Evaluation of the bioaccumulation of octocrylene after dietary and aqueous exposure

Highlights: • Saturated solutions of octocrylene could not be reliably produced by passive dosing. • Experimental data for OCR: BCF = 858 L kg⁻¹ (zebrafish), BMF: 0.0335 (rainbow trout) • Experimental BCF is in good agreement with BCF-estimation using OECD tools. -- Abstract: Octocrylene is used as UV filter in personal care products with a high production volume and can be detected in surface water and biota. It is liquid at ambient temperature, highly lipophilic, has a high adsorption capacity to organic material and is considered as persistent in the environment. The very low water solubility complicates the evaluation of potential long-term effects in aquatic toxicity testing, since effect thresholds are often above the water solubility limit. Thus, the evaluation of the bioaccumulation potential becomes highly relevant for the assessment of long-term environmental effects. However, even the determination of the water solubility limit for a substance with such difficult properties is challenging. The following experiments are described, and results compared to available environmental monitoring data: A bioconcentration study with aqueous exposure (BCF) in zebrafish and a biomagnification study with dietary exposure (BMF) in rainbow trout, as well as supporting experiments to evaluate the water solubility. The growth and lipid corrected BCF determined by aqueous exposure was 858 L kg⁻¹ while the corrected BMF was 0.0335. The model-based estimation of the BCF from BMF (152–1182 L kg⁻¹) is in good agreement with the measured BCF value. Environmental monitoring data provide only limited information on the bioaccumulation potential of octocrylene, as only few investigations were made in biota and water in parallel and concentrations of octocrylene vary by several orders of magnitude during seasons. Based on the determined fish BCF data, we conclude that OCR is not bioaccumulative according to the criteria as laid down by ECHA, 2017. Furthermore, the low BMF value indicates no accumulation along the food chain.