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PubMed1995

Is Daphnia magna an ecologically representative zooplankton species in toxicity tests?

Daphnia magna is commonly used in aquatic toxicity testing because of many characters that make it easy and economical to culture in the laboratory: it is relatively small, has short life cycle, high fecundity, and parthenogenetic reproduction. On the other hand, D. magna differs from other freshwater zooplankters in size, habitat, life-history, and ability to withstand fish predation. D. magna is a relatively large zooplankton species which makes it so vulnerable to fish predation that it is excluded from fish-inhabiting lakes. It occurs mainly in ephemeral habitats like small ponds and rockpools where vertebrate predators are rare. As a result, D. magna is seldom an indigenous species in lakes which receive pollutants, although representativeness is one important criterion for the standardised toxicity test species. Small ponds are unpredictable habitats with large temporal and spatial variability in abiotic factors. Adaptation to this natural abiotic stress may increase pollution tolerance. The life-history of D. magna also differs from that of lake-inhabiting cladocerans. Large daphnids produce many small neonates, whereas the opposite is true for small cladocerans. The large neonate size allows an earlier maturation of small cladocerans compared to daphnids. In a few comparative studies D. magna tended to be less sensitive to toxic substances than other cladocerans, and this may be due in part to life-history and size differences.

Journal Article↗
PubMed2003

A review on the application of microbial toxicity tests for deriving sediment quality guidelines.

The results of microbial toxicity tests are needed for the risk assessment of polluted sediments. In comparison with animals the anaerobic microorganisms are more tolerant to natural sediment conditions whereas they are more sensitive for a number of specific pollutants. Microbial toxicity tests from a literature search were classified in seven categories. Category A, B and C use polluted sediments and are applied for sediment monitoring. In category D, a pure chemical is added and the organisms and the test conditions were derived from sediment. Therefore this category can be used for setting sediment quality guidelines which protect sediment functions for the toxic effects of chemicals. In category E, organisms from a polluted site are separated from the sediment and are tested with pure chemicals. Organisms from a more polluted site can be more tolerant to a local pollutant. This is called pollution-induced community tolerance and can be used as evidence for the occurrence of toxic effects in a specific sediment. In category F pure chemicals are tested with a pure culture of microorganisms under sediment conditions. The results of category F tests can be combined with single species tests with animals and plants to obtain sediment quality guidelines sufficient for species protection. This can be compared with the sediment quality guidelines which protect sediment functions. When one of these quality guidelines is exceeded for a compound at a specific location a category E test can be used to determine whether the compound shows toxic effects in that sediment.

Bacteria, Anaerobic↗
PubMed2004

Reduction in labile copper in the 7-day Ceriodaphnia dubia toxicity test due to the interaction with zooplankton food.

Due to the increased popularity of zooplankton toxicity tests, it is important to investigate potential confounding factors. Though zooplankton food has been studied extensively to meet the nutritional needs of the zooplankton, less research has been done on whether food addition reduces the toxicity of metals in the tested sample. This investigation combines toxicity tests and metal speciation analysis to determine whether the EPA recommended food of YCT (yeast, cerophyll, and trout chow) and Pseudokirchneriella subcapitata (formerly Selenastrum capricornutum) reduces copper toxicity by decreasing the concentration of labile copper. Toxicity tests were performed with Ceriodaphnia dubia on culture water spiked with 0, 787, and 1574 nM copper with five different food levels. A Chelex-100 cation exchange resin and a graphite furnace-atomic absorption spectrophotometer were used in conjunction with the toxicity tests to measure the amount of labile copper in the culture water. At the EPA recommended food dosage, the C. dubia food has a chelating capacity of approximately 500 nM Cu. For both concentrations of spiked culture water, the toxicity to C. dubia was reduced with increasing food level, which seemed to be both from a decrease in labile copper concentration and an increase in the nutritional condition of the zooplankton.

Animal Feed↗
PubMed2003

Application of Neomysis awatschensis as a standard marine toxicity test organism in China.

