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Archives of Environmental Contamination and Toxicology (v.39, #3)
Relative Potencies of Individual Polychlorinated Naphthalenes to Induce Dioxin-Like Responses in Fish and Mammalian In Vitro Bioassays by D. L. Villeneuve; K. Kannan; J. S. Khim; J. Falandysz; V. A. Nikiforov; A. L. Blankenship; J. P. Giesy (pp. 273-281).
A growing body of evidence suggests that polychlorinated naphthalenes (PCNs) may be fairly widespread environmental contaminants. This may be cause for concern because exposure to PCNs has been linked to dioxin-like biological responses in a wide variety of species. This study used three in vitro bioassays to characterize the dioxin-like potency of 18 individual PCN congeners and 1 PCN metabolite. The PLHC-1 fish hepatoma cell bioassay was relatively insensitive to PCNs. At the concentrations tested, only 1,4 di-CN and 2,4-dichloro-1-napthol caused significant induction of ethoxyresorufin O-deethylase (EROD) activity in the PLHC-1 assay. In vitro EROD and luciferase assays using recombinant H4IIE rat hepatoma cells were more responsive to PCNs. Structure-activity relationships were observed both in terms of the degree of chlorination and the positions of chlorine substitutions. Hexa-chlorinated naphthalenes (CNs), exhibiting relative potencies (REPs) around 10−3 (relative to TCDD), were the most potent congeners tested. Penta-CNs were also rather potent, yielding REPs between 10−3 and 10−7. Tetra-, tri-, di-, and mono-CNs were less active. REPs for the active congeners were similar to those for some PCBs. The relative potency estimates reported here contribute to an emerging body of information that will aid determination of the relative contribution of PCNs to the total dioxin-like activity associated with environmental samples.
Metalaxyl and Simazine Toxicity to and Uptake by Typha latifolia by P. C. Wilson; T. Whitwell; S. J. Klaine (pp. 282-288).
This research focused on the potential use of common cattails (Typha latifolia) for removing metalaxyl and simazine residues from contaminated water. Specifically, it established toxicity thresholds to the herbicide simazine and characterized the uptake and distribution of simazine and metalaxyl by the plants. Simazine tolerance levels were determined by exposing plants to a series of six concentrations (0–3.0 mg L−1) in aqueous nutrient media for 7 days. Metalaxyl toxicity was not evaluated because other studies indicated it was relatively nontoxic to plants. Toxicity endpoints measured included fresh mass production after 7 days of exposure and 7 days postexposure. Pesticide uptake and distribution were determined by growing plants in nutrient media amended with 14C-ring-labeled metalaxyl (0.909 mg L−1) or simazine (0.242 mg L−1) for 1, 3, 5, or 7 days. Plants were dissected, and tissues were combusted and analyzed by liquid scintillation spectroscopy. Cattail fresh mass production was reduced 84 and 117% at 1.0 and 3.0 mg L−1 simazine, respectively, after 7 days of exposure. Metalaxyl and simazine activity in solution was reduced 34 and 65%, respectively, after 7 days. By day 7, activity from both pesticides was detected predominantly in the leaves. Uptake of each pesticide was correlated with water uptake throughout the 7 days. These results suggest that the common cattail may be a good candidate for incorporation into a phytoremediation scheme for metalaxyl and simazine.
Modeling the Toxicity of Chemicals to Tetrahymena pyriformis Using Molecular Fragment Descriptors and Probabilistic Neural Networks by S. P. Niculescu; K. L. E. Kaiser; T. W. Schultz (pp. 289-298).
The results of an investigation into the use of a probabilistic neural network (PNN)–based methodology to model the 48-h ICG50 (inhibitory concentration for population growth) sublethal toxicity of 825 chemicals to the ciliate Tetrahymena pyriformis are presented. The information fed into the neural networks is solely based on simple molecular descriptors as can be derived from the chemical structure. In contrast to most other toxicological models, the octanol/water partition coefficient is not used as an input parameter, and no rules of thumb or other substance selection criteria are employed. The cross-validation and external validation experiments confirmed excellent recognitive and predictive capabilities of the resulting models and recommend their future use in evaluating the potential of most organic molecules to be toxic to Tetrahymena.
A Comparative Study of Chironomus riparius Meigen and Chironomus tentans Fabricius (Diptera:Chironomidae) in Aquatic Toxicity Tests by M. M. Watts; D. Pascoe (pp. 299-306).
