Cancer risk due to occupational exposure to polycyclic aromatic hydrocarbons

Association between residential exposure to petrochemical industrial complexes and pancreatic cancer: a systematic review and meta-analysis

Increased in the global demand-expansion of the petrochemical industry is a possible environmental risk factor pancreatic cancer among residents living close to petrochemical complexes. This meta-analysis aimed to estimate the pooled risk of pancreatic cancer among residents living near petrochemical industrial complexes. We systematically searched and reviewed published studies in six databases based on the inclusion criteria derived from the population, exposure, comparator, and outcomes framework (population: general population; exposure: residence near petrochemical industrial complexes/living in cities with petrochemical industrial complexes; comparators: residents living farther away from petrochemical industrial complexes/living in cities without petrochemical industrial complexes; outcome: pancreatic cancer). We identified seven studies, covering 1,605,568 residents. Pooled analysis showed a significantly higher risk of pancreatic cancer among residents living near petrochemical industrial complexes (relative risk [RR] = 1.31, 95% confidence interval [CI] = 1.21-1.42) than those living farther away from petrochemical industrial complexes. Such effect was higher in female residents (RR = 1.34, 95% CI = 1.18-1.53) than in male residents (RR = 1.26, 95% CI = 1.12-1.41). This study suggests that exposure to petrochemical industry-related activities should be recognized as a risk factor for pancreatic cancer among residents living near petrochemical industrial complexes.

Occupational Exposures and Lung Cancer Risk-An Analysis of the CARTaGENE Study

OBJECTIVE

To determine the associations between prevalent occupational agents and lung cancer risk.

METHODS

A case-cohort design (ncases= 147; nsub-cohort= 1,032) was nested within the CARTaGENE prospective cohort study. The Canadian Job Exposure Matrix was used to determine the probability of exposure to 27 agents in participants' longest-held jobs. Multivariable logistic regression with robust variance estimators was used to determine the associations between each agent and lung cancer risk while adjusting for established lung cancer risk factors.

RESULTS

Increased lung cancer risk was observed among those exposed to ashes, calcium sulfate, formaldehyde, cooking fumes, alkanes, aliphatic aldehydes, and cleaning agents. Lower lung cancer risk was found among participants exposed to carbon monoxide and polycyclic aromatic hydrocarbons from petroleum.

CONCLUSION

Our findings support the role of several occupational agents, for which we have limited knowledge, in contributing to lung cancer risk.

Trametes coccinea IDEA, un hongo súper productor de lacasa aislado de un lago natural de asfalto: Tolerancia y biotransformación de hidrocarburos policíclicos aromáticos

Los hidrocarburos policíclicos aromáticos (HPAs) son compuestos tóxicos que no se degradan fácilmente bajo condiciones naturales tales como fenómenos físicos (fotooxidación, volatilización), químicos (intercambio iónico, complejación, transformación) y biológicos (degradación por microorganismos autóctonos) que además, dependen de la temperatura, humedad y niveles de oxígeno. El objetivo del presente trabajo fue aislar, identificar y caracterizar fenotípicamente hongos hidrocarbono clásticos de ambientes extremos que sean capaces de tolerar HPAs, tales como Trametes coccinea IDEA, que se aisló del Lago de asfalto natural de Guanoco en Venezuela. A fin de estudiar su tolerancia a los HPAs, el hongo se expuso a diferentes concentraciones de naftaleno, fenantreno y pireno (0, 2.5, 25, 50, 100, 200, 400, 800 y 1600 mg/L). Posteriormente, en ensayo en medio de cultivo líquido, se procedió a estudiar el efecto de los HPAs sobre la actividad de enzimas del sistema enzimático de degradación de lignina (SEDL), así como sobre la posible variación en los niveles de toxicidad empleando Lactuca sativa como bioindicador. Los resultados mostraron una mayor tolerancia al pireno, seguido por el naftaleno y fenantreno. Se observó una fuerte inducción de la actividad lacasa en presencia de naftaleno (167.96 U/mgP) y pireno (124.89 U/mgP) con respecto al control, mientras que con fenantreno se obtuvo una baja actividad (88.67 U / mgP). De manera interesante, se evidenció una generación de sub-productos más tóxicos cuando el naftaleno y el fenantreno fueron biotratados por el hongo, mientras que el nivel de toxicidad del pireno disminuyó significativamente. T. coccinea IDEA tiene un alto potencial para ser utilizado en estrategias de biorremediación de hidrocarburos, las cuales deben ser monitoreadas mediante análisis ecotoxicológicos para detectar posibles variaciones de toxicidad de los productos parcialmente biotransformados.

Occupational exposure to polycyclic aromatic hydrocarbons and risk of prostate cancer

BACKGROUND

Several industries entailing exposure to polycyclic aromatic hydrocarbons (PAHs) are known or suspected carcinogens. A handful of studies have assessed the role of PAHs exposure in prostate cancer risk, but none has examined tumor aggressiveness or the influence of screening practices and detection issues. We aimed to examine the association between lifetime occupational exposure to PAHs and prostate cancer risk.

METHODS

Detailed work histories were collected from 1,929 prostate cancer cases (436 aggressive) and 1,994 controls from Montreal, Canada (2005-2012). Industrial hygienists applied the hybrid expert approach to assign intensity, frequency and certainty of exposure to benzo[a]pyrene, PAHs from wood, coal, petroleum, other sources, and any source, in each job held. Odds ratios (ORs) for prostate cancer risk associated with lifetime PAHs exposure, adjusted for age, ancestry, education, lifestyle and occupational factors, and 95% confidence intervals (CI), were estimated using unconditional logistic regression.

RESULTS

After restriction to probable and definite exposures, and application of a 5-year lag, no clear association emerged for any of the PAHs, although small excesses in risk were apparent with 5-year increments in exposure to PAHs from wood (OR = 1.06, 95%CI 0.95 to 1.18). While analyses by cancer aggressiveness suggested no major differences, some elevated risk of high-grade cancer was observed for exposure to PAHs from wood (OR = 1.37, 95%CI 0.65 to 2.89), frequently occurring among firefighters.

CONCLUSION

Findings provide weak support for an association between occupational exposure to PAHs from wood and prostate cancer risk.

Epigenetic Regulation of Cancer Stem Cells by the Aryl Hydrocarbon Receptor Pathway

Compelling evidence has demonstrated that tumor bulk comprises distinctive subset of cells generally referred as cancer stem cells (CSCs) that have been proposed as a strong sustainer and promoter of tumorigenesis and therapeutic resistance. These distinguished properties of CSCs have raised interest in understanding the molecular mechanisms that govern the maintenance of these cells. Numerous experimental and epidemiological studies have demonstrated that exposure to environmental toxins such as the polycyclic aromatic hydrocarbons (PAHs) is strongly involved in cancer initiation and progression. The PAH-induced carcinogenesis is shown to be mediated through the activation of a cytosolic receptor, aryl hydrocarbon receptor (AhR)/Cytochrome P4501A pathway, suggesting a possible direct link between AhR and CSCs. Several recent studies have investigated the role of AhR in CSCs self-renewal and maintenance, however the molecular mechanisms and particularly the epigenetic regulations of CSCs by the AhR/CYP1A pathway have not been reviewed before. In this review, we first summarize the crosstalk between AhR and cancer genetics, with a particular emphasis on the mechanisms relevant to CSCs such as Wnt/β-catenin, Notch, NF-κB, and PTEN-PI3K/Akt signaling pathways. The second part of this review discusses the recent advances and studies highlighting the epigenetic mechanisms mediated by the AhR/CYP1A pathway that control CSC gene expression, self-renewal, and chemoresistance in various human cancers. Furthermore, the review also sheds light on the importance of targeting the epigenetic pathways as a novel therapeutic approach against CSCs.

