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NITRO MUSK ADDUCTS OF RAINBOW TROUT HEMOGLOBIN: DOSE-RESPONSE AND TOXICOKINETICS DETERMINATION BY GC-NICI-MS FOR A SENTINEL SPECIES
Mottaleb, M. A., W C. Brumley, AND G W. Sovocool. NITRO MUSK ADDUCTS OF RAINBOW TROUT HEMOGLOBIN: DOSE-RESPONSE AND TOXICOKINETICS DETERMINATION BY GC-NICI-MS FOR A SENTINEL SPECIES. American Biotechnology Laboratory. International Scientific Communications, Inc., Shelton, CT, 23(7):26-29, (2005).
The research focused on in the subtasks is the development and application of state-of the-art technologies to meet the needs of the public, Office of Water, and ORD in the area of Water Quality. Located In the subtasks are the various research projects being performed in support of this Task and more in-depth coverage of each project. Briefly, each project's objective is stated below.
Subtask 1: To integrate state-of-the-art technologies (polar organic chemical integrative samplers, advanced solid-phase extraction methodologies with liquid chromatography/electrospray/mass spectrometry) and apply them to studying the sources and fate of a select list of PPCPs. Application and improvement of analytical methodologies that can detect non-volatile, polar, water-soluble pharmaceuticals in source waters at levels that could be environmentally significant (at concentrations less than parts per billion, ppb). IAG with USGS ends in FY05. APM 20 due in FY05.
Subtask 2: Coordination of interagency research and public outreach activities for PPCPs. Participate on NSTC Health and Environment subcommittee working group on PPCPs. Web site maintenance and expansion, invited technical presentations, invited articles for peer-reviewed journals, interviews for media, responding to public inquiries.
Subtask 3: To apply state-of-the-art environmental forensic techniques to the recognition and characterization of emerging pollutants in the aquatic environment. There is a need for high sensitivity and for a powerful method of structural characterization, advanced mass spectrometric and chromatographic techniques to be employed to meet the challenge of emerging pollutants, including pharmaceuticals and personal care products, agents of sabotage, and explosives. Ongoing efforts continue to identify previously unrecognized pollutants from a range of problematic samples having importance to regional and state contacts.
Subtask 4: To provide the Agency with a set of practical analytical methods for the selective and sensitive determination of selenium species (organic, inorganic, volatile and non volatile forms) in multiple media to accurately assess and if necessary control the risk of selenium exposure to organisms. This includes development of optimal extraction, digestion, separation and detection approaches.
Subtask 5: To develop and apply an analytical method that can extract and detect synthetic musks. The extent of exposure may be determined by measuring levels of synthetic musks from their potential source (communal sewage effluent). This subtask ends in FY05 with the deliverable of APM 21. Future applications to biosolids will be covered in subtask 6.
Subtask 6: Application, and improvement, of previously in-house developed sensitive, robust, and green, methodologies regarding the use of urobilin and sterols as a possible markers of sewage contamination.
Subtask 7: Adaptation and improvement of previously developed in-house methods, for PPCPs (e.g., antibiotics and musks) to solid materials (e.g. biosolids, sediments).
Subtask 8: Study of the presence of personal care products, incombustible organic compounds from the direct-piping of small engines exhaust in Lake Tahoe, and lake deposition of airborne pollutants from industrial activity
Rainbow trout and other fish species can serve as 'sentinel' species for the assessment of ecological status and the presence of certain environmental contaminants. As such they act as bioindicators of exposure. Here we present seminal data regarding dose-response and toxicokinetics of trout hemoglobin adduct formation from exposure to nitro musks that are frequently used as fragrance ingredients in formulations of personal care products. Hemoglobin adducts serve as biomarkers of exposure of the sentinel species as we have shown in previous studies of hemoglobin adducts formed in trout and environmental carp exposed to musk xylene (MX) and musk ketone (MK). Gas chromatography-electron capture negative ion chemical ionization-mass spectrometry (GC-NICI-MS) employing selected ion monitoring is used to measure 4-amino-MX (4-AMX), 2-amino-MX (2-AMX), and 2-amino-MK (2-AMK) released by alkaline hydrolysis from the sulfinamide adducts of hemoglobin. Dose-response and toxicokinetics were investigated using this sensitive method for analysis of these metabolites. In the dose-response investigation, the concentrations of 4-AMX and 2-2AMX are observed to pass through a maximum at 0.10 mg/g. In the case of 2-AMK, the adduct concentration is almost the same at dosages in the range of 0.030 to 0.10 mg/g. For toxicokinetics, the concentration of the metabolites in the Hb reaches a maximum in the 3-day sample after administration of MX or MK. Further elimination of the metabolites exhibited kinetics with a presumed exponential decay and a half-life estimated to be 1-2 days. This suggests that a robust mechanism of elimination of the adducts exists in fish erythrocytes apparently analogous to that observed in mammals.
Two sick fish were observed to yield from 5 to 24 times the amount of adducts of similarly exposed fish, suggesting that this elimination mechanism may have been impaired or lacking in susceptible individual fish. It appears that adducts are destroyed in times far shorter than the expected life spans of the erythrocytes. This finding may have implications for the use of Hb biomarkers as integrative measures of exposure in some contexts. Additional conclusions from these preliminary data include the additive burden of exposure to multiple compounds and the increased susceptibility and direct observation of metabolic differences of individual members of the species completely independent of habitat and feeding habit variations.