Chironomus riparius Meigen and Chironomus tentans Fabricius were examined under controlled conditions and exposed to the reference toxicants cadmium and lindane (γ-hexachlorocyclohexane) to identify any differences that could have implications for their use in aquatic toxicity testing. Preliminary studies showed that both species could be cultured in the laboratory using similar methodology, resulting in the typical bimodal emergence of adult males prior to females. However, adults of C. riparius emerged earlier and in greater numbers than C. tentans. Comparative measurements of head capsule width and body length for the four larval instars revealed similar dimensions for each species up to and including the third instar. Fourth-instar larvae of C. tentans were considerably larger than those of C. riparius. Median lethal concentrations (LC50) determined over a 10-day exposure period suggested no difference in species response to cadmium; however, with increasing exposure time, C. tentans was significantly more sensitive to lindane. The investigations showed that the pattern of response was similar for the two species, and that both C. riparius and C. tentans are suitable test organisms for acute exposure assays.
Effects of Benzo(a)pyrene and Size of Organic Matter Particles on Bioaccumulation and Growth of Asellus aquaticus by E. T. H. M. Peeters; T. J. De Jager; J. A. J. Beijer; A. A. Koelmans (pp. 307-314).
The effects of sediment-bound toxicants to aquatic invertebrates may vary due to differences in bioavailability, food quality, or food structure. The equilibrium partitioning theory (EPT) assumes that organic matter content of sediments and not structure of organic matter is relevant for biological effects of polycyclic aromatic hydrocarbons.To test this hypothesis effects of benzo(a)pyrene (B(a)P) and size of sediment organic matter particles on the bioaccumulation and growth of the waterlouse Asellus aquaticus were studied in laboratory microcosms. Sediments and A. aquaticus were both sampled in an unpolluted, spring-fed pond. The sampled sediment was divided into two portions. From one portion the size of the organic matter particles was mechanically reduced. One set of each sediment fraction (fine and coarse) was spiked with B(a)P and incubated for 3 weeks resulting in a concentration of 70 mg B(a)P per kg sediment. Bioassays of 32 days were performed in a 2 × 2 factorial design with four replicas of each treatment.The results showed that the growth of A. aquaticus was mainly influenced by the size of organic matter particles. Growth was significantly less (27%) on finer sediments than on coarser sediments. The increase in length was 9–14% lower in the spiked sediments, but this difference was not significant. The reduced growth of A. aquaticus on finer sediments may be due to a change in the availability and/or quality of food together with a change in feeding behavior.The coarse and fine spiked sediment types did not differ significantly with respect to the sediment water partition coefficient, the organic carbon water partition coefficient, and the bioconcentration factor. In contrast, the biota to sediment accumulation factors were significantly 15% higher in the cosms with coarse sediments than in cosms with fine sediments. However, this difference is too small to conflict with EPT.
Ecotoxicity of Contaminated Suspended Solids for Filter Feeders (Daphnia magna) by R. Weltens; R. Goossens; S. Van Puymbroeck (pp. 315-323).
It is generally assumed that the dissolved fraction of a toxic substance in surface water is mainly responsible for toxicity to aquatic organisms. However, toxic compounds are often adsorbed or chemically bound to suspended particles in the water column, depending upon the physico-chemical conditions. In the present study potential adverse effects to filter feeding organisms by metal contaminated particles were investigated. In our hypotheses the adsorbed metals might desorb in the gastrointestinal tract—due to different physico-chemical conditions—and exert toxic effects.Clay and sand particles, algae and organic material (peat) were artificially contaminated with cadmium and zinc. The contaminated materials were resuspended in standard conditions and toxicity was measured for the water flea Daphnia magna (mortality at 48 hours). As a reference, supernatant solutions were used containing the same concentration of dissolved metal as the suspensions. It was also established that the test concentrations of solid material (250 and 500 mg/l uncontaminated particles) did not cause any mortality within 48 hours. Daphnids are filter feeders: they filtrate large amounts of surrounding water, redrawing particles as a food source. Results strongly indicate that contaminated particles threaten the health of these particle-feeding organisms. Compared to the reference severe acute toxic effects were seen and cadmium accumulation was increased when contaminated solid material was present. Results were essentially the same for the different materials used in the experiments, except for sand contaminated with cadmium. This shows that mineral as well as organic materials can contribute to the particle bound toxicity.Different results were obtained when a static set up was used instead of a flow through set up, illustrating that the route of administration is important to make particles available and thus to evaluate their toxicity.Contaminated particles clearly have toxic potency, not only because they are a continuous source of dissolved xenobiotics, but also because the particle bound fraction can become available within the body of particle feeding organisms. This could lead to unexpected high tissue concentrations. More insight is needed to predict the bioavailability of adsorbed pollutants. Results of this study already indicate that suspended solids should be considered as a separate compartment in risk evaluation of chemicals, effluents or natural surface waters.
