Document 2qqwr9RpjXBBVymx19BzZByzR

BACK TO MAIN TOXICITY TO AQUATIC PLANTS (Duckweed, Lemna gibba G3) 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 obtained from 3M production lot number 217. The test substance is a white powder. Sample was stored under ambient conditions prior to testing. Purity determined to be 86.9% by LC/MS, 1HHMR, 19F-NMR and elemental analyses techniques. METHOD Method: OPPTS 850.4400 Test: Static acute GLP: Yes Year completed: 2001 Species: Lemna gibba G3 Source: Originally from The United States Department of Agriculture. Maintained in culture medium at Wildlife International Ltd., Easton, MD Analytical monitoring: Test concentrations measured at 0, 3, 5, and 7days Element basis: Number of fronds Exposure period: 7-days Start date: 3/3/00 End date: 3/10/00 Test organisms laboratory culture: Duckweed cultures had been actively growing in freshwater medium (20X AAP) for at least two weeks prior to test initiation. Stock nutrient solutions were prepared by adding reagent-grade chemicals to reverse osmosis-purified well water. Test Conditions: Test temperature range: 24.2 - 25.2C Light levels: 5000 + 750 lux from continuous warm-white fluorescent lighting BACK TO MAIN Growth medium: USEPA OPPTS 850.4400 20X AAP, 1996 Compound Nominal Concentration Units MgCl2.6H20 CaCl2.2H20 243.2 88.0 mg/L mg/L H3BO3 MnCl2.4H20 3.712 8.32 mg/L mg/L ZnCl2 65.6 ug/L FeCl3.6H20 CoCl2.6H20 3.196 28.56 mg/L ug/L Na2Mo04.2H20 CuCl2.2H20 145.2 ug/L 0.240 ug/L Na2EDTA.2H20 6.00 mg/L NaNO3 510 mg/L MgSO4.7H20 294 mg/L K2HPO4 20.88 mg/L NaHCO3 300 mg/L The pH of the medium was adjusted to 7.5 + 0.1 using 10% HCl. Dilution water source: Wildlife International Ltd. well water purified by reverse osmosis. The test medium was prepared by adding the appropriate volumes of stock nutrient solutions to purified well water. The pH of the medium was adjusted to 7.5 + 0.1 using 10% HCl and the medium was sterilized by filtration (0.22 m) prior to use. Stock and test solution preparation: A primary stock solution was prepared in duckweed medium at a concentration of 351 mg/L. The primary stock solution was stirred with a magnetic stir plate for approximately 24 hours. After mixing, the primary stock solution was proportionally diluted with duckweed medium to prepare the five additional test concentrations. All final test solutions appeared clear and colorless. Exposure vessels: 250 mL plastic beakers containing 100 mL test solution, each covered with a disposable petri dish lid. Agitation: None Number of replicates: three plys 2 additional replicates for analytical sampling on Days 3 and 5 Initial loading: 5 plants/replicate, 15 fronds/replicate Number of concentrations: six plus a negative control plus abiotic controls at the highest concentration tested BACK TO MAIN Water chemistry: pH range (0 - 96 hours) 7.9 - 8.9 (control exposure) 8.4 - 8.7 (230 mg/L exposure) Method of calculating mean measured concentrations: arithmetic mean obtained using results obtained at Days 0, 3, 5, and 7. RESULTS Nominal concentrations: Negative control, 11, 22, 43.9, 87.9, 176, and 351 mg/L plus 351 mg/L abiotic control. Measured concentrations: <LOQ, 7.74, 15.1, 31.9, 62.5, 147, 230 mg/L; abiotic control = 231 mg/L Element value and 95% confidence interval (based on frond number): 3-day IC10: 101 mg/L (C.I. not calculable) 3-day IC50: > 230 mg/L (C.I. not calculable) 3-day IC90: > 230 mg/L (C.I. not calculable) 5-day IC10: 30.7 mg/L (13.3 - 142 mg/L) 5-day IC50: 182 mg/L (89.1 - 240 mg/L) 5-day IC90: > 230 mg/L (C.I. not calculable) 7-day IC10: 22.1 mg/L (13.3 - 26.0 mg/L) 7-day IC50: 108 mg/L (45.7 - 144 mg/L) 7-day IC90: > 230 mg/L (C.I. not calculable) 7-day NOAEC (number of fronds): 15.1 mg/L All element values based on mean measured concentrations Statistical methods: Mean plant and frond numbers, percent inhibition values and the percentages of necrotic, chlorotic and dead fronds were calculated using "Microsoft Excel