Systematic review: the etiology of esophageal squamous cell carcinoma in low-income settings

Esophageal carcinoma causes over 380 000 deaths per year, ranking sixth worldwide in mortality amongst all malignancies. Globally, the squamous cell subtype is most common and accounts for 80% of esophageal cancers. Nonetheless, esophageal squamous cell carcinoma is much more poorly understood than esophageal adenocarcinoma, including what is driving such high prevalences, why it often presents in young patients, and shows such marked geographical delineations Areas covered: The current literature was searched for articles focusing on aetiopathogenesis of squamous cell esophageal carcinoma via a systematic review, particularly in low-resource settings. This was supplemented by papers of interest known to the authors. Expert commentary: Current putative mechanisms include polycyclic aromatic hydrocarbons, nitrosamines, acetaldehyde, cyclo-oxygenase-2 pathways, androgen and their receptor levels, as well as smoking & alcohol, micronutrient deficiencies and diet, mycotoxins, thermal damage, oral hygiene and microbiotal factors, inhaled smoke, viral infections such as HPV, and chronic irritative states. Etiology is likely multifactorial and varies geographically. Though smoking and alcohol play a predominant role in high-income settings, there is strong evidence that mycotoxins, diet and temperature effects may play an under-recognized role in low and middle-income settings.

Five-year single-centre experience of carcinoma of the oesophagus from Blantyre, Malawi

Background

Oesophageal squamous cell carcinoma (OSCC) is increasing worldwide and has an exceptionally high prevalence in certain distinct geographical locations such as the African oesophageal SCC corridor. Despite this, there is a paucity of evidence to characterise the disease particularly in the Malawian context.

Method

We retrospectively audited our endoscopy database over 5 years, including for patient demographics, endoscopy findings, therapeutic intervention and recommendations for treatment.

Results

1586 patients with oesophageal cancer were identified from a total of 5882 endoscopy records from 2013 to 2017. Our cohort showed a larger proportion of oesophageal cancers found higher in the oesophagus compared with other African studies and a female preponderance in this upper-oesophagus disease subset though a male preponderance overall. 39% of patients with oesophageal cancer underwent bougie dilatation and 11% underwent palliative stent placement, which likely reflects local availability of resources.

Conclusion

This study validates the observation that OSCC predominates in sub-Saharan Africa in Malawi over other forms of oesophageal carcinoma, though our cohort appears to have subtly distinct demographics and disease-specific data. This highlights the need to prioritise preventative and therapeutic strategies for OSCC in this and similar settings.

Human health risk assessment of ground water contaminated with petroleum PAHs using Monte Carlo simulations: A case study of an Indian metropolitan city

Underground pipelines are frequently used to transport petroleum fuels, through industrial as well as residential zones. Chennai is one of the four largest metropolitan cities of India. The region of interest in this study is located in the northern part of the Chennai. Ground water of this area was contaminated with polyaromatic hydrocarbons (PAHs) from the leaking oil storage tanks and pipe lines. Health risk assessment was conducted for exposure to PAHs in the ground water using incremental life time cancer risk (ILCR) models coupled with benzo[a]pyrene toxic equivalent method. The exposure pathways considered in this study were direct water ingestion and dermal contact under residential scenario. Exposure input parameters were transformed to statistical parameters using lognormal/uniform distributions and resultant probabilities of cancer risk were estimated by performing Monte Carlo simulations. Preliminary remediation goals were predicted using the combination of the cancer risk models of all the exposure routes with the consideration of high-safety risk of 1-in-1 million. Results showed that the cancer risk is predominantly contributed (greater than 98%) by dermal exposure than the oral in both adults and children. The total ILCR is found to be greater than a low safety risk of 1-in-10,000 with higher probability percentages (>90%). The 95th percentile values of the risk were presented in order to address the need for remediation. Appropriate remedial and treatment methods for the subject site were proposed. The results of the study will be useful for the regulatory boards and policy makers in India in understanding the actual impact of the contamination on receptors, setting up final remediation goals and deciding on a specific remedial method.

An assessment of subsurface contamination of an urban coastal aquifer due to oil spill

Incidences of leakages of chemicals from underground oil storage tanks or oil-carrying pipelines have posed huge threat to the coastal aquifers around the world. One such leak was recently identified and notified by the people of Tondiarpet, Chennai, India. The assessment of the contamination level was done by obtaining electrical resistivity maps of the subsurface, drilling of 20 new borewells for soil and water analysis, and testing the water quality of 30 existing borewells. Samples were collected from the borewells, and observations were made that included parameters such as odor, moisture, contamination characteristics, lithology, groundwater level, thickness of the free product that are used to demarcate the extent of soil, and water contamination. Furthermore, a multigas detector was used to detect hydrocarbon presence as soil vapor. Moreover, to capture the transport of dissolved hydrocarbons, 10 samples were collected in the periphery of the study area and were analyzed for the presence of petroleum hydrocarbon and polyaromatic hydrocarbon. Analysis of the data indicated the presence of free-phase hydrocarbon in soil and groundwater close to the junction of Thiruvottiyur high (TH) road (TH) and Varadaja Perumal Koil (VPK) street. Although the contaminant plume is confined to a limited area, it has spread more to the southern and eastern side of the pipeline possibly due to continuous abstraction of groundwater by residential apartments. After cutting a trench along the VPK street and plotting of the plume delineation map, observations indicated that the source of the hydrocarbon leak is present in VPK street close to TH road. A multipronged strategy was suggested targeting the remediation of oil in various phases.

Pathologic Findings and Trends in Mortality in the Beluga (Delphinapterus leucas) Population of the St Lawrence Estuary, Quebec, Canada, From 1983 to 2012

An isolated population of beluga (Delphinapterus leucas) inhabits the St Lawrence Estuary, Quebec, Canada. This population has failed to recover despite the prohibition of hunting >30 years ago, suggesting the presence of other limiting factors. The authors summarize the reported causes of death and propose risk factors to explain the lack of recovery of this population. From 1983 to 2012, a total of 472 beluga were found stranded. Complete necropsies were carried out on 222 beluga, including 178 adults, 25 juveniles, and 19 newborn calves. Infectious diseases, the most prevalent cause of mortality in this population, accounted for the death of one-third of all beluga (32%). Verminous pneumonia was the cause of mortality of 13 juvenile beluga (52% of juvenile beluga). A total of 39 malignant neoplasms, diagnosed in 35 beluga, caused the death of 31 beluga (20% of beluga >19 years old). Median age at diagnosis of cancer was 48 years (range, 30-61 years). Dystocia and postpartum complications were the cause of death in 18 beluga, accounting for 19% of the females >19 years old examined. The occurrence of parturition-associated complications, as well as mortality of calves <1 year old, have increased recently in this population and may be the probable cause of the recent decrease in the size of this population. One of the hypotheses proposed to explain the unusually high occurrence of some of the pathologic conditions observed in this population is chronic exposure to environmental contaminants.

High urine 1-hydroxypyrene glucuronide concentrations in Linxian, China, an area of high risk for squamous oesophageal cancer

Most squamous cell carcinomas of the oesophagus in low-risk populations are attributable to alcohol and tobacco consumption, but the aetiologic agents in many high-risk populations have yet to be definitively identified. Linxian, China has some of the highest oesophageal cancer rates in the world. Recent studies suggest that an association exists between high-level exposure to carcinogenic polycyclic aromatic hydrocarbons (PAHs), such as benzo[a]pyrene (B[a]P), and the development of oesophageal cancer. The inhabitants of this high-risk region extensively use coal and wood for cooking and heating in unvented stoves, and thus may be exposed to PAHs produced during the incomplete combustion of these fuel sources. High levels of B[a]P were recently detected in staple food samples from Linxian and histopathologic changes that may be associated with PAH exposure have also been identified in oesophagectomy specimens from the region. In an effort to determine whether this high-risk population is exposed to high levels of PAHs, voided urines from non-smokers (n = 22) without occupational exposure were collected and analysed using immunoaffinity chromatography and synchronous fluorescence spectroscopy for 1-hydroxypyrene glucuronide, a PAH metabolite and index biomarker for mixed PAH exposure. The median urine 1-hydroxypyrene glucuronide concentration (2.06 pmol ml(-1)) was equivalent to concentrations detected in current smokers. To the authors' knowledge, this represents the first report of elevated urine 1-hydroxpyrene glucuronide concentrations in Linxian, and the first biologic confirmation that the inhabitants of this rural, non-industrial, high oesophageal cancer risk region are exposed to carcinogenic PAHs.

