Bioconcentration of 15N-tamoxifen at environmental concentration in liver, gonad and muscle of Danio rerio

• Danio rerio were exposed during 21 d at environmental tamoxifen concentrations.
• Tamoxifen concentration were measured in gonads, liver and muscle.
• 15N labelling demonstrated tamoxifen bioconcentration in fish.
• Maximum BCF up to 85,000 were estimated in gonads of female Danio rerio.

Pharmaceutical compounds (PCs) are ubiquitous in aquatic ecosystems. In addition to the direct ecotoxicological risk presented by certain PCs, others can accumulate inside organisms and along trophic webs, subsequently contaminating whole ecosystems. We studied the bioconcentration of a bioaccumulative PC already found several times in the environment: tamoxifen. To this end, we exposed Danio rerio for 21 d to 15N-tamoxifen concentrations ranging from 0.1 to 10 µg/L and used an analytic method based on stable isotopes to evaluate the tamoxifen content in these organisms. The evolution of the 15N/14N ratio was thus measured in liver, muscle and gonads of exposed fish compared to control fish. We succeeded in quantifying 15N-tamoxifen bioconcentrations at all the exposure concentrations tested. The highest bioconcentration factors of tamoxifen measured were 14,920 in muscle, 73,800 in liver and 85,600 in gonads of fish after 21 d exposure at a nominal concentration of 10 µg/L. However, these bioconcentration factors have to be considered as maximal values (BCFMAX). Indeed, despite its proven stability, tamoxifen can be potentially partially degraded during experiments. We now need to refine these results by using a direct analytic method (i.e. LC–MS/MS).

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