Document Yr0GY7a4dpOdbem0oMrkYYyMV

BACK TO MAIN TOXICITY TO AQUATIC PLANTS (Marine Diatom, Skeletonema costatum) TEST SUBSTANCE Identity: Perfluorooctanesulfonate; may also be referred to as PFOS or FC-95. (1-Octanesulfonic acid, 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8heptadecafluoro-, potassium salt, CAS # 2795-39-3) Remarks: Sample from 3M production lot number 217. The test substance is a white powder. Purity determined to be 86.9% by LC/MS, 1H-HMR, 19F-NMR and elemental analyses techniques. METHOD Method: OPPTS 850.5400 Test: Acute static GLP: Yes Year completed: 2001 Species: Skeletonema costatum Source: Originally from The Culture Collection of Algae and Protozoa, Dunstaffnage marine Laboratory at Oban Argyll, Scotland, and maintained in culture medium at Wildlife International Ltd., Easton, MD Analytical monitoring: PFOS measured at 0, 72, 96-hours Element basis: Reported three ways: number of cells/ml, area under the growth curve and growth rate Exposure period: 96-hours Start date: 5/19/00 End date: 5/23/00 Analytical monitoring: Test concentrations measured at 0, 72, and 96hours. Test organisms laboratory culture: Algae cultures had been actively growing in saltwater algal culture medium for at least two weeks prior to test initiation. Stock nutrient solutions were prepared by adding reagentgrade chemicals to reverse osmosis-purified well water. Solutions were then diluted in artificial saltwater to prepare final growth media. BACK TO MAIN Test Conditions: Algal saltwater medium Compound FeCl3.6H20 MnCl2.4H2O ZnSO4.7H2O CuSO4.5H2O CoCl2.6H20 Nominal Concentration 0.72 2.16 0.675 2.36 6.06 Units mg/L mg/L mg/L g/L g/L H3BO3 Na2EDTA.2H20 17.1 15.0 mg/L mg/L K3PO4 3.0 mg/L NaNO3 Na2SiO3.9H20 50.0 mg/L 20.0 mg/L Thiamine Hydrochloride 0.25 mg/L Biotin 0.05 g/L B12 0.5 g/L Dilution water source: The stock nutrient solutions were prepared by adding the appropriate volumes reagent-grade chemicals to Wildlife International Ltd. well water purified by reverse osmosis. The algal medium was prepared by adding appropriate volumes of the stock nutrient solutions to artificial saltwater at 30 ppt salinity. The pH of the medium was 8.1 and it was sterilized by filtration (0.22m) prior to use. Test solution preparation: A single test solution (3.46 mg/L) was prepared for this study in algal saltwater medium. The solution was sonicated for approximately 30 minutes and was stirred with a magnetic stir plate for approximately 43 hours. The final test solution appeared clear and colorless. Exposure vessels: Sterile 250 mL glass Erlenmeyer flasks plugged with foam stoppers containing 100 mL of test solution. Agitation: Shaken continuously at 100 rpm Number of replicates: six. Initial algal cell loading: 7.7 X 104 cells/mL Number of concentrations: one plus a negative control plus an abiotic control at the highest concentration tested Water chemistry: pH range (0 - 96 hours) 8.0 - 8.4 (control exposure) BACK TO MAIN 8.0 - 8.4 (3.20 mg/L exposure) Test temperature range (0 - 96 hours) 20.2 - 21.4C Light levels: (0 - 96 hours) 3880 - 4710 lux from cool-white fluorescent lighting Photoperiod: 14-hours light and 10 hours dark Method of calculating mean measured concentrations: arithmetic mean obtained using results obtained at 0-hours, 72hours and 96-hours RESULTS Nominal concentrations: Negative control, 3.46 mg/L plus 3.46 mg/L abiotic control. This is apparently the highest concentration of PFOS attainable in this saltwater algal media. Measured concentrations: <LOQ, 3.20 mg/L; abiotic control = 3.18 mg/L Element value (95% confidence interval): 72 and 96-hour EC10 via cell density, area under the curve and growth rate: > 3.20 mg/L (C.I. not calculable) 24, 48, 72, and 96-hour EC50 via cell density, area under the curve and growth rate: > 3.20 mg/L (C.I. not calculable) 72 and 96-hour EC90 via cell density, area under the curve and growth rate: > 3.20 mg/L (C.I. not calculable) 72-hour NOAEC (cell density, area