Polychlorinated Biphenyls (PCBs) and Sex Hormone Concentrations in Ringed and Grey Seals: A Possible Link to Endocrine Disruption?

Polychlorinated biphenyls (PCBs) are recognised reproductive and immune system toxicants in marine mammals mediated by endocrine-disrupting mechanisms. As with other predators, seals are exposed to elevated bioaccumulated concentrations of PCBs and other persistent organic pollutants (POPs). Cryopreserved plasma samples from adult ringed (Phoca hispida; n = 39) and grey (Halichoerus grypus; n = 38) seals, sampled between 1998 and 2002 from Baltic Sea, Svalbard, and Sable Island (Canada) were used to investigate relationships between PCB exposure and sex hormone concentrations (progesterone; P4, 17α-hydroxy progesterone; 17α-OH-P4, testosterone; T4, 17ß-estradiol; E2, estrone; E3). Immunoassay methods were used for quantification of analytes due to the limited sample volumes available. PCB concentrations were found to be significantly higher in Baltic seals than other sampling locations and were classed as "Exposed" seals while Svalbard and Sable Is seal were classed "Reference" seals (sexes and species separate). Mean hormone concentrations in Exposed seal were lower than Reference seals, and this was statistically significantly for 17α-OH-P4 (both sexes and both species), E2 (ringed and grey seal females), and E3 (grey seal females). Regression analyses (PCB v hormone concentrations) for each sex and species revealed significant correlations for P4 (Sable Is. female grey seals and female ringed seals), 17α-OH-P4 (Sable Is. male grey seals and Svalbard male ringed seals), T4 (Svalbard male ringed seals), E2 (female ringed seals), and E3 (female ringed seals and Baltic female grey seals). Although significant correlations are not evidence of cause and effect, the potential impact of hormone changes on endocrine homeostasis and reproductive health for seal populations warrants further investigation given that PCB concentrations found here are in the same range as those currently reported in seals from these populations.

Development of an immunoassay for the determination of polyaromatic hydrocarbons in plasma samples from oiled seabirds.

External exposure assessment of oiled seabirds is undertaken by assessment of the percentage oil coverage of the plumage. Nondestructive monitoring of the toxic fraction of petroleum oils and diesels (polyaromatic hydrocarbons, PAHs) which enters the general circulation (internal exposure burden) of oiled seabirds is rarely undertaken. This is because the traditionally used chromatographic methods for plasma PAH analysis require larger sample volumes than those that can be safely collected from smaller species, such as guillemots (Uria aalge). Furthermore, these methods are not a cost-effective or practical approach for analysis of large numbers of birds in a short time period as part of an oil spill response in wildlife rehabilitation centers. This study describes the modification and validation of a commercially available PAH immunoassay (cRaPID PAH) to enable high-throughput, cost-effective, simple, and rapid determination of total PAH concentrations in 50 microL volumes of plasma. The limit of detection of the assay was 0.1 ng/mL as benzo-apyrene (BaP) equivalents with a working range of 0.120 ng/mL. As further validation of the immunoassay, PAHs were determined by GC-MS. GC-MS data were significantly positively correlated with corresponding immunoassay data for the same birds (r2 = 0.976, p < 0.001). The plasma PAH concentrations of 40 oiled guillemots stranded on U.K. shores were determined using the assay to demonstrate its usefulness for biomonitoring studies. The mean ,PAH concentration observed was 1.05 +/- 0.67 ppm (range 0.02-2.40 ppm as BaP equivalents). The modifications to the cRaPID PAH kit in this study enable nondestructive, high-throughput, semiquantitative determination of PAH concentrations in plasma samples suitable for exposure assessment of oiled seabirds during oil spill response and rehabilitation.

Human health significance of organochlorine and mercury contaminants in Japanese whale meat.

The concentrations of total mercury, polychlorinated biphenyls (PCBs), and organochlorine pesticides (SigmaDDT, dieldrin, hexachlorobenzene [HCB], and SigmaHCH) were determined in 61 whale meat products (bacon, blubber, red meat, liver, intestine, and tongue) purchased from retail outlets across Japan. Mean (range) concentrations of contaminants in all samples were: total mercury 4.17 (0.01-204); SigmaPCB 1.14 (0-8.94); SigmaDDT 0.98 (0-7.46); dieldrin 0.07 (0-0.35); HCB 0.06 (0-0.22); and SigmaHCH 0.07 (0-0.19) micro g/g (wet weight). The data were used to calculate estimated daily intakes (EDIs) of contaminants at two hypothetical levels of whale meat consumption. These EDIs were compared with FAO/WHO "tolerable daily intake" (TDI) values for each chemical. EDIs calculated for higher levels of whale meat consumption were in some cases exceptionally high and for many products exceeded FAO/ WHO-TDIs for total mercury, PCBs, and dieldrin, with exceedance factor values (EDI/TDI) for total mercury, PCBs, and dieldrin reaching maxima of 175, 5.36, and 2.1, respectively. For sensitive consumers and those with high-level consumption (e.g., whaling communities), exposure to mercury and to a lesser extent PCBs from certain whale blubber and bacon and striped dolphin liver products could lead to chronic health effects. The Japanese community should therefore exercise a precautionary approach to the consumption of such foods in excess, particularly by high-risk members of the population.

