ATSDR evaluation of health effects of chemicals. IV. Polycyclic aromatic hydrocarbons (PAHs): understanding a complex problem

Weathering patterns of polycyclic aromatic hydrocarbons contained in submerged Deepwater Horizon oil spill residues when re-exposed to sunlight

The Deepwater Horizon (DWH) oil spill event released a large amount of sweet crude oil into the Gulf of Mexico (GOM). An unknown portion of this oil that arrived along the Alabama shoreline interacted with nearshore sediments and sank forming submerged oil mats (SOMs). A considerable amount of hydrocarbons, including polycyclic aromatic hydrocarbons (PAHs), were trapped within these buried SOMs. Recent studies completed using the oil spill residues collected along the Alabama shoreline have shown that several PAHs, especially higher molecular weight PAHs (four or more aromatic rings), are slowly weathering compared to the weathering levels experienced by the oil when it was floating over the GOM. In this study we have hypothesized that the weathering rates of PAHs in SOMs have slowed down because the buried oil was isolated from direct exposure to sunlight, thus hindering the photodegradation pathway. We further hypothesized that re-exposing SOMs to sunlight can reactivate various weathering reactions. Also, SOMs contain 75-95% sand (by weight) and the entrapped sand could either block direct sunlight or form large oil agglomerates with very little exposed surface area; these processes could possibly interfere with weathering reactions. To test these hypotheses, we completed controlled experiments to study the weathering patterns of PAHs in a field recovered SOM sample after re-exposing it to sunlight. Our experimental results show that the weathering levels of several higher molecular weight PAHs have slowed down primarily due to the absence of sunlight-induced photodegradation reactions. The data also show that sand particles in SOM material could potentially interfere with photodegradation reactions.

Effects of binary mixtures of benzo[a]pyrene, arsenic, cadmium, and lead on oxidative stress and toxicity in HepG2 cells

Mixed contamination of benzo[a]pyrene (B[a]P), arsenic (As), cadmium (Cd), and lead (Pb) is a major environmental and human health concern. The mixture toxicity data on these co-contaminants are important for their risk assessment. In this study, we have determined the mixture toxicity of As, Cd and Pb, and B[a]P with As, Cd or Pb in HepG2 cells. The binary mixtures of Cd + As, Cd + Pb and As + Pb and B[a]P + metals (B[a]P + As, B[a]P + Cd and B[a]P + Pb) were evaluated for their interaction on the cytotoxicity using the MTS assay. A full factorial design (4 × 5) was used to determine the interaction toxicity and all the six mixtures showed significant interaction on the cytotoxicity. We further investigated the role of oxidative stress (reactive oxygen species (ROS) generation) and antioxidant defense mechanism (total glutathione (GSH) level) with the observed cytotoxicity. The mixtures of metals reduced the total GSH level and increased the ROS generation, respectively. In the case of mixtures of B[a]P and metals, both total GSH level and ROS generation were increased. Overall, the binary mixtures of metals and B[a]P with metals caused a dose dependent toxicity to HepG2 cells. The results also showed a significant contribution of oxidative stress to the observed toxicity and the potential protective role of the total GSH level against this mixture toxicity. The findings of interaction between B[a]P and metals might have an impact on the potential human health risk of this mixtures at contaminated sites.

Biological impact of environmental polycyclic aromatic hydrocarbons (ePAHs) as endocrine disruptors

Polycyclic aromatic hydrocarbons (PAHs) are often detected in the environment and are regarded as endocrine disruptors. We here designated mixtures of PAHs in the environment as environmental PAHs (ePAHs) to discuss their effects collectively, which could be different from the sum of the constituent PAHs. We first summarized the biological impact of environmental PAHs (ePAHs) found in the atmosphere, sediments, soils, and water as a result of human activities, accidents, or natural phenomena. ePAHs are characterized by their sources and forms, followed by their biological effects and social impact, and bioassays that are used to investigate their biological effects. The findings of the bioassays have demonstrated that ePAHs have the ability to affect the endocrine systems of humans and animals. The pathways that mediate cell signaling for the endocrine disruptions induced by ePAHs and PAHs have also been summarized in order to obtain a clearer understanding of the mechanisms responsible for these effects without animal tests; they include specific signaling pathways (MAPK and other signaling pathways), regulatory mechanisms (chromatin/epigenetic regulation, cell cycle/DNA damage control, and cytoskeletal/adhesion regulation), and cell functions (apoptosis, autophagy, immune responses/inflammation, neurological responses, and development/differentiation) induced by specific PAHs, such as benz[a]anthracene, benzo[a]pyrene, benz[l]aceanthrylene, cyclopenta[c,d]pyrene, 7,12-dimethylbenz[a]anthracene, fluoranthene, fluorene, 3-methylcholanthrene, perylene, phenanthrene, and pyrene as well as their derivatives. Estrogen signaling is one of the most studied pathways associated with the endocrine-disrupting activities of PAHs, and involves estrogen receptors and aryl hydrocarbon receptors. However, some of the actions of PAHs are contradictory, complex, and unexplainable. Although several possibilities have been suggested, such as direct interactions between PAHs and receptors and the suppression of their activities through other pathways, the mechanisms underlying the activities of PAHs remain unclear. Thus, standardized assay protocols for pathway-based assessments are considered to be important to overcome these issues.

