title: Including Bioconcentration Kinetics for the Prioritization and Interpretation of Regulatory Aquatic Toxicity Tests of Highly Hydrophobic Chemicals.
abstract: Worldwide, regulations of chemicals require short-term toxicity data for evaluating hazards and risks of the chemicals. Current data requirements on the registration of chemicals are primarily based on tonnage and do not yet consider properties of chemicals. For example, short-term ecotoxicity data are required for chemicals with production volume greater than 1 or 10 ton/y according to REACH, without considering chemical properties. Highly hydrophobic chemicals are characterized by low water solubility and slow bioconcentration kinetics, which may hamper the interpretation of short-term toxicity experiments. In this work, internal concentrations of highly hydrophobic chemicals were predicted for standard acute ecotoxicity tests at three trophic levels, algae, invertebrate, and fish. As demonstrated by comparison with maximum aqueous concentrations at water solubility, chemicals with an octanol-water partition coefficient (Kow) greater than 106are not expected to reach sufficiently high internal concentrations for exerting effects within the test duration of acute tests with fish and invertebrates, even though they might be intrinsically toxic. This toxicity cutoff was explained by the slow uptake, i.e., by kinetics, not by thermodynamic limitations. Predictions were confirmed by data entries of the OECD's screening information data set (SIDS) (n = 746), apart from a few exceptions concerning mainly organometallic substances and those with inconsistency between water solubility and Kow. Taking error propagation and model assumptions into account, we thus propose a revision of data requirements for highly hydrophobic chemicals with log Kow> 7.4: Short-term toxicity tests can be limited to algae that generally have the highest uptake rate constants, whereas the primary focus of the assessment should be on persistence, bioaccumulation, and long-term effects.
authors.affiliation: Division of Environmental Science and Ecological Engineering, Korea University , 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea.
authors.forename: Jung-Hwan
authors.initials: JH
authors.lastname: Kwon
authors.affiliation: Division of Environmental Science and Ecological Engineering, Korea University , 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea.
authors.forename: So-Young
authors.initials: SY
authors.lastname: Lee
authors.affiliation: Division of Environmental Science and Ecological Engineering, Korea University , 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea.
authors.forename: Hyun-Joong
authors.initials: HJ
authors.lastname: Kang
authors.affiliation: Department of Environmental Engineering, Technical University of Denmark , Bygningstorvet B115, DK-2800 Kongens Lyngby, Denmark.
authors.forename: Philipp
authors.initials: P
authors.lastname: Mayer
authors.affiliation: Department of Cell Toxicology, Helmholtz Centre for Environmental Research - UFZ , Permoserstrasse 15, DE-04318 Leipzig, Germany.|Environmental Toxicology, Center for Applied Geoscience, Eberhard Karls University Tübingen , Hölderlinstrasse 12, DE-72074 Tübingen, Germany.
authors.forename: Beate I
authors.initials: BI
authors.lastname: Escher
mesh_terms: D000818:Animals; D005399:Fishes; D057927:Hydrophobic and Hydrophilic Interactions; D007448:Invertebrates / Q000187:drug effects*; D007700:Kinetics; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical