Nested interactions in the combined toxicity of uranium and cadmium to the nematode Caenorhabditis elegans.
Uranium is a natural, ubiquitous radioactive element for which elevated concentrations can be found in the vicinity of some nuclear fuel cycle facilities or intensive farming areas, and most often in mixtures with other contaminants such as cadmium, due to co-occurrence in geological ores (e.g. U- or P-ore). The study of their combined effects on ecosystems is of interest to better characterize such multi-metallic polluted sites. In the present study, the toxicity of binary mixture of U and Cd on physiological parameters of the soil nematode Caenorhabditis elegans was assessed over time. Descriptive modeling using concentration and response addition reference models was applied to compare observed and expected combined effects and identify possible synergistic or antagonistic interactions. A strong antagonism between U and Cd was identified for length increase and brood size endpoints. The study revealed that the combined effects might be explained by two nested antagonistic interactions. We demonstrate that the first interaction occurred in the exposure medium. We also identified a significant second antagonistic interaction which occurred either during the toxicokinetic or toxicodynamic steps. These findings underline the complexity of interactions that may take place between chemicals and thus, highlight the importance of studying mixtures at various levels to fully understand underlying mechanisms.
Biogeochemistry, Bioavailability and Radionuclide Transfer Laboratory (PRP-ENV/SERIS/L2BT), Institute of Radioprotection and Nuclear Safety (IRSN), Cadarache, Building 183, BP3, 13115 St-Paul-lez-Durance Cedex, France. Electronic address: adrien.margerit@gmail.com.
Adrien
A
Margerit
Laboratory of ECOtoxicology (PRP-ENV/SERIS/LECO), Institute of Radioprotection and Nuclear Safety (IRSN), Cadarache, Building 183, BP3, 13115 St-Paul-lez-Durance Cedex, France.
Catherine
C
Lecomte-Pradines
NERC Centre for Ecology and Hydrology, Maclean Building, Benson Lane, Crowmarsh-Gifford, Wallingford, Oxfordshire OX10 8BB, United Kingdom.
Claus
C
Svendsen
Biogeochemistry, Bioavailability and Radionuclide Transfer Laboratory (PRP-ENV/SERIS/L2BT), Institute of Radioprotection and Nuclear Safety (IRSN), Cadarache, Building 183, BP3, 13115 St-Paul-lez-Durance Cedex, France.
Sandrine
S
Frelon
UMR Hydrosciences- Université Montpellier 1, DSESP-Faculté de Pharmacie, BP 14491, no 15 Av Charles Flahault, 34093 Montpellier Cedex 05, France.
Elena
E
Gomez
Biogeochemistry, Bioavailability and Radionuclide Transfer Laboratory (PRP-ENV/SERIS/L2BT), Institute of Radioprotection and Nuclear Safety (IRSN), Cadarache, Building 183, BP3, 13115 St-Paul-lez-Durance Cedex, France. Electronic address: rodolphe.gilbin@irsn.fr.
Rodolphe
R
Gilbin
D000818:Animals; D002104:Cadmium / Q000633:toxicity*; D017173:Caenorhabditis elegans / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D012098:Reproduction / Q000187:drug effects; D012989:Soil Pollutants / Q000633:toxicity*; D014501:Uranium / Q000633:toxicity*
D012989:Soil Pollutants; D002104:Cadmium; D014501:Uranium
Antagonism; Joint effects; MIXTOX; Metals; Mixture toxicity