Analysis of toxicity tests on fish growth

We present a statistical analysis of bioassays for fish growth, such as the routine toxicity test that is described in the OECD guideline 210. The analysis is based on the Dynamic Energy Budget theory and a one-compartment kinetics for the toxic compound. It is fully process oriented. We compare a formulation in terms of direct effects on growth with indirect effects via assimilation and maintenance. All formulations characterize the effects by a no-effect concentration, a tolerance concentration and the elimination rate. Simplified formulations are obtained for very small and very large elimination rates. The accuracy of estimates for the no-effect concentration is judged with the profile likelihood function. The method is illustrated with applications to several data-sets for body size versus concentration of toxicant.     

Ammonia toxicity and pH control in fish toxicity bioassays of treated wastewaters

A means of preventing anomalous fish kills in static bioassay testing of ammonia-containing treated wastewaters is described. Low flow O₂ is used instead of air in order to prevent CO₂ stripping, subsequent pH rise and increases in the NH₃ levels during the course of the test.     

Effect of water hardness on the toxicity of an anionic detergent to fish

The toxicity to fish of anionic detergents in solution varies considerably according to the hardness of the water in which the fish are treated. Trout and goldfish are more susceptible to sodium lauryl sulphate (SLS) in hard water than soft, and the rate of absorption of detergent is greater in hard water. It has been shown that the concentration of bivalent cations has a direct effect on the toxicity of SLS. Acclimatization experiments have shown that the toxicity of SLS depends not only on the hardness of the water in which the fish are treated, but also on the hardness of the water in which the fish have previously been acclimatized. The mechanism whereby water hardness affects detergent toxicity is discussed.     

Effect of water hardness on the toxicity of a nonionic detergent to fish

Fish (trout and goldfish) were placed in treatment solutions of different water hardnesses containing ethoxylate (EO) detergents. Survival times were recorded, ¹⁴C-labelled EO was used to assess absorption. The toxicity of ethoxylates to fish acclimatised and treated in different water hardnesses, and the effect of cations on ethoxylate toxicity were also investigated, EO is slightly less toxic in hard water than in soft water. The hardness of the treatment solution has no marked influence on the amount of EO absorbed by the fish. Evidence suggests that there is little relationship between the composition of cations constituting a particular hardness and the toxicity of EO. Acclimatisation in different water hardnesses does not affect the susceptibility of fish to nonionic ethoxylate detergents.     

Estimation of demographic toxicity through the double bootstrap

Toxicity to organisms is usually expressed in terms of an observable effect on individuals from which a summary endpoint (such as the NOEC or ECx) is derived for risk assessment and environmental quality standards. However, toxicity evaluated in terms of a demographic endpoint may be more relevant to such regulatory applications. In this paper the effect of toxicity on population growth rate r is explored in tandem with a 'double bootstrap' to incorporate uncertainty. Exemplifying the approach with a set of individualized life table response data obtained for Daphnia magna exposed to zinc sulphate solution, the influence of increasing concentrations is assessed. A demographic-based metric for r, the ErCx (effect on r concentration percentage), is defined to permit alternative population level estimation of a 'safe effect' concentration.     

Apparatus for control of poison concentration in toxicity studies with fish

In order to facilitate accurate maintenance of defined experimental conditions in studying the effects of water pollutants on fish, automatic apparatus is frequently used.

The equipment described here provides an automatic delivery of poison solutions to 14 aquaria; single poisons can be added at constant concentrations or poisons can be mixed or delivered in fluctuating or alternating concentrations.     

Sources and transformations of chlorophenols in the natural environment

The present review updates our knowledge about chlorophenols, their chemical reactions and transformations in the natural environment, as well as factors affecting kinetics and mechanisms of these processes. Effects of pH of the environment and structure of molecules (also the number of chlorine atoms and their position in the molecule) on the behaviour of these compounds in the natural environment are also discussed. In addition, ways of propagation of chlorophenols in the natural environment are presented and discussed on the background of their physical and chemical properties, which influence the propagation rate in the ecosystems.     

