Bioassay quality

Beeause the 2,3,7,8-TCDD calibration curve is used for quantification of analysis results, the stability and quality of the calibration curves is important. Furthermore, the calibration curves themselves are used as a DR CALUX bioassay quality eriterion. Aecording to the performanee eriteria set for the DR CALUX bioassay, the fitted EC50 should be within the range of 6 to 18 pM... 

Methods. As discussed in the previous chapter, a number of approaches have been used to assess the presence of potentially toxic trace elements in water. The approaches used in this assessment include comparative media evaluation, a human health and aquatic life guidelines assessment, a mass balance evaluation, probability plots, and toxicity bioassays. Concentrations of trace elements were determined by atomic absorption spectrometry according to standard methods (21,22) by the Oregon State Department of Environmental Quality and the U.S. Geological Survey. 

Seeds of lettuce and other species have frequently been used to bioassay for the allelopathic activity of plant exudates (17.18.19). As with the use of cell suspensions, there are certain advantages and disadvantages to this methodology. The experimental simplicity, small amounts of material required and short time frame are certainly attractive qualities. However, species used in such bioassays quite often do not represent the actual target species under consideration. This is especially true when terrestrial crop species are substituted for weeds of aquatic systems. Nevertheless, information obtained from such experiments are often valuable when used in conjunction with results of other assays. 

Hansen PD, Blasco J, de Vails A et al (2007) Biological analysis (bioassays, biomarkers, biosensors). In Barcelo D, Petrovic M (eds) Sustainable management of sediment resources. Sediment quality and impact assessment of pollutants. Elsevier Publishers, Amsterdam... 

Hutchinson, T.C. and P.M. Stokes. 1975. Heavy metal toxicity and algal bioassays. Pages 320-343 in S. Barabas (ed.). Water Quality Parameters. ASTM Spec. Tech. Publ. 573. Amer. Soc. Testing Mater., 1916 Race Street, Philadelphia, PA. 

Episodic pollution events can adequately be addressed by acute toxicity bioassays, however these are not sufficient to investigate the water quality for delayed toxicity effects of chemicals present. Chronic effects of pesticides can include carcinogenicity, teratogenicity, mutagenicity, neurotoxicity, and reproductive effects (endocrine disruption). 

While reported data on the acute and chronic toxicity of many pesticides is plentiful, few studies have been published on toxicity bioassays applied to wastewaters containing pesticides. The application of toxicity bioassays to the quality control of wastewaters offers several advantages in addition to being a... 

The specific and robust nature of the pups response to milk allowed Keil et al. (1990) to develop a behavioural bioassay for use in characterizing the actual pheromonal substance or substances. Using the bioassay it was found that pups responsiveness declines linearly with the exponent of dilution, and that cues contained in the milk are so potent that milk diluted by as much as 10 4 still elicits significantly more responses than cow s milk or other control substances (Keil et al. 1990). However, when left at room temperature milk loses most of its behaviour-releasing quality within about 30 minutes, but retains it for several weeks when stored at -40°C (Muller 1978 Keil et al. 1990). 

In subsequent chapters, we provide an overview of SPMD fundamentals and applications (Chapter 2) the theory and modeling which includes the extrapolation of SPMD concentrations to ambient environmental concentrations (Chapter 3) study considerations such as the necessary precautions and procedures during SPMD transport, deployment, and retrieval (Chapter 4) the analytical chemistry and associated quality control for the analysis of SPMD dialysates or extracts (Chapter 5) a survey and brief description of bioassays-biomarkers used to screen the toxicity of SPMD environmental extracts (Chapter 6) discussions on how HOC concentrations in SPMDs may or may not relate to similarly exposed biomonitoring organisms (Chapter 7) and selected examples of environmental studies using SPMDs (Chapter 8). In addition, two appendices are included which provide... 

SPMD dialysates (extracts), rinses of the exterior membrane surface (only SPMDs exposed to air), and aliquots thereof often contain a number of classes of chemicals. Figure 6.1 shows various levels of processing and enrichment used for SPMD derived bioassay samples. We strongly recommend the use of SPMDs with triolein purified by the method of Lebo et al. (2004) for bioassays to reduce the probability of false-positive results or for controls that fail to meet quality control... 

Let us skip by the question of the adequacy of the animal tests used to identify these agents. The general quality of the animal test is obviously of great importance in the overall evaluation and these questions cannot be ignored in the case of cancer bioassays any more than they can in any other type of toxicity test. But the more interesting questions arise when we move beyond the question of study quality. 

