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Keri C Hornbuckle

Publications and source records attributed to Keri C Hornbuckle.

13 recordsLinked to original sources
PubMed2007

Enantioselective disposition of PCB 136 (2,2',3,3',6,6'-hexachlorobiphenyl) in C57BL/6 mice after oral and intraperitoneal administration.

Studies of xenobiotic disposition in rodents often employ experimental designs using differing routes of administration. In an effort to investigate the effects of route of administration on enantioselective disposition of xenobiotics, a chiral polychlorinated biphenyl (PCB), racemic PCB 136, was administered as a single dose (50 mg/kg body weight) to male or female C57BL/6 mice either orally or via intraperitoneal injection. Mice were sacrificed after either 3 or 6 days, and blood and organs were collected for PCB analysis. Intraperitoneal injection of PCB 136 produced statistically higher PCB levels in blood and organs than did the oral administration. Tissue levels were higher after 3 days than those after 6 days. Enantioselective analysis showed that (+)-PCB 136 was enriched in most organs, with the most pronounced enrichment found in the liver and the brain of animals dosed orally or by intraperitoneal injection, respectively. Significantly higher retained enantiomeric fractions of PCB 136 were found in the oral treatment groups compared with those found in intraperitoneal treatment groups, possibly as a result of the lower PCB levels in oral treatment groups. Therefore, the choice of administration route may well have implications for the enantioselective disposition of PCB 136 and other chiral substances.

Administration, Oral↗
PubMed2006

Synthetic musk fragrances in Lake Erie and Lake Ontario sediment cores.

Two sediment cores collected from Lake Ontario and Lake Erie were sectioned, dated, and analyzed for five polycyclic musk fragrances and two nitro musk fragrances. The polycyclic musk fragrances were HHCB (Galaxolide), AHTN (Tonalide), ATII (Traseolide), ADBI (Celestolide), and AHMI (Phantolide). The nitro musk fragrances were musk ketone and musk xylene. Chemical analysis was performed by gas chromatography/mass spectrometry (GC/MS), and results from Lake Erie were confirmed using gas chromatography/triple-quadrupole mass spectrometry (GC/MS/MS). The chemical signals observed at the two sampling locations were different from each other primarily because of large differences in the sedimentation rates at the two sampling locations. HHCB was detected in the Lake Erie core whereas six compounds were detected in the Lake Ontario core. Using measured fragrance and 210Pb activity, the burden of synthetic musk fragrances estimated from these sediment cores is 1900 kg in Lake Erie and 18 000 kg in Lake Ontario. The input of these compounds to the lakes is increasing. The HHCB accumulation rates in Lake Erie for 1979-2003 and 1990-2003 correspond to doubling times of 16 +/- 4 and 8 +/- 2 years, respectively. The results reflect current U.S. production trends for the sum of all fragrance compounds.

Environmental Pollutants↗
PubMed2006

Distribution of chiral PCBs in selected tissues in the laboratory rat.

The enantiomeric enrichment of polychlorinated biphenyl (PCB) atropisomers has been reported in both wildlife and in humans. The biological processes causing this enrichment are only poorly investigated, a fact that limits the use of enantiomeric fractions (EFs) as a tool to study various processes of environmental relevance. To further understand these enantioselective processes, this study investigates the tissue distribution and EFs of some PCB atropisomers after administration of PCB mixtures to immature male Sprague-Dawley rats. The mixtures selected for this study, Aroclor 1254 and an environmental mixture extracted from Chlorofen-contaminated soil, are qualitatively different and are known to induce different groups of hepatic enzymes. Animals were sacrificed 6 days after dosing, PCBs were extracted, and, whenever possible, the EFs of PCBs 84, 91, 95, 149, 174, and 176 were determined by chiral gas chromatography. The EFs of PCB 95 (adipose tissue, liver, and skin) and PCB 149 (adipose tissue, liver, skin, and blood) in tissues from Aroclor 1254-treated animals differed significantly from EFs in the Aroclor standard, while only EFs of PCB 95 (blood) and PCB 174 (adipose tissue) in tissues from soil-extract-treated animals were different from those of the Chlorofen soil extract. PCB 149 in tissues from soil-extract-treated animals underwent no statistically significant enantiomeric enrichment. These differences in the EFs clearly suggest that the enantioselective enrichment of PCB atropisomers may correlate with exposure history, and with the induction of hepatic enzymes, and that EFs may be useful chemical markers of physiologic and biochemical changes following exposure to PCBs.

