREED is demonstrated through three case studies, which also were used during beta testing of the methodology. As experience with the CREED approach application develops, further improvements may be identified and incorporated into the framework. Such development is to be encouraged in the interest of better science and decision-making, and to make environmental monitoring and assessment more cost-effective. Integr Environ Assess Manag 2024;20:1019-1034. © 2024 SETAC.

Petroleum refinery effluent contribution to chemical mixture toxic pressure in the environment.

Petroleum refinery effluents (PRE) are wastewaters from industries associated with oil refining. Within Europe, PREs are regulated through local discharge permits and receive substantial treatment before emission. After treatment, PREs can still contain low levels of various pollutants potentially toxic to organisms. Earlier work, including whole-effluent toxicity assessments, has shown that the toxicity of permitted PREs is often limited. However, the extent to which PREs contribute to chemical pollution already present in the receiving environment is unknown. Therefore, our study aimed to assess the contribution of PREs to mixture toxic pressure in the environment, using the multi-substance potentially affected fraction of species (msPAF) as an indicator. Based on measured chemical concentrations, compiled species sensitivity distributions (SSD) and a mechanistic solubility model, msPAF levels were estimated for undiluted effluents at discharge points and diluted effluents downstream in receiving waters. Median msPAF-chronic and msPAF-acute levels of PREs at discharge points were 74% (P50) and 40% (P95), respectively. The calculated msPAF levels were reduced substantially to <5% downstream for most effluents (82%), indicating low to negligible toxicity of PREs in receiving environments beyond the initial mixing zone. Regardless of differences in endpoints and locations, hydrocarbons (mainly total petroleum hydrocarbons) and inorganics (mainly ammonia) explained at least 85% of the mixture toxic pressure. The msPAF levels of PREs were on average 2.5-4.5 orders of magnitude lower than msPAF levels derived from background pollution levels, suggesting that PREs were minor contributors to the toxic pressure in the environment. This study presents a generic methodology for quantifying the potential toxic pressure of PREs in the environment, identifying hotspots where more effective wastewater treatment could be needed. We explicitly discuss the uncertainties for further refinement and development of the method.

The heterodimeric ecdysteroid receptor complex in the brown shrimp Crangon crangon: EcR and RXR isoform characteristics and sensitivity towards the marine pollutant tributyltin.

Decapod crustaceans are characterized by multiple ecdysteroid receptor (EcR) and retinoid-X-receptor (RXR) isoforms, which likely exhibit variant dimerization and transactivation interactions. In the brown shrimp C. crangon we cloned C-terminally truncated CrcEcR and CrcRXR isoforms and isoforms exhibiting deletions within the hinge region. For the former, in silico modeling of the CrcEcR indicated that, where the conserved helices H10 and H11 of the ligand-binding domain (LBD) are missing, an alternative C-terminal α-helix repairs the ligand-binding pocket (LBP). The truncated CrcRXR isoforms lack a major part of the LBD (H4-H12), thereby compromising ligand binding and dimerization. Through an in vitro ecdysteroid responsive reporter assay, we showed that these natural receptor variations do not impair receptor functioning but probably alter the receptor dimerization preferences. By the same in vitro assay, using full-length CrcEcR and CrcRXR, the effect of tributyltin (TBT) on ecdysteroid-induced transactivation was evaluated. The transactivation by 10nM PonA was reduced with 64% by 20 nM TBT. In silico modeling confirmed that TBT fits in the full-length CrcRXR-LBD. Furthermore, semi-quantitative PCR indicated altered expression of CrcEcR and CrcRXR isoforms after in vivo acute exposure to TBT, especially in the ovaries.

The brown shrimp (Crangon crangon L.) ecdysteroid receptor complex: cloning, structural modeling of the ligand-binding domain and functional expression in an EcR-deficient Drosophila cell line.

cDNAs encoding ecdysteroid receptor (EcR) and retinoid X receptor (RXR) were cloned and sequenced from brown shrimp Crangon crangon (Crustacea: Decapoda), a common faunal species and commercially important in the North-West European coastal waters. A 3D model of the ligand-binding domain (LBD) of EcR was created and docking of ponasterone A (PonA) was simulated in silico. Finally, we report the transfection of expression plasmids for these receptors in the mutant Drosophila L57-3-11 cell line. Through an ecdysteroid responsive reporter assay we clearly prove the functionality of shrimp ecdysteroid receptor in the transfected L57-3-11 cell line. Our results indicate that the Drosophila L57-3-11 cell line and in silico LBD modeling can be used to study the function of crustacean ecdysteroid receptors and be applied to assess endocrine disrupting effects on non-target crustacean species.