• Chironomus dilutus;
  • Fiber–water partition coefficients (Kfw);
  • Freely dissolved chemical concentration;
  • Hyalella azteca;
  • Solid phase microextraction


Use of solid-phase microextraction (SPME) fibers as a dose metric for toxicity testing was evaluated for hydrophobic pesticides to the midge Chironomus dilutus and the amphipod Hyalella azteca. Test compounds included p,p′-dichlorodiphenyltrichloroethane (p,p′-DDT), p,p-dichlorodiphenyldichloroethane (p,p′-DDD), p,p-dichlorodiphenyldichloroethylene (p,p′-DDE), permethrin, bifenthrin, tefluthrin, and chlorpyrifos. Acute water toxicity tests were determined for 4- and 10-d exposures in both species. Median lethal and sublethal concentrations were expressed both on a water concentration (LC50 and EC50) and on an equilibrium SPME fiber concentration (LC50fiber and EC50fiber) basis. A significant log dose–response relationship was found between log fiber concentration and organism mortality. It has been shown in the literature that equilibrium SPME fiber concentrations reflect the bioavailable concentrations of hydrophobic contaminants, so these fiber concentrations should be a useful metric for assessing toxic effects from the bioavailable contaminant providing a framework to expand the use of SPME fibers beyond estimation of bioaccumulation. Environ. Toxicol. Chem. 2012; 31: 2159–2167. © 2012 SETAC