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Archives of Environmental Contamination and Toxicology (v.42, #2)
Glutaraldehyde in Hospital Wastewater by B. Jolibois; M. Guerbet; S. Vassal (pp. 137-144).
Glutaraldehyde (GA) solutions are widely used in hospitals to disinfect reusable fiber-optic endoscopes. These solutions are dumped after use in the aquatic environment without any particular safety precautions. Taking into account the quantity of GA consumed daily and the released water volume, the predicted hospital wastewater concentration was estimated at 0.50 mg/L.To measure the real GA concentration present in hospital wastewater, we developed an analytical technique that is simple, sensitive, and reliable. This method consists of a water sample concentration and purification by solid phase extraction and then a spectrophotometric determination. This analytical method was used for a 1-week surveillance program at Rouen University Hospital (2,600 beds). The wastewater tested showed the presence of a concentrated peak approximately eight times higher than the predicted wastewater concentration.The environmental impact of GA release into the aquatic environment was then studied. A predicted no-effect concentration (PNEC) < 1 μg/L was calculated. In most situations the predicted environmental concentration (PEC) was found to be <0.5 μg/L taking into account the hospital wastewater dilution in its way to the sewage treatment plant and GA biodegradation. The PEC/PNEC ratio is then < 1, showing that this release are not expected to present a significant risk to the aquatic environment. However in situations of insufficient dilution or of major release, the PEC/PNEC ratio become > 1, and an environmental risk should be expected. An internal prevention program of the various hospital departments to assure GA rational use, and a release spreading would give an additional safety margin to consider GA as safe in terms of environmental risk.
Total Mercury in Mushrooms and Underlying Soil Substrate from the Borecka Forest, Northeastern Poland by J. Falandysz; M. Gucia; B. Skwarzec; A. Frankowska; K. Klawikowska (pp. 145-154).
Total mercury concentrations were determined by cold-vapor atomic absorption spectroscopy in 240 composite samples of the caps, 240 of the stalks, and 16 of the whole fruiting bodies of 13 species of wild mushrooms and in 256 samples of underlying soil substrate collected from the Borecka Forest and the adjacent area in 1998. The area of the study is a background site with no known local sources of mercury emission. The mercury concentrations of the fruiting bodies varied largely (range between 14 and 14,000 ng/g dry weight) depending on the site and mushroom species investigated, but were less varied in soil samples (between 5 and 86 ng/g dry weight). The fruiting bodies of king bolete (Boletus edulis) showed greatest content of mercury. King bolete and yellow-cracking bolete (Xerocomus subtomentosus) collected from the Borecka Forest both contained in the caps around threefold greater concentrations of mercury than were noted for the same species collected from the surrounding area with 9,900 ± 2,700 and 3,600 ± 1,400, and 480 ± 190 and 160 ± 70 ng/g dry weight, respectively. Apart from the king bolete, relatively elevated concentrations of mercury were quantified also in a whole fruiting bodies of common puffball (Lycoperdon perlatum) with 3,400 ± 1,300 ng/g as well as in the caps and stalks of common scaber stalk (Leccinum scabrum) with 1,200 ± 740 and 1,100 ± 380 ng/g dry weight. In other species investigated, the mercury concentrations were below 1,000 ng/g dry weight, and the smallest values were noted for crab-scended brittle gills (Russula xerampelina) with 60 ± 20 in the caps and 40 ± 20 ng/g dry weight in the stalks. For the species such as larch bolete, bay bolete (Xerocomus badius), yellow-cracking bolete, king bolete, common scaber stalk, fly agaric (Amanita muscaria), crab-scented brittle gills, honey mushroom (Amariella mellea) and safron milk cap (Lactarius deliciosus) a positive correlation (0.01 < p < 0.05) between the mercury content and size (diameter) of the caps was found, and in some cases also between mercury content of the stalks and size (height) of the fruiting body. The bioconcentration factor (BCF) values of total mercury were greatest for king bolete, i.e., 250 ± 65 in the caps and 140 ± 47 in the stalks, while for the other species investigated were between 200 ± 91 and 1.8 ± 0.5 in the caps, and 94 ± 57 and 1.7 ± 0.4 in the stalks. Nevertheless, despite great values of BCF of mercury indicated for some species and also a positive correlation between mercury content of the caps/stalks and underlying soil substrate, subsequent coefficients of determination were usually below 40%, and only for bay bolete (stalk), yellow-cracking bolete (cap), common scaber stalk (cap), hard bolete (Leccinum griseum) (cap, stalk), crab-scented gills (stalk), and honey mushroom (cap) were up to 68, 82, 42, 82, 51, 74, and 45%, respectively. The values of the cap/stalk Hg quotient were greatest for larch bolete (Suillus flavus) collected from the Borecka Forest (4.4 ± 1.3) and for honey mushroom (2.7 ± 0.9) from the adjacent area.
