Polycyclic Aromatic Hydrocarbons Body Burden Research Articles

Polycyclic aromatic hydrocarbons and risk of rheumatoid arthritis: a cross-sectional analysis of the National Health and Nutrition Examination Survey, 2007–2016

ObjectiveWhile there are several well-established environmental risk factors for rheumatoid arthritis (RA), a paucity of evidence exists linking environmental toxicants with RA prevalence. We aimed to examine the associations between...

A comparison of PAH exposure in red snapper (Lutjanus campechanus) around natural and artificial reefs in the northwestern Gulf of Mexico

Red Snapper (Lutjanus campechanus) are an important fishery resource in the Gulf of Mexico (GoM) and are found in abundance around artificial (e.g. oil and gas platforms) and natural habitats (e.g. coral reefs, outcroppings). Polycyclic aromatic hydrocarbons (PAHs), are a small but toxic component of crude oil released into GoM waters through both anthropogenic (e.g., oil and gas activities) and natural (e.g., hydrocarbon seeps) sources. The objectives of this study were to measure and compare PAH concentrations between tissue matrices (liver, gonad, muscle, and bile), by sex and location (e.g., artificial oil and gas infrastructure vs. natural reefs), of Red Snapper collected in the northwestern GoM. In 2016, Red Snapper (n = 88) were collected from natural and artificial reefs to evaluate potential differences in PAH exposures and body burdens. There were no significant results from the biometric analysis or their association with PAH's. Average PAH concentrations were significantly higher (p < 0.001) in livers than in gonads and muscle tissue. No significant differences were found in PAH concentrations between sexes or between structure type for both biliary, liver, or, muscle PAH concentrations, likely due to the close proximity of the natural and anthropogenic sites sampled (within 97 km radius). However, biliary PAH concentrations in fish collected outside of the densely populated oil and gas infrastructure fields had significantly lower PAH levels (p < 0.001). Thus, the scale at which samples are collected and compared is critical to understanding the cumulative impacts of oil and gas activities and underscores the need for further research at multiple scales across the GoM.

Exposure to retene, fluoranthene, and their binary mixture causes distinct transcriptomic and apical outcomes in rainbow trout (Oncorhynchus mykiss) yolk sac alevins.

Polycyclic aromatic hydrocarbons (PAHs) are widely spread environmental contaminants which affect developing organisms. It is known that improper activation of the aryl hydrocarbon receptor (AhR) by some PAHs contributes to toxicity, while other PAHs can disrupt cellular membrane function. The exact downstream mechanisms of AhR activation remain unresolved, especially with regard to cardiotoxicity. By exposing newly hatched rainbow trout alevins (Oncorhynchus mykiss) semi-statically to retene (32µg l-1; AhR agonist), fluoranthene (50µg l-1; weak AhR agonist and CYP1a inhibitor) and their binary mixture for 1, 3, 7 and 14 days, we aimed to uncover novel mechanisms of cardiotoxicity using a targeted microarray approach. At the end of the exposure, standard length, yolk area, blue sac disease (BSD) index and PAH body burden were measured, while the hearts were prepared for microarray analysis. Each exposure produced a unique toxicity profile. We observed that retene and the mixture, but not fluoranthene, significantly reduced growth by Day 14 compared to the control, while exposure to the mixture increased the BSD-index significantly from Day 3 onward. Body burden profiles were PAH-specific and correlated well with the exposure-specific upregulations of genes encoding for phase I and II enzymes. Exposure to the mixture over-represented pathways related to growth, amino acid and xenobiotic metabolism and oxidative stress responses. Alevins exposed to the individual PAHs displayed over-represented pathways involved in receptor signaling: retene downregulated genes with a role in G-protein signaling, while fluoranthene upregulated those involved in GABA signaling. Furthermore, exposure to retene and fluoranthene altered the expression of genes encoding for proteins involved in calcium- and potassium ion channels, which suggests affected heart structure and function. This study provides deeper understanding of the complexity of PAH toxicity and the necessity of investigating PAHs as mixtures and not as individual components.

