A Scientifically Robust and Regulatory Critical Fish ( Pimephales promelas ) Full Life Cycle Study with Ibuprofen: Fulfilling Chronic Toxicity Data Gaps to Support Informed Environmental Risk Assessment

Abstract

Robust chronic ecotoxicological data are essential for EU pharmaceutical regulation, yet many ibuprofen studies in the public domain fail to meet quality criteria, creating uncertainty in its chronic aquatic toxicity profile. Additionally, due to the cost and complexity of full life-cycle fish tests, most studies focus on early/specific life stages rather than reproductive outcomes, limiting insights into population-level effects.

The authors used a collaborative approach that included consultation with leading academic experts and regulatory authorities to develop a full life cycle test suitable for investigating the toxicological effects of ibuprofen to fish (Pimephales promelas).

Fish were continuously exposed from F0 embryos (<24-hours old) through all growth and reproduction stages to the production and growth of free feeding F1 juveniles. The nominal test concentrations (0.01, 0.032, 0.10, 0.32, and 1.0 mg/L) were selected based on scientific literature and the findings of OECD 236 Fish Embryo Toxicity Tests (FET) and a larval growth test that were used as range finding tests. Ecotoxicology endpoints (NOEC, LOEC, EC10) of relevance were determined and no statistically significant effects were identified at the highest test concentration (1.0 mg/L) for all endpoints except F0 survival and F1 hatching success.

These endpoints were considered to represent the most sensitive NOEC (0.32 mg/L) based on statistical significance (p < 0.05) but following additional statistics that identified an outlier the NOEC of ≥ 1.0 mg/L based on biological significance was concluded.