Version 5.0", while statistical analyses were conducted using "TOXSTAT Version 3.5". Percent inhibition values were calculated for each treatment group as the percent reduction in mean frond number relative to mean frond number in the control replicates. The IC 10, IC50, and IC 90 values and 95% confidence intervals were determined, when possible, using linear interpolation with frond number and exposure concentration data. The percentages of dead, chlorotic and necrotic fronds also were calculated relative to the total number of fronds in each test chamber. The frond number data was evaluated for normality and homogeneity of variances (p = 0.05) using the Shapiro-Wilks' and Levene's tests, respectively. The data were normally distributed and the variances were homogeneous, thus statistically significant differences between the control and treatment groups were identified using ANOVA and Dunnett's test. Results of the statistical BACK TO MAIN analyses, as well as an evaluation of the concentration-response pattern and other observations of effects were used in the determination of the no observed-adverse-effect-concentration (NOAEC). Analytical Methodology: Analyses of test solutions were performed at Wildlife International Ltd. using high performance liquid chromatography with mass spectrometric detection (HPLC/MS). Samples were centrifuged as necessary 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 4.39 mg/L in this study. The mean percent recovery of matrix fortifications analyzed concurrently during sample analysis was 104%. Samples collected at test initiation had measured values from 64.2 to 82.6% of nominal. Measured values for samples taken at Day 3 ranged from 67.3 to 83.3% of nominal. Measured values for samples taken at Day 5 ranged from 65.4 to 85.4% of nominal. Samples collected at test termination (Day 7) ranged from 63.9 to 83.8% of nominal. For the abiotic controls, measured values for samples taken at Day 3, Day 5, and Day 7 ranged from 64.2 - 66.9% of nominal. Summary of analytical chemistry data: Nominal Test Concentration, mg/L Negative Control Measured Values at Days 0, 3, 5, and 7, Respectively, mg/L Mean Measured Concentration, mg/L All < LOQ <LOQ Percent of Nominal - 11 7.57, 8.35, 7.47, 7.55 7.74 70 22 15.2, 15.4, 14.6, 15.2 15.1 69 43.9 32.2, 31.9, 31.8, 31.7 31.9 73 87.9 63.5, 63.1, 61.5, 61.8 62.5 71 176 145, 146, 150, 147 147 84 351 226, 237, 232, 224 230 66 351 (abiotic) not analyzed, 225, 235, 232 231 66 BACK TO MAIN Biological observations after 7-Days: Counts Mean Measured Concentration, mg/L Mean Number of Plants Mean Number of Fronds Percent Inhibition via Frond Number Negative Control 19 197 - 7.74 18 177 10 15.1 20 219 -11 31.9 14 151* 24 62.5 11 134* 32 147 15 69* 65 230 17 37* 81 *Statistically significant difference (p < 0.05) from the negative control using ANOVA and Dunnett's Test. Effects Mean Measured Concentration, mg/L Negative Control 7.74 15.1 31.9 62.5 147 230 Mean Dead Fronds, % 0 0 0 0 0 1.0 3.8 Mean Chlorotic Fronds, % 0 0 1.1 0 0.9 11 9.4 Mean Necrotic Fronds, % 0 0 0 0.23 0.61 4.5 19 Control response: satisfactory. Plants appeared healthy and exhibited normal growth throughout the test with the exception of one necrotic frond observed on Day 3 and Day 5 of the test. Observations: Duckweed exposed to 147 and 230 mg PFOS/L exhibited a dose-responsive increase in the incidence of dead, chlorotic or necrotic fronds during the test. By Day 7, all treatment groups > 31.9 gm/L showed evidence of sublethal effects, including root destruction and/or a cupping of the plant downward on the water surface. BACK TO MAIN CONCLUSIONS The potassium perfluorooctanesulfonate 7-Day IC50 and 95% confidence interval for duckweed was determined to be 108 (45.7 - 144) mg/L. The 7-Day NOAEC, based on the inhibition of frond production and evidence of sublethal effects, was 15.1 mg/L. 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. OTHER Last changed: 6/19/01