Bioaccumulation of polychlorinated biphenyls (PCBs) and dichlorodiphenylethane (DDE) methyl sulfones in tissues of seal and dolphin morbillivirus epizootic victims.

Polychlorinated biphenyl (PCB) and dichlorodiphenylethane (DDE) methyl sulfone (MSF) metabolites possess high affinities for binding two homologous 16,000 Da homodimeric receptor proteins in the lung (Clara cell secretory protein, CCSP) and the uterus (uteroglobin, UG), leading to selective bioaccumulation of MSFs in these tissues. As marine mammals are highly exposed to organochlorines, concentrations of PCBs, PCB MSFs, DDT, and DDE MSF were analyzed in blubber, lung, and uterus samples from harbor seal (Phoca vitulina) and striped dolphin (Stenella coeruleoalba) morbillivirus epizootic victims to investigate uterine and lung MSF accumulation. Mean uterus concentrations of PCB MSFs and DDE MSF in harbor seals were 0.61 and 0.04 microg/g lipid weight and in striped dolphins 0.05 and 0.01 microg/g lipid weight. Mean lung concentrations of PCB MSFs and DDE MSF in harbor seals were 0.96 and 0.02 microg/g lipid weight and in striped dolphins 0.16 and 0.01 microg/g lipid weight. To ascertain whether uterine and lung bioaccumulation of MSFs is possible due to the presence of CCSP and UG in seals, CCSP and UG proteins in uterine flushings and in uterine and lung and epithelial tissue from Baltic gray and ringed seals were characterized using gel electrophoresis and Western blotting techniques. UG- and CCSP-like proteins with molecular weights of 16,000 Da were resolved in all samples. This is the first demonstration of this protein in any marine mammalian species. The toxicological implications of MSF binding with UG and CCSP in marine mammals are discussed.

PCB-associated alteration of hepatic steroid metabolism in harbor seals (Phoca vitulina).

Hepatic cytochrome P-450 (CYP450) isozymes are involved in xenobiotic detoxification and steroid metabolism. Seals are highly exposed to polychlorinated biphenyls (PCBs) in the environment, resulting in CYP450 induction, which may have concomitant effects on CYP450 steroid metabolism. Experiments were conducted to determine rates of steroid metabolism in harbor seal (Phoca vitulina) liver. CYP450 was induced with increasing liver PCB concentrations between 0.2 and 5.73 microg/g (wet weight). Progesterone metabolism was significantly decreased with increasing liver PCB concentration. Testosterone metabolism was also increased with increasing liver PCB concentration. The results indicate a change in steroid metabolism associated with increasing PCB burden, suggesting that PCBs may have a modulating effect on hepatic steroid biotransformation in environmentally exposed seals. The possible implications of this for endocrine homeostasis in seals are discussed.

Methyl sulphone metabolites of polychlorinated biphenyls (PCBs) in cetaceans from the Irish and the Aegean Seas.

The levels of PCBs and PCB methyl sulphone metabolites were determined in the blubber of six species of cetaceans that originated from the Irish Sea and the Aegean Sea (Mediterranean). Burdens ranging from 2.80 to 27.80 microg g-1 (lipid weight) total PCBs and 0.03 to 0.58 microg g-1 (lipid weight) total methyl sulphones were recorded. The highest cetacean methyl sulphone burden (0.58 microg g-1) was in an Irish Sea harbor porpoise (Phocoena phocoena). Methyl sulphone isomer formation capacity, as determined by PCB:MSF ratios, varied considerably between species as follows: harbour porpoise (1:10) > pilot whale (Globicephalus melas), white-sided dolphin (Lagenorhyncus acutus) (1:50) > common dolphin (Delphinus delphis), Risso's dolphin (Grampus griseus), and striped dolphin (Stenella coerueoalba), (1:100), and was related to interspecific variation in PCB methyl sulphone formation capacity.

Cytochromes P450, P420 & mixed-function oxidases as biomarkers of polychlorinated biphenyl (PCB) exposure in harbour seals (Phoca vitulina).

Hepatic microsomal cytochrome P450, EROD and ECOD activity were investigated as biomarkers of PCB exposure in harbour seals (Phoca vitulina). Due to the difficulty of obtaining undegraded seal liver samples, standard spectrophotometric methodology was adapted to investigate P420 (degraded P450) as a PCB biomarker with partially degraded samples. Total PCB burdens in both blubber and liver had positive correlations with P450, P420 and MFO activity levels. The use of P420 biomarkers in this study supports the inclusion of samples from by-caught marine mammals for future biomonitoring studies. P450 isozymes CYP1A (P4501A) and CYP2B (P4502B) in conjunction with MFO activity were investigated as "specific" biomarkers of PCB exposure. They were found to reliably reflect levels of [MC] and [PB]-type PCB exposure in harbour seal liver.