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Substances with (very) persistent, (very) bioaccumulative, and/or toxic properties (PBT/vPvB) are of environmental concern and are identified via hazard-based PBT-assessment approaches. The PBT-assessment of well-defined substances is optimized over the past decades, but is under development for substances of unknown or variable composition, complex reaction products or biological materials (UVCBs). Particularly, the large number of constituents and variable composition complicate the PBT-assessment of UVCBs. For petroleum UVCBs, the use of the hydrocarbon block method (HBM) is proposed. Within this method, groups of constituents with similar physicochemical properties and structure are treated as a single entity and are expected to have comparable environmental fate and hazard properties. So far, however, there is a lack of experience with the application of the HBM for PBT-assessment purposes. The aim of this study is to investigate the suitability of the HBM for the PBT-assessment of petroleum UVCBs by evaluating the group of alkylated three-ring polycyclic aromatic hydrocarbons (PAHs). The presented approach is based on experimental data and model predictions and followed the guidelines of the European Chemicals Agency. Because of a lack of relevant experimental data, relative trend analyses were applied. The results indicate that alkylated three-ring PAHs are more persistent, bioaccumulative, and toxic than the parent three-ring PAHs. As the parent three-ring PAHs are currently identified within Europe as PBT/vPvB substances, the alkylated three-ring PAHs could also be considered as PBT/vPvB. Accordingly, this case study provides the prospects for the application of the HBM for the PBT-assessment of UVCBs using trend analysis., (Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

The fish bioconcentration factor (BCF) is an important aspect within bioaccumulation assessments. Several factors have been suggested to influence BCF values - including species, developmental stage, mixture exposure, and calculation method. However, their exact contribution to variance in BCF values is unknown. Within this study we assessed the relative impact of these test characteristics on BCF values and analyzed the reproducibility of aquatic exposure bioconcentration tests. Linear mixed effects analyses were performed on a newly develop database to investigate the relationship between the response variable (i.e. lipid normalized log BCF values) and several test characteristics as fixed effects. Lower BCF values were observed for substances that were simultaneously applied with high molecular weight polycyclic aromatic hydrocarbons compared to single substance exposure (with an average difference of -0.81 log BCF). Also, lower BCFs upon kinetic determination were observed compared to steady-state BCFs (log BCF -0.27), and lower BCFs for species from the Ostariophysi subcohort level (log BCF -0.17 to -0.15). In addition, data analysis showed high variation within BCF values for single substances (average SD = log BCF 0.21), which questions the robustness of the current bioaccumulation assessments. For example, the 95% confidence range of a BCF value of 2500 ranges from 953 ('not-bioaccumulative') to 6561 ('very bioaccumulative'). Our results show that the use of one single BCF leads to a high uncertainty in bioaccumulation assessments. We strongly recommend that within future bioconcentration studies, the used experimental design and test conditions are described in detail and justified to support solid interpretation., (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: It has been suggested that the plasticizer di(2-ethylhexyl) phthalate (DEHP) exerts obesogenic effects after pre- or perinatal exposure., Objective: A systematic review with meta-analyses was conducted of early life exposure to DEHP, or its biologically active metabolite mono(2-ethylhexyl) phthalate (MEHP), on the obesity related outcome measures body weight, fat (pad) weight, triglycerides, free fatty acids and leptin in experimental rodent studies., Methods: The applied methodology was pre-specified in a rigorous protocol. Relevant articles were identified using PubMed and EMBASE and meta-analyses were performed using mean differences (MD) and random effects model when at least five studies could be included per outcome measure. Risk of bias and the quality of evidence was assessed using established methodologies., Results: Overall, 31 studies could be included and meta-analyses could be performed for body weight and fat weight. Early life exposure to DEHP was significantly associated with increased fat weight (MD = 0.02; 95% CI: 0.00, 0.03), while a non-significant association was estimated for body weight (MD = -0.14; 95% CI: -0.32, 0.04). There was substantial heterogeneity across studies and the information was insufficient to assess the risk of bias for most studies. No meta-analyses could be conducted for other outcome measures, because too few studies were available., Conclusions: The results of this systematic review indicate that early life exposure to DEHP is potentially associated with increased adiposity in rodents. More data is needed to strengthen the evidence base., (Copyright © 2017. Published by Elsevier Ltd.)