James Lazorchak

Publications (60) View all

• Source

  Available from: Alistair Boxall

  Article: Pharmaceuticals and personal care products in the environment: what are the big questions?

  Alistair B A Boxall, Murray A Rudd, Bryan W Brooks, Daniel J Caldwell, Kyungho Choi, Silke Hickmann, Elizabeth Innes, Kim Ostapyk, Jane P Staveley, Tim Verslycke, [......], Jason R Snape, Richard Murray-Smith, Mark R Servos, Paul K Sibley, Jürg Oliver Straub, Nora D Szabo, Edward Topp, Gerald R Tetreault, Vance L Trudeau, Glen Van Der Kraak
  [show abstract] [hide abstract]
  ABSTRACT: Background: Over the past 10-15 years, a substantial amount of work has been done by the scientific, regulatory, and business communities to elucidate the effects and risks of pharmaceuticals and personal care products (PPCPs) in the environment.Objective: This review was undertaken to identify key outstanding issues regarding the effects of PPCPs on human and ecological health in order to ensure that future resources will be focused on the most important areas.Data sources: To better understand and manage the risks of PPCPs in the environment, we used the "key question" approach to identify the principle issues that need to be addressed. Initially, questions were solicited from academic, government, and business communities around the world. A list of 101 questions was then discussed at an international expert workshop, and a top-20 list was developed. Following the workshop, workshop attendees ranked the 20 questions by importance.Data synthesis: The top 20 priority questions fell into seven categories: a) prioritization of substances for assessment, b) pathways of exposure, c) bioavailability and uptake, d) effects characterization, e) risk and relative risk, f ) antibiotic resistance, and g) risk management.Conclusions: A large body of information is now available on PPCPs in the environment. This exercise prioritized the most critical questions to aid in development of future research programs on the topic.
  Environmental Health Perspectives 05/2012; 120(9):1221-9. · 7.04 Impact Factor
• Source

  Available from: James Lazorchak

  Article: Temporal dynamics of periphyton exposed to tetracycline in stream mesocosms.

  Erin L Quinlan, Christopher T Nietch, Karen Blocksom, James M Lazorchak, Angela L Batt, Richard Griffiths, Donald J Klemm
  [show abstract] [hide abstract]
  ABSTRACT: Significant amounts of antibiotics enter the environment via point and nonpoint sources. We examined the temporal dynamics of tetracycline exposure to stream periphyton and associated organisms across a logarithmically dosed-series of experimental mesocosms, designed to mimic natural conditions. Target in-stream tetracycline exposures were based on environmentally relevant concentrations in aquatic ecosystems throughout the United States (<1-100 μg L(-1)). Significant changes in the stream biotic community were observed within 7 days with in-stream tetracycline concentrations as low as 0.5 μg L(-1), including significant changes in antibiotic resistance, bacteria abundance and productivity, algae biomass, cyanobacteria, organic biomass, and nematodes. These effects were magnified with increased exposure time and dosing concentration. Recovery of the periphyton community after 28 days of exposure was dependent upon the tetracycline dose. At the highest doses, 10 and 100 μg L(-1), bacteria productivity recovered; however, bacteria, algae, and nematode abundance did not recover at the same rate and remained low even after a 28-day recovery period (of nondosing). This study demonstrates that tetracycline exposure under near-natural conditions and at concentrations currently observed in aquatic environments may have important consequences for the structure and function of stream periphyton and, potentially, public health via increasing resistance of naturally occurring bacteria.
  Environmental Science & Technology 11/2011; 45(24):10684-90. · 4.80 Impact Factor
• Source

  Available from: James Lazorchak

  Article: A computational model of the hypothalamic: pituitary: gonadal axis in female fathead minnows (Pimephales promelas) exposed to 17α-ethynylestradiol and 17β-trenbolone.