PAM Fluorometry in the Determination of the Sensitivity of Chlorella vulgaris, Selenastrum capricornutum, and Chlamydomonas reinhardtii to Copper by P. Juneau; A. El Berdey; R. Popovic (pp. 155-164).
The pulse-amplitude-modulation (PAM) fluorometric method was used in the past as a sensitive and rapid method for assessing toxic effect of pollutants in plants. Here, we used the advantages of this method to evaluate the difference in sensitivity of Chlorella vulgaris, Selenastrum capricornutum, and Chlamydomonas reinhardtii to copper toxicity. We found by using the PAM-fluorescence parameters (φM, φ′M, QP, and QN), that C. reinhardtii is the most sensitive species, followed by S. capricornutum and C. vulgaris. Indeed, the copper 5-, 48-, and 96-h EC50 for φM, φ′M, and QP vary between 11 and 34 μg/L for C. reinhardtii, while for S. capricornutum this value is between 25 and 50 μg/L. However, the same parameters obtained from C. vulgaris did not show susceptibility to copper, even at very high concentrations (100 μg/L). In this study, the estimated 5-h EC50 for C. reinhardtii and S. capricornutum are lower than the 24-h EC50 reported earlier for these species with other bioassays, indicating that the use of PAM fluorometry in copper bioassay provides a more sensitive method than the other biotests in aquatic toxicology.
Interactions Between Toxic and Essential Trace Metals in Cattle from a Region with Low Levels of Pollution by M. López Alonso; J. L. Benedito; M. Miranda; C. Castillo; J. Hernández; R. F. Shore (pp. 165-172).
Studies on the impacts of pollutant metals and metalloids on livestock have largely focused on animals with relatively high levels of exposure. The impact of low-level environmental contamination, which is more common on agricultural land, is largely unknown. The principal aim of the present study was to examine the effects of low-level environmental contamination on trace metal metabolism in cattle from the rural and relatively uncontaminated region of Galicia (NW Spain). Correlations between toxic (cadmium, lead, and arsenic) and essential trace elements (copper and zinc) were evaluated in the tissues (liver, kidney, and muscle) and blood of 494 cattle from throughout Galicia. Cadmium was the toxic element that had the greatest influence on copper and zinc homeostasis. There was a significant positive association between renal cadmium and zinc residues and a significant negative correlation between kidney cadmium and copper. These interactions are likely to be the result of cadmium-induced effects on metallothionein synthesis. Lead and zinc were positively associated in the kidney, although the mechanism of this interaction is uncertain. Arsenic and copper concentrations were strongly correlated with each other in the liver and may indicate that the high copper levels in animals from copper-rich areas in Galicia interfere with their arsenic excretion. The essential metals copper and zinc were also significantly associated with each other in calves but not in cows.
Toxicity and Bioconcentration Potential of the Agricultural Pesticide Endosulfan in Phytoplankton and Zooplankton by M. E. DeLorenzo; L. A. Taylor; S. A. Lund; P. L. Pennington; E. D. Strozier; M. H. Fulton (pp. 173-181).
