Accounting for the dissociating properties of organic chemicals in LCIA: An uncertainty analysis applied to micropollutants in the assessment of freshwater ecotoxicity

Abstract

In life cycle impact assessment (LCIA) models, the sorption of the ionic fraction of dissociating organic chemicals is not adequately modeled because conventional non-polar partitioning models are applied. Therefore, high uncertainties are expected when modeling the mobility, as well as the bioavailability for uptake by exposed biota and degradation, of dissociating organic chemicals. Alternative regressions that account for the ionized fraction of a molecule to estimate fate parameters were applied to the USEtox model. The most sensitive model parameters in the estimation of ecotoxicological characterization factors (CFs) of micropollutants were evaluated by Monte Carlo analysis in both the default USEtox model and the alternative approach. Negligible differences of CFs values and 95% confidence limits between the two approaches were estimated for direct emissions to the freshwater compartment; however the default USEtox model overestimates CFs and the 95% confidence limits of basic compounds up to three orders and four orders of magnitude, respectively, relatively to the alternative approach for emissions to the agricultural soil compartment. For three emission scenarios, LCIA results show that the default USEtox model overestimates freshwater ecotoxicity impacts for the emission scenarios to agricultural soil by one order of magnitude, and larger confidence limits were estimated, relatively to the alternative approach.

Characterizing antibiotics in LCA—a review of current practices and proposed novel approaches for including resistance

“…Seventeen LCA-related articles deal with ABs, of which two consider indirect toxic impacts related to AB production and transportation (Stone et al 2010(Stone et al , 2011, three calculate freshwater ecotoxicity CFs for ABs and use them in LCAs (Muñoz et al 2008;Henriksson et al 2015;Li et al 2019), two only calculate CFs for ABs (Alfonsín et al 2014;Ortiz de García et al 2017) and eight use available CFs for ABs to conduct LCAs (Muñoz et al 2009;Hospido et al 2010;Igos et al 2012Igos et al , 2013Lorenzo-Toja et al 2016;Rahman et al 2018;Tarpani and Azapagic 2018;Tarpani et al 2020). Meanwhile, Morais et al (2013) compare the uncertainty and variability of characterization results at various pH using the USEtox scientific consensus model V1.01 (Rosenbaum et al 2008) (Guinée et al 2002). Henriksson et al (2015), Tarpani and Azapagic (2018), and Tarpani et al (2020) all characterize freshwater ecotoxicity using USEtox V1.01, while Lorenzo-Toja et al ( 2016) characterize emissions using USES-LCA 2.0.…”

“…The cause for inconsistencies in freshwater ecotoxicity CFs remains unclear since the underlying toxicity data used for calculating the effect factors remain unavailable. However, Morais et al (2013) show that CFs are sensitive to differences in abiotic degradation rates as well as ecotoxicological effect (EC50) data, which generally are sourced from different empirical experiments, as no standardized database for such data is available for ABs. Nonetheless, the chemical properties and experimental data on ABs that support the CFs remain inconsistent across literature.…”

Modeling pharmaceutical emissions and their toxicity‐related effects in life cycle assessment (LCA): A review

“…In LCIA models, such as USEtox, the dissociating properties of organic chemicals such as pharmaceuticals (i.e., their acid‐base character and their ionization under varying pH conditions) are not considered in the fate modeling, because conventional nonpolar partitioning models are applied. This omission, in turn, leads to high uncertainties when modeling API distribution or mobility between environmental matrices, their degradation, and their bioavailability for uptake (Morais et al ). Furthermore, human medicinal products have the unique route of “direct exposure” of patients undergoing treatment with a 100% chemical intake fraction compared to the indirect uptake of PhACs (or other chemical pollutants) via water, air, or food products.…”

“…As for the inaccurate fate modeling disregarding the dissociating properties of pharmaceuticals, a few advancements have been made in this regard. Morais et al () and van Zelm et al () updated the fate models in USEtox and USES‐LCA, respectively, to account for the influence of ionization and pH dependency of ionic chemicals (including APIs) in the estimation of their fate factors. Direct exposure of patients to pharmaceuticals may potentially be modeled by use of advancements within the USEtox model, which improved the exposure modeling to account for direct consumer exposure to chemicals encompassed in consumer products during the use phase (Fantke et al ).…”

A Review of the Environmental Fate and Effects of Acesulfame‐Potassium

“…Tran et al (2015) reported comparably low ACE‐K sludge K d sorption coefficients of 10.1 L/kg to 34.7 L/kg in lab batch experiments for conventional activated sludge and nitrifying activated sludge, respectively. The K d values <500 indicate a strong potential to migrate with water rather than attach to soil or sludge particles (Morais et al 2013). In addition, the p K a of ACE‐K is 2.0 (Supplemental Data Figure S1), which suggests that it will exist almost completely in the anion form in the environment.…”