Lymphohematopoietic Malignancies and Oil Exploitation in Koprivnica-Krizevci County, Croatia

To determine lymphohematopoietic malignancy incidence rates between populations living near oil-gas fields (two regions) compared with those living in areas free from oil-gas exploitation (one region) in Koprivnica-Krizevci County, Croatia, 803 new cases of lymphohematopoietic malignancies were studied for two time periods: 1971-1980 (prior to oil-gas exploitation) and 1981-2000 (during oil-gas exploitation). The results showed considerable geographic differences in the incidences of chronic myeloid leukemia and multiple myeloma. The authors conclude that proximity to oil or gas fields represents an increased population risk of developing lymphohematopoietic cancers.

Cotton dust, endotoxin and cancer mortality among the Shanghai textile workers cohort: a 30-year analysis

BACKGROUND

Although occupational exposure to cotton dust and endotoxin is associated with adverse respiratory health, associations with cancer are unclear. We investigated cancer mortality in relation to cotton dust and endotoxin exposure in the Shanghai textile workers cohort.

METHODS

We followed 444 cotton textile and a reference group of 467 unexposed silk workers for 30 years (26 777 person-years). HRs for all cancers combined (with and without lung cancer) and gastrointestinal cancer were estimated in Cox regression models as functions of cotton textile work and categories of cumulative exposure (low, medium, high), after adjustment for covariates including pack-years smoked. Different lag years accounted for disease latency.

RESULTS

Risks of mortality from gastrointestinal cancers and all cancers combined, with the exclusion of lung cancer, were increased in cotton workers relative to silk workers. When stratified by category of cumulative cotton exposure, in general, risks were greatest for 20-year lagged medium exposure (all cancers HR=2.7 (95% CI 1.4 to 5.2); cancer excluding lung cancer HR=3.4 (1.7-7.0); gastrointestinal cancer HR=4.1 (1.8-9.7)). With the exclusion of lung cancer, risks of cancer were more pronounced. When stratified by category of cumulative endotoxin exposure, consistent associations were not observed for all cancers combined. However, excluding lung cancer, medium endotoxin exposure was associated with all cancers and gastrointestinal cancer in almost all lag models.

CONCLUSIONS

Cotton dust may be associated with cancer mortality, especially gastrointestinal cancer, and endotoxin may play a causative role. Findings also indirectly support a protective effect of endotoxin on lung cancer.

An evidence-based analysis of epidemiologic associations between lymphatic and hematopoietic cancers and occupational exposure to gasoline

The presence of benzene in motor gasoline has been a health concern for potential increased risk of acute myelogenous leukemia and perhaps other lymphatic/hematopoietic cancers for approximately 40 years. Because of the widespread and increasing use of gasoline by consumers and the high exposure potential of occupational cohorts, a thorough understanding of this issue is important. The current study utilizes an evidence-based approach to examine whether or not the available epidemiologic studies demonstrate a strong and consistent association between occupational exposure to gasoline and lymphatic/hematopoietic cancers. Among 67 epidemiologic studies initially identified, 54 were ranked according to specific criteria relating to the relevance and robustness of each study for answering the research question. The 30 highest-ranked studies were sorted into three tiers of evidence and were analyzed for strength, specificity, consistency, temporality, dose-response trends and coherence. Meta statistics were also calculated for each general and specific lymphatic/hematopoietic cancer category with adequate data. The evidence-based analysis did not confirm any strong and consistent association between occupational exposure to gasoline and lymphatic/hematopoietic cancers based on the epidemiologic studies available to date. These epidemiologic findings, combined with the evidence showing relatively low occupational benzene vapor exposures associated with gasoline formulations during the last three decades, suggest that current motor gasoline formulations are not associated with increased lymphatic/hematopoietic cancer risks related to benzene.

Polycyclic aromatic hydrocarbons and esophageal squamous cell carcinoma

Esophageal cancer (EC) is the 8th most common cancer and the 6th most frequent cause of cancer mortality worldwide. Esophageal squamous cell carcinoma (ESCC) is the most common type of EC. Exposure to polycyclic aromatic hydrocarbons (PAHs) has been suggested as a risk factor for developing ESCC. In this paper we will review different aspects of the relationship between PAH exposure and ESCC. PAHs are a group of compounds that are formed by incomplete combustion of organic matter. Studies in humans have shown an association between PAH exposure and development of ESCC in many populations. The results of a recent case-control study in a high risk population in northeastern Iran showed a dramatic dose-response relationship between PAH content in non-tumor esophageal tissue (the target tissue for esophageal carcinogenesis) and ESCC case status, consistent with a causal role for PAH exposure in the pathogenesis of ESCC.  Identifying the main sources of exposure to PAHs may be the first and most important step in designing appropriate PAH-reduction interventions for controlling ESCC, especially in high risk areas. Coal smoke and drinking mate have been suggested as important modifiable sources of PAH exposure in China and Brazil, respectively. But the primary source of exposure to PAHs in other high risk areas for ESCC, such as northeastern Iran, has not yet been identified. Thus, environmental studies to determining important sources of PAH exposure should be considered as a high priority in future research projects in these areas.

Occupational risk factors have to be considered in the definition of high-risk lung cancer populations

BACKGROUND

The aim of this study was to compute attributable fractions (AF) to occupational factors in an area in North-Eastern France with high lung cancer rates and a past of mining and steel industry.

METHODS

A population-based case-control study among males aged 40-79 was conducted, including confirmed primary lung cancer cases from all hospitals of the study region. Controls were stratified by broad age-classes, district and socioeconomic classes. Detailed occupational and personal risk factors were obtained in face-to-face interviews. Cumulative occupational exposure indices were obtained from the questionnaires. Attributable fractions were computed from multiple unconditional logistic regression models.

RESULTS

A total of 246 cases and 531 controls were included. The odds ratios (ORs) adjusted on cumulative smoking and family history of lung cancer increased significantly with the cumulative exposure indices to asbestos, polycyclic aromatic hydrocarbons and crystalline silica, and with exposure to diesel motor exhaust. The AF for occupational factors exceeded 50%, the most important contributor being crystalline silica and asbestos.

CONCLUSION

These AFs are higher than most published figures. This can be because of the highly industrialised area or methods for exposure assessments. Occupational factors are important risk factors and should not be forgotten when defining high-risk lung cancer populations.

Investigation on the protective effects of cranberry against the DNA damage induced by benzo[a]pyrene

There are few reports that demonstrate the antigenotoxic potential of cranberries. Although the types of berry fruits consumed worldwide are many, this paper focuses on cranberries that are commonly consumed in Mexico (Vaccinium macrocarpon species). The purpose of the present study is to determine whether cranberry ethanolic extract (CEE) can prevent the DNA damage produced by benzo[a]pyrene (B[a]P) using an in vivo mouse peripheral blood micronucleus assay. The experimental groups were organized as follows: a negative control group (without treatment), a positive group treated with B[a]P (200 mg/kg), a group administered with 800 mg/kg of CEE, and three groups treated with B[a]P and CEE (200, 400, and 800 mg/kg) respectively. The CEE and benzo[a]pyrene were administered orally for a week, on a daily basis. During this period the body weight, the feed intake, and the determination of antigenotoxic potential were quantified. At the end of this period, we continued with the same determinations for one week more (recovery period) but anymore administration of the substances. The animals treated with B[a]P showed a weight increase after the first week of administration. The same phenomenon was observed in the lots combined with B[a]P and CEE (low and medium doses). The dose of 800 mg/kg of CEE showed similar values to the control group at the end of the treatment period. In the second part of the assay, when the substances were not administered, these experimental groups regained their normal weight. The dose of CEE (800 mg/kg) was not genotoxic nor cytotoxic. On the contrary, the B[a]P increases the frequency of micronucleated normochromatic erythrocytes (MNNE) and reduces the rate of polychromatic erythrocytes (PE) at the end of the treatment period. With respect to the combined lots, a significant decrease in the MN rate was observed from the sixth to the eighth day of treatment with the two high doses applied; the highest protection (60%) was obtained with 800 mg/kg of CEE. The same dose showed an anticytotoxic effect which corresponded to an improvement of 62.5% in relation to the animals administered with the B[a]P. In the second period, all groups reached values that have been seen in the control group animals. Our results suggest that the inhibition of clastogenicity of the cranberry ethanolic extract against B[a]P is related to the antioxidant capacity of the combination of phytochemicals present in its chemical composition.