The small mysid crustacean Neomysis awatschensis was collected in the west coast of Jiaozhou Bay, Qingdao, China in 1992 and acclimated and cultured in laboratory conditions since then. Standard acute toxicity tests using 4-6 d juvenile mysids of this species were conducted and the results were compared with Mysidopsis bahia, a standard toxicity test organism used in the US in terms of their sensitivities to reference toxins, as well as their taxonomy, morphology and geographic distributions. Because of its wide distribution along the Chinese coast, similar sensitivity to pollutants as M. bahia, short life history, small size and the ease of handling, this study intended to use N. awatschensis as one of the standard marine organisms for toxicity testing in China. The species were applied to acute toxicity evaluations of drilling fluid and its additives, organotin TPT and toxic algae, and to chronic (life cycle) toxicity assays of organotin TPT and a toxic dinofalgellate Alexandrium tamarense, respectively. Using N. awatschensis as a standard toxicity testing organism in marine pollution assessment in China is suggested.

Animal Experimentation↗
PubMed2000

A battery of toxicity tests as indicators of decontamination in composting oily waste.

Heterogeneous oily waste from an old dumping site was composted in three windrows constructed from different proportions of waste, sewage sludge, and bark. The objectives of this pilot study were to examine the usefulness of composting as a treatment method for this particular waste and to study decontamination in the composting process by using a battery of toxicity tests. Five samples from the windrow having intermediate oil concentrations were tested with toxicity tests based on microbes (Pseudomonas putida growth inhibition test, ToxiChromotest, MetPLATE, and three different modifications of a luminescent bacterial test), enzyme inhibition (reverse electron transport), plants (duckweed growth inhibition and red clover seed germination), and soil animals (Folsomia candida, Enchytraeus albidus, and Enchytraeus sp.). The luminescent bacterial tests were used as prescreening tests. Chemical analyses of samples were carried out simultaneously. Both toxicity and oil concentration, including those of polyaromatic hydrocarbons (PAHs), were reduced during composting and soil quality improved significantly. The total oil hydrocarbon concentration decreased from 90,000 to 19,000 mg/kg, measured with the IR method, in 4 months, and from 86,000 to 1400 mg/kg, measured with GC method. The concentration of PAHs decreased from 135 to 23.5 mg/kg. During the fourth month of composting (stabilization stage), the proportion of the heaviest oil fractions (asphaltenes) became dominant. Toxicity varied between different samples and between different bioassays; however, the first sample was significantly more toxic than the others, and most of the tests revealed a decrease in toxicity during the composting process.

Animals↗
PubMed1999

Potential of two hydra species as standard toxicity test animals.

The potential for using pink hydra (Hydra vulgaris) and green hydra (Hydra viridissima) as a model invertebrate for the toxicity testing of xenobiotics was investigated. Test compounds were 4-chlorophenol, endosulfan, and copper. The reference toxicant 4-chlorophenol was used as a standard during toxicity testing to ensure the sensitivity of hydra did not change over time. Hydra had a low sensitivity to 4-chlorophenol and endosulfan compared to other freshwater species. The 96-h LC50 (SE) values for 4-chlorophenol and endosulfan were 32 mg/L (1.3) and 0.81 mg/L (0.1), respectively, for pink hydra, and 45 mg/L (6.1) and 0.67 mg/L (0.02), respectively, for green hydra. Based on population growth rates, the 6-day NOEC and LOEC results for pink hydra exposed to 4-chlorophenol and endosulfan were <1.1 and 1.1 mg/L, and 0.044 microg/L and 0.080 mg/L, respectively; results for green hydra were 10.3 and 22.3 mg/L, and 0.060 and 0.080 mg/L, respectively. Following exposure to copper, the 96-h LC50 (SE) values were 26 microg/L (3.4) for pink hydra and 8.5 microg/L (0.3) for green hydra, respectively. Based on population growth rates, the 7-day population growth NOEC and LOEC values for both pink and green hydra exposed to copper were 4 and 8 microg/L, respectively. Results indicate that hydra have the potential for use in acute and subchronic toxicity testing of inorganic toxicants, but have a low sensitivity to organic toxicants.

Algorithms↗
PubMed1984

General toxicity testing: sense and non-sense, science and policy.

The dramatic increase in the number and variety of industrial chemicals in addition to natural compounds, and the increased public concern about their health effects, has in the last few decades led to a remarkable development in number and types of toxicity tests employed to assess safety of chemicals. Not too many years ago, toxicity tests were relatively simple in design and conduct. They were sometimes inadequate in a number of aspects. Toxicity testing has now become an unbalanced mixture of sound science and policy. Many times companies wishing to market products internationally are faced with a plethora of different national regulatory requirements. In this presentation attention is given to requirements for toxicity data and the need for harmonization in guidelines while avoiding rigid protocols. The wisdom and necessity of conducting all currently required tests will be considered. The relevance of certain biochemical, hematological, and pathological parameters is discussed as is the relevance of Good Laboratory Regulation for toxicity testing. The importance of a scientific evaluation of all chemical biological data derived from modern sensibly designed toxicity tests with respect to extrapolation and safety assessment is emphasized. Future development in certain areas of toxicity research is stressed and examples are given.