A baseline evaluation of PAH body burden in sardines from the southern Brazilian shelf

The concentrations of 37 polycyclic aromatic hydrocarbons (PAHs) and their potential risk to human health were determined in fifty sardine muscle (Sardinella brasiliensis) samples collected along the southern Brazilian shelf. Parental and alkylated PAHs were identified and quantified using a pressurized liquid extraction with in-cell purification method and gas chromatography–mass spectrometry identification and quantification. The concentrations of Σ37 PAHs in muscle ranged between 6.02 and 4074 μg kg−1 wet weight, which are comparable to levels reported for commercially important fish worldwide. The most abundant compounds were pyrene and fluoranthene, which originate from both petrogenic and pyrolytic hydrocarbon inputs. In only 4% of the samples the benzo[a] pyrene equivalent concentration was above the threshold of 6 μg kg−1 suggested for safe fish consumption in Brazil. These findings will serve as baseline data for monitoring the quality of sardines consumed in the country and for studying fish populations.

The PAH body burdens and biomarkers of wild mussels in Port Phillip Bay, Australia and their food safety implications

Wild Mediterranean mussels (Mytilus galloprovincialis) were collected from 10 coastal sites of Port Phillip Bay, Australia, and 16 types of Polycyclic aromatic hydrocarbons (PAHs) in their bodies were measured. Also, mussels from 4 of the 10 sites were sampled and the activities of Metallothioneins (MTs), superoxide dismutase (SOD), glutathione S-transferase (GST), and Ethoxyresorufin -o- deethylase (EROD) in the gills were tested. The results demonstrated spatial variation of different PAHs in mussels, which differed from trace metal accumulations to mussels reported in previous studies. Besides, the results of SOD, GST, and EROD showed highly similar features among mussels from all the sites while the results of MTs appeared to be different. The estimation of possible excessive cancer risks caused by wild mussel consumption using the results in this study demonstrated that the PAHs in wild mussels in Port Phillip Bay is a moderate concern for consumers.

Contaminant Concentrations in Sediments, Aquatic Invertebrates, and Fish in Proximity to Rail Tracks Used for Coal Transport in the Pacific Northwest (USA): A Baseline Assessment.

Railway transport of coal poses an environmental risk, because coal dust contains polycyclic aromatic hydrocarbons (PAHs), mercury, and other trace metals. In the Pacific Northwest of the United States, proposed infrastructure projects could result in an increase in coal transport by train through the Columbia River corridor. Baseline information is needed on current distributions, levels, and spatial patterns of coal dust-derived contaminants in habitats and organisms adjacent to existing coal transport lines. To that end, we collected aquatic surface sediments, aquatic insects, and juvenile fish in 2014 and 2015 from Horsethief Lake State Park and Steigerwald National Wildlife Refuge, both located in Washington state close to the rail line and within the Columbia River Gorge National Scenic Area. Two subsites in each area were selected: one close to the rail line and one far from the rail line. Detected PAH concentrations were relatively low compared with those measured at more urbanized areas. Some contaminants were measured at higher concentrations at the subsites close to the rail line, but it was not possible to link the contaminants to a definitive source. Trace metal concentrations were only slightly higher than background concentrations, but a few of the more sensitive benchmarks were exceeded, including those for arsenic, lead, and selenium in fish tissue and fluoranthene, cadmium, copper, manganese, nickel, zinc, iron, and arsenic in sediments. At Horsethief Lake, Chinook salmon and yellow perch showed lower total mercury body burdens than other species, but PAH body burdens did not differ significantly among species. Differences in the species caught among subsites and the low number of invertebrate samples rendered food web comparisons difficult, but these data show that the PAHs and trace metals, including mercury, are accumulating in these wetland sites and in some resident organisms.

Hypoxia and reduced salinity exacerbate the effects of oil exposure on sheepshead minnow (Cyprinodon variegatus) reproduction

