Compartment‐Specific Screening Tools for Persistence: Potential Role and Application in the Regulatory Context

Abstract

The persistence assessment under the European Union regulation Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) relies on compartment‐specific degradation half‐lives derived from laboratory simulation studies with surface water, aquatic sediment, or soil. Although these data are given priority, they are not available for most of the compounds. Therefore, according to the Integrated Assessment and Testing Strategy (ITS) for persistence assessment, results from ready biodegradability tests (RBTs) are used within a persistence screening to decide whether a substance is considered as “not persistent” or “potentially persistent.” However, ready biodegradability is currently tested only in water. Consequently, there is a lack of approaches that include the soil and sediment compartments for persistence assessment at the screening level. In previous studies, compartment‐specific screening tools for water‐sediment (Water‐Sediment Screening Tool [WSST]) and soil (Soil Screening Tool [SST]) were developed based on the existing test guideline Organisation for Economic Development and Co‐operation (OECD TG 301C [MITI (Ministry of International Trade and Industry, Japan) test]). The test systems MITI, WSST, and SST were successfully applied to determine sound and reliable biodegradation data for 15 test compounds. In the present study, these results are used within the scope of a new alternative persistence screening approach, the Compartment‐Specific Persistence Screening (CSPS). Compared to the persistence screening under REACH, the CSPS is a more conservative approach that provides additional reasonable results, particularly for compounds that sorb to sediment and soil, and for which the current standard persistence screening might be insufficient. Thus, the CSPS can be used to identify potentially persistent and nonpersistent compounds in the regulatory context by a comprehensive assessment that includes water, soil, and sediment. Moreover, experimentally determined half‐lives from the compartment‐specific screening tools can be used as input for multimedia models that estimate, for example, overall persistence (Pov). The application of fixed half‐life factors to extrapolate from water to soil and sediment, which is here demonstrated to be inappropriate, can thereby be avoided. Integr Environ Assess Manag 2019;00:000–000. © 2019 SETAC

Moving persistence assessments into the 21st century: A role for weight‐of‐evidence and overall persistence

“…First introduced by Mackay ( 1979 ), P ov is defined as the residence time of a contaminant within a defined environment and is based on compartment‐specific half‐lives, compartment‐specific dimensions, and mass transfer processes. In contrast to single‐compartment, half‐life criteria, this metric treats the environment as a single, unified set of connected media, integrating single‐media half‐lives based on degradation processes and phase partitioning, and allowing for the persistence of a substance in the whole environment to be estimated (Junker et al, 2019 ; Webster et al, 1998 ; Wegmann et al, 2009 ). P ov can be calculated using various multimedia fate and transport models (MFTMs), which are applied mathematical models that relate multiphase partitioning and environmental fate properties to residence time to predict P ov or overall half‐life ( t 1/2 , ov ) of a substance of interest.…”

Publicly available QSPR models for environmental media persistence

“…Chemicals that are persistent, bioaccumulative and toxic (PBT) or very persistent and very bioaccumulative (vPvB) are of high concern for the environment. Their low ability for degradation lead to accumulation in the environment, possible bioaccumulation and long-term effects in living organisms, and in some cases they can undergo long-range transport and contaminate remote areas [1]. Persistence is defined as the ability of a chemical to stay unchanged in the environment for a long time [2].…”