Sediment PAH source apportionment in the Liaohe River using the ME2 approach: A comparison to the PMF model

Environmental contaminant source apportionment is essential for pollution management and control. This study analysed surface sediment samples for 16 priority polycyclic aromatic hydrocarbons (PAHs). PAH sources were identified by two receptor models, which included positive matrix factorization (PMF) and multilinear engine 2 (ME2). Three PAH sources in the Liaohe River sediments were identified by PMF, including traffic, coke oven and coal combustion. The ME2 model apportioned one additional source. The two models yielded excellent correlation coefficients between the measured and predicted PAH concentrations. Traffic emission was the primary PAH source associated with the Liaohe River sediments, with estimated PMF contributions of 58% in May and 63% in September. Coke oven (19%-25%) and coal combustion (13%-18%) were the other two major PAH sources. For ME2, gasoline and diesel were separated: accounted for 14% in May and 16% in September; and 53% in May and 48% in September. This study marks the first application of the ME2 model to study sediment contaminant source apportionment. The methodology can potentially be applied to other aquatic environment contaminants.

Urinary polycyclic aromatic hydrocarbons and measures of oxidative stress, inflammation and renal function in adolescents: NHANES 2003-2008

OBJECTIVE

Recent evidence has suggested that polycyclic aromatic hydrocarbons (PAHs) may contribute to cardiometabolic and kidney dysfunction by increasing oxidative stress, but little is known about impacts in childhood.

STUDY DESIGN

We performed cross-sectional analyses of 660 adolescents aged 12-19 years in the 2003-2008 National Health and Nutrition Examination Survey (NHANES), using levels of 10 monohydroxylated urinary PAH metabolites as our exposure. Our primary outcomes of interest were biomarkers of oxidative stress and renal function, including estimated glomerular filtration rate (eGFR), urinary albumin to creatinine ratio (ACR), insulin resistance, and serum uric acid, gamma glutamyl transferase (GGT) and C-reactive protein (CRP).

RESULTS

We observed statistically significant associations between PAH metabolites and levels of serum GGT, CRP, uric acid and eGFR. Each 100% increase in 2-hydroxyphenanthrene was related to a 3.36% increase in uric acid (95% CI: 0.338-6.372; p=0.032), a 3.86% increase in GGT (95% CI: 1.361-6.362; p=0.005) and a 16.78% increase in CRP (95% CI: 1.848-31.689; p=0.029). Each 100% increase in 4-hydroxyphenanthrene was associated with a 6.18% increase in GGT (95% CI: 4.064-8.301; p<0.001) and a 13.66% increase in CRP (95% CI: 2.764-24.564; p=0.017). Each 100% increase in 9-hydroxyfluorene was associated with a 2.58% increase in GGT (95% CI: 0.389-4776; p=0.024). Each 100% increase in 3-hydroxyphenanthrene was associated with a 2.66% decrease in eGFR (95% CI: -4.979 to -0.331; p=0.028).

CONCLUSIONS

Urinary PAH metabolites were associated with serum uric acid, GGT and CRP, suggesting possible impacts on cardiometabolic and kidney function in adolescents. Prospective work is needed to investigate the potential long-term health consequences of these findings.

Distribution and Health Risk Assessment on Dietary Exposure of Polycyclic Aromatic Hydrocarbons in Vegetables in Nanjing, China

In a market basket study made in Nanjing, China, in which the most common consumed nine kinds of vegetables foodstuffs were sampled, the contents of 16 polycyclic aromatic hydrocarbons (PAHs) were analyzed using gas chromatography with mass spectrometer detector (GC-MS). The results showed that the total amount of 16 PAHs was within the range of 60.5~312 ng g−1 (wet weight). The ranking of total concentrations for different types of vegetables in decreasing order was leafy vegetable, fruit vegetable, and rhizome vegetable. Source analysis suggested that coal, oil, or other incomplete combustion of biomass mainly contributed to the concentration of PAHs. The margin of exposure (MOE) approach with age/gender group-specific daily dietary exposure level was used to estimate the carcinogenic risk. The calculated total mean MOE in the case of BaP and PAH4 (sum of BaA, CHR, BbF, and BaP) was 14960 and 7723, respectively, for local residents. In addition, the MOEs in PAH4 for some groups of both male and female were below the critical limit of 10 000 proposed by EFSA. Therefore, health effect owing to the consumption of vegetables on local residents needs high concern.

Characterising the exchangeability of phenanthrene associated with naturally occurring soil colloids using an isotopic dilution technique

The association of polycyclic aromatic hydrocarbons (PAHs) with inorganic and organic colloids is an important factor influencing their bioavailability, mobility and degradation in the environment. Despite this, our understanding of the exchangeability and potential bioavailability of PAHs associated with colloids is limited. The objective of this study was to use phenanthrene as a model PAH compound and develop a technique using (14)C phenanthrene to quantify the isotopically exchangeable and non-exchangeable forms of phenanthrene in filtered soil water or sodium tetraborate extracts. The study was also designed to investigate the exchangeability of colloidal phenanthrene as a function of particle size. Our findings suggest that the exchangeability of phenanthrene in sodium tetraborate is controlled by both inorganic and organic colloids, while in aqueous solutions inorganic colloids play the dominant role (even though coating of these by organic matter cannot be excluded). Filter pore size did not have a significant effect on phenanthrene exchangeability.

