Tom Hom

Toxicopathic hepatic lesions in subadult English sole (pleuronectes vetuls) from Puget Sound, Washington, USA: Relationships with other biomarkers of contaminant exposure

Liver neoplasms are rarely detected in young wild fish. Therefore, other lesions occurring early in the histogenesis of hepatic neoplasia need to be considered as biomarkers of chemical contaminant exposure effects in monitoring studies, especially where adult fish are not available. Moreover, exposure effects may be more reliably assessed in younger fish that have not yet migrated extensively. Accordingly, livers of subadult English sole were histologically examined from nine sites in Puget Sound, WA and the same fish were assessed for contaminant exposure by measurement of fluorescent aromatic compounds (FACs) in bile, hepatic levels of polychlorinated biphenyls (PCBs) and cytochrome P4501A (CYP1A) as catalytic activity of aryl hydrocarbon hydroxylase (AHH), and Hydrophobic DNA adducts in liver by 32P-postlabelling. Although neoplasms were rare, higher prevalences of preneoplastic, regenerative, and unique degenerative/ necrotic lesions were detected in sole from contaminated sites. Prevalences of these early histopathologic biomarkers were significantly higher at the more contaminated sites, and concentration of mean biliary FACs at each capture site was a significant risk factor for most lesions, as determined by stepwise logistic regression. By this statistical method, we also demonstrated that several measures of bioaccumulation or biochemical response to contaminants were significant and near-significant risk factors for prevalences of most hepatic lesion categories. For example, mean hepatic AHH activity was a significant risk factor for prevalence of all lesion types, except neoplasms; hepatic PCB and xenobiotic-DNA adduct concentrations were significant risk factors for the most frequently detected lesion category, hepatocellular nuclear pleomorphism/megalocytic hepatosis, and the inclusive category ‘any early toxicopathic lesion’. These findings further support the utility of certain non-neoplastic liver lesions as early indicators of biological damage in subadult as well as adult fish exposed to xenobiotics in the marine environment.

Accumulation and dose-response of hepatic DNA adducts in English sole (Pleuronectes vetulus) exposed to a gradient of contaminated sediments

Abstract Levels of hepatic DNA adducts and concentrations of fluorescent aromatic compounds (FACs) in bile were measured in English sole (Pleuronectes vetulus) exposed for up to 5 weeks to a reference sediment amended with a sediment containing high concentrations of polycyclic aromatic compounds (PACs) from Eagle Harbor, Puget Sound, WA. Levels of hepatic DNA adducts increased linearly with both concentration of sediment polycyclic aromatic hydrocarbons (PAHs) and length of exposure, whereas concentrations of biliary FACs were dose-responsive to levels of sediment PAHs but attained steady-state concentrations after 2 weeks of exposure. The levels of DNA adducts and concentrations of biliary FACs in fish exposed to the reference sediment remained at baseline levels throughout the exposure. Formation of PAC-DNA adducts was observed in liver of English sole injected with an extract of Eagle Harbor sediment (EHSE) and in English sole hepatocytes incubated with EHSE or the neutral fraction of EHSE containing predominantly PACs. In addition, DNA adduct and biliary FAC levels measured in feral English sole captured from Eagle Harbor, when compared with levels measured in fish from the laboratory sediment exposure study, also suggested accumulation of DNA adducts in the fish captured from Eagle Harbor. These findings, in conjunction with previous studies showing PAC-DNA adducts are persistent in fish, suggest that a substantial proportion of PAC-induced DNA damage was not readily repaired in English sole, and thus, measurement of hepatic DNA adducts can be used as an indicator of cumulative exposure to genotoxic PACs.