Estuaries of the northern Gulf of Mexico are dynamic environments, with fluctuations in salinity and dissolved oxygen, including areas of seasonal hypoxia. Fish that reside and reproduce in these estuaries, including sheepshead minnow (Cyprinodon variegatus; SHM), were at significant risk of oil exposure following the Deepwater Horizon oil spill. It is poorly understood how differences in environmental conditions during oil exposure impact its toxicity. The present study investigated the effects of crude oil high-energy water accommodated fraction (HEWAF) on SHM reproduction in three environmental scenarios (normoxic, hypoxic, and hypoxic with low salinity) to determine if differences in salinity (brackish vs low salinity) and dissolved oxygen (normoxia vs hypoxia) could exacerbate the effects of HEWAF-derived polycyclic aromatic hydrocarbons (PAHs). We observed that HEWAF exposure significantly increased liver somatic index of SHM compared to control, but this effect was not exacerbated by hypoxia or low salinity. HEWAF exposure also significantly decreased egg production and egg fertilization rate, but only in the hypoxic and hypoxic with low salinity scenarios. A significant correlation existed between body burdens of PAHs and reproductive endpoints, providing substantial evidence that oil exposure reduced reproductive capacity in SHM, across a range of environmental conditions. These data suggest that oil spill risk assessments that fail to consider other environmental stressors (i.e. hypoxia and salinity) may be underestimating risk.

Naturally occurring hydrocarbon content and baseline condition of deep-sea benthic fauna from the Great Australian Bight

The deep sea (> 500 m) of the Great Australian Bight (GAB) has not been well studied even though it is believed to have high conservation values as evidenced by large marine reserves, and where adjacent (continental shelf) waters support important commercial fisheries and large populations of marine mammals. Recent interest in developing the region's deep-sea hydrocarbon resources has drawn attention to this sparsity of data and the need to characterise the region's benthic ecology in order to detect and understand any potential impacts linked to a developing oil and gas industry. To that end, we measured the naturally occurring hydrocarbon content and baseline condition of a variety of benthic fishes and invertebrates collected during two surveys of the continental slope and seabed geological features. A total of 225 individuals, representing 15 species (7 invertebrates and 8 fishes) were analysed for (i) polycyclic aromatic hydrocarbons (PAH) body burdens or biliary PAH metabolites; (ii) 7-Ethoxyresorufin O-deethylase (EROD), a commonly used oil exposure biomarker; and (iii) lipid profiles and histology. Hydrocarbon concentrations, although measurable at some sites, did not indicate any anthropogenic contamination or unequivocal hydrocarbon seepage. PAH body burdens in the invertebrate species were below the levels of detection, and phenanthrene metabolites showed differences between species of fish surveyed, but were consistently low relative to oil exposed fish. EROD levels varied between species but also did not indicate exposure to oil. Lipid levels were highly variable between individuals and sites, suggesting that a lipid-related metric would not be suitable for monitoring organism health. Histological analysis indicated no gross deformity or infection in either the liver, gill, kidney or spleen. Pathologies identified were of minimal pathological important and likely to be recoverable. Liver exhibited varying levels of lipid accumulation across all fish species. These results, obtained before the commencement of oil and gas industry activity, can be used as a part of a baseline benthic ecosystem characterisation to guide future ecological monitoring programs.

Examining the Association between Body Burdens of Harmful Chemicals and Heaviness of Marijuana Smoking

Marijuana is seeing increased use both globally and domestically. However, the scientific community has not fully reached a consensus about what negative health effects and to what extent marijuana smoking may cause. In this study, we evaluated the associations between the body burdens of polycyclic aromatic hydrocarbons (PAHs) among marijuana smokers and the smoking heaviness. We observed clear, increasing trends of PAH body burdens as marijuana smoking increased. The findings highlight the importance of capturing the heaviness of marijuana smoking in future studies and support the need for well-designed toxicological and epidemiological studies for understanding the health effects of marijuana use in a changing environment.

ETS Exposure and PAH Body Burden in Nonsmoking Italian Adults.