There are numerous advantages to the FAC approach that differentiate it from many forms of bioassay - MS-dependent or otherwise. The FAC method offers thermodynamic and kinetic binding data from the breakthrough curves. As with the classical application of the FA method, the quality of the data is superb relative to other chromatographic or electrophoretic methods [9, 10]. It is an equilibrium method, as opposed to systems that rely upon the separation of bound from unbound, and this forms the basis of its accuracy. 

Due to the lack of bioassays that mimic the situation of toxin-containing food particles, most of the work has been performed on herbivores that feed on diets of phytoplankton species with different degrees of toxicity. This has led to multiple variant parameters, not allowing the direct comparison of effects due to the varying toxin contents. In a few cases, these studies have the advantage of being able to directly compare different clones of one species with variable toxicities but otherwise comparable biochemical composition. There, the effect of the toxins can be determined without overlaying effects due to different nutritional quality of the food. 

Kwan, K.K. Dutka, B.J. A novel bioassay approach direct application of Toxi-Chromotest and SOS Chromotest to sediments. Environ. Toxic. Water Quality 1992, 7, 49-60. 

Chao, L. Wang, L.K. Wang, M.H.S. Use of the Ames Mutagenicity Bioassay as a Water Quality Monitoring Method, PB88-168422/AS US Department of Commerce, National Technical Information Service Springfield, VA, 1986 25 p. 

New, powerful techniques in chemistry, odor formulations, bioassays, and olfactometry have supplied us with deeper as well as fresh insights into olfactoiy effects on our behavior. Medicine, psychology, environmental design, occupational safety, air-quality control, marketing, and advertising now consider and contribute to human chemical ecology. 

As part of this field study, relevant quality assurance/quality control (QA/QC) criteria and guidelines (SETAC, 1993 JAMP, 1998a,b) have to be set to insure the quality of data generated during the assessments. The development of QA/QC criteria for this study involved conducting a series of replicate bioassays with each of the methods. Samples tested included a control sediment, contaminated sediments and reference toxicants. Based on the results of the bioassay replicates, the variability associated with the tests was quantified and we were able to determine what we considered acceptable QA/QC criteria for these methods. 

Both the EC50 values and the 3-pM point of the 2,3,7,8TCDD ealibration curve serve as quality criteria. For each participant, the results for both data points from all 96-well plates analyzed during the presented study were collected and reeorded in Shewhart control charts. The Shewhart control chart is used to identify variations on performanee of the DR CALUX bioassay brought about by unexpected or unassigned causes. The Shewhart eontrol chart shows the mean of the EC50 and 3-pM control point and the upper and lower eontrol limits. In Figure 2, a typical Shewhart control chart is shown. Over the analysis period, none of the participants exceeded the aetion levels (AVG 3 S). 

For the determination of the intralaboratory repeatability of the DR CALUX bioassay for sediment samples, two sediment extracts were analyzed 10 times. Each analysis was performed in triplicate. As a prerequisite for a correct triplicate analysis, the percentage standard deviation in the triplicate determination should be below 15%. This is in accordance with the harmonized quality criteria for eell-based bioassay analyses of PCDDs/PCDFs in feed and food as formulated by Behnisch et al. (Behnisch et al, 2001 a) and as detailed in European Union directive 2002/69/ EC and direetive 2002/70/EC. The repeatability for the low-2,3,7,8-TCDD-content sediment... 

Several overall conclusions can be drawn based on the statistical evaluation of the data submitted by the participants of the DR CALUX intra-and interlaboratory validation study. First, differences in expertise between the laboratories are apparent based on the results for the calibration curves (both for the curves as provided by the coordinator and for the curves that were prepared by the participants) and on the differences in individual measurement variability. Second, the average results, over all participants, are very close to the true concentration, expressed in DR CALUX 2,3,7,8-TCDD TEQs for the analytical samples. Furthermore, the interlaboratory variation for the different sample types can be regarded as estimates for the method variability. The analytical method variability is estimated to be 10.5% for analytical samples and 22.0% for sediment extracts. Finally, responses appear dependent on the dilution of the final solution to be measured. This is hypothesized to be due to differences in dose-effect curves for different dioxin responsive element-active substances. For 2,3,7,8-TCDD, this effect is not observed. Overall, based on bioassay characteristics presented here and harmonized quality criteria published elsewhere (Behnisch et al., 2001a), the DR CALUX bioassay is regarded as an accurate and reliable tool for intensive monitoring of coastal sediments. 

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