Hepatic lesions other than neoplasms in subadult flatfish from puget sound, washington: relationships with indices of contaminant exposure

Abstract Liver neoplasms are rare in young wild fish; therefore, it is essential to consider toxicopathic liver lesions that occur earlier than neoplasms as biomarkers of contaminant exposure in studies where targeted or available fish are not adults. Also some exposure effects may be more reliably assessed in younger fish that have not yet migrated extensively. We addressed these issues by histologically examining subadult English sole, rock sole, and starry flounder captured from eight sites in Puget Sound, and by measuring fluorescent aromatic compounds (FACs) in bile and polychlorinated hiphenyls (PCBs) in liver. Neoplasms were detected rarely; higher prevalences of preneoplastic, regenerative, and degenerative lesions were detected in most species, primarily from contaminated sites, including hydropic vacuolation of hepatocytes and biliary cells in rock sole and starry flounder. These nomeoplastic lesion types are inducible in fish by exposure to various toxicants in the laboratory, and/or (in the case of hydropic vacuolation) are associated with contaminant exposure and liver neoplasia in adult wild fish. Prevalences of these ‘early’ lesions were significantly higher at the more contaminated sites, as determined by several statistical approaches, including logistic regression. Moreover, prevalences of most lesions in all three species correlated with mean bile FAC levels at the sites, and prevalences of some lesions in English sole correlated with liver PCB levels. The present findings further support the utility of certain liver lesions other than neoplasms as early indicators of biological damage in subadult as well as adult fish exposed to xenobiotics in the marine environment.

Chemical contaminant exposure and effects in four fish species from Tampa Bay, Florida

Concentrations of selected anthropogenic chemical contaminants and levels of pollution-related biological effects were measured during three consecutive years (1990–1992) in hardhead catfish (Arius felis), Gulf killifish (Fundulus grandis), longnose killifish (F. majalis), and red drum (Scieaenops ocellatus) from 12 subtidal and intertidal sites in Tampa Bay and nearby Sarasota Bay. Each species was collected from at least four sites. Compared to nonindustrialized sites, concentrations of PCBs, DDTs, and alpha-chlordane in liver, and of fluorescent aromatic compounds in bile, were highest in fish from sites in or near Hillsborough Bay, the most industrialized portion of Tampa Bay. The results of analyses for two biochemical markers of contaminant-induced effects in fish, hepatic cytochrome P4501A activities and levels of hepatic DNA adducts, also showed the highest levels to be in all four fish species from sites in the vicinity of Hillsborough Bay. Liver lesions, considered to be pollution-associated in several other bottom-feeding fish species, were found in hardhead catfish and longnose killifish, exclusively from sites in Hillsborough Bay. Overall, concentrations of selected contaminants and their derivatives in the four target fish species generally reflected concentrations of these contaminants found in sediment. The biochemical and histopathological responses demonstrated that chemical contaminant concentrations in the vicinity of Hillsborough Bay are sufficiently high to cause adverse effects in indigenous fish species. The results, collectively, showed that the extent of contaminant exposure and biological effects in fish from sites in Tampa Bay were low to moderate compared to more urbanized coastal sites of the United States. *** DIRECT SUPPORT *** A01BY073 00009

Field studies of reproductive success and bioindicators of maternal contaminant exposure in English sole (Parophrys vetulus)

Our studies have shown that early stages of the reproductive process in female English sole (Parophrys vetulus) are disrupted by contaminant exposure. To determine the potential for contaminants to affect later stages of the reproductive cycle, we examined the effects of maternal contaminant exposure on egg and larval viability in this species, in a field study conducted on running ripe fish collected for two consecutive years from spawning grounds. Maternal contaminant exposure was assessed by measuring levels of polychlorinated biphenyls (PCBs) in ovarian and hepatic tissue, biliary levels of fluorescent aromatic compounds (FACs), and hepatic aryl hydrocarbon hydroxylase (AHH) activities. Additionally, the presence of significant liver disease or ovarian atresia was documented, and levels of plasma estradiol were measured. Stepwise multiple regression of the data showed that contaminant exposure was only a minor factor in determining both egg and larval viability. Hepatic AHH activity showed a slight negative correlation with fertilization success, explaining only 4% of the variability. Increased levels of PCBs in ovaries of spawning female English sole were not associated with reduced reproductive success. However, because the range of contaminant exposure in the spawning fish did not encompass the high levels seen in non-spawning fish captured from contaminated areas, it can be hypothesized that female English sole exposed to substantial levels of contaminants might be at least partially excluded from the spawning population.