Active smoking is associated with increased body burden of polycyclic aromatic hydrocarbons (PAHs); the aim of this study was to assess whether environmental tobacco smoking (ETS) increases the internal dose of PAHs. In 344 nonsmoking Italian adults, out of 497 individuals selected as representative of the population of the town of Modena, ETS exposure was evaluated by a self-administered questionnaire and by the measurement of urinary cotinine (COT-U). PAH exposure was assessed by the measurement of urinary 1-hydroxypyrene (1-OHPYR) and of ten urinary PAHs. In all subjects, median (5th–95th percentile) COT-U was 0.47 (<0.1–3.91) µg/L. While 58 subjects reported to be ETS exposed (ETSQUEST), 38 individuals were identified as ETS exposed on the basis of a COT-U value of 1.78 (90% confidence interval 1.75–1.80) µg/L, previously derived as an upper reference value in not ETS exposed Italian adults (ETSCOT). Median COT-U levels were 1.38 (<0.1–9.06) and 3.63 (1.80–17.39) µg/L in ETSQUEST and in ETSCOT subjects, respectively. Significant correlations between COT-U and 1-OHPYR, and urinary anthracene, fluoranthene, pyrene, and chrysene were found among all subjects. Significantly higher levels of 1-OHPYR, and urinary fluorene, anthracene, and pyrene were found in ETSCOT individuals. The results of multiple linear regression analyses, taking into consideration diet and other sources of PAHs exposures such as the residence area/characteristics and traffic, confirmed that 1-OHPYR and urinary fluorene were affected by ETS exposure, even if ETS played a minor role.

Environmental exposure to polycyclic aromatic hydrocarbons, kitchen ventilation, fractional exhaled nitric oxide, and risk of diabetes among Chinese females.

Diabetes is related to exposure to polycyclic aromatic hydrocarbons (PAHs), inflammation in the body, and housing characters. However, associations of urinary monohydroxy-PAHs (OH-PAHs) or fractional exhaled nitric oxide (FeNO) with diabetes risk in relation to housing characters are unclear. In this study, 2645 individuals were drawn from the baseline survey of the Wuhan-Zhuhai Cohort Study. Associations of diabetes with urinary OH-PAHs or FeNO among cooking participants were estimated using logistic regression models. Among women with self-cooking meals, urinary OH-PAH levels were positively associated with diabetes risk (P<.05); the cooking women with high FeNO (≥25ppb) had a 59% increase in the risk of diabetes (OR: 1.59, 95% CI: 1.06, 2.38), compared with those with low FeNO (<25ppb). The cooking women with use of kitchen exhaust fans/hoods had a 52% decrease in the risk of diabetes (OR: 0.48, 95% CI: 0.27, 0.84), compared with those with nonuse of kitchen exhaust fans/hoods. The results indicated that the cooking women had an elevated risk of diabetes, which may be partly explained by an increase in the PAH body burden and higher inflammatory responses. Use of kitchen exhaust fan/hood can be associated with a lower risk of diabetes.

Application of gas chromatography/tandem mass spectrometry to determine a wide range of petrogenic alkylated polycyclic aromatic hydrocarbons in biotic samples.

Due to the inherent toxicity of these compounds, analysis of petrogenic alkylated polycyclic aromatic hydrocarbons (PAHs) and heteroaromatic compounds in environmental samples is crucial. However, most existing methods are not sensitive enough when the analyte concentrations are low. Gas chromatography/tandem mass spectrometry (GC/MS/MS) is well suited to tackle this challenge, but methods are yet to be fully developed. A gas chromatograph coupled with a triple quadrupole mass spectrometer operated in multiple reaction monitoring (MRM) mode was applied for the analysis. MRM transitions and analytical conditions were optimized for the cluster analysis of 24 different compound classes of alkylated PAHs and heteroaromatics present in crude oils. Further, the method was verified and applied to analyze the body burden of these compounds in crude oil-exposed haddock eggs. A comprehensive and sensitive method for the determination of C1-C4 alkylated naphthalenes, benzothiophenes, fluorenes, phenanthrenes, dibenzothiophenes, chrysenes, pyrenes and fluoranthenes was developed. The method showed good precision (RSD <15%), and the obtained concentrations were similar to those obtained by traditional GC/MS analysis. We demonstrate the successful application of this method towards crude oil-exposed fish eggs, where we are able to precisely measure total PAH body burden below 0.5μg/g. The demonstrated method facilitates further miniaturization in sample preparation. Copyright © 2016 John Wiley & Sons, Ltd.

Polycyclic aromatic hydrocarbon residues in serum samples of autopsied individuals from Tennessee.