Evaluating Mosquito Control Pesticides for Effect on Target and Nontarget Organisms by C. D. Milam; J. L. Farris; J. D. Wilhide (pp. 324-328).
Recent requirements for biomonitoring of urban stormwater runoff have raised the issue of toxic contributions from mosquito control products. A comparison of seven pesticides for their toxicity to target and nontarget organisms was conducted in field and laboratory trials to determine relative impacts in and around Craighead County, Arkansas. Twenty-four and forty-eight-hour acute toxicity tests using Ceriodaphnia dubia, Daphnia magna, Daphnia pulex, and Pimephales promelas were employed with U.S. Environmental Protection Agency (U.S. EPA) suggested procedures as standard test organisms. Additional tests with resident mosquito fish, Gambusia affinis, and mosquito larvae, Anopheles quadrimaculatus, included ditch-receiving waters to compare the somewhat sterile laboratory exposures to actual field conditions. Exposure to as much as 31.4 μg/L of the pesticides Dursban®, malathion, Permanone®, Abate®, Scourge®, B.t.i, and Biomist® were required for effective control of An. quadrimaculatus, whereas as little as 2.7 μg/L resulted in substantial mortality of some nontarget organisms. These data suggest that prevailing application rates for effective mosquito control not only affect nontarget organisms but may also confound stormwater and nonpoint toxicity evaluations that utilize sensitive indicator species.
The Toxicity of a Neem Insecticide to Populations of Culicidae and Other Aquatic Invertebrates as Assessed in In Situ Microcosms by I. M. Scott; N. K. Kaushik (pp. 329-336).
Microcosm trials were conducted with the botanical insecticide Margosan-O® to assess the potential hazards of the product to aquatic organisms. Laboratory chronic bioassays with water from the treated microcosms were conducted to provide an estimate of the residual effect of Margosan-O. Results from chronic tests showed Margosan-O toxicity to be greater in the laboratory exposures than in situ with Culicidae larvae exposed to the same concentrations. Residue analyses of the active ingredient, azadirachtin, determined that it had a half-life of 36 to 48 h in water exposed to natural sunlight. Two applications of Margosan-O at the recommended application rate for pests did not harm aquatic invertebrates that are categorized as planktonic and filter feeding (Culex sp. and Daphnia sp.). However, the benthic invertebrate (Chironomus riparius) was affected by multiple applications of neem. These results show that the use of Margosan-O and possibly other neem extracts in or near aquatic environments could lead to disturbances in benthic populations and may cause decreases in numbers of organisms that are important in food web and nutrient cycling processes.
Comparison of Embryonic Development and Metal Contamination in Several Populations of the Sea Urchin Sphaerechinus granularis (Lamarck) Exposed to Anthropogenic Pollution by M. Guillou; F. Quiniou; B. Huart; G. Pagano (pp. 337-344).
Over the past years the functional deficiencies observed in the sea urchin Sphaerechinus granularis from the Bay of Brest (France) have led us to select several populations within this species to assess water quality in the Bay of Brest. The present study reports on the comparison of the quality of embryonic development and of the level of metal contamination in sea urchin gonads and gut wall in four populations. Three of them lived in the Bay of Brest, and the last one was considered a reference, being settled in the Glénan Archipelago in southern Brittany (France). The sea urchin population living at the mouth of the River Aulne, at the Armorique Point, seemed to be the most affected, for it displayed the highest rate of blockage and the longest delay in embryonic development along with the highest concentrations in heavy metals, i.e., Fe, Cu, Pb, Cd, and Hg, in the gut wall and in the gonads. A comparison with previous data highlighted a degradation of health conditions in the population living at Marloux in the vicinity of Brest harbor. The comparison of the metal levels detected in individuals from these two populations with the data reported in the literature allowed us to conclude for a local contamination of the bay waters by Fe and Hg. In addition, this study also revealed that Zn and Cd concentrations were sometimes higher than the maximum values reported in the literature and evidenced an increase of contamination by Cu and Pb over the period of study; it should be noted, however, that these values were not excess levels. Our investigations also suggest that Zn, Cd, Pb, and Cu levels should be monitored in the future.
