565 (DUK-1117-466630) Field Verification of Responses of a Problematic Algal Species to Exposures of a Copper Formulation.
Start time: 1:50 PM
Duke, B¹, Rodgers, J¹, ¹ Clemson University, Clemson, SC, USA
Pond-based treatment systems (such as ash basins) can occasionally grow algae in concentrations or forms (species) that are problematic. Extensive algal growth can consume CO₂, resulting in a severely high pH (>10) and may cause elevation of total suspended solids. In order to regain control of pH and total suspended solids, the causative algal species must be controlled (loss of algae from the water column). Copper-containing algaecides are an alternative for controlling the growth of problematic algal species in these situations. It is important to understand the specific consequences of application of a copper-containing algaecide in these critical situations where National Pollutant Discharge Elimination System (NPDES) compliance must be achieved. This study was initiated at Lee Steam Station (LSS) near Pelzer, SC (Anderson County). LSS experienced high pH in their ash basin waters due to a bloom of Anabaena circinalis. Samples of ash basin water and associated algae were collected and treated in the laboratory with a series of concentrations of a copper-containing algaecide (Cutrine®-Plus). The results of this laboratory experiment indicated that 0.4-0.6 ppm Cu/L of Cutrine®--Plus should control the growth of this alga in the ash basin water at Lee Steam Station. This estimate was tested in a field study. The site water characteristics returned to background after treatment.

566 (ESC-1117-137295) Comparative ecotoxicological hazard assessment of beta-blockers and their human metabolites.
Start time: 2:10 PM
Escher, B¹, Bramaz, N¹, Richter, M¹, Lienert, J¹, ¹ EAWAG, Dübendorf, CH, Switzerland
A mode-of-action based screening test battery was used to analyze the non-target effects of the beta-blockers propranolol, metoprolol, and atenolol. The test battery consists of six tests and encompasses non-specific, receptor-mediated, and reactive modes of toxic action. It has earlier been used to assess a range of different drugs (Escher, B. I., Bramaz, N., Eggen, R. I. L., Richter, M. (2005), "In-vitro Assessment of Modes of Toxic Action of Pharmaceuticals in Aquatic Life", Environ. Sci. Technol., 39, 3090-3100). In all test systems, toxicity increased with hydrophobicity. Propranolol was more toxic than metoprolol, followed by atenolol. All beta-blockers were baseline toxicants in all test systems with the exception of the chlorophyll fluorescence test for inhibition of photosynthesis. In this test all investigated beta-blockers were about ten times more toxic than their baseline toxicity predictions. The human metabolites were included in the second part of the analysis. A model was developed using baseline QSAR and the QSAR for the chlorophyll fluorescence assay described above. The identity and fraction of human metabolites excreted in feces and urine were compiled from the literature and their ecotoxic potential predicted with these QSARs. The total toxic potential of the beta-blockers and their human metabolites were modeled under the following assumptions: (1) similar mode of action of parent drug and metabolite as worst case, and (2) baseline toxicity of the metabolites as realistic case, and consequently the concept of concentration addition to describe mixture effects. In general, human metabolism decreased the overall toxicity of beta-blockers with exception of the poorly metabolized atenolol. The proposed method is a simple approach to initial hazard assessment of pharmaceuticals and can guide higher tier testing. It can be applied to other classes of pollutants, e.g., biocides as well as environmental metabolites.