Long-term monitoring data to describe the fate of polycyclic aromatic hydrocarbons in Deepwater Horizon oil submerged off Alabama's beaches

The 2010 Deepwater Horizon (DWH) catastrophe had considerable impact on the ∼ 50 km long sandy beach system located along the Alabama shoreline. We present a four-year dataset to characterize the temporal evolution of various polycyclic aromatic hydrocarbons (PAHs) and their alkylated homologs trapped in the residual oil buried along the shoreline. Field samples analyzed include the first arrival oil collected from Perdido Bay, Alabama in June 2010, and multiple oil spill samples collected until August 2014. Our field data show that, as of August 2014, DWH oil is still trapped along Alabama's beaches as submerged oil, predominately in the form of surface residual oil balls (SRBs). Chemical characterization data show that various PAHs present in the spilled oil (MC252 crude) weathered by about 45% to 100% when the oil was floating over the open ocean system in the Gulf of Mexico. Light PAHs, such as naphthalenes, were fully depleted, whereas heavy PAHs, such as chrysenes, were only partially depleted by about 45%. However, the rate of PAH weathering appears to have decreased significantly once the oil was buried within the partially-closed SRB environment. Concentration levels of several heavy PAHs have almost remained constant over the past 4 years. Our data also show that evaporation was most likely the primary weathering mechanism for PAH removal when the oil was floating over the ocean, although photo-degradation and other physico-chemical processes could have contributed to some additional weathering. Chemical data presented in this study indicate that submerged oil containing various heavy PAHs (for example, parent and alkylated chrysenes) is likely to remain in the beach system for several years. It is also likely that the organisms living in these beach environments would have an increased risk of exposure to heavy PAHs trapped in the non-recoverable form of buried DWH oil spill residues.

Associations between exposure to polycyclic aromatic hydrocarbons and glucose homeostasis as well as metabolic syndrome in nondiabetic adults

PURPOSE

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental toxic compounds formed from incomplete combustion of carbon-containing materials, cigarette smoking, and food cooking. The genotoxic effects of PAHs have been widely studied. However, their nongenotoxic effects such as their impacts on glucose and metabolic homeostasis have not been well examined.

METHODS

We used the National Health and Nutritional Examination Survey (NHANES) 2001-2008 to investigate the associations between eight monohydroxy urinary metabolites of four PAHs and glucose homeostasis as well as metabolic syndrome in 1,878 nondiabetic participants aged 18 years or older.

RESULTS

In linear regression models, increased level of 2-PHEN was significantly associated with increased insulin resistance (β coefficient 0.05 ± 0.02), and increased concentrations of 3-FLUO (β coefficient -0.02 ± 0.01) were significantly associated with decreased β-cell function (all p<0.05) after controlling for selected covariates. In addition, increased concentrations of 2-FLUO (OR=1.25, 95% CI: 1.04-1.51), 1-PHEN (OR=1.36, 95% CI: 1.09-1.70), and 2-PHEN (OR: 1.49, 95% CI: 1.22-1.83) were significantly associated with a higher prevalence of the metabolic syndrome after adjusting for covariates. Consistent results were observed in the subgroup analysis among nonsmokers.

CONCLUSIONS

Our findings suggest that environmental exposure to PAHs independent of cigarette smoking is associated with insulin resistance, β-cell dysfunction, and increased prevalence of metabolic syndrome.

Statistical Modeling of Occupational Exposure to Polycyclic Aromatic Hydrocarbons Using OSHA Data

Polycyclic aromatic hydrocarbons (PAHs) are a group of pollutants with multiple variants classified as carcinogenic. The Occupational Safety and Health Administration (OSHA) provided access to two PAH exposure databanks of United States workplace compliance testing data collected between 1979 and 2010. Mixed-effects logistic models were used to predict the exceedance fraction (EF), i.e., the probability of exceeding OSHA's Permissible Exposure Limit (PEL = 0.2 mg/m3) for PAHs based on industry and occupation. Measurements of coal tar pitch volatiles were used as a surrogate for PAHs. Time, databank, occupation, and industry were included as fixed-effects while an identifier for the compliance inspection number was included as a random effect. Analyses involved 2,509 full-shift personal measurements. Results showed that the majority of industries had an estimated EF < 0.5, although several industries, including Standardized Industry Classification codes 1623 (Water, Sewer, Pipeline, and Communication and Powerline Construction), 1711 (Plumbing, Heating, and Air-Conditioning), 2824 (Manmade Organic Fibres), 3496 (Misc. Fabricated Wire products), and 5812 (Eating Places), and Major group's 13 (Oil and Gas Extraction) and 30 (Rubber and Miscellaneous Plastic Products), were estimated to have more than an 80% likelihood of exceeding the PEL. There was an inverse temporal trend of exceeding the PEL, with lower risk in most recent years, albeit not statistically significant. Similar results were shown when incorporating occupation, but varied depending on the occupation as the majority of industries predicted at the administrative level, e.g., managers, had an estimated EF < 0.5 while at the minimally skilled/laborer level there was a substantial increase in the estimated EF. These statistical models allow the prediction of PAH exposure risk through individual occupational histories and will be used to create a job-exposure matrix for use in a population-based case-control study exploring PAH exposure and breast cancer risk.

Toxicity of atmospheric particle-bound PAHs: an environmental perspective

Atmospheric polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants that represent a risk not only to humans, but to all living organisms. High-molecular weight PAHs are more toxic than lighter relatives, and also have a higher tendency to bind onto air particles (i.e., particle matter, PM). PM is a major constituent of air pollution. Adequate assessment of the biological impact of PM requires the analysis, not only of the effects on human health, but also on the environment. Since the aquatic systems work as a natural sink to these air pollutants, assessing the effects of particle-bound PAHs on aquatic organisms may further characterize its potential aquatic toxicity, also providing simple and low-cost alternative assays to investigate PM biological effects in vivo. We review the current scientific literature, addressing the atmospheric PAHs fate, transformation and deposition, pertinent particle-bound PAHs toxicity data, and the potential aquatic toxic burden. Conceptual and experimental procedures that could improve future investigations and risk assessments are also considered.