This study reports the concentrations of Polycyclic Aromatic Hydrocarbons (PAHs) in human blood sera samples (n = 650) obtained at autopsy from individuals who died of drug abuse, alcohol toxicity, homicide, suicide and other unknown causes. The analyzed samples from decedents revealed the presence of PAHs of which B(a)P was the most predominant one, followed by benzo(b)fluoranthene and benzo(k)fluoranthene. The other PAHs detected sporadically and measured were benzo(g,h,i)perylene, acenaphthene, anthracene, phenanthrene, and fluoranthene The mean concentrations of PAHs were greater in the twenties to fifties age groups compared to others. The PAH residue levels detected were high in African Americans compared to Caucasians, Asians, and Hispanics. It appears that environmental exposure, dietary intake and in some cases occupational exposure may have contributed to the PAH body burden. While the PAH residue concentrations measured fall within the range of those reported for healthy adults elsewhere, in isolated cases, the concentrations detected were high, calling the need for a reduction in PAH emissions and human biomonitoring studies for purposes of risk assessment.

Structurally distinct polycyclic aromatic hydrocarbons induce differential transcriptional responses in developing zebrafish

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the environment as components of fossil fuels and by-products of combustion. These multi-ring chemicals differentially activate the aryl hydrocarbon receptor (AHR) in a structurally dependent manner, and induce toxicity via both AHR-dependent and -independent mechanisms. PAH exposure is known to induce developmental malformations in zebrafish embryos, and recent studies have shown cardiac toxicity induced by compounds with low AHR affinity. Unraveling the potentially diverse molecular mechanisms of PAH toxicity is essential for understanding the hazard posed by complex PAH mixtures present in the environment. We analyzed transcriptional responses to PAH exposure in zebrafish embryos exposed to benz(a)anthracene (BAA), dibenzothiophene (DBT) and pyrene (PYR) at concentrations that induced developmental malformations by 120h post-fertilization (hpf). Whole genome microarray analysis of mRNA expression at 24 and 48hpf identified genes that were differentially regulated over time and in response to the three PAH structures. PAH body burdens were analyzed at both time points using GC–MS, and demonstrated differences in PAH uptake into the embryos. This was important for discerning dose-related differences from those that represented unique molecular mechanisms. While BAA misregulated the least number of transcripts, it caused strong induction of cyp1a and other genes known to be downstream of the AHR, which were not induced by the other two PAHs. Analysis of functional roles of misregulated genes and their predicted regulatory transcription factors also distinguished the BAA response from regulatory networks disrupted by DBT and PYR exposure. These results indicate that systems approaches can be used to classify the toxicity of PAHs based on the networks perturbed following exposure, and may provide a path for unraveling the toxicity of complex PAH mixtures.

PAH body burden and biomarker responses in mussels (Mytilus edulis) exposed to produced water from a North Sea oil field: Laboratory and field assessments

In order to study the impact of produced water (PW) from a North Sea oil field on blue mussels (Mytilus edulis), chemical and biological markers were selected. A laboratory exposure (0.125%, 0.25% and 0.5% of PW) and a field study (6 stations 0.2–2km from a PW discharge point) were conducted. In the laboratory study, PAH bioaccumulation increased in mussel soft tissue even at the lowest exposure dose. Micronuclei frequency demonstrated a dose–response pattern, whereas lysosomal membrane stability showed tendency towards a dose–response pattern. The same markers were assessed in the field study, biomarker analyses were consistent with the contamination level, as evaluated by mussel polycyclic aromatic hydrocarbons body burden. Overall, obtained results confirmed the value of an ecotoxicological approach for a scientifically sound characterisation of biological effects induced by offshore oilfield operational discharges.

Preliminary study of children's exposure to PAHs and its association with 8-hydroxy-2′-deoxyguanosine in Guangzhou, China