Occupational exposure to gasoline and the risk of non-Hodgkin lymphoma: a review and meta-analysis of the literature

AIMS

Gasoline comprises over 500 chemicals, including the known or suspected carcinogens benzene, 1,3-butadiene, ethylbenzene and methyl tert-butyl ether (MTBE). To assess whether work in the production, distribution and use of gasoline is associated with non-Hodgkin lymphoma (NHL), we reviewed the published literature on this topic.

METHOD

English-language peer-reviewed articles were identified by keyword searches of bibliographic databases. Twenty-two cohorts and thirteen case-control studies examined the risk of NHL among persons employed in the downstream petroleum industry.

RESULT

No positive associations were found with the exception of one study. The pooled risk estimate from a random-effects meta-analysis was 1.02 (95% confidence interval (CI) 0.94-1.12). Although there were no estimates available, exposure is likely to have varied by occupation, location and time period; there was no evidence however that risk estimates varied by any of these factors. NHL is a heterogeneous disease, yet no data were reported for NHL subtypes.

CONCLUSION

In summary, there is no suggestion across an extensive literature that exposure to gasoline at the levels workers' experience in an occupational setting increases the risk of NHL.

Spatial and temporal trends of polycyclic aromatic hydrocarbons and other traffic-related airborne pollutants in New York City

Traffic-related air pollutants have been associated with adverse health effects. We hypothesized that exposure to polycyclic aromatic hydrocarbons (PAHs), elemental carbon (EC, diesel indicator), particulate matter (PM2.5), and a suite of metals declined from 1998 to 2006 in NYC due to policy interventions. PAH levels from personal monitoring of pregnant mothers participating in the Columbia's Center for Children's Environmental Health birth cohort study, and EC, PM2.5, and metal data from five New York State Department of Environmental Conservation stationary monitors were compared across sites and over time (1998-2006). Univariate analysis showed a decrease in personal PAHs exposures from 1998 to 2006 (p < 0.0001). After controlling for environmental tobacco smoke, indoor heat, and cooking, year of personal monitoring remained a predictor of decline in sigmaPAHs (beta = -0.269, p < 0.001). Linear trend analysis also suggested that PM2.5 declined (p = 0.09). Concentrations of EC and most metals measured by stationary site monitors, as measured by ANOVA, did not decline. Across stationary sites, levels of airborne EC and metals varied considerably. By contrast PM2.5 levels were highly intercorrelated (values ranged from 0.725 to 0.922, p < 0.01). Further policy initiatives targeting traffic-related air pollutants may be needed for a greater impact on public health.

Involvement of Tetrahymena pyriformis and selected fungi in the elimination of anthracene, and toxicity assessment of the biotransformation products

Anthracene (AC) is a non-mutagenic and non-carcinogenic, low-molecular-weight polycyclic aromatic hydrocarbon present in the environment. Its toxicity can be dramatically increased after solar-light exposure. Biotransformation capacities of AC by Tetrahymena pyriformis and a selection of eight micromycetes were studied, and the ability of these microorganisms to detoxify the polluted ecosystems was assessed. We showed that T. pyriformis was able to accumulate high amounts of AC without any transformation. In contrast, the fungi Cunninghamella elegans, Absidia fusca, Absidia cylindrospora, Rhodotorula glutinis, and Aspergillus terreus were able to transform AC with a high efficiency. Cytotoxicity assays conducted on HeLa cells and T. pyriformis showed that crude extract from A. fusca culture medium obtained after AC biotransformation was not toxic. For A. fusca and A. cylindrospora, 1-4 dihydroxyanthraquinone was shown to be the major product during the biotransformation process. This compound seemed to be a dead-end metabolite at least for the Absidia strains. The cytotoxicity of 1-4 dihydroxyanthraquinone was higher than that of AC to T. pyriformis but lower to HeLa cells. On the whole our results showed that the microorganisms studied were all able to decontaminate an AC-polluted ecosystem, either by accumulating or transforming the compound. A possible detoxification process resulting from AC biotransformation can be considered only using the human cell model.

Prostate cancer risk from occupational exposure to polycyclic aromatic hydrocarbons interacting with the GSTP1 Ile105Val polymorphism

BACKGROUND

Variation in the glutathione S-transferase (GSTP1) gene and occupational polycyclic aromatic hydrocarbons (PAH) exposure are putative prostate cancer risk factors. An Ile/Val polymorphism in codon 105 of GSTP1 affects its enzymatic activity toward PAH detoxification, a possible mechanism in prostate carcinogenesis.

METHODS

To determine whether the GSTP1 Ile105Val polymorphism modifies prostate cancer risk associated with occupational PAH exposure, we studied 637 prostate cancer cases and 244 controls of White and African-American race from the Henry Ford Health System in Detroit, Michigan. Occupational exposure to PAH from wood, petroleum, coal or other sources through respiratory and cutaneous routes was retrospectively assessed by expert review of job histories. The association of occupational PAH exposure and GSTP1 Ile105Val polymorphism with prostate cancer was tested in multiple logistic regression models adjusting for potential confounders. Cases were over sampled compared with controls to evaluate gene-environment interaction with the statistically efficient case-only analytic approach.

RESULTS

Neither carriage of the GSTP1 Val(105) variant allele nor occupational PAH exposure was significantly associated with prostate cancer. However, case-only analyses revealed that carriage of the GSTP1 Val(105) variant allele was associated with increasing levels of occupational respiratory PAH exposures from any source and from petroleum (trend test p=0.01 for both). The GSTP1 Val(105) allele was observed most frequently in cases in the highest quartile of occupational respiratory PAH exposures from petroleum (OR=1.74; 95% CI=1.11-2.72) or from any source (OR=1.85; 95% CI=1.19-2.89). The gene-environment risk estimate in the highest PAH petroleum exposure quartile was greatest in men under age 60 (OR=4.52; 95% CI=1.96-10.41) or with a positive family history of prostate cancer (OR=3.02; 95% CI=1.15-7.92).

CONCLUSIONS

Our results suggest men who carry the GSTP1 Val(105) variant and are exposed at high levels to occupational PAH have increased risk for prostate cancer. This increased risk is more pronounced in men under age 60 or with a family history of prostate cancer.

Higher urine 1-hydroxy pyrene glucuronide (1-OHPG) is associated with tobacco smoke exposure and drinking maté in healthy subjects from Rio Grande do Sul, Brazil

Background

The highest rates of esophageal squamous cell carcinoma (ESCC) in Brazil occur in Rio Grande do Sul, the most southern state, which has incidence rates of 20.4/100,000/year for men and 6.5/100,000/year for women. Exposure to carcinogenic polycyclic aromatic hydrocarbons (PAHs) through tobacco smoke and other sources may increase the risk of ESCC. The aims of the current study were to investigate the degree and sources of PAH exposure of the inhabitants of this region of southern Brazil.