Enhanced enzymatic removal of chlorophenols in the presence of co-substrates

The effect of reactive co-substrates such as guaiacol and 2,6-dimethoxyphenol on the removal of chlorinated phenols by horseradish peroxidase (HRP) and a laccase from the fungus Trametes versicolor was investigated. Addition of 50 mM guaiacol enhanced the precipitation of 4-chlorophenol, 2,4-dichlorophenol, and 2,4,5-trichlorophenol with peroxidase by 12, 32 and 65%, respectively, and with laccase by 20, 32 and 80%, respectively. Addition of 10 mM 2,6-dimethoxyphenol enhanced the precipitation of 2,4,5-trichlorophenol by 90% with peroxidase and by 98% with laccase. Products from the reaction of 2,6-dimethoxyphenol and peroxidase were filtered to exclude compounds of a molecular weight greater than 500. Incubation of the resulting enzyme-free filtrate with a solution of unreacted 2,4,5-trichlorophenol caused precipitation and a 72% removal of the 2,4,5-trichlorophenol. Chlorophenol precipitation in the presence of co-substrates may be a useful strategy for improving the efficiency of enzymatic decontamination methods, particularly in the case of heterogenous pollution.     

微量元素对鲤生长和营养状况的影响

在基础饲料中分别添加无机盐、螯合盐、麦饭石、麦饭石稀土 ,对比养鲤结果表明 :麦饭石稀土 (Ⅰ )组鲤生长最快 ,其次是螯合盐组、麦饭石稀土 (Ⅱ )组、麦饭石组、无机盐组。未添加微量元素的基础组生长最慢。方差分析表明 ,添加麦饭石的 3个试验组及螯合盐组鱼平均增重率与无机盐组差异显著 (P <0 0 5) ,与基础组差异极显著(P <0 0 1 ) ;麦饭石稀土 (Ⅰ )组与麦饭石组、无机盐组差异极显著 (P <0 0 1 ) ,与麦饭石稀土 (Ⅱ )组、螯合盐组差异不显著 (P >0 0 5)。对鲤的肌肉营养分析表明 ,螯合盐组及添加麦饭石的 3个试验组鱼肌肉中粗蛋白、粗脂肪含量都略高于基础组和无机盐组 ,但差异不显著 (P >0 0 5)。     

论现行日本失业保险法制度

现行日本失业保险法制度的特点是政府和企业高度重视员工在职培训,提高员工自身的素质以预防失业的发生。上述特点的形成原因在于:借鉴西方国家失业保险法制度改革的经验,应对结构性失业的能动反映,强化政府在失业保险法制度中的作用以及重视员工技能培训的历史传统等。日本的失业保险法制度的经验对处于改革中的我国的失业保险法制度具有重要的借鉴意义。     

Studies on the toxicity of tribromoethene, cyclohexene and bromocyclohexane to different freshwater organisms

In order to get an impression about the possible environmental effects of tribromethene. cyclohexene and bromocyclohexane, short-term toxicity tests were carried out with green algae (Chlorella pyrenoidosa), crustaceans (Daphnia magna) and fishes (Poecilia reticulata) and long-term toxicity tests with Daphnia magna.The LC(EC)₅₀ values from the short-term tests with tribromoethene, cyclohexene and bromocyclohexane were 3.5–7.2, 3.8–5.3 and 2.2–2.5 mg 1⁻ respectively, whereas the lowest NOEC (No Observed Effect Concentration)-values from these tests were 0.52, 0.22 and 1.1 mg 1⁻¹ respectively; based on the criterion reproduction in the long-term tests the NOEC-values were 3.1, 2.4 and 0.5 mg 1⁻¹ respectively;All these values were corrected for the actual concentrations during the experiments and the tests were carried out in completely closed systems: in open systems the concentration of the test compounds decreased more than 90% within 48 h. Based on the log p (octanol-water partition coefficient) the calculated bio-accumulation factor value for tribromoethene and bromocyclohexane was 160, and for cyclohexene was 16.As for water quality criteria, values of 0.2 mg 1⁻¹ for tribromoethene, 0.01 mg 1⁻¹ for cyclohexene and 0.4 mg 1⁻¹ for tribromoethene 0.01 mg 1⁻¹ for cyclohexene and 0.4 mg 1⁻¹ for bromocyclohexane are proposed.     