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous air pollutants generated mainly from incomplete combustion such as automobile exhaust and cigarette smoke. Oxidative stress is believed to be involved in carcinogenesis, and urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG) was used as the biomarker to assess such DNA damage. The children's urinary PAH metabolite (OH-PAHs) level were explored in Guangzhou and their associations with 8-OHdG. Two groups of subjects were selected: (1) one group (n=39, 6–7years old) from an elementary school situated near a heavy traffic road (polluted area) and (2) another group (n=35, 4–6years old) from a kindergarten situated in a corner of the main campus of a big university (non-polluted area). Urinary 8-OHdG and nine urinary monohydroxylated PAH metabolites were measured, including 2-hydroxynaphthalene (2-OHN), 2-hydroxyfluorene (2-OHF), 2-, 3-, 4-, 9-hydroxyphenanthrene (2-, 3-, 4-, 9-OHPhe), 1-hydroxypyrene (1-OHP), 6-hydroxychrysene (6-OHChr) and 3-hydroxybenzo(a)pyrene (3-OHBaP). All other PAH metabolites were detected in urine samples from both children groups except for 6-OHChr and 3-OHBaP. Levels of 2-OHN, 2-OHF, 3-OHPhe, 9-OHPhe and 1-OHP were significantly different between two groups (P<0.05, T-test). The elementary school children from the polluted area had higher urinary levels of 2-OHN, 2-OHF, 2-, 3-, 4-OHPhe and 1-OHP ((9.10±7.39, 3.72±2.91, 0.32±0.50, 0.37±0.28, 0.23±0.29 and 0.64±0.07 μmol/mol creatinine, respectively) than those from the control group. The results suggested that heavy traffic pollution led to higher PAH body burden. There existed no significant difference for urinary 8-OHdG concentration between two groups (p>0.05, T-test), and no strong correlations between the individual OH-PAHs and 8-OHdG. However, the urinary 8-OHdG concentration in the elementary school children from the traffic polluted area was slightly higher than those in the non-polluted area (20.87±14.42μmol/mol creatinine vs. 16.78±13.30μmol/mol creatinine). It may be that the potential co-exposure of the children to other pollutants affects 8-OHdG concentration besides the PAHs.

Oxidative stress in the clam Ruditapes decussatus (Linnaeus, 1758) in relation to polycyclic aromatic hydrocarbon body burden

Seasonal variation of antioxidant enzymes activities (superoxide dismutase, catalase, and glutathione peroxidases) and lipid peroxidation (LPO) were studied in the clam Ruditapes decussatus in relation to body burdens of polycyclic aromatic hydrocarbons (PAHs). Clams were sampled in eight sites from the Ria Formosa lagoon. PAH concentrations were seasonally rather than spatially dependent, being higher in summer (August). Antioxidant enzymes activities and LPO levels in the clam digestive gland were also seasonally dependent. Antioxidant enzymes presented distinct seasonal variations: Mit SOD (superoxide dismutase activity measured in the mitochondrial fraction) was induced in the summer and down-regulated in winter and spring, while Cyt SOD activity (measured in the cytosolic fraction) was highest in autumn and lower in the summer. Neither Mit nor Cyt SOD were related to the clam PAH body burden, suggesting that cells are using other antioxidant systems to eliminate oxyradicals. Catalase (CAT), however, was induced in spring and down-regulated in summer, the inverse of the PAH concentrations in clam tissues. CAT induction in spring appears to be related to the excess of oxyradicals arising from the metabolic activity associated with the reproductive cycle. Conversely, the decrease in CAT activity in the summer may be related to the high water temperatures reached in the Ria Formosa (up to 30 degrees C). Glutathione peroxidases (total fraction - T-GPx and dependent on selenium - Se-GPx) presented a similar seasonal pattern, and were negatively related to PAH concentrations, which may indicate a precarious state of the clams, associated with PAH toxicity. Similarly, LPO was also inversely correlated to the PAH concentrations indicating that increases in PAH concentrations were not causing membrane oxidative damage in R. decussatus digestive gland. The results suggest that antioxidant enzymes in R. decussatus digestive gland are strongly affected by seasonal factors stressing the need of other experiments to clarify the PAHs effect on this clam species.

Antioxidant enzymes and peroxisome proliferation in relation to contaminant body burdens of PAHs and PCBs in bivalve molluscs, crabs and fish from the Urdaibai and Plentzia estuaries (Bay of Biscay)