Agricultural pesticide runoff in southeastern coastal regions of the United States is a critical issue. Bioconcentration of pesticides by phytoplankton and zooplankton at the base of the aquatic food web may increase the persistence of pesticides in aquatic ecosystems and cause effects at higher trophic levels. This study examined the toxicity of a widely used agricultural pesticide, endosulfan, to Pseudokirchneriella subcapitatum (freshwater green alga) and Daphnia magna (freshwater cladoceran). We then investigated the potential of both plankton species to sequester endosulfan from their surrounding media. We also assessed the degree to which endosulfan is accumulated by D. magna via food (endosulfan-contaminated P. subcapitatum). A 96-h growth rate EC50 of 427.80 μg/L endosulfan was determined for P. subcapitatum, whereas a 24-h immobilization EC50 of 366.33 μg/L endosulfan was determined for D. magna. The 5-h EC50s for filtration and ingestion in D. magna were 165.57 μg/L and 166.44 μg/L, respectively. An average bioconcentration factor (BCF) of 2,682 was determined for P. subcapitatum exposed to 100 μg/L endosulfan for 16 h. An average BCF of 3,278 was determined for D. magna in a 100 μg/L endosulfan water-only exposure. There was negligible uptake of endosulfan by D. magna feeding on contaminated algae in clean water (BCF ∼ 0). Different proportions of parent isomers (endosulfan I and II) and the primary degradation product (endosulfan sulfate) were detected among treatments. Endosulfan was rapidly accumulated and concentrated from water by P. subcapitatum and D. magna neonates. Endosulfan contained in phytoplankton, however, was not bioaccumulated by zooplankton. These findings may prove useful in assessing ecosystem risk, because uptake from the water column appears to be the dominant route for bioconcentration of endosulfan by zooplankton.
Effects of Iron Sulfate Dosage on the Water Flea (Daphnia magna Straus) and Early Development of Carp (Cyprinus carpio L.) by R. D. van Anholt; F. A. T. Spanings; A. H. Knol; J. A. van der Velden; S. E. Wendelaar Bonga (pp. 182-192).
Adult water fleas, Daphnia magna Straus, and the early life stages of carp, Cyprinus carpio L., were exposed to river water near an iron sulfate dosage installation to determine the effects of phosphate precipitation with iron(II)sulfate. Tests were conducted during two consecutive dosage periods of 3,000 and 5,000 kg/day iron sulfate (520 and 620 μg/L total Fe respectively) at the dosage site and at a reference site (60 μg/L total Fe) further downstream. Though survival remained unaffected, the filter-feeding D. magna accumulated iron and other metals at the dosage site. Viability of offspring was strongly reduced at the highest dose of iron sulfate compared to the lower dose and the reference site. Specific staining of microscopic sections revealed a strong accumulation of iron(III) in the digestive tract. The egg membranes of the carp embryos accumulated not only substantial amounts of iron but also other metals, including cadmium and aluminium. Hardly any of the metals passed the egg membranes and reached the embryos. After hatching the accumulation of cadmium by the larvae increased rapidly and iron levels were elevated at the highest dose of iron sulfate, parallel with the onset of exogenous feeding. Iron(III) particles were observed in the intestines at histological examination. In addition, at 620 μg/L total Fe a strong increase in whole-body levels of the stress hormone cortisol was observed in the carp larvae, indicating a physiological response to adverse conditions. The results indicate that the rapid oxidation of free Fe2+ into iron(III) forms and the precipitation of iron(III) into larger particles resulted in a low acute toxicity of the river water directly at the iron sulfate dosage site. The observed chronic and sublethal effects at the dosage site probably resulted from the intestinal uptake of iron(III) and other toxic metals associated with the food particles. However, these effects could no longer be observed at the reference site, 9 km downstream from the dosage site.
The Juvenile Growth Rate of Daphnia: A Short-Term Alternative to Measuring the Per Capita Rate of Increase in Ecotoxicology? by I. Trubetskova; W. Lampert (pp. 193-198).
The juvenile growth rate (g j ) of Daphnia is a good predictor of the per capita rate of increase (r), which is considered the ecologically most meaningful parameter. The hypothesis is tested that g j may be used as a surrogate for r in short-term ecotoxicological tests to replace the time-consuming population-based testing. The effects of 3,4-dichloroaniline (DCA) on various reproductive parameters of Daphnia magna, including r, net reproductive rate in 21 days (R21), age at first reproduction (AFR), adult survival, and egg viability, were measured simultaneously with g j . Reproductive parameters were not affected below a concentration of 9 μg/L DCA, but all of them responded strongly above this concentration. DCA reduced the total number of eggs produced only moderately, but induced strong egg mortality in particular in the first brood. Because egg mortality is an important factor, measures of sublethal toxic effects must be based on viable eggs. Although (g) is a good predictor of individual fitness of Daphnia under variable natural conditions when egg mortality is negligible, it is not a good predictor of the effects of xenobiotic stress; hence it cannot replace r. Short-term tests based solely on either somatic growth or egg viability are not sufficiently correlated with r to give ecologically meaningful results, but protocols based on the number of viable eggs in the first clutch and the time to release of the first neonates may be an alternative to the 21-day test or longer life-table experiments.