under the curve, growth rate): 3.20 mg/L 96-hour NOAEC (cell density, area under the curve, growth rate): 3.20 mg/L All element values based on mean measured concentrations Statistical methods: Cell densities, area under the growth curve values, growth rates and percent inhibition values were calculated using "The SAS System for Windows", Release 6.12. The EC10, EC50, and EC90 values and 95% confidence limits could not be calculated using statistical methods. Cell densities, areas under the growth curve and growth rates at 72 and 96 hours were evaluated for normality using the Shapiro-Wilk's test and for equality of variance using an F-test. The treatment group were then compared to the control using ANOVA and a 2-sample t-test. BACK TO MAIN Results of the statistical analyses were used to determine the NOAEC values. Analytical Methodology: Analyses of test solutions were performed at Wildlife International Ltd. using high performance liquid chromatography with mass spectrometric detection (HPLC/MS). The 72 and 96-hour samples were centrifuged approximately 10 minutes at approximately 2000 rpm prior to analysis. When determining the concentration of the test substance in the test solutions, the same and most prominent peak response for perfluorooctanesulfonate was used. No attempt was made to quantify on the basis of individual isomeric components. The LOQ (limit of quantitation) was 0.480 mg/L in this study. The mean percent recovery of matrix fortifications analyzed concurrently during sample analysis was 108%. Samples collected at test initiation had measured values from 96.2 to 88.5% of nominal. The measured value for the sample taken at 72hours was 92.2% of nominal. The measured value for the sample taken at 96-hours was 91.2% of nominal. For the abiotic control, the measured value for the sample taken at 72-hours was 97.1% of nominal and for the sample taken at 96-hours, 86.8% of nominal. Summary of analytical chemistry data: Nominal Test Concentration, mg/L Negative Control 3.46 3.46 (abiotic) Measured Values at 0, 72, and 96hours, Respectively, mg/L All < LOQ Mean Measured Concentration, mg/L <LOQ Percent of Nominal - 3.26, 3.19, 3.15 3.20 92.5 Not analyzed, 3.36, 3.00 3.18 91.9 Biological observations after 96-hours: Mean Measured Concentration, mg/L Mean Number of Cells per mL Percent Inhibition via Density Percent Inhibition via Area Under the Curve Percent Inhibition via Growth Rate Negative Control 2,481,667 - - - 3.20 2,601,667 -4.8 -7.3 -1.3 Control response: satisfactory BACK TO MAIN Observations: After 96 hours of exposure, there were no signs of aggregation or adherence of the algae to the flasks in the negative control or the treatment group. In addition, there were no noticeable changes in cell morphology when compared to the negative control. Reversibility of Growth Inhibition: After 96-hours of exposure, there was no significant inhibition of growth in the highest concentration tested (3.20 mg/L). Therefore, a recovery phase was not conducted. CONCLUSIONS A single concentration of potassium perfluorooctanesulfonate was evaluated for toxicity to Skeletonema costatum. This mean measured concentration, 3.20 mg/L, was the highest concentration attainable in this algal media. The 96-hour EC50 and 95% confidence interval fo r Skeletonema costatum, as determined by cell density, area under the growth curve, and by growth rate was found to be > 3.20 mg/L. The 96hour NOAEC was determined by ANOVA and a 2-sample t-test to be 3.20 mg/L calculated using cell density, area under the curve and growth rate. No signs of cell aggregation or adherence were noted in any of the test solutions or the controls. Submitter: 3M Company, Environmental Laboratory, P.O. Box 33331, St. Paul, Minnesota, 55133 DATA QUALITY Reliability: Klimisch ranking = 1 REFERENCES This study was conducted at Wildlife International Ltd., Easton, MD at the request of the 3M Company, Lab Request number U2723. OTHER Last changed: 6/12/01