  Zhenhong Li, Kevin J Kroll, Kathleen M Jensen, Daniel L Villeneuve, Gerald T Ankley, Jayne V Brian, María S Sepúlveda, Edward F Orlando, James M Lazorchak, Mitchell Kostich, Brandon Armstrong, Nancy D Denslow, Karen H Watanabe
  [show abstract] [hide abstract]
  ABSTRACT: Endocrine disrupting chemicals (e.g., estrogens, androgens and their mimics) are known to affect reproduction in fish. 17α-ethynylestradiol is a synthetic estrogen used in birth control pills. 17β-trenbolone is a relatively stable metabolite of trenbolone acetate, a synthetic androgen used as a growth promoter in livestock. Both 17α-ethynylestradiol and 17β-trenbolone have been found in the aquatic environment and affect fish reproduction. In this study, we developed a physiologically-based computational model for female fathead minnows (FHM, Pimephales promelas), a small fish species used in ecotoxicology, to simulate how estrogens (i.e., 17α-ethynylestradiol) or androgens (i.e., 17β-trenbolone) affect reproductive endpoints such as plasma concentrations of steroid hormones (e.g., 17β-estradiol and testosterone) and vitellogenin (a precursor to egg yolk proteins). Using Markov Chain Monte Carlo simulations, the model was calibrated with data from unexposed, 17α-ethynylestradiol-exposed, and 17β-trenbolone-exposed FHMs. Four Markov chains were simulated, and the chains for each calibrated model parameter (26 in total) converged within 20,000 iterations. With the converged parameter values, we evaluated the model's predictive ability by simulating a variety of independent experimental data. The model predictions agreed with the experimental data well. The physiologically-based computational model represents the hypothalamic-pituitary-gonadal axis in adult female FHM robustly. The model is useful to estimate how estrogens (e.g., 17α-ethynylestradiol) or androgens (e.g., 17β-trenbolone) affect plasma concentrations of 17β-estradiol, testosterone and vitellogenin, which are important determinants of fecundity in fish.
  BMC Systems Biology 01/2011; 5:63. · 3.15 Impact Factor
• Article: Changes in agglomeration of fullerenes during ingestion and excretion in Thamnocephalus platyurus.

  Manomita Patra, Xin Ma, Carl Isaacson, Dermont Bouchard, Helen Poynton, James M Lazorchak, Kim R Rogers
  [show abstract] [hide abstract]
  ABSTRACT: The crustacean Thamnocephalus platyurus was exposed to aqueous suspensions of fullerenes C(60) and C(70) . Aqueous fullerene suspensions were formed by stirring C(60) and C(70) as received from a commercial vendor in deionized water (termed aqu/C(60) and aqu/C(70) ) for approximately 100 d. The Z-average (mean hydrodynamic) diameters of aqu/C(60) and aqu/C(70) aggregates as measured by dynamic light scattering were 517 ± 21 nm and 656 ± 39 nm (mean ± 95% confidence limit), respectively. Exposure of T. platyurus to fullerene suspensions resulted in the formation of dark masses in the digestive track visible under a stereo microscope (×40 magnification). Fullerene ingestion over 1 h of exposure was quantitatively determined after extraction and analysis by high-performance liquid chromatography-mass spectrometry (HPLC-MS). One-hour exposures (at 3 mg/L and 6 mg/L) resulted in aqu/C(60) burdens of 2.7 ± 0.4 µg/mg and 6.8 ± 1.5 µg/mg wet weight, respectively. Thin-section transmission electron microscopy (TEM) images of aqu/C(60) -exposed T. platyurus showed the formation in the gut of fullerene agglomerates (5-10 µm) that were an order of magnitude larger than the suspended fullerene agglomerates. Upon excretion, the observed fullerene agglomerates were in the 10- to 70-µm size range and settled to the bottom of the incubation wells. In contrast to the control polystyrene microspheres, which dispersed after depuration, the aqu/C(60) agglomerates (greater than two orders of magnitude larger than the suspended fullerenes) remained agglomerated for up to six months. When exposed to fullerenes, T. platyurus shows the potential to influence agglomerate size and may facilitate movement of these nanoparticles from the water column into sediment.
  Environmental Toxicology and Chemistry 01/2011; 30(4):828-35. · 2.81 Impact Factor
• Source

  Available from: James Lazorchak

  Article: Differential gene expression in Daphnia magna suggests distinct modes of action and bioavailability for ZnO nanoparticles and Zn ions.

  Helen C Poynton, James M Lazorchak, Christopher A Impellitteri, Mark E Smith, Kim Rogers, Manomita Patra, Katherine A Hammer, H Joel Allen, Chris D Vulpe
  [show abstract] [hide abstract]
  ABSTRACT: Zinc oxide nanoparticles (ZnO NPs) are being rapidly developed for use in consumer products, wastewater treatment, and chemotherapy providing several possible routes for ZnO NP exposure to humans and aquatic organisms. Recent studies have shown that ZnO NPs undergo rapid dissolution to Zn(2+), but the relative contribution of Zn(2+) to ZnO NP bioavailability and toxicity is not clear. We show that a fraction of the ZnO NPs in suspension dissolves, and this fraction cannot account for the toxicity of the ZnO NP suspensions to Daphnia magna. Gene expression profiling of D. magna exposed to ZnO NPs or ZnSO(4) at sublethal concentrations revealed distinct modes of toxicity. There was also little overlap in gene expression between ZnO NPs and SiO(x) NPs, suggesting specificity for the ZnO NP expression profile. ZnO NPs effected expression of genes involved in cytoskeletal transport, cellular respiration, and reproduction. A specific pattern of differential expression of three biomarker genes including a multicystatin, ferritin, and C1q containing gene were confirmed for ZnO NP exposure and provide a suite of biomarkers for identifying environmental exposure to ZnO NPs and differentiating between NP and ionic exposure.
  Environmental Science & Technology 01/2011; 45(2):762-8. · 4.80 Impact Factor