Bioavailability of Sediment-Associated Benzo(a)pyrene Within Single- Versus Multiple-Species Systems by L. J. Schuler; M. G. Heagler; M. J. Lydy (pp. 199-204).
A series of experiments were conducted with benzo(a)pyrene (B(a)P) spiked sediments to determine if bioavailability of sediment-associated contaminants is affected by multiple species interactions. Three benthic invertebrates, Hyalella azteca, Chironomus tentans, and Lumbriculus variegatus, were exposed to sediments spiked with radiolabeled B(a)P that was aged for 60 days. Organisms were introduced into the spiked sediments in single, binary, and ternary combinations. Changes in bioavailability were then determined for each species by estimating uptake clearance coefficients (k s ) and bioaccumulation factors (BAFs) during 7-day exposures. In general, there was a trend toward lower k s values in binary and ternary exposures compared to the single-species systems. In contrast, BAF estimates were more variable with fewer significant differences noted among treatments. BAF estimates were highest for L. variegatus followed by C. tentans and H. azetca and appear to be dependent on specific feeding and habitat requirements as well as the relative biotransformation/elimination potential of each species. Overall, these results suggest that animal–animal interactions may be important to consider when estimating bioavailability of sediment-bound chemicals.
Effects of Zinc Contamination on a Natural Nematode Community in Outdoor Soil Mesocosms by C. E. Smit; A. J. Schouten; P. J. Van den Brink; M. L. P. van Esbroek; L. Posthuma (pp. 205-216).
The effect of zinc on the indigenous nematode fauna of a sandy soil was determined in an experimentally contaminated outdoor field plot. The aims of the study were to describe and quantify the changes in density of separate nematode taxa and total nematodes, and the changes in the number of taxa, species diversity, community maturation, and species composition in response to zinc exposure with time, and to compare the observed responses with benchmark concentrations for soil as derived from the species sensitivity distribution (SSD) for zinc toxicity. Speciation of zinc in pore water was considered and CaCl2-exchangeable zinc concentrations were used as a measure of the bioavailable zinc fraction. After contamination, a reduction of total zinc and an increase of labile sorbed zinc over time occurred, concurrent with various changes in soil and biological characteristics. Data analyses on the nematode species revealed different sensitivity levels for several population and community endpoints to zinc exposure. Based on no observed effect concentration (NOEC) values, the most sensitive community-level response was obtained with principal response curve (PRC) analysis, which incorporates all density data in a single analysis. The PRC-based community NOECs were 56, 100, and 100 mg total Zn/kg dry soil after 3, 10, and 22 months of exposure, respectively. Based on 0.01 M CaCl2-exchangeable zinc, the community response appeared to increase, as NOECs were 4.9, 4.4, and 0.67 mg exchangeable Zn/kg dry weight. Total density was least sensitive, followed by diversity of taxa and the Shannon-Wiener index. NOECs for separate species covered a broad range from sensitive to tolerant species. This range of sensitivities was similar to the one found for other species groups tested in the field plot soil. A comparison was made between benchmark concentrations HC5 and HC50 derived from the general SSD of soil organisms for zinc and the nematode response data. These comparisons roughly confirm the predictions of the SSD model, that is, the community NOEC is in agreement with the benchmark that should protect the soil ecosystem's integrity, and large adverse effects were found at the benchmark derived for setting remediation urgency.
The Effect of Lindane on Terrestrial Invertebrates by K. Lock; K. A. C. De Schamphelaere; C. R. Janssen (pp. 217-221).
Acute and chronic ecotoxicity tests with lindane were carried out using the soil invertebrates Eisenia fetida, Enchytraeus albidus, and Folsomia candida. To assess the influence of soil type on the bioavailability, these tests were carried out in a standard artificial OECD soil and in sandy and loamy field soil. For each species, differences in lindane toxicity were observed for the three soil types. These differences were, however, not related to the organic matter content. The relative differences in lindane toxicity between the soils was species-specific. These results therefore indicate that the pore-water hypothesis, i.e., the pore-water contaminant fraction being the toxicological bioavailable fraction, is not always applicable for organic substances. NOEC, NEC, as well as EC10 data were subsequently used to calculate hazardous concentrations for 5% of the species; this methodology, aimed at setting environmental quality criteria, is discussed.