Animals↗
PubMed2003

Effects of ammonia on juvenile unionid mussels (Lampsilis cardium) in laboratory sediment toxicity tests.

Ammonia is a relatively toxic compound generated in water and sediments by heterotrophic bacteria and accumulates in sediments and pore water. Recent data suggest that unionid mussels are sensitive to un-ionized ammonia (NH3) relative to other organisms. Existing sediment exposure systems are not suitable for ammonia toxicity studies with juvenile unionids; thus, we modified a system to expose juveniles to ammonia that was continuously infused into sediments. This system maintained consistent concentrations of ammonia in pore water up to 10 d. Juvenile Lampsilis cardium mussels were exposed to NH3 in pore water in replicate 96-h and 10-d sediment toxicity tests. The 96-h median lethal concentrations (LC50s) were 127 and 165 microg NH3-N/L, and the 10-d LC50s were 93 and 140 microg NH3-N/L. The median effective concentrations (EC50s) (based on the proportion affected, including dead and inactive mussels) were 73 and 119 microg NH3-N/L in the 96-h tests and 71 and 99 microg NH3-N/L in the 10-d tests. Growth rate was substantially reduced at concentrations between 31 and 76 microg NH3-N/L. The lethality results (when expressed as total ammonia) are about one-half the acute national water quality criteria for total ammonia, suggesting that existing criteria may not protect juvenile unionids.

Age Factors↗
PubMed2002

A flow-through chamber for toxicity testing of 80-200 microm organisms.

A flow-through chamber was developed for toxicity testing of mobile species that require microscopic observation to assess viability and development; no sub-sampling was required in this method. Organisms were held in 1.5 mL volumes in 30 mm plastic petri plates adapted with two side sections containing 35 microm screening to provide drainage. Test solutions continuously entered via a drip tube; five 1.5 mL volumes were exchanged per hour. The 30 mm organism dish was housed in an outer dish (60 mm petri plate) that captured effluent for water quality measurements. Direct observation of organisms in the thin water layer occurred without refocusing the microscope. The flow-through chamber was used to test the toxicity of copper to Mercenaria mercenaria (hard clam) as they developed from free swimming larvae (approximately 80 + microm) through metamorphosis to the settlement stage (approximately 200 microm). The flow-through chamber performed well and good water quality was maintained throughout the assay. Metamorphosis occurred at the appropriate developmental time with relatively low variability between replicates. Copper, at a concentration of 14 microg/L Cu, was shown to significantly increase mortality and inhibit metamorphosis after 36 h of exposure.

Animals↗
PubMed2001

Freeze concentration of ambient waters for toxicity testing.

We have developed a method to concentrate aqueous samples for toxicity testing. This method relies on the phenomenon of freezing exclusion, whereby solutes are rejected from the interstices of a growing ice crystal. Tenfold freeze concentration gave excellent recoveries of inorganic and organic analytes, phenol and ZnSO4 toxicity from spiked natural waters, and toxicity of both pre- and postdischarge municipal wastewater. Simultaneous 10-fold concentration of strong mineral or humic ambient matrices did not substantially modify the expressed toxicity of phenol or ZnSO4, and it did not seem to generate spurious toxicity to the marine bioassay organism used (Vibrio fischeri). Hundredfold freeze concentration permitted the quantification of low levels of ambient toxicity in a wide variety of natural waters using a rapid, inexpensive microbioassay. Precipitation of matrix elements may limit the degree of concentration that can be achieved with highly mineralized or strongly humic waters. This approach is well suited to ambient toxicity testing, because it is nonspecific and has low potential for solvent contamination. Furthermore, the low temperatures involved minimize volatilization and degradation of organic contaminants.

Animals↗
PubMed2005

A novel in vitro exposure technique for toxicity testing of selected volatile organic compounds.