With the aim of studying levels of antioxidant and peroxisomal enzymes and the structure of peroxisomes in relation to body burdens of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), mussels Mytilus galloprovincialis, oysters Crassostrea sp., crabs Carcinus maenas and mullets Mugil cephalus were sampled in two Basque estuaries (Bay of Biscay): Urdaibai (Laida, Txatxarramendi, Arteaga, and downstream a sewage treatment plant—STP) and Plentzia. In general, animals showed higher concentrations of contaminants in winter than in summer and no relevant differences were detected among locations. Conversely, antioxidant enzyme activities were higher in summer. Enzyme expression was studied in mullets using immunochemical methods. By immunoblotting season-dependent differences were detected for Mn-superoxide dismutase (Mn-SOD). As for the immunohistochemical staining, mullets sampled in summer in Plentzia showed significantly higher optical densities for acyl-CoA oxidase and lower for both Cu,Zn-SOD and Mn-SOD than those collected downstream a STP as well as higher catalase immunostaining than those collected in winter. Peroxisomal volume density ( V vp) of mussels sampled in Laida and Txatxarramendi did not show seasonal variations, while for oysters collected in Laida and Arteaga V vp was higher in summer. Crab and mullet V vp were also higher in summer. In conclusion, the estuaries of Urdaibai and Plentzia can be considered as low to moderately polluted areas and levels of PAHs and PCBs do not show marked variations apart from seasonal variations. Animals can be adapted to low pollution conditions and, under these circumstances, seasonal factors might affect biomarker responses to a greater extent than pollution variations.

Development of cytochrome P450 as a biomarker of organic pollution in Mytilus sp.: field studies in United Kingdom ('Sea Empress' oil spill) and the Mediterranean Sea

Literature on the properties, forms and regulation of cytochrome P450 (CYP) in digestive gland of Mytilus sp., including studies indicating the existence of an organic contaminant-inducible CYP1A-like protein, are briefly reviewed. Laboratory and field studies show increases in digestive gland microsomal CYP1A-immunopositive protein levels and/or benzo[a]pyrene hydroxylase (BPH) activity (i.e. metabolism of benzo[a]pyrene to phenols) with exposure of Mytilus sp. to certain polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls. In order to examine further the relationship between these two parameters, M. edulis were collected 25 and 130 days after the release of oil following the grounding of the tanker 'Sea Empress' in South Wales, UK (15 February 1996); and M. galloprovincialis were sampled from sites in south-western France and south-eastern Spain during a cruise aboard the IFREMER Research Vessel 'L'Europe' (2-18 August 1996). In both studies, sites with higher levels of CYP1A-immunopositive protein showed higher levels of BPH activities. Positive correlations were observed between the two measurements - R=0.65 (M. edulis) and 0.68 (M. galloprovincialis), and both fitted linear regression models (P < 0.05). The CYP1A-immunopositive protein levels and BPH activities tended to be highest at sites with greatest PAH body burden for the Mediterranean study. It is concluded that development of the CYP1A-like protein into a robust biomarker of exposure to organic contaminants will depend upon sequencing of the gene/protein and the subsequent production of Mytilus-specific cDNA and antibody probes. Such probes will then allow a full characterization of the enzyme's properties and gene regulation.

Seasonal responses of the mixed-function oxygenase system in the American oyster, Crassostrea virginica (Gmelin 1791), to urban-derived polycyclic aromatic hydrocarbons

Mixed-function oxygenase (MFO) system components (cytochrome P 450 and b 5, “423 peak” and NADPH cytochrome c reductase) and body burdens of polycyclic aromatic hydrocarbons (PAHs) were determined seasonally in oysters, Crassostrea virginica (Gmelin 1791), collected from an undeveloped estuary (North Inlet, SC) and an urbanized estuary (Murrells Inlet, SC). All MFO system components monitored in oysters from North Inlet demonstrated seasonal variations; levels were lowest during October 1992. Whole oyster PAH tissue levels were always higher in Murrells Inlet oysters compared with North Inlet oysters. Seasonal variation of PAH body burdens was evident in oysters from Murrells Inlet; the highest levels occurred during April 1993. Differences between the two estuaries were seasonally evident in most oyster MFO system components. Reductase activity was highest at the most contaminated Murrells Inlet site during October 1992 and April 1993. This seasonal variation was positively correlated to that of their PAH body burdens. Cytochrome P 450 content was also elevated at the most contaminated site during April 1993. These results suggest that reductase activity and cytochrome P 450 content in Murrells Inlet oysters were induced by the high PAH body burdens during April 1993 and indicate their potential as molecular biomarkers of PAH contamination.