Profiling of biomarkers for the exposure of polycyclic aromatic hydrocarbons: lamin-A/C isoform 3, poly[ADP-ribose] polymerase 1, and mitochondria copy number are identified as universal biomarkers

This study investigated the profiling of polycyclic aromatic hydrocarbon- (PAH-) induced genotoxicity in cell lines and zebrafish. Each type of cells displayed different proportionality of apoptosis. Mitochondrial DNA (mtDNA) copy number was dramatically elevated after 5-day treatment of fluoranthene and pyrene. The notable deregulated proteins for PAHs exposure were displayed as follows: lamin-A/C isoform 3 and annexin A1 for benzopyrene; lamin-A/C isoform 3 and DNA topoisomerase 2-alpha for pentacene; poly[ADP-ribose] polymerase 1 (PARP-1) for fluoranthene; and talin-1 and DNA topoisomerase 2-alpha for pyrene. Among them, lamin-A/C isoform 3 and PARP-1 were further confirmed using mRNA and protein expression study. Obvious morphological abnormalities including curved backbone and cardiomegaly in zebrafish were observed in the 54 hpf with more than 400 nM of benzopyrene. In conclusion, the change of mitochondrial genome (increased mtDNA copy number) was closely associated with PAH exposure in cell lines and mesenchymal stem cells. Lamin-A/C isoform 3, talin-1, and annexin A1 were identified as universal biomarkers for PAHs exposure. Zebrafish, specifically at embryo stage, showed suitable in vivo model for monitoring PAHs exposure to hematopoietic tissue and other organs.

Detection of organic compounds with whole-cell bioluminescent bioassays

Natural and manmade organic chemicals are widely deposited across a diverse range of ecosystems including air, surface water, groundwater, wastewater, soil, sediment, and marine environments. Some organic compounds, despite their industrial values, are toxic to living organisms and pose significant health risks to humans and wildlife. Detection and monitoring of these organic pollutants in environmental matrices therefore is of great interest and need for remediation and health risk assessment. Although these detections have traditionally been performed using analytical chemical approaches that offer highly sensitive and specific identification of target compounds, these methods require specialized equipment and trained operators, and fail to describe potential bioavailable effects on living organisms. Alternatively, the integration of bioluminescent systems into whole-cell bioreporters presents a new capacity for organic compound detection. These bioreporters are constructed by incorporating reporter genes into catabolic or signaling pathways that are present within living cells and emit a bioluminescent signal that can be detected upon exposure to target chemicals. Although relatively less specific compared to analytical methods, bioluminescent bioassays are more cost-effective, more rapid, can be scaled to higher throughput, and can be designed to report not only the presence but also the bioavailability of target substances. This chapter reviews available bacterial and eukaryotic whole-cell bioreporters for sensing organic pollutants and their applications in a variety of sample matrices.

PAH-CALUX, an optimized bioassay for AhR-mediated hazard identification of polycyclic aromatic hydrocarbons (PAHs) as individual compounds and in complex mixtures

Polycyclic aromatic hydrocarbons (PAHs) represent a class of ubiquitously occurring environmental compounds that are implicated in a wide range of toxicological effects. Routine measurement of PAH contamination generally involves chemical analytical analysis of a selected group of representatives, for example, EPA-16, which may result in underestimation of the PAH-related toxicity of a sample. Many high molecular weight PAHs are known ligands of the aryl hydrocarbon receptor (AhR), a nuclear receptor that mediates toxic effects related to these compounds. Making use of this property we developed a PAH CALUX assay, a mammalian, H4IIe- cell-based reporter assay for the hazard identification of total PAH mixtures. The PAH CALUX reporter cell line allows for specific, rapid (4 h exposure time) and reliable quantification of AhR-induced luciferase induction relative to benzo[a]pyrene (BaP), which is used as a positive reference PAH congener. Full dose response relationships with inductions over 100-fold were reached within only 2 h of exposure to BaP. The PAH CALUX is highly sensitive, that is, using a 4 h exposure time, a limit of detection (LOD) of 5.2 × 10(-11) M BaP was achieved, and highly accurate, that is, a repeatability of 5.9% and a reproducibility of 6.6% were established. Screening of a selection of PAHs that were prioritized by the European Union and/or the U.S. Environmental Protection Agency showed that the PAH CALUX bioassay has a high predictability, particularly for carcinogenic PAHs. Experiments with synthetic mixtures and reference materials containing complex PAH mixtures show the suitability of the assay for these types of applications. Moreover, the presented results suggest that application of the PAH CALUX will result in a lower risk of underestimation of the toxicity of a sample than chemical analytical approaches that focus on a limited set of prioritized compounds.

Oil contamination in Ogoniland, Niger Delta

The study shows extensive oil contamination of rivers, creeks, and ground waters in Ogoniland, Nigeria. The levels found in the more contaminated sites are high enough to cause severe impacts on the ecosystem and human health: extractable petroleum hydrocarbons (EPHs) (>10-C40) in surface waters up to 7420 μg L(-1), drinking water wells show up to 42 200 μg L(-1), and benzene up to 9000 μg L(-1), more than 900 times the WHO guidelines. EPH concentrations in sediments were up to 17 900 mg kg(-1). Polycyclic aromatic hydrocarbons concentrations reached 8.0 mg kg(-1), in the most contaminated sites. The contamination has killed large areas of mangroves. Although the natural conditions for degradation of petroleum hydrocarbons are favorable with high temperatures and relatively high rainfall, the recovery of contaminated areas is prevented due to the chronic character of the contamination. Oil spills of varying magnitude originates from facilities and pipelines; leaks from aging, dilapidated, and abandoned infrastructure; and from spills during transport and artisanal refining of stolen oil under very primitive conditions.

