Organ toxicity tests

QSAR methods based on neural nets have also shown promise in modeling gross or in vivo toxicity of compounds to a number of species. Such models may be faster, and cheaper, and constitute useful surrogates for whole organism toxicity tests involving animal sacrifice. Bradbury reviewed the role of QSARs as tools for predicting the toxicity of chemicals when little or no empirical data are available (59). Bradbury observed that there has been an evolution of QSAR development and application, from that of a chemical-class perspective, to one that is more consistent with assumptions regarding modes of toxic action. 

Toxicity Test (Bioassay). Organisms representative of those to be protected are exposed to the test water under rigorously controlled conditions, usually in a laboratory environment. In this test the organisms, normally fish, are exposed for a standard time period in aquaria to various dilutions of waste or river water while some physiological parameter is carefully monitored to determine fish response. Behavior is also observed. 

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. 

Fig. 15-13 Organism mortality as a function of SEM/AVS ratio for a hypothetical sediment. This figure is generalized from results typical of sediment toxicity tests (e.g., Hansen et al, 1996). Organisms evaluated in such tests include amphipods and poly-chaetes. The symbols represent different sediments. The vertical line at 10° is positioned at an SEM/AVS ratio of 1.0 the horizontal line at 24% represents the limit of toxicity, that is, mortality 24% is defined as not the consequence of toxicity.

Data sets on toxicity to aquatic organisms vary considerably from compound to compound, with dibutyltin being the best studied. Results of toxicity tests for all compounds are summarized in Figure 2. Values for all but one test on the octyltins have been set at the solubility of the compounds, since no toxicity was observed below the solubilities derivation of PNECs for the octyltins are, therefore, more precautionary than for the other compounds. 

Apart from the scientific advantages offered by this new technology, it has also been welcomed by organizations seeking a reduction in the number of animals used in toxicity testing (see Chapter 15, Section 15.6, and Walker 1998b). 

Most statutory toxicity testing is done on individual compounds. In the natural environment, however, organisms are exposed to complex mixtures of pollutants. Toxicity testing procedures are described for environmental samples that contain mixtures of different chemicals. 

There is a continuing interest in the development of biomarker assays for use in environmental risk assessment. As discussed elsewhere (Section 16.6), there are both scientific and ethical reasons for seeking to introduce in vitro assays into protocols for the regulatory testing of chemicals. Animal welfare organizations would like to see the replacement of toxicity tests by more animal-friendly alternatives for all types of risk assessment—whether for environmental risks or for human health. 

With improvements in scientific knowledge and related technology, there is an expectation that more environmentally friendly pesticides will continue to be introduced, and that ecotoxicity testing procedures will become more sophisticated. There is much interest in the introduction of better testing procedures that work to more ecologically relevant end points than the lethal toxicity tests that are still widely used. Such a development should be consistent with the aims of organizations such as FRAME and ECVAM, which seek to reduce toxicity testing with animals. Mechanistic biomarker assays have the potential to be an important part of... 

McCrary JE, Heagler MG. 1997. The use of a simultaneous multiple species acute toxicity test to compare the relative sensitivities of aquatic organisms to mercury. J Environ Sci Health Part A Environ Sci Eng Toxic Hazardous Substance Control 32 73-81. 

In the case of surface water, the LOQ must not exceed a concentration which has an impact on nontarget organisms deemed to be unacceptable according to the requirements of Annex VI. At present, no harmonized limits for surface water exist. Therefore, provisions in Annex VI of Directive 91/414/EEC will be used to calculate guidance limits for analytical methods for surface water. In SANCO/825/00 the limits given in Table 6 are established [the relevant concentrations (the lowest will always be taken into consideration) depend on the species as indicated and can be taken from toxicity tests]. 

I. H. Suffet and M. Malalyandi, (Eds.), "Organic Pollutants in Hater. Sampling, Analysis, and Toxicity Testing", American Chemical Society, Washington, D.C., 1987. 

Different samples of chlorinated camphene containing from 62 to 72% of chlorine all give the same infrared spectra. However, the toxicity to flies reaches a maximum at a chlorine content of 67 to 69% and drops off rapidly below 60% and above 72%. From the results of both the infrared spectroscopic examination and the fly-toxicity tests given below, it is concluded that the organic-chlorine compound in the fat was essentially unchanged toxaphene. 

Major organ function tests Acute and subacute toxicity studies... 

A waste is toxic under 40 CFR Part 261 if the extract from a sample of the waste exceeds specified limits for any one of eight elements and five pesticides (arsenic, barium, cadmium, chromium, lead, mercury, selenium, silver, endrin, methoxychlor, toxaphene, 2,4-D and 2,4,5-TP Silvex using extraction procedure (EP) toxicity test methods. Note that this narrow definition of toxicity relates to whether a waste is defined as hazardous for regulatory purposes in the context of this chapter, toxicity has a broader meaning because most deep-well-injected wastes have properties that can be toxic to living organisms. 

Toxicity in estuarine sediments—use of Mutatox and Microtox to evalu- 173 ate the acute toxicity and genotoxicity of organic sediments Toxicity tests for the analysis of pore water sediment a comparison of 4 174... 

Martin, M., J.W. Hunt, B.S. Anderson, S.L. Turpen, and F.H. Palmer. 1989. Experimental evaluation of the mysid Holmesimysis costata as a test organism for effluent toxicity testing. Environ. Toxicol. Chem. 8 1003-1012. 

In acute toxicity tests with aquatic organisms, LC50 (96 h) values — with only one exception — exceeded 130 pg/L. The exception was the larva of a marine crab with an LC50 (96 h) value of... 

---