Comparative Toxicity of Dissolved Metals to Early Larval Stages of Palaemon serratus, Maja squinado, and Homarus gammarus (Crustacea:Decapoda) by J. C. Mariño-Balsa; E. Poza; E. Vázquez; R. Beiras (pp. 345-351).
The acute lethal toxicities of mercury, copper, and cadmium to the first larval stage of the prawn (Palaemon serratus), spider crab (Maja squinado), and lobster (Homarus gammarus) were tested. Chromium was also tested with the prawn. Mortality was recorded after 48 h (for lobster) or 72 h (for other species) incubation at 18°C, and the median lethal concentrations (LC50± 95% confidence intervals) per individual and per mass unit were calculated. The LC50 values were, 74 μg Hg/L, 3,304 μg Cu/L, 1,686 μg Cd/L, 12,486 μg Cr/L for prawn; 72 μg Hg/L, 50 μg Cu/L, 158 μg Cd/L for spider crab; and 48 μg Hg/L, 46 μg Cu/L, 34 μg Cd/L for lobster. Therefore, larvae of spider crab and lobster were markedly more sensitive than prawn to heavy metals and thus more suitable to use in seawater quality bioassays. Of these two species, spider crab is recommended due to its abundance, easier maintenance, and higher fecundity. The mercury LC50 values for different larval stages of P. serratus (zoea I, II, V, and VI) were obtained, and no ontogenetic change in sensitivity to the metal could be detected.
Toxicokinetics of 2,4,5-Trichlorophenol and Benzo(a)pyrene in the Clam Pisidium amnicum: Effects of Seasonal Temperatures and Trematode Parasites by J. Heinonen; J. V. K. Kukkonen; I. J. Holopainen (pp. 352-359).
Several biotic and abiotic stress factors may affect aquatic organisms simultaneously. However, not much is known about the effects of, e.g., low temperatures and parasite infections on the toxicokinetics of organic hydrophobic chemicals. Here we studied the accumulation and depuration of [14C]2,4,5-trichlorophenol (TCP) and [3H]benzo(a)pyrene (BaP) in the sediment-dwelling freshwater clam Pisidium amnicum. Experiments were made in October (+15°C), April (+4°C), and July (+15°C) both with uninfected clams and clams infected with Bunodera luciopercae (Trematoda).The accumulation rate for both chemicals was slower at 4°C than at 15°C. The depuration of TCP was biphasic, and the slowest depuration occurred at 4°C. For BaP, the depuration was very slow and monophasic at all temperatures. The highest BCFs for both chemicals were found in July at 15°C. Surprisingly, the BCFs for TCP were higher in April at 4°C than in October at 15°C. For BaP, no steady-state was reached in April. Differences in chemical toxicokinetics between the infected and uninfected clams were only minor. However, for both chemicals a trend of slightly lower BCFs in the infected clams was found. In conclusion, low temperatures modify the toxicokinetics of organic chemicals in P. amnicum and the effects depend on hydrophobicity of the chemical. The effects of parasites on toxicokinetics seem to be small.
Instrumental and Bioanalytical Measures of Persistent Organochlorines in Blue Mussel (Mytilus edulis) from Korean Coastal Waters by J. S. Khim; D. L. Villeneuve; K. Kannan; W. Y. Hu; J. P. Giesy; S.-G. Kang; K.-J. Song; C.-H. Koh (pp. 360-368).