Studying the effects of polycyclic aromatic hydrocarbons on peripheral arterial disease in the United States

PURPOSE

Polycyclic aromatic hydrocarbons are a group of prevalent pollutants which are produced by incomplete combustion of organic materials such as coal, fuel, tobacco smoking and food cooking. The associations between exposures to polycyclic aromatic hydrocarbons (PAHs) and peripheral arterial disease (PAD) have not been well studied.

METHODS

We used the 2001-2004 National Health and Nutrition Examination Survey (NHANES) to investigate the associations between eight monohydroxy urinary metabolites of four PAHs and PAD.

RESULTS

In a logistic regression model, subjects within the middle and highest tertiles of fluorene metabolites, 2-hydroxyfluorene (2-FLUO) and 3-hydroxyfluorene (3-FLUO), and phenanthrene metabolites, 1-hydroxyphenanthrene (1-PHEN) and 2-hydroxyphenanthrene (2-PHEN), had significantly higher prevalence of PAD as compared to subjects within the lowest tertile after adjusting for cigarette smoking, diabetes mellitus and other covariates (For 2-FLUO, the 3rd tertile: OR=2.22, 95% CI=1.13-4.37, p for trend=0.02; For 3-FLUO, the 3rd tertile: OR=2.36, 95% CI: 1.16-4.77, p for trend=0.02; For 1-PHEN, the 3rd tertile: OR=1.84, 95% CI: 1.01-3.37, p for trend=0.04; For 2-PHEN, the 3rd tertile: OR=1.76, 95% CI: 1.07-2.88, p for trend=0.03).

CONCLUSIONS

Our findings suggest that exposure to PAHs may increase the risk of PAD. Further studies are necessary to explore the associations between PAHs and PAD.

Occurrence and Distribution of Polycyclic Aromatic Hydrocarbons in Water and Sediment Collected along the Harbour Line, Mumbai, India

This study investigated the occurrence of polycyclic aromatic hydrocarbons (PAHs) in water and sediment samples collected along the harbour line, Mumbai, India. The ∑PAHs quantified in water and sediment samples were ranged from 8.66 ng/L to 46.74 ng/L and from 2608 ng/g to 134134 ng/g dry wt., respectively. Significantly high concentration of ∑PAHs was found in water samples of Sewri and sediment samples of Mahul (P<0.05). PAH concentrations detected in the present study were several folds higher than the existing sediment quality criteria suggested by various statutory agencies. The PAH composition patterns in water and sediments suggest the dominance of high molecular weight compounds and indicate important pyrolytic and petrogenic sources. The occurrence of PAHs in the marine environment has attracted the attention of the scientific community as these compounds are frequently detected in seawater and sediments at increasing levels and can have adverse health effects on marine organisms and humans. PAH concentrations detected at Sewri-Mahul site were sufficiently high to pose a risk to marine organisms if they are exposed continuously to this concentration. Hence, continuous monitoring of the ecosystem is highly warranted.

Xenobiotic effects on ovarian preantral follicles

Women are born with a finite population of ovarian follicles, which are slowly depleted during their reproductive years until reproductive failure (menopause) occurs. The rate of loss of primordial follicles is determined by genetic and environmental influences, but certain toxic exposures can accelerate this process. Ionizing radiation reduces preantral follicle numbers in rodents and humans in a dose-dependent manner. Cigarette smoking is linked to menopause occurring 1-4 yr earlier than with nonsmokers, and components of smoke, polycyclic aromatic hydrocarbons, can cause follicle depletion in rodents or in ovaries in vitro. Chemotherapeutic agents, such as alkylating drugs and cisplatin, also cause loss of preantral ovarian follicles. Effects depend on dose, type, and reactivity of the drug, and the age of the individual. Evidence suggests DNA damage may underlie follicle loss induced by one common alkylating drug, cyclophosphamide. Occupational exposures have also been linked to ovarian damage. In an industrial setting, 2-bromopropane caused infertility in men and women, and it can induce ovarian follicle depletion in rats. Solvents, such as butadiene, 4-vinylcyclohexene, and their diepoxides, can also cause specific preantral follicle depletion. The mechanism(s) underlying effects of the latter compound may involve alterations in apoptosis, survival factors such as KIT/Kit Ligand, and/or the cellular signaling that maintains primordial follicle dormancy. Estrogenic endocrine disruptors may alter follicle formation/development and impair fertility or normal development of offspring. Thus, specific exposures are known or suspected of detrimentally impacting preantral ovarian follicles, leading to early ovarian failure.

Cytotoxicity of water-soluble fraction from biodiesel and its diesel blends to human cell lines

The designation of biodiesel as a green fuel has increased its commercialization and use, making its fate in the environment a matter of concern. Fuel spills constitute a major source of aquatic pollution and, like diesel spills, biodiesel can produce adverse effects on aquatic environments, animals and humans. The present study assessed cytotoxic effects of water systems contaminated with neat biodiesel and its diesel blends by means of different procedures on human T cell leukemia (Jurkat) and human hepatocellular carcinoma (HepG2) cells [detection of changes in mitochondrial membrane potential (ΔΨ(m)) using tetramethylrhodamine ethyl ester (TMRE), apoptosis recognition by Annexin V and impedance real-time cell analyzer (xCELLigence™ system)]. The data obtained showed concordance across the different bioassays, with cytotoxic effects observed as a dose-dependent response only for waters contaminated with pure diesel (D100) and B5 blend, which is characterized by a mixture of 95% diesel and 5% biodiesel. The data can also lead us to hypothesize that diesel accounts for the harmful effects observed, and that biodiesel does not worsen the impacts caused by diesel pollution.

