Toxicity of Fire Retardant Chemicals to Aquatic Organisms: Progress Report
Methods and Materials
The toxicity of five fire retardant chemicals and foams were determined for two species of fish, two aquatic invertebrates, and one algae. The test organisms were rainbow trout (Oncorhynchus mykiss), fathead minnow (Pimephales promelas), Daphnia magna (daphnid), Hyalella azteca (amphipod), and the algae (Selenastrum capricornutum).
The specific chemicals tested were determined based on a critical review of the literature and interactions with qualified personnel familiar with use of various chemical and foam retardants. Studies were conducted with three retardants: Fire-Trol GTS-R (powder; lot number 84-FT-232), Fire-Trol LCG-R (liquid; lot number 91FT11), Phos-Chek D-75-F (powder; lot number 2468762-A); and two foams: Phos-Chek WD-881 (liquid; lot number 3616836A, batch number 18227) and Silv-Ex (liquid; lot number 75451, batch number US6203).
All tests were conducted under the existing quality assurance program of National Fisheries Contaminant Research Center (NFCR-Columbia, Missouri, USA). Eyed-eggs and juvenile fish were handled so as to minimize stress in accordance with the NFCR-Columbia Animal Welfare Plan (Animal Welfare Committee 1991). This research involved conducting several 96-hour acute toxicity studies with fish, adult Hyalella azteca, and algae (log-growth phase), and 48-hour studies with <24-hour-old Daphnia magna.
Acute toxicity tests with fish and Daphnia magna were conducted according to established methods (ASTM 1989). In each test, 10 organisms were exposed to each of seven to eight toxicant concentrations plus a control treatment for a total of 80-90 organisms per test. For Hyalella azteca, individual animals were tested instead of groups of 10 animals per test vessel. Each test apparatus was a 20 cm x 26 cm plexiglass sheet with 20 holes for holding 30-mL "shot-glass" vials containing 20 ml of test water. A group of 10 vials, each containing one animal, was used for each concentration of a test chemical tested. Other conditions in Hyalella tests followed those of ASTM (1989).
The exposures were conducted in test solutions under static conditions in glass jars and continued for 48 or 96 hours duration. The test temperature was maintained at 25°C for fathead minnow, 20°C for Hyalella azteca, 20°C for Daphnia magna, and 12°C for rainbow trout. The test water for the studies were blended to simulate ASTM soft and hard water (Table 1; ASTM 1989). Test water was prepared by addition of salts to ultra-pure water prepared by reverse osmosis and deionization. The test waters were analyzed using standard methods (APHA et al. 1975) to insure that the water quality met the criteria of the experimental design in terms of hardness, alkalinity, and concentrations of major cations (calcium, magnesium) and anions (chloride, sulfate) before it was used in tests with fish and aquatic invertebrates. Observations on mortality were recorded daily. The moving average-angle method (Peltier and Weber 1985) was used to calculate 48-hour EC50 or 96-hour LC50 values.
| pH | 7.3 - 7.5 | 7.8 - 8.0 |
| Hardness (mg/L as CaCO3) | 40 - 48 | 160 - 180 |
| Akalinity (mg/L as CaCO3 | 30 - 35 | 110 - 120 |
Acute toxicity tests with algae were conducted according to established methods (ASTM 1990). In each test, 2x104 cells/mL were exposed to each of five to six toxicant concentrations plus a control treatment. The exposures were conducted in ASTM algal assay medium test solutions under static conditions in glass jars and continued for 96 hours duration. The test temperature was maintained at 24°C. Observations on cell counts, biomass dry weight, and chlorophyll a were recorded at the end of the test. The moving average-angle method (Peltier and Weber 1985) was used to calculate 96-hour IC50 values for reduced cell counts, biomass dry weight, and chlorophyll a.
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