Methods

Two hundred healthy adults (half smokers, half non smokers, half male and half female) were recruited, given a standardized questionnaire, and asked to provide a urine sample for measurement of 1-hydroxypyrene glucuronide (1-OHPG), a PAH metabolite). Urine 1-OHPG concentrations were measured using immunoaffinity chromatography and synchronous fluorescence spectroscopy and urine cotinine was measured using a dipstick test. We examined factors associated with 1-OHPG concentration using Wilcoxon tests and multiple linear regression.

Results

Urine 1-hydroxypyrene glucuronide (1-OHPG) was successfully measured on 199 subjects. The median (interquartile range) of urine 1-OHPG in the 199 participants was 2.09 pmol/mL (0.51, 5.84). Tobacco smoke exposure and maté drinking were statistically significantly associated with higher urine 1-OHPG concentrations in the multivariate linear regression model.

Conclusion

Tobacco smoke and maté both contribute to high levels of benzo[a]pyrene exposure in the people of southern Brazil. This high PAH exposure may contribute to the high rates of ESCC observed in this population. The increased urine 1-OHPG concentrations associated with maté suggest that contaminants, not just thermal injury, may help explain the increased risk of ESCC previously reported for maté consumption.

Increased cytochrome P4501B1 gene expression in peripheral leukocytes of municipal waste incinerator workers

Incinerator workers are exposed to polycyclic aromatic hydrocarbons (PAHs) and dioxins in workplace. Previous studies indicated that aryl hydrocarbon receptor activation, following by increased cytochrome P4501A1 (CYP1A1) and 1B1 (CYP1B1) activity and expressions, was required for PAHs and dioxin induced toxicities. This study investigated whether municipal waste incinerator workers with frequent exposure to PAHs/dioxins in fly/bottom ash had increased CYP1A1 and CYP1B1 expressions in peripheral leukocytes and assessed whether CYP1B1*3 polymorphism modified the association between PAHs/dioxins exposure and CYP1B1 expressions. Based on job contents and time-activity profiles, 112 workers were classified into high exposure, medium exposure and control groups. CYP1A1 and CYP1B1 gene expressions in workers' leukocytes were determined with the real-time reverse transcriptase polymerase chain reaction method. After taking into account age, gender and smoking in the multiple regression analyses, CYP1B1, but not CYP1A1, levels were significantly higher in the high and medium exposure groups than in the control group, and there was a statistically significant interaction between exposure group and CYP1B1 genotype. These results suggested that CYP1B1 gene expression could be a potential biomarker of biologically effective dose for occupational exposure to PAHs/dioxins and CYP1B1*3 polymorphism modified effects of occupational exposures on CYP1B1 expression.

Predicting Solubility of Anthracene in Non-aqueous Solvent Mixtures Using a Combination of Jouyban-Acree and Abraham Models

Quantitative structure property relationships were proposed to calculate the binary interaction terms of the Jouyban-Acree model using coefficients of Abraham solvational models. The applicability of the proposed methods for reproducing solubility data of anthracene in binary solvents has been evaluated using 56 solubility data sets collected from the literature. The mean percentage deviation (MPD) of experimental and calculated solubilities, using predicted mole fraction solubility of anthracene in solvents 1 and 2, has been computed as a measure of accuracy and the MPD of the proposed methods were 5.5 and 4.2%. The accuracy of the method was compared with that of a previously reported method where the MPD was 14.4% and the mean differences between proposed and previous methods was statistically significant. To provide a predictive model, solubility of anthracene was computed using Abraham solvational models and employed to predict the solubility in binary solvents using derived model constants of Jouyban-Acree model and the obtained MPDs were 37.9 and 22.2%, respectively.

Cytochrome P450 1B1 is overexpressed and regulated by hypomethylation in prostate cancer

PURPOSE

Cytochrome P450 1B1 (CYP1B1), a dioxin inducible member of the CYP supergene family, is overexpressed in various human malignancies including prostate cancer. We hypothesized that promoter/enhancer CpG methylation contributes to the regulation of CYP1B1 expression in human prostate tissue.

EXPERIMENTAL DESIGN

Expression and induction of the CYP1B1 gene in clinical prostate tissues and prostate cancer cell lines were investigated. The methylation status of the CYP1B1 gene was analyzed in 175 prostate cancer and 96 benign prostatic hyperplasia samples using methylation-specific PCR (MSP) and bisulfite-modified DNA sequencing. MSP primers covered dioxin response elements (DRE) and Sp1 sites that are important for the expression of CYP1B1.

RESULTS

Expressions of CYP1B1 mRNA and protein were increased in prostate cancer. The aryl hydrocarbon receptor (AhR)/AhR nuclear translocator (ARNT) heterodimer complex activates gene transcription by binding to the DREs of CYP1B1. In prostate cancer cells, CYP1B1 mRNA was induced by 2,3,7,8-tetrachlorodigenzo-p-dioxin (TCDD) and/or demethylation agent (5-aza-2-deoxycytidine). There was no change in the expressions of AhR and ARNT. Methylation of promoter/enhancer regions was significantly higher in benign prostatic hyperplasia compared with prostate cancer. MSP-positive patients had significantly lower risk for prostate cancer as compared with MSP-negative patients. There was no correlation between CYP1B1 methylation status and clinicopathologic features.

CONCLUSIONS

CYP1B1 is overexpressed in prostate cancer and regulated by hypomethylation of its promoter/enhancer region. This is the first report about CYP1B1 regulation in human clinical prostate samples showing that hypomethylation of the CYP1B1 gene may play an important role in prostate cancer.

Polycyclic aromatic hydrocarbon-DNA adduct formation in prostate carcinogenesis

The evidence for polycyclic aromatic hydrocarbons (PAH) playing a role in prostate carcinogenesis comes mainly from associations between reported PAH exposures and prostate cancer in epidemiologic studies. Associations between prostate cancer and DNA repair genotypes and phenotypes have also been reported, lending further credence to a PAH-induced carcinogenesis pathway in prostate cancer. Recent work that demonstrates the human prostate has metabolic enzyme activity necessary for PAH activation and will form DNA adducts upon exposure to PAH further supports PAH carcinogenesis. We have demonstrated the presence of PAH-DNA adducts in prostate cancer cases, but further validation of this biomarker as a carcinogenic agent in human prostate is needed.

The influence of occupational exposure to pesticides, polycyclic aromatic hydrocarbons, diesel exhaust, metal dust, metal fumes, and mineral oil on prostate cancer: a prospective cohort study

AIMS

To investigate the relation between exposure to pesticides, polycyclic aromatic hydrocarbons (PAHs), diesel exhaust, metal dust, metal fumes, and mineral oil in relation to prostate cancer incidence in a large prospective study.

METHODS

This cohort study was conducted among 58,279 men in the Netherlands. In September 1986, cohort members (55-69 years) completed a self-administered questionnaire on potential cancer risk factors, including job history. Follow up for prostate cancer incidence was established by linkage to cancer registries until December 1995 (9.3 years of follow up). The analyses included 1386 cases of prostate cancer and 2335 subcohort members. A blinded case-by-case expert exposure assessment was carried out to assign cases and subcohort members a cumulative probability of exposure for each potential carcinogenic exposure.

RESULTS

In multivariate analyses there was a significant negative association for pesticides (RR 0.60; 95% CI 0.37 to 0.95) when comparing the highest tertile of exposure to pesticides with no exposure. No association was found for occupational exposure to PAHs (RR 0.75; 95% CI 0.42 to 1.31), diesel exhaust (RR 0.81; 95% CI 0.62 to 1.06), metal dust (RR 1.01; 95% CI 0.72 to 1.40), metal fumes (RR 1.11; 95% CI 0.80 to 1.54), or mineral oil (RR 0.99; 95% CI 0.66 to 1.48) when comparing the highest tertile of exposure with no exposure. In subgroup analysis, with respect to tumour invasiveness and morphology, null results were found for occupational exposure to pesticides, PAH, diesel exhaust, metal dust, metal fumes, and mineral oil.

