Static-renewal tests

Toxicity tests may be static, continuous-flow, or static renewal based on the toxicant dosing technique. Static and continuous-flow procedures are more widely used in toxicity tests conducted with pure chemicals and animal test species. Chronic toxicity tests conducted with effluents are usually static renewal, and those with algae are static. There is no change or renewal of the test substance with dilution water in a static test. This design is the simplest and least expensive however, the toxicant concentrations may decrease due to adsorption and biodegradation. The test solutions and dilution water are renewed periodically, usually daily in a static-renewal test. In a continuous-flow test, the dilution water and test substance are continuously or intermittently renewed. The exposure concentrations remain fairly constant and dose-response relationships can be well defined. 

The species in Table 3 were selected based on several criteria, primarily ease of culture, commercial availability, and size. The test species are acclimated for a specific period of time prior to testing to eliminate diseased organisms. Generally, a minimum of 10 animals are exposed in static and static-renewal tests and 20 in a flow-through test for each test concentration and control. The recommended loading... 

Comparison of MATCs with LCi and LCio Values Determined in Static Renewal Tests with Trout... 

Determined in static renewal tests at 4 days posthatching with the method of Finney (78), rather than the procedure of Daum (62) used in earlier investigations (13, 75). 

Fig. 5. Effects of lead on embryos and larvae of fish and amphibians. Lead was administered in static renewal tests conducted on developmental stages of the goldfish (O), rainbow trout ( ), and narrow-mouthed toad ( ). Exposure was initiated at fertilization and maintained through 4 days posthatching. Teratic larvae were counted as lethals.

Table III obviously were somewhat complicated by differences in test procedures, water conditions, and animal test species. However, it is apparent that static renewal tests conducted with developmental stages of sensitive aquatic species, such as the rainbow trout, provide a rapid and reliable method for the initial toxicological screening of aquatic contaminants.

Mercury and selenium were administered in equal proportions in static renewal tests. 

In static renewal tests with embryos and larvae of seven species of fish and amphibians, the toxicity of PCB compounds (i.e.. Capacitor 21, Aroclor 1016, i roclor 1242, Aroclor 1254) was found to increase with percent chlorination 20). The more chlorinated PCBs also exhibit longer environmental half-life (757). The combination of high toxicity and persistence in aquatic ecosystems renders these compounds especially hazardous. Despite curtailment of production in the United States, PCBs still in use or disposed of in recent years continue to pose a problem to water quality. These compounds not only exhibit high toxicity to eggs, embryos, and larvae of aquatic species, but also affect sex hormones and the endocrine mechanisms which regulate reproduction in fish 82). 

Toxicity Bioassay. Ninety-six hour acute toxicity tests were conducted on the effluent streams of major industries. A static renewal procedure was used in which waste waters of various dilutions were renewed at 24 hour intervals over a 96 hour period. Rainbow trout was used as the test organism. Tests were conducted at 13°C in 20 liter aquaria according to standard procedures (22), Results are summarized in Table 8. Chemical and toxicity test results indicate that the trace element quantities identified in Table 8 are not acutely toxic under the prevailing conditions and unlikely to pose an acute threat to aquatic life. In this case a chronic toxicity assessment would require additional research. 

Gersich, F.M. 1984. Evaluation of a static renewal chronic toxicity test method for Daphnia magna Straus using boric acid. Environ. Toxicol. Chem. 3 89-94. 

Toxicity test in which test solutions are renewed (replaced) periodically (e.g., at specific intervals) during the test period. Synonymous terms are batch replacement, renewed static, renewal, intermittent renewal, static replacement, and semistatic (Environment Canada, 1999). Volume 1(7,10). 

Four types of exposure conditions are employed in both acute and chronic tests and in both freshwater and saltwater media static, static-renewal (semi-static), recirculation, and flow-through. The choice for which test type to use usually depends on test substance characteristics, test duration, test species, and regulatoiy requirements. 

Acute tests can be further divided with respect to flow regime typically either static or static-renewal. During the static procedure, test organisms are exposed to the environmental sample in relatively nontoxic and nonreactive cups, glass beakers, or aquaria... 

Besides the complexity of the biological system and the length of the test, there are more practical aspects to toxicity tests. In aquatic test systems the tests may be classified as static, static renewal, recirculating, or flow-through. 

The next step in complexity is static renewal. In this exposure scheme, a toxicant solution is replaced after a specified time period by a new test solution. This method has the advantage of replacing the toxicant solution so that metabolic wastes can be removed, and toxicant and oxygen concentrations... 

What differences are there between a static and a static-renewal toxicity test ... 

Conducting Static Toxicity Tests with the Lemma gibba G3 Conducting a Terrestrial Soil-Core Microcosm Test Conducting Three-Brood, Renewal Toxicity Tests With Ceriodaphnia dubia Hazard of a Material to Aquatic Organisms and Their Uses... 

This toxicity test is usually run as a static renewal, but some researchers have used a continuous flow setup with a proportional diluter. Handling the organisms during the transfer to new media is a potential problem for inexperienced technicians. 

Test Type Static, Renewal, Flow-Through... 

Blaylock and Frank (30) recently reported static renewal studies with eggs and larvae of the carp (Cyprinus carpio), which were treated with nickel sulfate. Test water and toxicant were renewed at 24-h intervals. Carp larvae that hatched from untreated eggs were exposed to nickel concentrations of 1-10 mg/liter, and median lethal concentrations were determined for exposure periods that varied from 72 to 257 h. The LC50 determined at 184 h was 3.18 mg Ni/liter, and this was in close agreement with the LC50 of 2.78 mg/liter determined in 7-day tests with embryo-larval stages of the goldfish (Table II). 

The exposure protocol was daily static renewal of the test medium. Exposure solutions were formed by the addition of uL quantities of an alcohol or acetone stock solution to the requisite amount of 15 (parts per thousand) seawater. Exposure continued for the duration of zoeal development, 11 days, until the exposed zoeae died or metamorphosed to the megalops. This is sufficient time for a steady-state in the partitioning of the organotins between the organism and the milieu. 

Graves, W. and J. Swigert. 1997. Cry9C Protein in Corn Pollen A 48-Hour Static-Renewal Acute Toxicity Test with the Cladoceran Daphnia magna) Final Report Lab Project Number 452A-101. Unpublished study prepared by Wildlife International Ltd. 23 p. 

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