Growth-Dependent and Species-Specific Accumulation of Polychlorinated Biphenyls (PCBs) in Tidal Flat Organisms Collected from the Ariake Sea, Japan by H. Nakata; Y. Sakai; T. Miyawaki (pp. 222-228).
The growth-related as well as species-specific accumulation of polychlorinated biphenyls (PCBs) was studied for tidal flat organisms collected from the Ariake Sea, western Japan. Elevated concentrations of PCBs were found in omnivore fishes, followed in decreasing order by crabs, herbivore fishes, and mussels. This revealed that trophic levels play an important role in PCB accumulation in these organisms. Age- and body length–dependent accumulations of PCBs were observed in herbivorous mudskippers, although a large range of concentrations was found in similar growth stage of fishes. High correlations have been found between concentrations and body length rather than age, which may indicate that the growth rate, which is strongly influenced by the feeding rate of diets, seems to be the predominant factor in determining PCB accumulation. Besides, based on PCB levels in eggs and the whole body in herbivore fishes, the transfer rate of PCBs was estimated to be approximately 10% of female body burdens. Comparison of PCB compositions between eggs and whole body suggests the selective transfer of lower-chlorinated congeners to eggs, which may be due to their instantaneous periods to achieve steady state between egg and whole body lipids. The relationship between BSAFs (biota-sediment accumulation factors) in organisms and log K ow revealed that omnivore mudskipper significantly accumulated PCBs in their body, which might be due to their greater feeding rate and/or higher trophic status in the tidal flat environment.
Bioaccumulation of Chlorpyrifos Through an Experimental Food Chain: Study of Protein HSP70 as Biomarker of Sublethal Stress in Fish by I. Varó; R. Serrano; E. Pitarch; F. Amat; F. J. López; J. C. Navarro (pp. 229-235).
The accumulation and transfer of the organophosphorus pesticide chlorpyrifos has been studied in an experimental aquatic two-level food chain using two species of the crustacean Artemia (A. franciscana and A. parthenogenetica) and the small fish Aphanius iberus. Artemia adults contaminated by exposure to the pesticide in water were used as live prey for Aphanius, the next trophic level. During the experimental bioaccumulation phase, fish were fed chlorpyrifos-contaminated Artemia pools with concentrations between 6.5 and 14.5 ng/g fresh weight for 32 days. Both concentrations accumulated in fish, and biomagnification factor (BMF) values showed a continuous decrease during the bioaccumulation phase, probably due to the physicochemical characteristics of the organophosphorus pesticide, to the biotransformation ability of fish and to the progressive adaptation of fish metabolism to toxic exposure. The first day that fish were fed uncontaminated preys, the pesticide accumulated via food was rapidly eliminated and was not detected.The effect of chlorpyrifos exposure through the food chain on stress protein (HSP70) synthesis was measured as a general biochemical response of stress in the fish (A. iberus). The levels of HSP70 were significantly higher in fish fed on contaminated Artemia than in the control fish fed on uncontaminated Artemia. Results showed that the HSP70 induction in fish could be associated to exposure of chlorpyrifos via food.
Effects of Fractions from Biodegraded Alaska North Slope Crude Oil on Embryonic Inland Silversides, Menidia beryllina by D. P. Middaugh; P. J. Chapman; M. E. Shelton; C. L. McKenney, Jr.; L. A. Courtney (pp. 236-243).