Adipose Tissue↗
PubMed2006

Concentrated animal feeding operations, row crops, and their relationship to nitrate in eastern Iowa Rivers.

Concentrated animal feeding operations (CAFO) and fertilizer application to row crops may contribute to poor water quality in surface waters. To test this hypothesis, we evaluated nutrient concentrations and fluxes in four Eastern Iowa watersheds sampled between 1996 and 2004. We found that these watersheds contribute nearly 10% of annual nitrate flux entering the Gulf of Mexico, while representing only 1.5% of the contributing drainage basin. Mass budget analysis shows streamflow to be a major loss of nitrogen (18% of total N output), second only to crop harvest (63%). The major watershed inputs of nitrogen include applied fertilizer for corn (54% of total N input) and nitrogen fixation by soybeans (26%). Despite the relatively small input from animal manure (approximately 5%), the results of spatial analysis indicate that row crop and CAFO densities are significantly and independently correlated to higher nitrate concentration in streams. Pearson correlation coefficients of 0.59 and 0.89 were found between nitrate concentration and row crop and CAFO density, respectively. Multiple linear regression analysis produced a correlation for nitrate concentration with an R2 value of 85%. High spatial density of row crops and CAFOs are linked to the highest river nitrate concentrations (up to 15 mg/L normalized over five years).

Agriculture↗
PubMed2005

Evaluation of perfluorooctane surfactants in a wastewater treatment system and in a commercial surface protection product.

The origin and amount of perfluorooctane surfactants in wastewater treatment systems, and the transformation these compounds may undergo during treatment, were evaluated through measurement and experiment. Influent, effluent, and river water at the point of discharge for a 6-MGD wastewater treatment plant (WWTP) were screened for eight perfluorooctane surfactants. N-EtFOSAA was quantified in influent (5.1 +/- 0.8 ng/L), effluent (3.6 +/- 0.2 ng/ L), and river water samples (1.2 +/- 0.3 ng/L), while PFOS and PFOA were quantified in effluent (26 +/- 2.0 and 22 +/- 2.1 ng/L, respectively) and river water (23 +/- 1.5 and 8.7 +/- 0.8 ng/L, respectively). Signals for PFOS and PFOA were observed in influent samples, but exact quantitative determination could not be made due to low recoveries of these two compounds in field spike samples. Although the source of PFOS and PFOA observed in WWTP effluents is not clear, two hypotheses were examined: (1) the highly substituted perfluorooctane surfactants that constitute commercially available fabric protectors can be transformed to PFOS and PFOA during biological treatment in wastewater treatment systems, and (2) the end products themselves are directly introduced to WWTPs because they are present as residual in the commercial mixtures. Biotransformation experiments of 96 h were run to determine whether N-EtFOSE (a primary monomer used in 3M's polymer surface protection products) could be transformed to lesser-substituted perfluorooctane compounds in bioreactors amended with aerobic and anaerobic sludge from the sampled plant. At the end of the aerobic biotransformation experiment, N-EtFOSAA and PFOSulfinate were the only two metabolites formed and each accounted for 23 +/- 5.0% and 5.3 +/- 0.8% of the transformed parent on a molar basis, respectively. Transformation of N-EtFOSE was not observed under anaerobic conditions. A sample of a commercially available surface protection product from 1994 was analyzed and found to contain six of the targeted perfluorinated surfactants, including PFOS and PFOA. These findings suggest transformation of precursors within wastewater treatment is not an important source of these compounds compared to direct use and disposal of products containing the end products as residual amounts.

Aerobiosis↗
PubMed2005

Congener-specific tissue distribution of aroclor 1254 and a highly chlorinated environmental PCB mixture in rats.