Exposure to vapours of volatile chemicals is a major occupational and environmental health concern. Toxicity testing of volatile organic compounds (VOCs) has always faced significant technological problems due to their high volatility and/or low solubility. The aim of this study was to develop a practical and reproducible in vitro exposure technique for toxicity testing of VOCs. Standard test atmospheres of xylene and toluene were generated in glass chambers using a static method. Human cells including: A549-lung derived cell lines, HepG2-liver derived cell lines and skin fibroblasts, were grown in porous membranes and exposed to various airborne concentrations of selected VOCs directly at the air/liquid interface for 1 h at 37 degrees C. Cytotoxicity of test chemicals was investigated using the MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) and NRU (neutral red uptake) assays following 24 h incubation. Airborne IC(50) (50% inhibitory concentration) values were determined using dose response curves for xylene (IC(50)=5350+/- 328 ppm, NRU; IC(50)=5750+/- 433 ppm, MTS in skin fibroblast) and toluene (IC(50)=0 500+/- 527 ppm, NRU; IC(50)=11,200 +/- 1,044 ppm, MTS in skin fibroblast). Our findings suggest that static direct exposure at the air/liquid interface is a practical and reproducible technique for toxicity testing of VOCs. Further, this technique can be used for inhalational and dermal toxicity studies of volatile chemicals in vitro as the exposure pattern in vivo is closely simulated by this method.

Air Pollutants↗
PubMed1983

Toxicity testing of atracurium.

The toxicity of atracurium has been investigated in subacute tests in rat, dog and monkey, in a fetal toxicity test in the rabbit and in a paranatal study in the cat. No specific adverse effects were found despite administration of supraparalysing doses. It appeared not to cross the placenta at term and the neonatal kitten seemed resistant to its neuromuscular blocking action. In the dog, cat and pig, in which physiological monitoring was undertaken, i.v. injection of three to four times the paralysing dose had little or no effect on arterial pressure or heart rate. The solution did not cause local irritation. Atracurium was not mutagenic in the Ames test.

Animals↗
PubMed2004

Development of a whole-sediment toxicity test using a benthic marine microalga.

An acute whole-sediment toxicity test with a benthic marine microalga was developed and optimized using flow cytometry to distinguish algae (based on their chlorophyll a autofluorescence) from sediment particles. Of seven benthic marine algae screened, the diatom Entomoneis cf punctulata was most suitable because of its tolerance of a wide range of water and sediment physicochemical parameters, including salinity, pH, ammonia, and sulfide. A whole-sediment and water-only toxicity test based on inhibition of esterase activity in this species was developed. Enzyme activity rather than growth was used as the test endpoint, as nutrient release from sediments has previously been found to stimulate algal growth, potentially masking contaminant toxicity. The sensitivity of the bioassay to a range of metals (copper, zinc, cadmium, lead, arsenic, manganese) and phenol in water-only exposures was compared to the standard 72-h growth rate inhibition test. The esterase enzyme inhibition test was sensitive to copper, with a 3-h inhibitory concentration to cause a 50% (IC50) reduction in a fluorescein diacetate fluorescence value of 97 +/- 39 microg Cu/L. A concentration-dependent response was also observed in the presence of sediment particles (copper tailings), with and without dilution, using a control clean sediment. The primary route of exposure to copper was via pore water rather than by direct contact with tailings particles. This is the first whole-sediment bioassay developed with a benthic alga suitable for sediment quality assessment in marine/estuarine systems, and its advantages and limitations are discussed.

Biological Assay↗
PubMed1998

Identification of rodent carcinogens and noncarcinogens using genetic toxicity tests: premises, promises, and performance.

The basic premises that guide genetic toxicity testing for identifying carcinogens and to support administrative and regulatory decisions are: the Salmonella mutagenicity test is a necessary component of testing schemes; a chromosome aberration test is needed in addition to a gene mutation test; a mammalian cell mutagenicity test is needed in addition to the Salmonella test; in vivo tests are needed to confirm the results of in vitro tests; and test batteries are more predictive than the individual tests of the battery. Results from the Salmonella mutagenicity, in vitro chromosome aberration, mutations in mouse lymphoma cells, rodent bone marrow micronucleus, and rodent carcinogenicity tests, performed by the U.S. National Toxicology Program, were used to evaluate these premises. A positive Salmonella test was most predictive of carcinogenicity. However, the data do not support using the other tests in addition to Salmonella for predicting carcinogenicity. The genetic toxicity tests did not complement each other, and batteries or combinations of the tests were no more predictive of carcinogenicity than Salmonella alone. If a chemical is mutagenic in Salmonella it should be considered a potential rodent carcinogen, unless ancillary information suggests otherwise. Positive responses in the other in vitro or in vivo tests do not increase the probability that the chemical is a carcinogen, and negative responses in the other tests do not diminish the implications of the positive Salmonella response.