Embryonic inland silversides, Meinida beryllina, were exposed to neutral, water-soluble fractions (WSFs) resulting from microbial degradation of artificially weathered Alaska North Slope (ANS) crude oil. Three individual microbes obtained from Prince William Sound, Alaska, and designated Phe#6 (enriched on phenanthrene), Hexaco#2 (enriched on the straight-chain alkane, hexacosane), and EI2V (grown by enrichment on Bushnell-Haas medium containing 0.2% pristane, a branched alkane) were used to individually biodegrade weathered ANS crude oil for 14 days in darkness in 20-L glass carboys containing nutrient enriched, sterilized 20‰ salinity sea water at 20 ± 1°C. Neutral WSFs resulting from biodegradation of ANS (lot 521) by each microbe were recovered and weighted. Neutral WSFs recovered were: 1.76 mg/L for Phe#6, 1.85 mg/L for Hexaco#2, and 13.02 mg/L for the EI2V microbe. Embryo toxicity and teratogenicity tests revealed that exposure of embryos to the WSFs from the EI2V incubation (with a total recovered neutral fraction approximately seven times greater than the Phe#6 and Hexaco#2 incubations) resulted in the most severe responses in craniofacial, cardiovascular, and skeletal organ systems. The total neutral WSFs recovered from the EI2V biodegradation of weathered ANS 521 were subfractionated into saturated (eluted with hexane), aromatic (eluted with CH2Cl2), polar (eluted with ethyl ether), and recombined (saturated + aromatic + polar) fractions. Developing fish embryos were then exposed to each subfraction and the recombined subfractions. The polar subfraction and recombined subfractions proved to be the most embryo toxic and teratogenic. They resulted in statistically significant (p ≤ 0.05) responses (compared to controls) for craniofacial, cardiovascular, skeletal, and total severity effects in one or both tests with these subfractions.
Polychlorinated Dibenzo-p-Dioxins, Dibenzofurans, and Dioxin-Like Polychlorinated Biphenyls in Livers of Birds from Japan by K. Senthilkumar; N. Iseki; S. Hayama; J. Nakanishi; S. Masunaga (pp. 244-255).
Concentrations of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and non- and mono-ortho-chlorine-substituted polychlorinated biphenyls (dioxin-like PCBs) were measured in livers of 17 species of birds collected from Japan. Birds were grouped according to their feeding habits as granivores, piscivores, omnivores, and predators for discussions. Livers of granivores contained relatively low concentrations of PCDD/DFs (80–660 pg/g) followed in increasing order by omnivores (2,300–8,000 pg/g), piscivores (61–12,000 pg/g) and predators (480–490,000 pg/g on a fat weight basis). Especially, one species of predatory bird (mountain hawk eagle) contained elevated concentrations of PCDDs, PCDFs, and dioxin-like PCBs, and the measured concentration is one of the highest reported to date. Homolog and congener patterns of PCDDs and PCDFs varied among species; hence, the results suggested that feeding habits, specific elimination, and metabolism influence contamination pattern. Concentrations of dioxin-like PCBs were in the order of granivores (32–83 ng/g) < predators [excluding mountain hawk eagle] (32–2,500 ng/g) < piscivore (61–12,000 ng/g) < omnivores (1,800–67,000 ng/g on a fat weight basis). Mountain hawk eagle contained the highest concentration of dioxin-like PCBs (55,000 ng/g fat weight). 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) toxic equivalents (TEQs) ranged from 53–450,000 pg/g fat weight. 23478-PeCDF, 2378-TCDD/TCDF, and PCB congeners IUPAC 126 and 77 were major contributors to TEQs in birds. To our knowledge, this is the first study of PCDD/DFs and dioxin-like PCBs in livers of several species of Japanese birds.
Embryo-Larval Toxicity Tests with the African Catfish (Clarias gariepinus): Comparative Sensitivity of Endpoints by L. T. H. Nguyen; C. R. Janssen (pp. 256-262).
Embryo-larval toxicity tests with the African catfish (Clarias gariepinus) were performed to assess the comparative sensitivity of different endpoints. Measured test responses included embryo and larval survival, hatching, morphological development, and larval growth. Chromium, cadmium, copper, sodium pentachlorphenol (NaPCP), and malathion were used as model toxicants. Hatching was not affected by any of the chemicals tested, and embryo survival was only affected by chromium at ≥ 36 mg/L. The growth of larvae was significantly reduced at ≥ 11 mg/L Cr, ≥ 0.63 mg/L Cu, ≥ 0.03 mg/L NaPCP, and ≥ 1.25 mg/L malathion. Morphological development of C. gariepinus was affected by all of the toxicants tested. Different types of morphological aberrations were observed, i.e., reduction of pigmentation in fish exposed to cadmium and copper, yolk sac edema in fish exposed to NaPCP and malathion, and deformation of the notochord in fish exposed to chromium and malathion. The sensitivity of the endpoints measured can be summarized as follows: growth > abnormality > larval survival > embryo survival > hatching.