Elaidic acid enhanced the simultaneous neurotoxicity attributable to the cerebral pathological lesion resulted from oxidative damages induced by acrylamide and benzo(a)pyrene

Acrylamide (ACR), benzopyrene [B(a)P] and trans-fatty acids (TFA) could be found to co-exist in many foods processed by high temperature. Our study investigated the effects of elaidic acid (ELA), a predominant TFA, on neuropathology induced by simultaneous exposure of ACR and B(a)P to mice. Results showed ELA enhanced the decrease of weight gains induced by simultaneous exposure of ACR and B(a)P (AB). Moreover, ELA enhanced ACR-induced increase of gait abnormality, B(a)P-induced damage to learning and memory, and AB-induced both of the damage above. Meanwhile, ELA enhanced B(a)Pinduced axonal degeneration in hippocamp, ACR- and AB-induced up-regulating of abnormal cerebellar Purkinje cells. ELA enhanced ACR-induced up-regulating of MDA in cerebrum and 8-OHdG in cerebrum and cerebellum; ELA enhanced B(a)P-induced up-regulating of MDA in cerebrum, PCO in cerebellum and 8-OHdG in cerebrum and cerebellum. Meanwhile, the enhancing role of ELA, on ACR-induced reduction of SOD activity in cerebrum and cerebellum, on B(a)P-induced reduction of GPx activity in cerebrum were found. Results suggested that ELA play a enhancing role on ACR-induced and B(a)P-induced oxidative damage, which attributable to the cerebral pathological lesion, and subsequent effect on gait abnormality and deficit on learning and memory in mice.

Health risk assessment on dietary exposure to polycyclic aromatic hydrocarbons (PAHs) in Taiyuan, China

Twenty-five kinds of seven categories of foods were sampled in December 2008 and the concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) were determined. The highest level of total PAHs was detected in pork (195.30ng/g) whereas the lowest concentration was found in milk (8.73ng/g). The median values of B[a]P equivalent (B[a]P(eq)) daily exposure doses for children, adolescents, adults and seniors of male were estimated to be 392.42, 511.01, 571.56 and 532.56ng/d, respectively, whereas those for the above population groups of female were found to be 355.16, 440.51, 487.64 and 444.85ng/d, respectively. The incremental lifetime cancer risk (ILCR) values at the 22.1th, 26.1th, 12.7th, 24.9th, 22.7th, 27.0th, 12.9th, and 25.5th percentiles for male children, male adolescents, male adults, male seniors, female children, female adolescents, female adults and female seniors, respectively, were larger than 10(-6), indicating high potential carcinogenic risk, and were larger than 10(-4) at the 74.5th, 78.7th, 60.6th, 77.4th, 75.3th, 79.5th, 60.8th and 77.9th percentiles for the above groups, respectively, which implied significant cancer risk. Sensitivity analysis found that the two variables of oral cancer slope factor of benzo(a) pyrene (SF) and the daily dietary PAH exposure level (ED) had the greater impact than that of body weight (BW) on the ILCR.

Polycyclic aromatic hydrocarbons (PAHs) in atmospheric urban area: monitoring on various types of sites

The air quality over the Toulouse urban area (France) is recorded daily by the regional "Midi-Pyrénées" atmospheric pollution measurements network (ORAMIP). Relevant data is collected from about 100 analysers spread over more than thirty stations. The regulations covering major indicators of atmospheric pollution (ozone, nitrogen dioxide, sulphur dioxide) have been updated in recent years to include additional compounds like polycyclic aromatic hydrocarbons (PAHs). The ORAMIP, in partnership with the ENSIACET has undertaken background PAH average concentration measurements over the urban agglomeration of Toulouse during spring 2006 for various types of sites (traffic, urban, industrial). The sampling was performed using a low volume air sampler equipped with quartz fiber filters and polyurethane foams For the two urban sites, total atmospheric concentrations between 12 and 20 ng/m(3) have been obtained, whereas for the industrial site the values averaged 22 ng/m(3). In addition, and regardless of site, the average concentrations of benzo[a]pyrene, at present the only regulated PAH, were always less than the 1 ng/m(3) limit.

Bulky DNA adduct formation and risk of bladder cancer

Exposure to polycyclic aromatic hydrocarbons (PAHs) has been associated with risk of bladder cancer and with increased bulky DNA adduct levels in several studies, mainly in smokers. We investigated the relation between bulky PAH-DNA adducts in peripheral blood mononuclear cells and bladder cancer in nonsmoking subjects from a large hospital-based case-control study in Spain. Additionally, we examined the association between DNA adduct formation and several air pollution proxies. The study comprised 76 nonsmoking cases and 76 individually matched controls by sex, region of residence, age, and smoking status (never, former). To maximize the relevance of the DNA adduct measurement as a proxy of PAH exposure, subjects selected had not changed residence, occupation, and major lifestyle factors during the last 10 years. Bulky DNA adducts were measured using the (32)P-postlabeling technique, nuclease P1 treatment. The percentage of detectable adducts was higher in controls (41%) than in cases (32%) with an odds ratio of 0.75 (95% confidence interval, 0.36-1.58). In an analysis limited to controls, a higher percentage of DNA adducts was found among those whose last residence was in a big city (50%) compared with those living in villages (19%; P = 0.04). No consistent associations were found for other markers of air pollution. In this study, among nonsmokers with stable environmental and lifestyle factors, bulky DNA adducts were not associated with bladder cancer risk. Results do not support an association of bladder cancer risk with low-level exposure to PAHs as measured through the formation of bulky DNA adducts in peripheral mononuclear cells.