567 (STO-1117-840470) Effect of pulse duration and recovery time on the toxicity of imidacloprid to Chrionnomus tentans.
Start time: 2:30 PM
Stoughton, S¹, Liber, K¹, Culp, J², Cessna, A, ¹ Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada² National Water Research Institute, Environment Canada, Fredericton, New Brunswick, Canada
Imidacloprid is a relatively new nicotine mimic insecticide that is widely used across North America. Imidacloprid residues are routinely found in surface waters near treated fields following periods of spray drift, surface runoff, or subsurface water flow, yet little is known about the effects of short and environmentally realistic pulse exposures of imidacloprid to aquatic biota. To address these data gaps, experiments were conducted to evaluate the toxicity of imidacloprid to the invertebrate, Chironomus tentans, using the formulated product, Admire® (240 g/L a.i.). The first experiment exposed C. tentans larvae to either constant, press (10 d) or pulse (96 h, followed by 6 d in clean water) exposure regimes. For the press exposure, growth decreased at 2.9 g/L; there was no effect at 2.9 g/L in the pulse exposure. The next experiment exposed C. tentans to higher concentrations of Admire® for either 24 or 96 h before being transferred to clean water for the remainder of the 10-d test. Larval growth and survival decreased at 4.7 and 13.3 g/L in the 96-h pulse treatment, with no effect at ≤13.4 g/L in the 24-h exposure treatment. Next, C. tentans were exposed for a total of 96 h, with different recovery times between pulses (four 24-h pulses with 24 h in-between, or two 48-h pulses with 72 h in-between), before being transferred to clean water for the remainder (3 d) of the 10 d test. In the 4x24 h treatment, survival decreased at 15.5 g/L and growth decreased at 5.0 and 15.5 g/L, while in the 2x48 h treatment, survival decreased at 5.7 and 15.8 g/L, and growth decreased at 15.8 g/L. Pulse exposures of imidacloprid can inhibit C. tentans larvae survival and growth when concentrations are > 2.9 g/L and pulse duration is longer than 24 h in total.

568 (BAR-1117-839584) The influence of soil type on the outcome of laboratory toxicity studies conducted with Collembola.
Start time: 2:50 PM
Barrett, K¹, Gray, J¹, Wainwright, M, ¹ Huntingdon Life Sciences, Huntingdon, Cambridgeshire, UK
As part of the regulatory data package of both agrochemicals and pharmaceuticals,where there is expected to be prolonged exposure of soil dwelling species, it is recommended that a laboratory toxicity study is conducted with a species of Collembolan (springtail). The recommended ISO guideline allows some degree of choice in the soil used in the study. The two soils most commonly used are LUFA 2.2 (standard sandy loam soil) or an artificial soil as used for the OECD earthworm toxcity evaluation. The artificial soil has a signiificantly higher organic carbon content. To compare the influence of soil type on the observed toxicity, a laboratory study was performed to compare survival and reproduction in the two soil types, following exposure to residues of dimethoate (a commonly used toxic reference substance). Reproduction in the control treatments was significantly higher in the artificial soil than in the LUFA 2.2 soil. Dimethoate was also found to be less toxic in artificial soil than in the LUFA 2.2 soil. The EC50 values for survival and fecundity respectively were approximately 3 and 15 times less than for LUFA 2.2. These results indicate that the choice of soil type should be taken into consideratin when interpreting the data from standard labortory evaluations.

(59362) Break.
Start time: 3:10 PM

569 (AAA-1117-814259) Environmental risk assessment of feed additives and veterinary medicina products - A regulatory perspective.
Start time: 3:50 PM
De Knecht, J.A.¹, ¹ RIVM, Bilthoven, The Netherlands
The presentation outlines the risk models for feed additives and veterinary medicinal products (VMPs) medicines applied at registration in the European Union. The decision-making criteria for the environmental risk assessment (ERA) of feed additives are given in Directive 2001/79/EC. The assessment includes a tiered approach based on two phases and is comparable to the assessment for VMPs described in the 1997 CVMP/EMEA Note for Guidance. Phase I evaluates the extent of environmental exposure and eliminates those products, where the extent of exposure is low, from the need for further assessment. For the products remained a complete phase II risk assessment is required, for which the applicant has to provide data on the environmental fate and effects of the residue on the environmental impact of concern. For VMPs the working group of the Veterinary International Co-operation of Harmonization (VICH) recently developed new guidelines for both phases in order to achieve harmonization between Europe, USA, Japan and Australia/New Zealand on the data requirements for registration. Once implemented, these guidelines will replace the CVMP/EMEA Note for guidance (foreseen in 2005-2006). Since the guidelines do not give technical guidance for predicting the environmental concentrations of feed additive and VMPs, technical guidance documents are now under construction by EFSA and EMEA. Specific aspects of the exposure assessment will be highlighted. The cocciodiostats used as feed additives will serve as case studies.