CONCLUSIONS

These results suggest a negative association between occupational exposure to pesticides and prostate cancer. For other carcinogenic exposures results suggest no association between occupational exposure to PAHs, diesel exhaust, metal dust, metal fumes, or mineral oil and prostate cancer.

Polycyclic aromatic hydrocarbon-DNA adducts in prostate cancer

The formation of DNA adducts can lead to DNA replication errors and the potential for carcinogenesis. DNA adducts have been detected in prostate cells, but the distribution of adducts with respect to prostate cancer risk factors and histology is unknown. In a study of 130 Caucasian (n = 61) and African-American (n = 69) men with prostate cancer who underwent radical prostatectomy, we quantified polycyclic aromatic hydrocarbon (PAH)-DNA adducts in prostate tumor and adjacent nontumor cells by immunohistochemistry. A strong correlation between paired adduct levels in the two cell types was observed (r = 0.56; P < 0.0001); however, nontumor cells had a significantly higher level of adducts compared with tumor (0.30 absorbance units +/- 0.05 versus 0.17 absorbance units +/- 0.04; P < 0.0001). Variables significantly associated with PAH-DNA adduct levels in tumor cells included primary Gleason grade, tumor volume, and log-transformed prostate-specific antigen (PSA) at time of diagnosis. Tumors with a primary Gleason grade of 5 had significantly lower PAH-DNA adduct levels than tumor cells with a primary Gleason grade of 3 or 4 (P < 0.0001 for both). Tumors that involved 10% or less of the prostate gland had significantly higher PAH-DNA adduct levels than tumors that involved 15 to 20% of the prostate gland (P = 0.004). PSA levels were inversely associated with PAH-DNA adduct levels in tumor cells (P = 0.009). A similar, albeit less significant, inverse association was observed between PSA and PAH-DNA adduct levels in nontumor cells (P = 0.07). Interestingly, increasing primary Gleason grade was associated with increasing PAH-DNA adduct levels in adjacent nontumor cells (P = 0.008). Our results show that PAH-DNA adducts are present in the prostate but vary with regard to cellular histology. In prostate tumor cells, decreased cellular differentiation and increased tumor proliferation may reduce PAH-DNA adduct levels.

Assessment of anthracene toxicity toward environmental eukaryotic microorganisms: Tetrahymena pyriformis and selected micromycetes

The toxicity of anthracene, a nonmutagenic, noncarcinogenic, low-molecular-weight polycyclic aromatic hydrocarbon present in the environment, was assessed using a ciliated protozoan, Tetrahymena pyriformis, and a selection of 10 micromycetes from different taxonomic groups living in two environmental compartments, namely aquatic and soil ecosystems. With T. pyriformis, a concentration-dependent inhibitory effect was shown on the cell proliferation rate, IC(50) = 33.40+/-4.84 mg/L (kinetic method). Phagocytosis of nonsoluble anthracene was confirmed by the presence of digestive vacuoles with photon microscopy. In fungi, anthracene did not exhibit a fungicide effect but showed a fungistatic action. Except for Absidia fusca and Cladosporium herbarum, the micromycetes showed a concentration-dependent decrease in growth. From IC(50) values determined by endpoint or kinetic methods, Rhodotorula glutinis and all of the Ascomycotina (except for Penicillium chrysogenum) were the most sensitive species, while Phanerochaete chrysosporium, P. chrysogenum, and the two Deuteromycotina were more resistant to anthracene. Our discussion focuses on the evaluation of toxicity by the two methods used for the calculation of the IC(50) values (endpoint and kinetic), the advantages of studying growth by a kinetic method (the dynamic aspect), and a comparison of toxicity to T. pyriformis and the different micromycetes.

Differential gene expression between squamous cell carcinoma of esophageus and its normal epithelium; altered pattern of mal, akr1c2, and rab11a expression

AIM: To identify the altered gene expression patterns in squamous cell carcinoma of esophagus (ESCC) in relation to adjacent normal esophageal epithelium.

METHODS: Total RNA was extracted using SV total RNA isolation kit from snap frozen tissues of ESCC samples and normal esophageal epithelium far from the tumor. Radio-labeled cDNA were synthesized from equal quantities of total RNAs of tumor and normal tissues using combinations of 24 arbitrary 13-mer primers and three different anchoring oligo-dT primers and separated on sequencing gels. cDNA with considerable different amounts of signals in tumor and normal tissue were reamplified and cloned. Using southern blot, the clones of each band were controlled for false positive results caused by probable heterogeneity of cDNA population with the same size. Clones that confirmed differential expression by slot blot selected for sequencing and northern analysis. Corresponding full-length gene sequences was predicted using human genome project data, related transcripts were translated and used for various protein/motif searches to speculate their probable functions.

RESULTS: The 97 genes showed different levels of cDNA in tumor and normal tissues of esophagus. The expression of mal gene was remarkably down regulated in all 10 surveyed tumor tissues. Akr1c2, a member of the aldo-keto reductase 1C family, which is involved in metabolism of sex hormones and xenobiotics, was up-regulated in 8 out of 10 inspected ESCC samples. Rab11a, RPL7, and RPL28 showed moderate levels of differential expression. Many other cDNAs remained to further studies.

CONCLUSION: The mal gene which is switched-off in all ESCC samples can be considered as a tumor suppressor gene that more studies in its regulation may lead to valuable explanations in ESCC development. Akr1c2 which is up-regulated in ESCC probably plays an important role in tumor development of esophagus and may be proposed as a potential molecular target in ESCC treatments. Differential display technique in spite of many disadvantages is still a valuable technique in gene function exploration studies to find new candidates for improved ones like gene chips.

Cancer risk in carbon electrode workers: an overview of epidemiological evidence

Carbon or graphite electrode manufacturing may lead to exposure to polycyclic aromatic hydrocarbons, some of which are considered human carcinogens. To provide comprehensive evidence on cancer risk, we have considered five cohort studies from the USA, France, Sweden and Italy, including about 6,500 workers and 80,000 man-years at risk. In two studies providing data on incidence, 52 incident cases of all neoplasms were reported versus 56.28 expected, corresponding to a standardized incidence ratio (SIR) of 0.92. There were nine cases of lung cancer (SIR=0.91) and three of urinary cancers (SIR=0.81). Four studies gave data on mortality. Overall, 853 deaths were observed versus 1,065.2 expected, corresponding to a standardized mortality ratio (SMR) of 0.80 (95% confidence interval, CI, 0.75-0.86). There were 269 deaths from all neoplasms, versus 292.1 expected (SMR=0.92, 95% CI 0.81-1.04), 82 deaths from respiratory cancers versus 95.8 expected (SMR=0.86), and 15 deaths from bladder and urinary cancers versus 12.7 expected (SMR=1.18). None of these estimates were significant, and for none of the other cancer sites there was evidence of excess risk. Thus, epidemiological data allow excluding any appreciable risk of cancer--in particular of the respiratory and the urinary tract--in carbon electrode workers.

Biodegradation capability of Absidia fusca Linnemann towards environmental pollutants

The purpose of this work was to study the bioremediation capability of Absidia fusca Linnemann (Zygomycete) towards different classes of xenobiotics (lignin-derived compounds, chloroaromatic compounds, polycyclic aromatic hydrocarbons) the presence of which in contaminated soils, water and sediments poses a significant risk to the environment and human health. Two strains from different origins were compared. One was from an official collection and grown in non-inducing conditions, while the other was isolated during the course of the survey of fungal flora in a polluted soil from Annaba (Algeria). All data were analyzed and results validated via a statistical treatment. We showed the effect of the factors studied (origin of the strain, xenobiotic) but also the interactions between these factors. The strain of A. fusca isolated from a polluted soil was able to efficiently degrade most of the xenobiotics tested, particularly: pentachlorophenol, phenol, catechol, guaiacol and ferulic acid. This property also existed in the other strain but at a very low level.

