Bioconcentration of 15N-tamoxifen at environmental concentration in liver, gonad and muscle of Danio rerio
Abstract
Pharmaceutical compounds (PCs) are ubiquitous in aquatic ecosystems. In addition to the direct eco- toxicological risk presented by certain PCs, others can accumulate inside organisms and along trophic webs, subsequently contaminating whole ecosystems. We studied the bioconcentration of a bioaccu- mulative 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 mg/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 mg/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 re␣ne these results by using a direct analytic method (i.e. LC–MS/MS).