In utero effects of chemicals on reproductive tissues in females

Chemicals found in the environment as industrial byproducts or pollutants as well as those that are prescribed or part of our daily lives can have multiple effects on the human body. The manner in which we are exposed, and the levels we are exposed to are significant contributing factors. Adults have the bodily defense mechanisms in place to combat exposures to adverse toxicants and general pollution at a variety of levels. However, developing organisms may not have adequate defense mechanisms, and toxicants can have a significant effect on their health and development. In this review, we take particular note of the toxicities of chemicals on the developing female reproductive system as a result of in utero exposure. Environmental and prescribed chemicals such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), diethylstilbestrol, and genistein, as well as others, will be reviewed for their in utero toxicity in the neuroendocrine system, the ovary, oviduct, placenta, uterus, vagina, cervix, and mammary gland.

Biomarkers of exposure to polycyclic aromatic hydrocarbons from environmental air pollution

Metabolites of pyrene and DNA adducts have been used as biomarkers of high level exposure to polycyclic aromatic hydrocarbons (PAHs). A systematic review was performed to evaluate whether these biomarkers are also valid markers of low level environmental exposure to PAHs. Thirty five studies were identified with more than 10 subjects that evaluated environmental air pollution to PAHs in relation to metabolites of PAHs, mainly hydroxypyrene (1-OHP), PAH-DNA adducts, or protein adducts. PAH metabolites and, to a less extent, PAH-DNA adducts correlated well at the group level with exposure to B(a)P even at low levels of air pollution. The use of these biomarkers should be more widely implemented in combination with more traditional techniques for the assessment of general population exposure to PAHs from ambient air pollution.

Health risk assessment after decontamination of the beaches polluted by the wrecked ERIKA tanker

Following the wreck of the oil tanker ERIKA off the north-west coast of France in December 1999, cleaning up of the beaches involved considerable work, which in any case could not be perfect. This raised the question of the short- and long-term health risks for the future bathers related to the toxicity of the remaining oil polycyclic aromatic hydrocarbons (PAHs). This risk assessment study was conducted to help health authorities plan risk management policies and inform the public. Thirty-six beaches were selected, representing a sample of the most frequently encountered topographic and beach usage situations; seven "control" beaches, unspoiled by ERIKA, were also investigated. Samples of water and sand were taken from each site, as well as from the surface of rocks. The 16 PAHs selected by the U.S. EPA were quantified in each environment. Several scenarios of exposure were contemplated: (1) a child between 2 and 4 years accidentally ingesting a small ball of fuel, (2) a child daily exposed throughout his holiday-time stay, (3) an adult (including a pregnant woman) spending his/her holidays on the coast, (4) an adult working on the beach, (5) and an adult practicing water sports. Among the available and significant toxicological values, the most conservative ones were selected for computing risks. The sand and water, after decontamination, were slightly polluted (respectively, 7.8 microg/kg and 23.3 ng/l of total 16 PAHs), with values similar to those found in the control beaches. By contrast, the rocky areas in some places were still highly polluted (up to 23 mg/kg on the surface layer). No lethal risk was found for a young child who had accidentally ingested a small ball of fuel. The life-long excess risks for skin cancer and for all other cancers were about 10-5 in scenarios including contact with the polluted rocks. In all other cases, excess risks were considerably lower. The hazard quotient for teratogenic effects was very small, except in scenarios where pregnant women would walk among rocks containing high pollution levels. In conclusion, exposure was mainly associated with polluted water among children, and with spoiled rocks for adults. Despite uncertainties, mainly dealing with the prediction of long-term risks following a short-term exposure, this study showed that beaches where pollution was no longer visible after decontamination did not entail any significant health risks and could be opened to the public.

Molecular characterization of dioxygenases from polycyclic aromatic hydrocarbon-degrading Mycobacterium spp

Polycyclic aromatic hydrocarbon (PAH)-degrading genes nidA and nidB that encode the alpha and beta subunits of the aromatic ring-hydroxylating dioxygenase have been cloned and sequenced from Mycobacterium vanbaalenii PYR-1 [Khan et al., Appl. Environ Microbiol. 67 (2001) 3577-3585]. In this study, the presence of nidA and nidB in 12 other Mycobacterium or Rhodococcus strains was investigated. Initially, all strains were screened for their ability to degrade PAHs by a spray plate method, and for the presence of the dioxygenase Rieske center region by polymerase chain reaction (PCR). Only Mycobacterium sp. PAH 2.135 (RJGII-135), M. flavescens PYR-GCK (ATCC 700033), M. gilvum BB1 (DSM 9487) and M. frederiksbergense FAn9T (DSM 44346), all previously known PAH degraders, were positive in both tests. From the three positive strains, complete open reading frames of the nidA and nidB genes were amplified by PCR, using primers designed according to the known nidA and nidB sequences from PYR-1, cloned in the pBAD/Thio-TOPO vector and sequenced. The sequences showed >98% identity with the M. vanbaalenii PYR-1 nidA and nidB genes. Southern DNA-DNA hybridization using nidA and nidB probes from PYR-1 revealed that there is more than one copy of nidA and nidB genes in the strains PYR-1, BB1, PYR-GCK and FAn9T. However, only one copy of each gene was observed in PAH2.135.