Blue mussels (Mytilus edulis) collected from 34 locations along the south and east coast of Korea were analyzed for polychlorinated biphenyls (PCBs) and organochlorine (OC) pesticides. Maximum concentrations of PCBs and total OC pesticides were 98.5 and 20.5 ng/g, wet weight, respectively. Extracts were fractionated by Florisil chromatography and each fraction was screened for dioxin-like activity in vitro, using recombinant rat hepatoma cells (H4IIE-luc). Fraction 2 (F-2), which contained hexachlorocyclohexanes, chlordanes, p,p′-DDD, and p,p′-DDT, generally elicited significant dioxin-like activity compared to control, whereas Fraction 1 (F-1), which contained PCBs, p,p′-DDE, and hexachlorobenzene, did not. The greatest magnitude of dioxin-like response observed was 44% of the maximum response elicited by a 2,000 pM 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) standard. The relatively low magnitudes of dioxin-like response observed for F-1 samples were consistent with the relatively low PCB concentrations. At concentrations equal to the maximum observed in the mussel samples, neither individual OC pesticides nor a mixture of OC pesticides yielded a significant dioxin-like response in the H4IIE-luc assay. Thus, the concentrations of OC pesticides in F-2 did not appear to have accounted for the dioxin-like activity observed. This suggests the presence of unidentified and/or unknown, acid-stable, dioxin-like compounds in F-2. This study suggests that in vitro bioassays are useful in assessing the contamination of mussels collected from coastal marine locations.
Relative Contributions of Aqueous and Dietary Uptake of Hydrophobic Chemicals to the Body Burden in Juvenile Rainbow Trout by P. Qiao; F. A. P. C. Gobas; A. P. Farrell (pp. 369-377).
This study assessed the relative contributions of aqueous versus dietary uptake of three hydrophobic chemicals, 1,2,4-trichlorobenzene (1,2,4-TCB), 1,2,3,4,5-pentachlorobenzene (PeCB), and 2,2′,4,4′,6,6′-hexachlorobiphenyl (HCBP). Juvenile rainbow trout (Oncorhynchus mykiss) were exposed separately to chemically spiked water and food for 4 days and 12 days, respectively. Chemical concentrations were measured in the food, water, and tissues, and this allowed calculation of uptake rate constants (k1 from water exposure, kd from food exposure). The k1 values for the three test chemicals were approximately five orders of magnitude greater than the kd values. Using these measured uptake rate constants, a simulation model was used to predict the relative aqueous versus dietary uptake when fish were exposed simultaneously to water and food contaminated with these hydrophobic chemicals. The model predicted for all three test chemicals that the two uptake routes would contribute equally to the chemical body burden in fish whenever the food:water chemical concentration ratio was near 105. However, using food:water chemical concentration ratios that might be expected in nature, the model predicted that gill uptake could account for over 98% of fish body burden for both 1,2,4-TCB and PeCB uptake (log Kow values of 3.98 and 5.03, respectively). For HCBP (log Kow of 7.55), the model predicted that the dietary uptake could contribute over 85% of the body burden. Thus, depending on the actual food:water chemical concentration ratio, aqueous uptake via the gills can predominate even when the chemicals have a log Kow value greater than 5.0. In addition, we confirmed that dietary uptake of hydrophobic xenobiotics increases with increasing log Kow.
Growth-Related Changes in Heavy Metal Accumulation in Green Turtle (Chelonia mydas) from Yaeyama Islands, Okinawa, Japan by H. Sakai; K. Saeki; H. Ichihashi; N. Kamezaki; S. Tanabe; R. Tatsukawa (pp. 378-385).
Concentrations of nine heavy metals (Fe, Mn, Zn, Cu, Pb, Ni, Cd, Co, and Hg) were determined in liver, kidney, and muscle of 50 green turtles (Chelonia mydas) collected from Yaeyama Islands, Okinawa, Japan, to elucidate growth-related changes in heavy metal accumulation during different growth stage. Considerably high Cu concentrations were found in the liver of smaller turtles. Mean hepatic concentration of Cu was 50.2 μg/g wet weight which varied widely (4.27–113 μg/g wet weight). Cadmium concentrations decreased with increasing the carapace length. The juvenile green turtles in the pelagic ocean are likely feed on zooplankton, while adult coastal inhabiting green turtles mainly feed on sea grasses and seaweeds. Concentrations of Cd in sea plants are lower than those in zooplankton. The specific accumulation of Cd found in the green turtle seems to be attributable to their feeding habit, which is a shift from carnivore to herbivore at different growth stages.
Development of a Bioassay to Test the Possible Role of Thiamine Disturbance as a Mechanism Behind Pollution-Induced Reproductive Failures in Birds by D. F. de Roode; L. Balk; J. H. Koeman; A. T. C. Bosveld (pp. 386-391).
