Bioconcentration test species

Data on the potential for accumulation of silver has been studied in several aquatic species. Several of these studies do not conform to current bioconcentration test procedures in terms of numbers of fish, duration of exposure, and measurement of concentrations in aquaria. EPA (1980a) reported a bioconcentration factor of less than I in bluegills (Lepomis macrochirus) exposed to silver nitrate for 28 days. Approximate bioaccumulation factors of 4-6 for bluegill were calculated based on a 6-month study and 2-10 for large mouth bass (Micropterus salmoides) exposed to silver nitrate for 4 months (both dry weight) (Coleman and Cearley 1974). 

Due to differences in test species among bioconcentration tests as well as differences in the types of chemicals used in the various studies, possible metabolic transformation, and experimental artifacts, empirical relationships between BCF and Kow are known to vary substantially. Because of these differences, assessments of the BCF of chemical substances can differ substantially, depending on the empirical model that is used. Special caution is required when empirical relationships report a value for the slope a that is significantly different from 1.0. 

At the meeting of the Chemical Substances Council held by the Japanese government in 2004, it was reported that a bioconcentration study was conducted in 2003 with SCCPs with Cn and Cly, g, 9, lo (chlorine 62.5, 65.7, 68.5 and 70.9%) containing 1% of stabilizer and the quantitative data on each individual substance were obtained [13]. The study was conducted with flow-through system at concentrations of 1 and 0.1 pg of SCCPs, and 20 mg of 2-metoxyethanol was used as dispersant. Liquid chromatography/mass spectrometry (LC/MS) was used for the analysis of the test species, carp Cyprinus carpio). After 62-day exposure, a 14-day excretion study was also conducted. The result is shown in Table 6. 

Food Chain Bioaccumulation. Bioconcentration factors have been determined for algae, shellfish, and fish and exhibit a wide range (29-17,000) (ERA 1976 Oliver and Niimi 1983 Pearson and McConnell 1975). This wide range may be explained in part by species differences in metabolism or differences in concentrations tested. Studies also indicate that hexachlorobutadiene preferentially accumulates in the livers of fish. Further studies which might explain the wide range of BCF values would be helpful. No information was located regarding the bioaccumulation of hexachlorobutadiene in plants or aquatic organisms. More information is needed to determine the importance of terrestrial/aquatic food chain bioaccumulation as a potential human exposure pathway. 

Spehar et al. [231] investigated the bioconcentration potential of hexachloro-norbornadiene and heptachloronorbornene using 30-day flow-through test with early juvenile fathead minnows Pimephales promelas) with a body weight of 0.12 g and 4% lipid content. The measured mean concentrations of hexa-chloronorbornadiene (HCND) in water was 20.0 3.9 pg and the water concentration of heptachloronorbornene (HepCNB) was 25.9 3.4 pg b. The bioconcentration factors on a wet weight basis after 30 days in this fish species were 6,400 and 11,200, respectively. The bio concentration factors on a lipid basis (BCFl) of HCND and HepCNB after 30 days were 160,000 and 280,000, respectively (see Table 13). 

The concept of extrapolation from experimental data on environmental effects to field situations is via a predicted no effect concentration , based on the no-effect concentrations seen in tests conducted in single species. Other data are aimed at indicating biodegradability and bioconcentration potential. Ideally, field data and actual no effect concentrations are more useful, but, because of the difficulties and expense in conducting such studies, this type of data tends to be acquired only in specific circumstances. 

Most methods for experimental BCF determinations represent an assessment of the potential for accumulation. They do not account for specific environmental conditions, such as diflferences in the species exposed or the environmental bioavailability of the chemicals. The tests generally use fish as a model organism to serve as a predictor for bioconcentration in other aquatic species as well, and for bioaccumulation/biomagnification along aquatic foodwebs. Test guidelines for BCF in fish are available (e.g. OECD, 1981a), where the fish are exposed to the chemicals and from the concentrations in fish and water the BCF is obtained. The tests vary with respect to ... 

The relationship between acute toxicity and bioconcentration, for the chemicals and species discussed in this paper, appears to be simple. For the organic chemicals discussed herein the difference between the internal toxicant concentration achieved in each of these two types of aquatic tests, which is proportional to the bioconcentration factor Kg, can be used to convert kinetic information derived by either procedure to a common format. 

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