Contaminant Effects on Ovarian Development and Spawning Success in Rock Sole from Puget Sound, Washington

Abstract The objective of this study was to determine if exposure to aromatic hydrocarbons (AHs) or polychlorinated biphenyls (PCBs) was associated with altered ovarian development or reduced spawning success in rock sole Pleuronectes bilineatus. This objective was addressed in two separate phases. In the first study, concentrations of AHs and PCBs were measured in individual fish from four sites in Puget Sound, Washington (Eagle Harbor, Sinclair Inlet, Yukon Harbor, and Pilot Point) with different levels of AH and PCB contamination in sediments and their ovarian development was monitored during the 1989–1991 spawning seasons. In these fish, egg weight was negatively correlated with levels of PCBs in the liver. However, contaminant exposure levels were not significantly associated with the probability of entering vitellogenesis or with gonadosomatic index, plasma estradiol concentrations, or fecundity. In the second study, gravid female soles were taken from Eagle Harbor, Sinclair Inlet, Yukon Harbor, and...

Exposure of juvenile chinook and chum salmon to chemical contaminants in the Hylebos Waterway of Commencement Bay, Tacoma, Washington

The Hylebos Waterway is an industrialized waterway ofCommencement Bay, Tacoma, Washington, that is severelycontaminated with aromatic and chlorinatedhydrocarbons in the sediment. Juvenile chinook (Oncorhynchus keta) and chum salmon (O.tshawytscha) inhabit this waterway for a few days orweeks during their outmigration from freshwaterstreams to saltwater. The purpose of thisinvestigation was to determine to what degree juvenilechum and chinook salmon captured from the HylebosWaterway might bioaccumulate organic contaminants. These levels of exposure will be compared to previousstudies where such exposures have been linked tobiological dysfunction in juvenile salmon. Theresults showed that juvenile chum and chinook salmonfrom the Hylebos Waterway take up a wide range ofchemical contaminants, compared to fish fromhatcheries or reference estuaries. These contaminantsinclude high and low molecular weight polycyclicaromatic hydrocarbons (PAHs), polychlorinatedbiphenyls (PCBs, including the toxic congeners 105 and118), hexachlorobutadiene (HCBD), hexachlorobenzene(HCB), DDTs, heptachlor, and several pesticides. Immunohistochemical examination of the gill and gut injuvenile chum salmon from the Hylebos Waterway showedthe induction of the P450 metabolizing enzyme. Moreover, concentrations of contaminants in juvenilechinook and chum salmon from the Hylebos Waterway arecomparable to levels previously shown to be associatedwith biological injury in juvenile chinook salmon,such as impaired growth, suppression of immunefunction as demonstrated by reduced B cell function,and increased mortality following pathogen exposure.

Bioindicators of contaminant exposure and sublethal effects in benthic fish from Puget Sound, WA, USA

Abstract A suite of chemical and biochemical parameters was measured in three species of benthic flatfish (English sole, Parophrys vetulus; rock sole, Lepidopsetta bilineata; and starry flounder, Platichthys stellatus) sampled from up to five sites in Puget Sound, WA, USA, to assess the sensitivity of the parameters to differences in levels of contaminant exposure and the relative merit of the use of a suite of indices for assessing exposure and sublethal effects. The indices examined were hepatic levels of polychlorinated biphenyls (PCBs) and biliary fluorescent aromatic-compound concentrations, hepatic activities of aryl hydrocarbon hydroxylase and ethoxyresorufin-O-deethylase, and levels of total hepatic GSH and hydrophobic DNA-xenobiotic adducts; the last-mentioned were determined by using the 32P-postlabeling assay. The results showed that the indices examined could discriminate among sites exhibiting different degrees of chemical contamination; however, species differences in the range of response of some indices were observed. Additionally, the use of multiple indices appeared to enhance the assessment of contaminant exposure and sublethal effects.