Polychlorinated biphenyl (PCB) mixtures were synthesized and marketed in Eastern European countries, but little is known abouttheir composition, distribution, ortoxicity. PCB-contaminated soil from the former production site of the Polish PCB mixture Chlorofen was collected, and the PCBs were extracted. An in vivo study was performed to investigate the PCB tissue distribution and biochemical effects of this soil extract in immature male Sprague-Dawley rats. Rats were administered 0.05 mmol/kg soil-extracted PCBs or Aroclor 1254 and sacrificed 7 days later, and congener-specific PCB profiles in selected tissues were determined. Distribution of SigmaPCBs (sum of 120 congeners) in tissues was primarily a function of lipid content of the tissues, except for the spleen, which retained more PCB than other tissues. Multivariate analysis of the PCB congener data showed that (a) congener profiles in tissues had changed, as compared to the parent mixture; (b) disposition and redistribution of individual congeners in vivo differed between both mixtures; and (c) more highly chlorinated congeners were retained in the spleens of both treatment groups. Differences in the induction of cytochrome P-450 1A and 2B subfamilies reflected the homologue composition of the respective mixtures and predict a different toxicity profile for Chlorofen than for Aroclor 1254.

Adipose Tissue↗
PubMed2005

Gas-phase concentrations of current-use pesticides in Iowa.

Local and regional atmospheric transport of current-use pesticides is an important source of these compounds to nontarget plants and ecosystems. Current-use pesticides were measured at urban, rural, and suburban sites in eastern Iowa during 2000-2002. The most detected compounds were hexachlorobenzene and trifluralin, which were found in 89% and 78% of the samples, respectively. As expected, many pesticides showed a strong seasonal trend with the most detections and highest concentrations occurring during the spring and early summer. The average detected concentrations of five heavily used herbicides were 0.52 ng/ m3 for trifluralin, 4.6 ng/m3 for acetochlor, 2.3 ng/m3 for metolachlor, 1.1 ng/m3 for alachlor, 1.7 ng/m3 for pendimethalin, and 1.2 ng/m3 for atrazine. The most frequently detected insecticides were phorate and chlorpyrifos, which were found in 20% and 19% of the samples, respectively. The average phorate and chlorpyrifos concentrations were 25 ng/m3 and 1.0 ng/m3, respectively. The maximum phorate concentration, the highest measured for all pesticides, was 91.2 ng/m3. The most frequently detected current-use fungicides were chloroneb and etridiazole, which were found in 14% and 10% of the samples, respectively.

Air Pollutants↗
PubMed2005

Milwaukee, WI, as a source of atmospheric PCBs to Lake Michigan.

A field study of atmospheric PCBs in Milwaukee, WI, U.S.A. was conducted on the shore of Lake Michigan. We believe this is the first report of atmospheric PCBs in Milwaukee, although PCBs are well-known to contaminate the sediments of the Milwaukee River and Outer Harbor. Concentrations of PCBs collected during the June 2001 study are similar to concentrations in other urban-industrial areas and higher than PCBs in background air. The average sigmaPCB (sum of 88 congener groups) gas-phase concentration in Milwaukee was 1.9 ng m(-3)+/-standard deviation 0.78 ng m(-3). The average and standard deviation for the particulate-associated PCBs are 0.05+/-0.02 ng m(-3). Particulate-phase PCBs account for less than 5% of the total atmospheric concentration. PCBs in Milwaukee air are a source of PCBs to Lake Michigan. Calculated net gas exchange fluxes predicted forthe Milwaukee sampling period ranged from -60 to -400 ng m(-2) d(-1), where net deposition is indicated by the negative sign. Calculated particle-associated PCB deposition ranged from 80 to 500 ng m(-2) d(-1). Most of the particle-phase deposition flux is a result of coarse particle deposition and decreases rapidly with distance from shore. Under typical meteorological conditions, particle-associated PCBs depositional flux to the lake surface decreases by 90% within 40 km. For net gas-exchange, the flux reaches zero at about the same distance. At greater distances, particle-phase PCB deposition is negligible, and PCBs are volatilizing at a higher rate than they are being deposited. We calculated that Milwaukee air contributes about 120 kg of PCBs to Lake Michigan each year. This is about 10 times larger than the discharge of PCBs from the Milwaukee River.

Air Movements↗
PubMed2005

Mass budget of perfluorooctane surfactants in Lake Ontario.