A test system was developed to examine the effects of environmental contaminants on thiamine homeostasis in bird embryos. This system employs fresh chicken egg yolk lipids as a vehicle for use in egg injection studies. Furazolidone, an antibiotic suspected to interfere with thiamine metabolism, was used as a positive control to evaluate the utility of the test system. It was determined that fresh chicken egg yolk lipids were preferable over chemical vehicles as it resulted in lower mortality rates (16% versus 23–62%) and did not induce any observable effects in the embryo. Injection of 1 mg/egg of furazolidone at day 0 of development resulted in decreased respiration followed by death, with mortality rates being twice as high as in carrier controls. In addition, transketolase activity, which was measured as an indicator of thiamine availability in the body, was decreased 25% in brains of 19-day-old embryos. This mechanism may be of importance for effects of environmental contaminants in wild bird populations.
The Transfer of Lead (Pb) from Earthworms to Shrews (Myosorex varius) by A. J. Reinecke; S. A. Reinecke; D. E. Musilbono; A. Chapman (pp. 392-397).
Shrews (Myosorex varius) were bait-trapped close to Stellenbosch in the Western Cape, South Africa, and analyzed to determine the Pb content of the liver, kidneys, muscle tissue, brain, skull, and bone. Shrews were also fed in the laboratory on mince meat and Pb-contaminated live earthworms for 12–17 days and the Pb content compared with control shrews from the field. The Pb levels in the control shrews from the field were exceptionally high and exceeded levels generally considered to be critical for the onset of pathological symptoms in target organs. The shrews that were fed with Pb-contaminated earthworms had significantly higher Pb concentrations in their livers and kidneys than the control shrews. Given that Pb is bioaccumulated in earthworms, this study showed that predation on earthworms could constitute a major pathway for the entry of Pb into the food chain. M. varius could, similar to other species of shrews in other parts of the world, be a suitable biological monitor to study the environmental hazard of Pb pollution.
Isomer-Specific Accumulation and Toxic Assessment of Polychlorinated Biphenyls, Including Coplanar Congeners, in Cetaceans from the North Pacific and Asian Coastal Waters by T. B. Minh; H. Nakata; M. Watanabe; S. Tanabe; N. Miyazaki; T. A. Jefferson; M. Prudente; A. Subramanian (pp. 398-410).
To elucidate the global distribution and toxicological impacts of polychlorinated biphenyls (PCBs) on cetaceans, the present study determined the concentrations of individual PCB congeners, including toxic non-ortho (IUPAC Nos. 77, 126, 169) and mono-ortho (IUPAC Nos. 105, 118, 156) coplanar congeners, in the blubber of 10 species of adult male odontocetes collected from several locations in the North Pacific Ocean and along coastal waters of Japan, Hong Kong, the Philippines, and India during 1985–1997. Total PCB concentrations in cetaceans from temperate and cold waters were higher than those in cetaceans from tropical regions. Residue levels were found to be the highest in Fraser's dolphins collected off Kii Peninsula, Japan, and hump-backed dolphins from Hong Kong, reflecting serious marine pollution by PCBs in industrialized Asian countries. Penta- and hexa-chlorobiphenyls were the predominant PCB congeners, accounting for about 70% of the total PCBs. 2,3,7,8-Tetrachlorodibenzo-p-dioxin equivalents (TEQs) of non- and mono-ortho coplanar PCBs in the blubber of cetaceans ranged from 36 (in spinner dolphins from the Philippines) to 510 pg/g wet weight (in hump-backed dolphins from Hong Kong). Toxic evaluation of coplanar PCBs using the TEQ concept indicates an greater impact on cetaceans from mid-latitudes. Toxicity contribution of mono-ortho congener IUPAC 118 was prominent in species from high latitude oceans, such as the Bering Sea and the North Pacific, whereas non-ortho congener IUPAC 126 accounted for the highest contribution in cetaceans from lower latitude regions, such as the Philippines and India. The estimated TEQ concentrations in the blubber of some cetacean species, such as northern right whale dolphin and Pacific white-sided dolphin from the northern North Pacific, Dall's porpoise from the Japan Sea, striped dolphin off Sanriku and Fraser's dolphin off Kii Peninsula, Japan, hump-backed dolphin and finless porpoise from Hong Kong, exceeded the levels associated with immunosuppression in harbour seals.