Animals↗
PubMed2005

Comparison of porewater and elutriate bivalve larval development toxicity testing in a sediment quality triad framework.

Concurrent porewater (PW) and elutriate (ELU) toxicity testing using newly fertilized larvae of the bivalve Mytilus galloprovincialis was conducted as part of sediment quality triad (SQT) investigations for urban harbor locations. PW samples were consistently more toxic to bivalve larvae than the corresponding ELU sample, including samples collected from uncontaminated reference locations. Ammonia was identified as the most likely toxic agent. EC(20) and EC(50) values of 0.028 and 0.036mg/L un-ionized N, respectively, were determined for M. galloprovincialis. The limitations of incorporating PW bivalve larval development toxicity tests using M. galloprovincialis for routine SQT investigations, as well as possible alternative methods, are discussed.

Ammonia↗
PubMed2003

Sediment toxicity tests using benthic marine microalgae Cylindrotheca closterium (Ehremberg) Lewin and Reimann (Bacillariophyceae).

A new method for sediment toxicity testing using marine benthic pennate noncolonial diatom (Cylindrotheca closterium, formerly Nitzschia closterium) has been developed. This microalgae showed a good growth rate during the experimental period, even when low enriched media were used. Sediment spiked with heavy metals [cadmium (Cd), copper (Cu), and lead (Pb)] was employed to determine the EC(50) values, using microalgal growth inhibition as the endpoint. The obtained results were as follows: Three heavy metals (Cd, Cu, and Pb), previously spiked on experimental sediment, were separately assayed in toxicity tests. The EC(50) values for these heavy metals in microalgal growth inhibition tests resulted to be 79 mg kg(-1) for Cd, 26 mg kg(-1) for Cu, and 29 mg kg(-1) for Pb (in experimental sediment). The influence of sediment granulometry on the growth of microalgal population was also studied, finding that the growth of the microalgal population on media containing sediment with a relation sand-size:silt size of 9:1 was not different from optimal growth (occurring in media containing 100% sand-sized sediment). The diatom C. closterium proved to be a suitable organism for sediment toxicity tests, due to its sensitivity and fast growth even in poorly enriched media.

Diatoms↗
PubMed1993

Acute and subacute toxicity tests of onion coat, natural colorant extracted from onion (Allium cepa L.), in (C57BL/6 x C3H)F1 mice.

The toxicity test of onion coat colorant (OC), a food colorant extracted from onion (Allium cepa L.), was undertaken using (C57BL/6 x C3H)F1 mice of both sexes for the safety assessment of this product. The acute toxicity test was performed by administration of OC suspended in corn oil by gavage at doses of 2500, 5000, 7500, and 10,000 mg/kg body weight to groups of 5 or 6 males and 6 or 7 females, maintained for 14 d. Six of 12 females dosed at 10,000 mg/kg body weight and 3 of 11 females dosed at 7500 mg/kg body weight were dead before the end of the study, indicating that the tolerated dose of OC was between 7500 and 5000 mg/kg body weight. The subacute toxicity test of OC was examined using 123 mice of both sexes (62 males and 61 females) by feeding a diet mixed with OC at concentrations of 5, 2.5, 1.25, 0.6, and 0.3% for 90 d. All mice tolerated these doses of OC well. The body weight gains of male and female mice were not affected by the treatment. Histopathological examinations showed that hyperplastic changes in the esophagus, forestomach, pancreas, cervix, and endometrium of mice were found in treated and control mice. However, their incidences were not related to the dose of OC. Moreover, only a spontaneous ovarian teratoma was found in an OC-treated mouse. These results suggest that OC has no acute and subacute toxic effects in mice.

Administration, Oral↗
PubMed2002

An investigation of new toxicity test method performance in validation studies: 3. Sensitivity and specificity are not independent of prevalence or distribution of toxicity.

Often, the only measures of toxicity test performance provided in validation studies are the contingent probability statistics (CPS) sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Sensitivity and specificity are generally used in preference to NPV and PPV since NPV and PPV are assumed to vary with changes in prevalence while sensitivity and specificity are assumed to be independent of changes in prevalence. The purpose of the studies reported here was to test whether or not sensitivity and specificity are actually independent of changes in prevalence. Results derived from these studies indicate that sensitivity and specificity vary significantly depending on the prevalence of toxic substances in the set of chemicals being tested. This means sensitivity and specificity should not always be considered constant indicators of toxicity test performance.

Models, Theoretical↗