570 (MAU-1117-725488) Effect of the fluoroquinolone antibiotic ciprofloxacin on stream microbial communities and detritivorous macroinvertebrates.
Start time: 4:10 PM
Maul, J.¹, Schuler, L.¹, Belden, J.¹, Whiles, M.¹, Lydy, M.¹, ¹ Southern Illinois University, Carbondale, IL, 62901
Microbial communities play an important role in stream ecosystem processes such as decomposition of senescent leaf litter and as a primary nutritional source for detritivorous macroinvertebrates or acting as symbionts for energy acquisition. Antibiotics may potentially affect stream microbial communities and associated ecosystem processes; especially since recent stream and river monitoring has indicated the presence of some antibiotics downstream of wastewater treatment plants and animal production facilities. In this study, effects of chronic exposure to the fluoroquinolone antibiotic ciprofloxacin (cipro) were examined on microbial community level physiological profiles (CLPP) and growth indices of stream detritivores (Gammarus spp. and Lepidostoma liba). Microcosm experiments were conducted using stream sediments and water, senesced labile leaf material (Acer saccharum), and organisms. Function of microbial communities (based on carbon source utilization) associated with leaf material varied among control, 1, 10, and 100 g/L cipro exposures after 12 d. Although the most dramatic shift in leaf-associated CLPP from controls was observed with exposure to 100 g/L cipro, variation of CLPP relative to controls was minimal at more environmentally relevant concentrations (1 g/L). For detritivorous macroinvertebrates, condition indices (i.e., mass adjusted for structural size) of Gammarus spp. did not differ among controls and experimental groups receiving 0.1 and 1.0 g/L cipro (p > 0.05). Similarly, mass of L. liba after 30 d exposures did not vary among controls, 10, and 100 g/L cipro treatments (p > 0.05). These results suggest that there may be some effect of cipro on leaf-associated microbial communities. However, the degree to which detritivorous macroinvertebrates or associated ecosystem processes may be influenced is not apparent from these experiments. Future work should focus on identifying specific changes in stream microbial communities as a result of cipro exposure.

571 (WAI-1118-091236) Effects of sulfonylurea herbicides on the biomass and production of microbial communities in prairie wetlands.
Start time: 4:30 PM
Waiser, M¹, Donald, D², Glozier, N², Cessna, A³, Holm, J¹, Froese, J², Bailey, J¹, Syrgiannis, J², Mollison, J¹, ¹ National Water Research Institute, Environment Canada, Saskatoon, SK, Canada² Prairie and Northern Region, Environment Canada, Regina and Saskatoon, SK, Canada³ Agriculture and Agri-food Canada, Saskatoon, SK, Canada
Five shallow prairie dugouts south of Regina, SK, CAN, were chosen as the study sites for this sulfonylurea herbicide effects experiment. During the last week in May, 2004, 5 enclosures were installed in each dugout (25 enclosures total). On June 8, after a one week acclimation period, enclosures were treated with expected environmental concentrations of herbicides. Of the 5 enclosures installed in each dugout, one was treated with thifensulfuron-methyl, one with metsulfuron-methyl, one with sulfosulfuron-methyl, one with ethametsulfuron-methyl, while the fifth was untreated and served as the control. Bacterial production (³H thymidine uptake), bacterial numbers (counts using epifluorescent microscopy) algal biomass (as Chlorophyll a) algal primary production (using ¹⁴C labelled bicarbonate) and water chemistry parameters (major nutrients and ions, oxygen, temperature, conductivity, pH) as well as herbicide concentrations were measured in each enclosure and in the surrounding dugout water at timed intervals (before and after treatment) over a 30 day period. Results from repeated measures analysis of variance suggest no chronic or acute effect of any of the tested herbicides on any of the microbial variables tested. Examination of trends within each individual enclosure, however, indicated the potential for a negative effect of sulfonylurea herbicides on bacterial numbers and production which may have been missed due to the high variation between replicate treatments.