Studies on the toxicity of ammonia, nitrate and their mixtures to guppy fry

Using guppy fry as the test fish the individual and joint toxicities of ammonia and nitrate were estimated in static tests at constant pH and temperature. The 72-h lc₅₀ values were 199 and 1.26 mg 1⁻¹ −N for potassium nitrate and free ammonia, respectively. The toxicities of mixtures of the two were additive except at very low ammonia to nitrate ratios. Watson's equation, a disinfection law relating toxicant concentration to survival, was applicable to both toxicants. The applicability of Chick's law and other kinetic models to fish toxicity was also evaluated.     

Applying whole-water samples directly to fish cell cultures in order to evaluate the toxicity of industrial effluent

Methodology was developed for presenting to fish cells in culture whole-water samples without extraction and used to evaluate the toxicity to a rainbow trout gill cell line, RTgill-W1, of more than 30 whole-water samples collected from a paper mill over approximately a year of operation. Presentation to cells was achieved by adding to water samples the amounts of salts, galactose and sodium pyruvate, as solids, that were necessary to give concentrations and osmolality of the basal growth medium, Leibovitz's L-15. Cell viability was measured with three fluorescent indicator dyes: alamar Blue for metabolism, 5-carboxyfluorescein diacetate acetoxymethyl ester (CFDA-AM) for membrane function, and neutral red for lysosomal activity. Eighteen samples were tested with the Daphnia lethality bioassay and 11 of these were toxic. None of these were judged cytotoxic to RTgill-W1. Sixteen samples were tested with the rainbow trout lethality bioassay and only one was toxic. This sample was also the only sample that was cytotoxic to RTgill-W1. Therefore, these methods for presenting water samples and measuring their cytotoxicity to RTgill-W1 are a promising substitute for toxicity tests of industrial effluent with rainbow trout but not with Daphnia.     

A comparison of the non-essential elements cadmium, mercury, and lead found in fish and sediment from Alaska and California

Concentrations of three non-essential elements (cadmium (Cd), mercury (Hg), and lead (Pb)) were determined in sediment and fish from several locations in Alaska (AK) and California (CA) and used to examine differences in bioaccumulation within and between geographic locations. We analyzed tissue (liver, muscle, gill, and stomach contents) from white croaker (Genyonemus lineatus) and English sole (Pleuronectes vetulus) in California and flathead sole (Hippoglossoides elassodon) in Alaska, in addition to several species of invertebrates (mercury only). As found in previous work on arsenic (As) [Meador et al., 2004], Cd in fish liver exhibited a negative correlation with sediment concentrations. No such correlations were found for Hg and Pb when fish liver and sediment were compared; however, these metals did exhibit a positive relationship between liver and organic carbon normalized sediment concentrations, but only for the CA sites. Sediment concentrations of Hg at the AK sites were lower than those for the CA sites; however, AK invertebrates generally bioaccumulated more Hg than CA invertebrates. Conversely, Hg bioaccumulation was higher in CA fish. Even though ratios of total metal/acid volatile sulfides (AVS) in sediment were one to two orders of magnitude higher for the AK sites, bioaccumulation of these elements was much higher in fish from the CA sites. Bioaccumulation factors ([liver]/[sediment]) (BAFs) were highest at relatively clean sites (Bodega Bay and Monterey), indicating that elements were more bioavailable at these sites than from more contaminated locations. The observation of high BAFs for As in fish from Alaska and low BAFs for the California fish, but reversed for Cd, Hg, and Pb in this study, implies that differences in fish species are less important than the unique geochemical features at each site that control bioavailability and bioaccumulation and the potential sources for each element. Additionally, these data were also used to examine the metal depletion hypothesis, which describes the inverse relationship between elements and organic contaminants documented in some monitoring studies. Our results suggest that the enhanced bioavailability of the metals at some uncontaminated sites is the main determinant for the inverse correlation between metal and organic contaminants in tissue.     