Primary cultures of prostate cells and their ability to activate carcinogens

Differences in the incidence of prostate cancer (CaP) amongst different migrant populations point to causative agents of dietary and/or environmental origin. Prostate tissues were obtained following transurethral resection of the prostate (TURP) or radical retropubic prostatectomy. After surgery, TURP-derived or tumour-adjacent tissue fragments were minced in warm PFMR-4A medium (37 degrees C) and suspensions pipetted into collagen-coated petri dishes. Non-adherent material was removed by washing with fresh medium after 12 h. Adhered cells subsequently reacted positively with monoclonal antibodies to prostate specific antigen (PSA). PSA was also detected in the medium. The genotoxicities of the chemical carcinogens 2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine (PhIP), its N-hydroxy metabolite (N-OH-PhIP) and benzo[a]pyrene (B[a]P) in adherent cell populations from different donors (n=8) were examined. Cells were treated in suspension for 30 min at 37 degrees C in the presence of the DNA repair inhibitors hydroxyurea (HU) and cytosine arabinoside (ara-C). DNA single-strand breaks were detected in cells by the alkaline single cell-gel electrophoresis ('Comet') assay and quantified by measuring comet tail length (CTL) in microm. All three carcinogens induced dose-related increases in CTLs (P<0.0001) in cells from four donors 24 h post-seeding. However, in cells from a further two donors the genotoxic effects of PhIP, N-OH-PhIP and B[a]P were much less apparent after 48 h than after 24 h in culture. After 96 h in culture, cells from these donors appeared to be resistant to the comet-forming activity of the compounds. However, B[a]P-DNA adducts were still measurable by (32)P-postlabelling for up to 14 days following a 24-h exposure to 50 microM B[a]P in adhered cells from another two donors. This study shows that primary cultures of cells derived from the prostate can activate members of two classes of chemical carcinogens. Further development may provide a robust model system in which to investigate the aetiology of CaP.

Geographical differences in cancer incidence in the Amazon basin of Ecuador in relation to residence near oil fields

BACKGROUND

Since 1972, oil companies have extracted more than 2 billion barrels of crude oil from the Ecuadorian Amazon, releasing billions of gallons of untreated wastes and oil directly into the environment. This study aimed to determine if there was any difference in overall and specific cancer incidence rates between populations living in proximity to oil fields and those who live in areas free from oil exploitation.

METHODS

Cancer cases from the provinces of Sucumbios, Orellana, Napo and Pastaza during the period 1985-1998 were included in the study. The exposed population was defined as those living in a county (n = 4) where oil exploitation had been ongoing for a minimum of 20 years up to the date of the study. Non-exposed counties were identified as those (n = 11) without oil development activities. Relative risks (RR) along with 95% CI were calculated for men and women as ratios of the age-adjusted incidence rates in the exposed versus non-exposed group.

RESULTS

The RR of all cancer sites combined was significantly elevated in both men and women in exposed counties. Significantly elevated RR were observed for cancers of the stomach, rectum, skin melanoma, soft tissue and kidney in men and for cancers of the cervix and lymph nodes in women. An increase in haematopoietic cancers was also observed in the population under 10 years in the exposed counties in both males and females.

CONCLUSION

Study results are compatible with a relationship between cancer incidence and living in proximity to oil fields. An environmental monitoring and cancer surveillance system in the area is recommended.

Biodegradation of anthracene and fluoranthene by fungi isolated from an experimental constructed wetland for wastewater treatment

Pilot-scale constructed wetlands were used to treat water contaminated by polycyclic aromatic hydrocarbons (PAHs), particularly fluoranthene, and the possible role of fungi present in these ecosystems was investigated. A total of 40 fungal species (24 genera) were isolated and identified from samples (gravel and sediments) from a contaminated wetland and a control wetland. All of them were assayed for their ability to remove anthracene (AC) and fluoranthene (FA) from liquid medium. FA was degraded efficiently by 33 species while only 2 species were able to remove AC over 70%. A selection of 10 strains of micromycetes belonging to various taxonomic groups was further investigated for FA and AC degradation, toxicity assays and phenoloxidases (POx) detection. Interesting and not previously reported species were revealed (Absidia cylindrospora, Cladosporium sphaerospermum, and Ulocladium chartarum). They were all able to highly degrade the PAH-model compounds chosen. An interesting inducibility was noted for Ulocladium chartarum. Degradative ability of fungi was not related to their extracellular POx activity. This study may contribute to the improvement of constructed wetlands for water treatment, which may be enriched in efficient fungi.

Exposures and cancer incidence near oil fields in the Amazon basin of Ecuador

OBJECTIVES

To examine environmental exposure and incidence and mortality of cancer in the village of San Carlos surrounded by oil fields in the Amazon basin of Ecuador.

METHODS

Water samples of the local streams were analyzed for total petroleum hydrocarbons (TPHs). A preliminary list of potential cancer cases from 1989 to 1998 was prepared. Cases were compared with expected numbers of cancer morbidity and mortality registrations from a Quito reference population.

RESULTS

Water analysis showed severe exposure to TPHs by the residents. Ten patients with cancer were diagnosed while resident in the village of San Carlos. An overall excess for all types of cancer was found in the male population (8 observed v 3.5 expected) with a risk 2.26 times higher than expected (95% confidence interval (95% CI) 0.97 to 4.46). There was an overall excess of deaths for all types of cancer (6 v 1.6 expected) among the male population 3.6 times higher than the reference population (95% CI 1.31 to 7.81).

CONCLUSIONS

The observed excess of cancer might be associated with the pollution of the environment by toxic contaminants coming from the oil production.

Metabolic activation of carcinogens and expression of various cytochromes P450 in human prostate tissue

Epidemiological evidence suggests a link between meat consumption and prostate cancer. In this study, benign prostatic hyperplasia tissues, obtained by transurethral resection or radical retropubic prostatectomy from UK-resident individuals (n = 18), were examined for CYP1 expression and for their ability, in short-term organ culture, to metabolically activate carcinogens found in cooked meat. Semi-quantitative RT-PCR analysis of CYP1 expression detected CYP1A2 mRNA transcripts in the prostates of four individuals, as well as mRNA transcripts from CYP1A1 and CYP1B1. The compounds tested for metabolic activation were 2-amino-1-methyl-6-phenylimidazo[4, 5-b]pyridine (PhIP; 500 microM, n = 9) and its metabolite N:-hydroxy PhIP (20 microM, n = 8), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ; 500 microM, n = 6) and benzo[a]pyrene (B[a]P; 50 microM, n = 5). After incubation (PFMR medium, 22 h, 37 degrees C), DNA was isolated from tissue fragments and DNA adducts were detected and quantified by (32)P-postlabelling analysis. DNA adduct formation was detected in all samples incubated with PhIP (mean, adducts per 10(8) nucleotides), N:-hydroxy-PhIP (2736/10(8)) or B[a]P (1/10(8)). IQ-DNA adducts were detected in 5/6 tissues (mean, 1/10(8)). The CYP1 inhibitor alpha-naphthoflavone (10 microM) reduced B[a]P-DNA adduct formation in tissues from two individuals by 96 and 64%, respectively. This pilot study shows that human prostate tissue can metabolically activate 'cooked meat' carcinogens, a process that could contribute to prostate cancer development.

Workplace exposures and oesophageal cancer

OBJECTIVES

To describe the relation between oesophageal cancer and many occupational circumstances with data from a population based case-control study.

METHODS

Cases were 99 histologically confirmed incident cases of cancer of the oesophagus, 63 of which were squamous cell carcinomas. Various control groups were available; for the present analysis a group was used that comprised 533 population controls and 533 patients with other types of cancer. Detailed job histories were elicited from all subjects and were translated by a team of chemists and hygienists for evidence of exposure to 294 occupational agents. Based on preliminary results and a review of literature, a set of 35 occupational agents and 19 occupations and industry titles were selected for this analysis. Logistic regression analyses were adjusted for age, birthplace, education, respondent (self or proxy), smoking, alcohol, and beta-carotene intake.

