Document beRqwLDxNErLy9zQaLOwQL9k

BACK TO MAIN TOXICITY TO AQUATIC PLANTS (SELENASTRUM CAPRICORNUTUM) TEST SUBSTANCE Identity: Perfluorooctanoic acid, tetrabutylammonium salt; may also be referred to as PFOA tetrabutylammonium salt, tetrabutylammonium perfluorooctanoate, N2803-2, or as a major component of L -13492. (Octanoic acid, pentadecafluoro-, tetrabutylammonium salt, CAS # 95658-53-0) Remarks: The 3M production lot number was 2327. The test sample is referred to by the testing laboratory as L-13492. The T.R. Wilbury study number is 841-TH. The purity of the sample was not sufficiently characterized, although current information indicates it is a solution of 44.9% tetrabutylammonium perfluorooctanoate, 27.9% water, and 27.2% isopropanol. The following summary applies to the test sample as a mixture of the test substance in an isopropanol/ water solution with incompletely characterized concentrations of impurities. Data may not accurately relate toxicity of the test sample with that of the test substance. METHOD Method: U.S. EPA-TSCA Guideline 797.1050 Test: Acute static GLP: Yes Year completed: 1995 Species: Selenastrum capricornutum Source: Originally from The Culture Collection of Algae at the University of Texas at Austin, maintained in culture medium at T.R. Wilbury, Inc., Marblehead, MA. Element basis: growth rate. Exposure period: 96-hours Test organisms laboratory culture: Algae cultures were growing in U.S. EPA-recommended sterile enriched medium for at least 14 days prior to test initiation. Statistical methods: The average specific growth rate was calculated as the natural log of the number of cells/mL at the exposure period minus the natural log of the number of cells/mL at 0 hours divided by the exposure period. The percent change from the control was calculated by subtracting the treatment average specific growth rate from the control average specific growth rate, dividing the difference by the average specific growth rate in the control, and multiplying that value by 100. The EC50 values were calculated based on a nonlinear regression estimation BACK TO MAIN procedure (Bruce and Versteeg, 1992). The NOEC was determined using a parametric one-way analysis of variance and the average specific growth in each test vessel at the end of the test. Test Conditions: Dilution water source: The algae medium was prepared to U.S. EPA recommended concentrations by spiking deionized water with nutrient stocks. The pH of the synthetic algal medium at test initiation was 7.5. Stock and test solutions preparation: A 16 mg/L primary stock solution was prepared in sterile enriched media. Appropriate amounts of this stock solution were added directly to dilution water to formulate the test media. A 1,000 mg/L isopropyl alcohol stock solution was also prepared and evaluated. Exposure vessels: 250 mL glass Erlenmeyer flasks containing 100 mL of test solution. Agitation: Continuous at 100 rpm Number of replicates: 3 Initial algal cell loading: 1.0 X 104 cells/mL Number of concentrations: Five plus a negative control Lighting: ~400 ft-c from continuous cool-white fluorescent lighting Water chemistry: pH range: (0 - 96 hours) 7.5 - 10.4 (control exposure) 7.4 - 7.6 (16 mg/L exposure) 7.4 - 10.4 (1,000 mg/L isopropyl alcohol exposure) Test temperature range: (0 - 96 hours) 23.4 - 23.7C RESULTS Nominal concentrations: Blank control, 1.0, 2.0, 4.0, 8.0, 16.0 mg/L. A test was performed simultaneously with isopropyl alcohol, a component that represents 27% of L-13492, at 4.4 and 1,000 mg/L. Element value and 95% confidence interval: 24-hour ErC10 (growth rate) = <1.0 mg/L (CI not calculable) 24-hour ErC50 (growth rate) = 15 (9.8 - >16) mg/L 24-hour ErC90 (growth rate) = >16 (7.7 - >16) mg/L 48-hour ErC10 (growth rate) = <1.0 mg/L (CI not calculable) 48-hour ErC50 (growth rate) = 14 (8.2 - >16) mg/L 48-hour ErC90 (growth rate) = >16 mg/L (CI not calculable) 72-hour ErC10 (growth rate) = <1.0 mg/L (CI not calculable) BACK TO MAIN 72-hour ErC50 (growth rate) = 7.1 (4.1 - 11) mg/L 72-hour ErC90 (growth rate) = >16 mg/L (CI not calculable) 96-hour ErC10 (growth rate) = <1.0 mg/L (CI not calculable) 96-hour ErC50 (growth rate) = 4.9 (3.5 - 6.7) mg/L 96-hour ErC90 (growth rate) = >16 mg/L (CI not calculable) 96-hour NOEC: 1.0 mg/L Algal growth was not affected by isopropyl alcohol concentrations of 4.4 or 1,000 mg/L. Element values are based on nominal concentrations. Biological observations after 96-hours: Nominal Concentration, mg/L Mean Number Percent Percent of Cells per Inhibition via Inhibition via mL Density Growth Rate Control 1,249,000 - - 1.0 1,311,000 -5 0 2.0 275,000 88 30 4.0 113,000 91 50 8.0 84,000 93 56 16 27,000 98 80 Control response: Satisfactory Biological observations after 96-hours for isopropyl alcohol: Nominal Concentration, mg/L Mean Number Percent of Cells per Inhibition via mL Density Control 4.4 1,000 1,249,000 - 1,190,000 5 1,347,000 -8 Observations: Algal cell counts in each test vessel were determined by means of direct microscope counts with a hemocytometer. After 96 hours of exposure, there were no signs of aggregation, flocculation or adherence of the algae to the flasks in the control or any test treatment group. In BACK TO MAIN addition, there were no noticeable changes in cell size, color or morphology when compared to the control. Reversibility of Growth Inhibition: Effect of the test substance was determined to be algistatic based on the results of the post-definitive test exposure. Remarks: Testing was conducted on the mixture as described in the Test Substance Remarks field. The values reported apply to that mixture and not the fluorochemical component alone. CONCLUSIONS The test sample 96-hour EC50 and 95% confidence interval for Selenastrum capricornutum was determined to be 4.9 mg/L with a 95% confidence interval of 3.5 - 6.7 mg/L. The 96-hour no observed effect concentration (NOEC) for the test substance in solution was 1.0 mg/L. Algae growth in the vessels containing isopropyl alcohol was not affected at 4.4 or 1,000 mg/L, indicating that the concentration of isopropyl alcohol in L-13492 can not, by itself, account for the toxicity of L-13492 to algae. No signs of aggregation, flocculation, or adherence were noted in any of the test solutions. This test substance was determined to be algistatic. Submitter: 3M Company, Environmental Laboratory, P.O. Box 33331, St. Paul, Minnesota, 55133 DATA QUALITY Reliability: Klimisch ranking 2. The study lacks analytical measurement of test substance concentrations in the test solutions and sample purity is not sufficiently characterized. REFERENCES This study was conducted at T.R. Wilbury Laboratories, Inc., Marblehead, MA, at the request of the 3M Company, Lab Request number N2332, 1995. OTHER Last changed: 4/01/01