A critical assessment of some biomarker approaches linked with dietary intake

In this review many examples are given of the complexities involved in using some biomarkers in relation to assessing the effects of dietary exposure, when there is frequently a need to determine changes following long-term low level exposure to dietary components. These range from understanding why the biomarker might be valuable and how best it can be measured, to the pitfalls which can occur in the interpretation of data. Analytical technique is considered in relation to folate and selenium, and flavonoid and carotenoid species are used to illustrate how the metabolism of a compound may alter the validity or adequacy of a marker. Vitamin A is discussed in relation to the difficulties which can arise when there are several biomarkers that may be available to assess exposure to one nutrient. Vitamin B12 is discussed in relation to the dietary choices made by individuals. Possible interactions and the role of measuring total antioxidant capacity is considered in some detail. In contrast to most nutrients, there is a marked lack of biomarkers of either exposure or effect for most non-nutrients. The role of biological effect monitoring is considered for dietary contaminants, fumonisins and polyhalogenated aromatic hydrocarbons. Aflatoxins are discussed to exemplify food contaminants for which the biomarker approach has been extensively studied. Finally some compounds which are deliberately added to foods and some which appear as processing contaminants are each considered briefly in relation to the requirement for a biomarker of exposure to be developed.

Suppression of arylamine toxicity in the Fischer-344 rat following ingestion of a complex mixture

The toxic effects of a mixture of 2-aminoanthracene (2-AA), benzanthracene (BA), and dinitropyrene isomers (DNP), and the toxic effects of these compounds individually, were investigated in the Fischer-344 rat following dietary exposure via a powdered basal diet. Animals were sacrificed at 14-, 30-, and 80-days of dietary exposure. Exposure to dietary 2-AA alone induced anorexia, cachexia, variable mortality, and altered serum chemistry profiles in the F-344 rat. Reduced lymphocyte counts were also shown in rats exposed to 2-AA. A temporal pattern of effect of 2-AA dietary exposure was observed in the progression of hepatic lesions in exposed animals. Dietary exposure to either DNP isomers or BA at a 10-fold higher concentration in the diet, relative to 2-AA, did not induce detectable toxic responses. However, exposure of rats to a mixture of 2-AA, BA, and DNP isomers (100 mg/kg, 1.0 g/kg, and 1.0 g/kg of diet, respectively) resulted in the attenuation of toxic effects when compared to exposure of F-344 rats to 2-AA alone. These results indicate that the toxic effects of 2-AA are suppressed by co-administration of DNP and BA and suggest that compound interactions need to be considered when predicting the toxic potential of specific environmental pollutants.

Feasibility of assessing dermal exposure to PAHs of workers on gaswork sites--the SOLEX study

Population exposure to pollutants in soil is an important public health concern. Difficult to measure, it is usually estimated using multimedia models. Modeling data predict that the skin surface is a predominant exposure route in roughly 15% of the US Superfund sites. Nonetheless, no study has confirmed these predictions. The SOLEX study was an opportunity to study the feasibility of estimating the cutaneous polycyclic aromatic hydrocarbons (PAHs: all 16 of the United States Environmental Protection Agency list) load of workers at three former manufactured gas sites, one of those being under remediation. Over two measurement periods (November 1997 and June 1998), 30 and 28 volunteers, respectively, were equipped for a single day work with five pads that collected soil particles and were placed at the neck, shoulder, wrist, groin, and ankle. Pad contamination was observed for six of the nine workers on the site being remediated but not on other sites. The wrist pad was most often affected, followed by the neck pad, these are, the exposed regions of the body. The PAHs most frequently identified were anthracene, fluoranthene, naphthalene, phenanthrene, and pyrene, at concentrations relatively high. In conclusion, this study showed that estimating skin exposure to soil pollutants is feasible. Secondly, it suggested that only subjects in close contact with the soil had a detectable exposure to PAHs. Extension of this approach to other exposure settings is warranted, especially among children playing in polluted public or private gardens, because their games lead to frequent contact with the soil.

Urinary 1-hydroxypyrene as a biomarker of polycyclic aromatic hydrocarbons exposure of workers on a contaminated site: influence of exposure conditions

The aim of the study was to determine the exposure levels of workers to polycyclic aromatic hydrocarbons on gasworks sites by the measurement of urinary 1-hydroxypyrene. Start-shift and end-shift urine samples were taken every day during an entire week (Monday to Friday), once in November and a second time in June. Four groups of workers were selected according to their activity. Increased exposure was only found among volunteers involved in the remediation of a site, 0.16 to 2.31 mumol/mol creatinine in non-smokers. The median of the non-smoker referent group was 0.02 mumol/mol creatinine (95% confidence interval, 0.01 to 0.04). Smokers had greater exposure levels than non-smokers in every group. Within and between variability was around 200%. Assessment of the exposure of persons on contaminated soil is possible, with the condition that the exposed subjects come in direct contact with the soil.

Urinary 17-KS and 17-OHCS as markers of endocrine disruption by air pollution in primary school children

The present study was undertaken to determine the effects of air pollution on urinary excretion of 17-ketosteroids (17-KS) and 17-hydroxycorticosteroids (17-OHCS), which are markers of adrenal cortex functions, in primary school children from five schools with different levels of air pollution. One hundred and twentynine fourth-grade children were included in the study. Urinary excretion of 17-KS and 17-OHCS were significantly lower in male children living in polluted areas than in children living in clean areas. We conclude that adrenal cortex functions before puberty can serve as practical markers of endocrine disruption by environmental factors in epidemiological studies.