572 (SOL-1117-854962) Environmental risk assessment of the use of glyphosate for the control of illicit crops in Colombia.
Start time: 4:50 PM
Solomon, K¹, Anadón, A², Cerdeira, A³, Marshall, J⁴, Sanin, L-H⁵, ¹ University of Guelph, Guelph, ON, Canada² Universidad Complutense de Madrid, Madrid, Spain³ EMBRAPA, Jaguariuna, SP, Brazil⁴ Marshall Agroecology, Barton Winscombe, UK⁵ Autonomous University of Chihuahua, Chihuahua, Mexico
Glyphosate has been used for the control of illicit crops in Colombia for several years. In practice, areas of production are identified by multispectral imagery from satellites. Once located, areas of production are mapped with the aid of lower-altitude images and direct aerial observation. GPS coordinates are used to identify locations for application of herbicide by application from fixed-wing aircraft at low altitude. The herbicide, glyphosate, and additional surfactants are applied using raindrop nozzles at rates of 4.8 and 1.2 kg AI/ha. The areas treated represent a fractional percentage of the total area of the country and they may receive applications from 1- 4 times per year. The herbicide and its formulants were tested for toxicity in the standard Tier-1 suite of terrestrial and aquatic organisms. These toxicity values were used to assess potential risk to terrestrial invertebrates and aquatic organisms resulting from a direct overspray of fields and surface waters. Recovery of treated plants was assessed on the basis or recolonization of sprayed areas and the success of replanted areas. Recovery began in less than 21 days and newly planted crops showed successful establishment within 56 days of application. Ecological risk assessment suggested low risk to terrestrial animals and low risks to aquatic organisms, except in shallow static water that may be accidentally over-sprayed. This work was supported by the Organization of American States.

573 (DUS-1117-854768) Water and Sediment toxicity of selected pharmaceuticals and personal care products to benthic invertebrates.
Start time: 5:10 PM
Dussault, E¹, Balakrishnan, V², Sverko, E³, Solomon, K¹, Sibley, P¹, ¹ University of Guelph, Guelph, Ontario, Canada² National Water Research Institute, Aquatic Ecosystem Protection Research Branch, Environment Canada, Burlington, Ontario, Canada³ National Laboratory for Environmental Testing, Environment Canada, Burlington, Ontario, Canada
Aquatic sediments may represent an important matrix for the deposition and storage of pharmaceuticals and personal care products (PPCPs), yet the potential risks that these compounds pose to sediment-dwelling organisms are virtually unknown. In this study, we evaluated the acute toxicity of the anti-epileptic drug carbamazepine (CBZ), the lipid regulator atorvastatin (ATO), the antimicrobial triclosan (TCS) and the synthetic hormone ethinylestradiol (EE2), toward the midge Chironomus tentans and the freshwater shrimp Hyalella azteca, using standard 10-d acute toxicity tests. In water-only exposures, LC10 values varied between 0.2 and 28.6 mg.L^-1 for C. tentans, with TCS being the most toxic and CBZ the least toxic compound. H. azteca was generally more sensitive than C. tentans, with LC10 values ranging from 0.2 to 8.5 mg.L^-1. The relative toxicity ranking of the four compounds was the same as observed for C. tentans; however ATO was approximately 10 times more toxic to H. azteca compared to C. tentans, and approached the toxicity of TCS. Growth was generally a more sensitive indicator of toxicity than mortality, with EC10 values being 1.5-14.7 times lower than LC10 values. Experiments are currently under way to evaluate the acute toxicity of spiked sediments. Measured toxicity thresholds in water-only short-term tests were several orders of magnitude higher than current environmental concentrations, indicating that these compounds likely pose little risk to benthic invertebrates. However, studies to examine chronic responses to PPCPs, particularly effects on reproduction, endocrine disruption and behaviour, are poorly known and will be the subject of future testing.