RESULTS

Sulphuric acid and carbon black showed the strongest evidence of an association with oesophageal cancer, particularly squamous cell carcinoma. Other substances showed excess risks, but the evidence was more equivocal-namely chrysotile asbestos, alumina, mineral spirits, toluene, synthetic adhesives, other paints and varnishes, iron compounds, and mild steel dust. There was considerable overlap in occupational exposure patterns and results for some of these substances may be mutually confounded. None of the occupations or industry titles showed a clear excess risk; the strongest hints were for warehouse workers, food services workers, and workers from the miscellaneous food industry.

CONCLUSIONS

The data provide some support for an association between oesophageal cancer and a handful of occupational exposures, particularly sulphuric acid and carbon black. Many of the associations found have never been examined before and warrant further investigation.

Fungal degradation of fluorene

A selection of 30 strains of micromycetes known as good degraders of polychlorinated aromatic compounds, mostly isolated from soil and belonging to various taxonomic groups, have been investigated to degrade fluorene. Toxicity assays, first evaluated on solid media, have shown high growth inhibition at concentrations above 0.001 g l-1 only towards 23% of strains. Degradation of fluorene (0.005 g l-1) was then investigated in liquid synthetic medium for 2 days and evaluated by HPLC. Among the 30 strains tested, 12 could be considered as best degraders because of a rate of degradation at 60% or over. 3 strains of Cunninghamella genus were very efficient (mean of degradation: 96%) but different strains from Ascomycetes. Basidiomycetes and Deuteromycetes were also efficient 11 strains are not yet reported in the literature: Aspergillus terreus, Bjerkandera adusta, Ceriporiopsis subvermispora, Colletotrichum dematium, Cryphonectria parasitica, Cunninghamella blakesleeana, C. echinulata, Drechslera spicifera, Embellisia annulata, Rhizoctonia solani and Sporormiella australis. A metabolic approach with standard compounds (9-fluorenol and 9-fluorenone) indicated the presence of these monooxygenated derivatives for most of the strains.

Cancer mortality among women in the Russian printing industry

BACKGROUND

This study evaluates cancer mortality among women employed in two large printing plants in Moscow.

METHODS

A total of 3,473 women who were actively employed as of December 31, 1978, with a minimum of 2 years employment were followed from 1 January 1979 to 31 December 1993. There were 47,791 person-years observed, with only 51 women lost to follow-up (1.5%). Standardized mortality ratios (SMRs) were calculated using the population of Moscow to generate expected numbers. Analyses by job (compositors, press operators, and bookbinders), age hired, latency, and duration of employment were conducted.

RESULTS

Among women employed in the two printing plants, there was a significant excess of esophageal cancer, based on seven deaths (expected = 2.7, SMR = 2.7, 95% CI = 1.1-5.4). Four of the seven esophageal cancer deaths occurred among bookbinders (expected = 1.0, SMR = 4.1, 95% CI = 1.1-10.4), all among workers hired before 1957 (expected = 0.6, SMR = 7.1, 95% CI = 1.9-18.3), the last year benzene was used in bookbinding. Ovarian cancer was also significantly elevated among bookbinders (12 observed, 4.2 expected, SMR = 2.9, 95% CI = 1.5-5.0), which, along with one death from mesothelioma of the abdomen, might be related to the use of asbestos-contaminated talc fillers in paper. Press operators had significantly elevated mortality from stomach cancer (observed = 9, expected = 4.1, SMR = 2.2, 95% CI = 1.0-4.2) and, based on two deaths each, melanoma and bladder cancer.

CONCLUSIONS

Women in this printing industry cohort experienced excess mortality of cancer of the esophagus and stomach, with suggested increases of melanoma and bladder cancer. Further follow-up of this cohort, which would allow more in-depth analysis of rare cancer sites, latency, and duration of employment, is warranted. Gender comparisons within the cohort should also be conducted to clarify the role of occupational and lifestyle factors in the etiology of cancer among workers in the printing industry.

Food heating and the formation of heterocyclic aromatic amine and polycyclic aromatic hydrocarbon mutagens/carcinogens

Heterocyclic aromatic amines (HAA) and polycyclic aromatic hydrocarbons (PAH) are mutagens and animal carcinogens sometimes formed when foods are heated or processed. Determining their role in cancer etiology depends on comparing human exposures and determining any significant dose-related effects. Chemical analysis of foods shows that flame-grilling can form both PAH and HAA, and that frying forms predominantly HAA. With detection limits of about 0.1 ng/g, amounts found in commercially processed or restaurant foods range from 0.1 to 14 ng/g for HAA, and levels of PAH up to 1 ng/g in a liquid smoke flavoring. Laboratory fried samples have greater amounts of PAH, up to 38 ng/g in hamburgers, and high levels of HAA, over 300 ng/g, are measured in grilled chicken breast. Understanding the processing conditions that form PAH and HAA can lead to methods to greatly reduce their occurrence in processed foods.

Exposure to mutagenic airborne particulate in a rubber manufacturing plant

Epidemiological studies conducted in the 1980s revealed that people working in the rubber manufacturing industry had an increased risk of cancer. Even now, workers employed in rubber processing are still at risk despite the measures adopted to improve their working conditions. The aim of the study was to evaluate the presence of a genotoxic risk in a rubber industry and to verify whether or not it was possible to locate the most dangerous position among the different rubber-working processes. The mutagenic activity of airborne particulate was evaluated in samples collected in the mixing department of a rubber manufacturing plant. Ambient air samples were taken over 3-h period in two stable positions near the mixing (Banbury mixer) and calendering areas. Personal air samples were taken over 2-h period during a normal workday from five workers employed in different rubber processing operations (mixing, weighing, calendering, compounding and extruding). The mutagenic activity of the air samples was determined by plate incorporation assay using Salmonella typhimurium strains (TA 98, TA 98NR, TA 100, YG 1021) with and without metabolic activation. Polycyclic aromatic hydrocarbon (PAH) concentrations were determined by high-performance liquid chromatography (HPLC); the presence of other presumable contaminants were carried out by gas chromatography-mass spectrometry (GC-MS). The results showed substantial direct and indirect frameshift mutagenicity in both ambient and personal samples. No mutagenic activity was present in S. typhimurium TA 100, except in the personal sample from a worker employed on the Banbury mixer. HPLC analysis revealed very low concentrations of PAHs. GC-MS analysis showed the presence of compounds such as azulene derivative, 1,2-dihydro-2,2,4-trimethylquinoline, N-methyl N-phenylbenzenamine, diphenylamine, bis(2-ethylhexyl)phthalate and bis(methyl-propyl)phthalate. We conclude that the high levels of mutagenic activity in ambiental and personal samples indicate the presence of substances with high genotoxic potency; no substantial differences were seen among the several rubber processing operations. PAHs were not involved in indoor pollution. GC-MS analysis revealed the presence of compounds which may be produced by high temperatures to which the raw materials are subjected during rubber manufacturing processes. These substances are potential carcinogen though their mutagen properties have not been clearly determined.

Assessment of exposure to polycyclic aromatic hydrocarbons during firefighting by measurement of urinary 1-hydroxypyrene

Firefighters may be exposed to carcinogenic agents in the smoke from fires, and there has been some concern regarding firefighters' risk of developing occupational-related cancer. Polycyclic aromatic hydrocarbons (PAHs) are present in most fires, posing a cancer risk. The objective of this study was to evaluate the PAH exposure among firefighters. Students (n = 9) and teachers (n = 4) at a firefighter training school delivered urine samples before and 6 to 7 hours after extinguishing burning diesel fuel. The urine samples were analyzed by high-performance liquid chromatography for 1-hydroxypyrene. A small but significant increase in 1-hydroxypyrene levels in the urine was found after the firefighting. This means that firefighting may cause exposure to PAHs. Although the exposure levels were low in this study, they may be different during other types of fires.