An investigation into the acute and chronic toxicity of eleven pharmaceuticals (and their solvents) found in wastewater effluent on the cnidarian, Hydra attenuata

Pharmaceuticals previously identified in the effluent from the wastewater treatment plant (WWTP) in Montreal discharging into the St. Lawrence river, were tested for acute and chronic toxicity using the cnidarian Hydra attenuata. Acute toxicity was based on the established technique looking at morphological changes in the Hydra, while recently developed endpoints of feeding behaviour, attachment and growth (hydranth number) were used to measure chronic effects. The compounds under investigation (ibuprofen, naproxen, gemfibrozil, bezafibrate, carbamazepine, sulfamethoxazole, sulfapyridine, oxytetracycline, novobiocin, trimethoprim and caffeine) were tested individually in controlled laboratory exposures with LC(50) and EC(50) results calculated. All compounds tested had relatively high LC(50) values with gemfibrozil, ibuprofen and naproxen having the lowest at 22.36 mg/L and EC(50) values based on morphology of 1.18 to 2.62 mg/L (all concentrations are nominal). The EC(50) values based on feeding were similar to those based on morphology but with increased sensitivity for carbamazepine, bezafibrate and novobiocin. A trend of a reduction in feeding with deterioration in morphology was observed in the Hydra, with the exception of novobiocin, where a lower than expected EC(50) of 13.53 mg/L was found with no negative effect on morphology. Significant reductions in attachment and hydranth number were seen at concentrations of 1 and 5 mg/L for gemfibrozil and ibuprofen respectively. A toxicity threshold (TT) of 320 microg/L was calculated for ibuprofen, only a factor of 10(2) or 10 higher than the concentration found in the effluent in the present study (1.19 mug/L) and in other Canadian effluents studied (22 microg/L [Brun GL, Bernier M, Losier R, Doe K, Jackman P, Lee HB, Pharmaceutically active compounds in Atlantic Canadian sewage treatment plant effluents and receiving waters and potential for environmental effects as measured by acute and chronic aquatic toxicity. Environ Toxicol Chem 2006; 25(8): 2163-2176.] respectively. Using EU directive 93/67/EEC the pharmaceuticals under investigation can be classified as toxic (gemfibrozil, ibuprofen and naproxen), harmful (carbamazepine, bezafibrate, sulfapyridine, oxytetracycline and novobiocin) and non-toxic (sulfamethoxazole, trimethoprim and caffeine) and their potential toxicity for the aquatic environment is discussed.     

Effect of pH on toxicity of kraft pulp and paper mill effluent to salmonid fish in fresh and seawater

In freshwater bioassays with juvenile rainbow trout (Salmo gairdneri), at initial pH values from 4 to 11, kraft mill effluents were considerably less toxic at pH 9–10 than at neutrality. When pH of test solutions was controlled throughout the bioassay period, the least toxic range was 8.5–9.5. Toxicity at typical receiving-water pH values was 50–67% greater.The acute toxicity of effluent samples to yearling coho salmon (Oncorhynchus kisutch) was identical for these effluents in seawater and freshwater respectively, provided that the pH was adjusted and held at the same value, and that test fish were previously acclimated to the dilution water for several months. Thus seawater constituents other than pH did not affect the acute toxicity of pulp and paper mill effluents appreciably.     

应用离心模型试验分析涵洞病害机理

利用离心模型试验,通过模拟实际依托工程的地基形式、回填材料、沟坡地形以及施工工艺,分析了涵洞发生病害的全过程,利用图片测量软件再现了土体、涵洞结构体、地基相互作用的过程,阐述了涵洞纵向不均匀沉降所产生的“扁担效应”对涵洞结构破坏的机理,根据实录影像描述了涵洞模型裂缝的发展形式,并与实际病害工程对比。