In the frame of the characterization of environmental risk assessment linked to abandoned uranium mines in the Limousin region (France) and in the context of the DEVIL program (Development and validation of fish biomarkers for the implementation of environmental legislation) led by INERIS (National institute for industry environment and risks), a study has been conducted on the effects of uranium mining releases on roach health status. The first part of the work was the search of potential sites for the study. Based on information from IRSN (National institute for radioprotection and nuclear safety) and from the owner of old mines, two private pounds were identified: one presenting uranium contamination, and one upstream the mining zone presenting no uranium in water. Roaches were therefore caged during one month on these two pounds. Biological sampling have been performed at the beginning of the experiment, and 2 and 4 weeks after, in order to measure several parameters: immune parameters followed by flow cytometry (phagocytosis, ROS production, apoptosis, lyosomes), genotoxicity (comet assay), oxidative stress (glutathione, lipoperoxidation), biotransformation (EROD, GST, ABC transporter), neurotoxicity (AChE), endocrine disruption (vitellogenin) and physiological parameters (ADN/ARN ratio, stomach contents, otoliths, condition index, sex ratio). Physico-chemical parameters of water and sediments (cations, anions, metals, radioactive elements) were also followed and bioaccumulation of metals in several organs (muscle, liver, kidney, gonad and gill) was measured. The results showed on the uranium contaminated site a water contamination of iron, aluminium, barium and manganese. Aluminium and iron were also present in the water of the uranium-free site. The sediments from the uranium contaminated site showed high levels of radioactive elements coming from the disintegration chain of uranium. Preliminary biological results indicated a stimulation of immune parameters, an increase of oxidative stress and a decrease of AChE in fish coming from the uranium contaminated site compared to the uranium-free site. The whole results, using integrated index, will allow the establishment of roach health status in the context of pluri-metallic mining release pollution. These data will strengthen the research for the improvement of methods and tools needed for the environmental risk assessment associated to radioactive substances in the environment.
The risk posed by complex chemical mixtures in the environment to wildlife and humans is increasingly debated, but has been rarely tested under environmentally relevant scenarios. To address this issue, two mixtures of 14 or 19 substances of concern (pesticides, pharmaceuticals, heavy metals, polyaromatic hydrocarbons, a surfactant, and a plasticizer), each present at its safety limit concentration imposed by the European legislation, were prepared and tested for their toxic effects. The effects of the mixtures were assessed in 35 bioassays, based on 11 organisms representing different trophic levels. A consortium of 16 laboratories was involved in performing the bioassays. The mixtures elicited quantifiable toxic effects on some of the test systems employed, including i) changes in marine microbial composition, ii) microalgae toxicity, iii) immobilization in the crustacean Daphnia magna, iv) fish embryo toxicity, v) impaired frog embryo development, and vi) increased expression on oxidative stress-linked reporter genes. Estrogenic activity close to regulatory safety limit concentrations was uncovered by receptor-binding assays. The results highlight the need of precautionary actions on the assessment of chemical mixtures even in cases where individual toxicants are present at seemingly harmless concentrations.