Perfluorooctane surfactants have been reported in biota, water, and air samples worldwide. Despite these reports, the main environmental sources of these compounds remain undefined. To address this gap in knowledge, an annual lake-wide mass budget of eight perfluorooctane surfactants was developed for Lake Ontario. To determine the atmospheric contribution to the mass budget, over-the-lake gas-phase air concentrations for N-EtFOSE and N-EtFOSA and particulate-phase air concentrations for PFOS in any air sample are reported for the first time, with mean concentrations when present of 0.5+/-0.32 (N-EtFOSE gas-phase), 1.1+/-0.9 (N-EtFOSA gas-phase), and 6.4+/-3.3 (PFOS particulate-phase) pg/m3. The mass budget finds inflow from Lake Erie (14 361+/-4489 kg sigma perfluorooctane surfactants) and wastewater discharge (1762+/-2697 kg sigma perfluorooctane surfactants) to be the major sources, while outflow through the St. Lawrence River is the dominant loss mechanism (22,727+/-7060 kg/year sigma perfluorooctane surfactants). Using the mass budget data, the steady state and measured mean concentrations in the lake water are the same at the 95% confidence level.

Environmental Monitoring↗
PubMed2004

Detection of perfluorooctane surfactants in Great Lakes water.

Widespread use of perfluorooctane surfactants has led to ubiquitous presence of these chemicals in biological tissues. While perfluorooctane surfactants have been measured in blood and liver tissue samples of fish, birds, and mammals in the Great Lakes region, data for the aqueous concentrations of these compounds in the Great Lakes or other ambient waters is lacking. Sixteen Great Lakes water samples were analyzed for eight perfluorooctane surfactants. The monitored perfluorooctane surfactants were quantitatively determined using single quadrupole HPLC/MS and qualitatively confirmed using ion trap MS/MS. Additionally, PFOS was quantitatively confirmed using triple quadrupole LC/MS/MS. Concentrations of PFOS and PFOA in the two lakes ranged from 21-70 and 27-50 ng/L, respectively. Analysis also showed the presence of PFOS precursors, N-EtFOSAA (range of 4.2-11 ng/L) and FOSA (range of 0.6-1.3 ng/L), in all samples above the LOQ. PFOSulfinate, another precursor, was identified at six of eight locations with a concentration range, when present, of <2.2-17 ng/L. Other PFOS precursors, N-EtFOSE, PFOSAA, and N-EtFOSA were not observed at any of the sampling locations. These are the first reported concentrations of perfluorooctane surfactants in Great Lakes water and the first report of PFOS precursors in any water body.

Alkanesulfonic Acids↗
PubMed2004

Synthetic musk fragrances in Lake Michigan.

Synthetic musk fragrances are added to a wide variety of personal care and household products and are present in treated wastewater effluent. Here we report for the first time ambient air and water measurements of six polycyclic musks (AHTN, HHCB, ATII, ADBI, AHMI, and DPMI) and two nitro musks (musk xylene and musk ketone) in North America. The compounds were measured in the air and water of Lake Michigan and in the air of urban Milwaukee, WI. All of the compounds except DPMI were detected. HHCB and AHTN were found in the highest concentrations in all samples. Airborne concentrations of HHCB and AHTN average 4.6 and 2.9 ng/m3, respectively, in Milwaukee and 1.1 and 0.49 ng/m3 over the lake. The average water concentration of HHCB and AHTN in Lake Michigan was 4.7 and 1.0 ng/L, respectively. A lake-wide annual mass budget shows that wastewater treatment plant discharge is the major source (3470 kg/yr) of the synthetic musks while atmospheric deposition contributes less than 1%. Volatilization and outflow through the Straits of Mackinac are major loss mechanisms (2085 and 516 kg/yr for volatilization and outflow, respectively). Concentrations of HHCB are about one-half the predicted steady-state water concentrations in Lake Michigan.

Air Pollutants↗
PubMed2003

The impact of an urban-industrial region on the magnitude and variability of persistent organic pollutant deposition to Lake Michigan.

A predictive model for gas-phase PCBs and trans-nonachlor over Lake Michigan has been constructed and the resulting data examined for trends. In this paper, we describe the model results to show how the magnitude and variability of a plume of contaminants from the Chicago area contributes to a highly variable region of net contaminant deposition over the entire lake. For the whole lake, gross annual deposition of PCBs is approximately 3200 kg, although the net annual gas exchange is not significantly different from zero. The data-driven model illustrates that on a daily basis, the net exchange of persistent organic pollutants (POPs) can change from net deposition to net volatilization depending on the area of plume impact. These findings suggest that i) control of urban areas can accelerate the rate of volatilization from lakes; and ii) release of POPs from urban areas is largely a result of volatilization processes.

Cities↗