Tamoxifen ecotoxicity and resulting risks for aquatic ecosystems

Area of Science:

• Environmental Science
• Ecotoxicology
• Pharmaceutical Chemistry

Background:

• Tamoxifen, a widely used cancer therapeutic, is frequently detected in aquatic environments at concentrations up to several hundred ng L(-1).
• Understanding the environmental impact of pharmaceutical compounds is crucial for maintaining ecosystem health.

Purpose of the Study:

• To assess the ecotoxicity of tamoxifen across multiple trophic levels.
• To establish a Predictive No Effect Concentration (PNEC) for tamoxifen in continental waters.
• To evaluate the environmental risk of tamoxifen in surface waters by calculating Risk Quotients (RQ).

Main Methods:

• A battery of ecotoxicity bioassays was performed on primary producers (Pseudokirchneriella subcapitata, Chlorella vulgaris, Chlamydomonas reinhardtii), primary consumers (Daphnia magna), and secondary consumers (Danio rerio).
• Standard ecotoxicological tests including immobilization, grazing, reproduction, and embryotoxicity were employed.
• PNEC was derived from experimental data and literature values, followed by RQ calculation using measured environmental concentrations.

Main Results:

• Tamoxifen exhibited varying degrees of ecotoxicity across the tested organisms and trophic levels.
• A PNEC of 81 ng L(-1) was established for continental water.
• Risk Quotients (RQ) greater than 1 were calculated for two of the four studied hydrosystems, indicating potential environmental risk.

Conclusions:

• The presence of tamoxifen in surface waters can pose ecotoxicological risks, with RQs exceeding 1 in some locations.
• Further investigation into the environmental risks associated with tamoxifen discharge is warranted.
• The proposed risk assessment approach can be applied to other pharmaceutical residues in the environment.