Significance of xenobiotic metabolism for bioaccumulation kinetics of organic chemicals in Gammarus pulex.

Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland.
Environmental Science & Technology (Impact Factor: 5.26). 02/2012; 46(6):3498-508. DOI: 10.1021/es204611h
Source: PubMed

ABSTRACT Bioaccumulation and biotransformation are key toxicokinetic processes that modify toxicity of chemicals and sensitivity of organisms. Bioaccumulation kinetics vary greatly among organisms and chemicals; thus, we investigated the influence of biotransformation kinetics on bioaccumulation in a model aquatic invertebrate using fifteen (14)C-labeled organic xenobiotics from diverse chemical classes and physicochemical properties (1,2,3-trichlorobenzene, imidacloprid, 4,6-dinitro-o-cresol, ethylacrylate, malathion, chlorpyrifos, aldicarb, carbofuran, carbaryl, 2,4-dichlorophenol, 2,4,5-trichlorophenol, pentachlorophenol, 4-nitrobenzyl-chloride, 2,4-dichloroaniline, and sea-nine (4,5-dichloro-2-octyl-3-isothiazolone)). We detected and identified metabolites using HPLC with UV and radio-detection as well as high resolution mass spectrometry (LTQ-Orbitrap). Kinetics of uptake, biotransformation, and elimination of parent compounds and metabolites were modeled with a first-order one-compartment model. Bioaccumulation factors were calculated for parent compounds and metabolite enrichment factors for metabolites. Out of 19 detected metabolites, we identified seven by standards or accurate mass measurements and two via pathway analysis and analogies to other compounds. 1,2,3-Trichlorobenzene, imidacloprid, and 4,6-dinitro-o-cresol were not biotransformed. Dietary uptake contributed little to overall uptake. Differentiation between parent and metabolites increased accuracy of bioaccumulation parameters compared to total (14)C measurements. Biotransformation dominated toxicokinetics and strongly affected internal concentrations of parent compounds and metabolites. Many metabolites reached higher internal concentrations than their parents, characterized by large metabolite enrichment factors.

  • [Show abstract] [Hide abstract]
    ABSTRACT: To investigate the distribution, bioconcentration, metabolism, and biomarker responses of macrolide antibiotic roxithromycin (ROX) in fish, crucian carp (Carassius auratus) were exposed to various concentrations of ROX (4, 20, and 100μgL(-1)) for 20d. The ROX content in different tissues was quantified using UPLC/MS/MS. The liver exhibited the highest ROX concentration followed by the bile, gills, and muscle tissues. After 15d of exposure to different concentrations of ROX, the bioconcentration factors were 2.15-38.0 in the liver, 0.950-20.7 in the bile, 0.0506-19.7 in the gill, and 0.0439-13.8 in the muscle; these results were comparable to the estimated BCF values. The metabolites formed in the bile were identified based on metabolic identification in human bile. Additionally, the biomarkers, including acetylcholinesterase in the brain, as well as 7-ethoxyresorufin O-deethylase and superoxide dismutase in the liver changed significantly after 5, 10, 15, and 20d of exposure (P<0.05). Our results suggest that ROX can accumulate and be metabolized in fish; therefore, interactions between ROX or its metabolites and the biological systems may induce biochemical disturbances in fish.
    Chemosphere 11/2013; · 3.14 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Changes in food uptake by detritivorous macro-invertebrates could disrupt the ecosystem service of leaf litter breakdown, necessitating the study of shredding under anthropogenic influences. Here, the impact of the neonicotinoid insecticide imidacloprid on the feeding rate of individual Gammarus pulex was measured at a daily resolution both during and after a four-day exposure period. We found that imidacloprid inhibits feeding of G. pulex during exposure at concentrations ≥30 µg/L and that there was no recovery in feeding on transfer into clean media for three days. Exposure to imidacloprid at concentrations ≥0.81 µg/L and ≤9.0 µg/L resulted in increased feeding after exposure even though there was no significant effect on feeding during the exposure itself. Comparison with the literature shows that concentrations found to influence feeding lie within the range of estimated and measured environmental concentrations. Additionally, effects on feeding rate were observed at concentrations two orders of magnitude lower than those causing mortality. The lethal concentration for 50% of test organisms after four days of exposure (LC50(96h) = 270 µg/L, literature data) and the obtained effect concentration for a reduction in feeding by 50% (EC50(96h) = 5.34 µg/L) were used for this comparison. The present study discusses the potential that effects on feeding may evoke effects at the population level or disturb leaf litter breakdown in the environment. Environ Toxicol Chem © 2013 SETAC.
    Environmental Toxicology and Chemistry 12/2013; · 2.62 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: As aquatic macroinvertebrates may be regularly exposed to pesticides in edge of the field water bodies, an accurate assessment of potential adverse effects and subsequent population recovery is essential. Standard effect risk assessment tools are not able to fully address the complexities arising from multiple exposure patterns, nor can they properly address the population recovery process. In the present study, we use an individual-based model of the freshwater amphipod, Gammarus pulex, to evaluate the consequences of exposure to 4 compounds with different modes of action on individual survival and population recovery. Effects on survival were calculated using concentration-effect relationships and the threshold damage model (TDM), which accounts for detailed processes of toxicokinetics and toxicodynamics. Delayed effects as calculated by the TDM had a significant impact on individual survival and population recovery. We also evaluated the standard assessment of effects after short-term exposures using the 96h concentration-effect model and the TDM which was conservative for very short-term exposure. An integration of a TKTD submodel with a population model can be used to explore the ecological relevance of ecotoxicity endpoints in different exposure environments. Environ Toxicol Chem © 2013 SETAC.
    Environmental Toxicology and Chemistry 12/2013; · 2.62 Impact Factor

Full-text (2 Sources)

Available from
May 26, 2014

Roman Ashauer