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PubMed2002

[Changes in occupational morbidity among workers of petroleum, oil-processing and petroleum chemical industries over 40 years].

Analysis covered 3784 cases of occupational diseases diagnosed first in Research Institute for Industrial Medicine and Human Ecology in Ufa from 1960 till 2000. Locomotory and peripheral nervous system disorders appeared to predominate in structure of occupational morbidity. The authors failed to reveal direct correlation between occupational morbidity level and work conditions jeopardy class.

Adult↗

PubMed1981

[Comparative studies on toxicity of various dielectrics, petroleum derivatives, used in electroerosion technology. IV. Morphological and cytoenzymatic changes in the lungs and acid-base imbalance in rats chronically exposed to petroleum hydrocarbons].

In rats exposed to odourless kerosene of 75 and 300 mg/m3 concentration, for 14 weeks, morphologic and cytoenzymatic examinations of lungs have been carried out and acid-base equilibrium indices in blood have been determined. Passive congestion of lung parenchyma, subpleural blood extravasation, atelectasis foci, thickened interalveolar septa with infiltrates from neutrophils, lymphocytes, eosinophils and macrophages have been found. In addition a decrease in succinic dehydrogenase activity, NADPH -- tetrazolium reductase, and Mg++-ATP-ase and increase in acid phosphatase activity have been revealed. Those have been focal changes, involving, apart from bronchial tree (low exposure -- 75 mg/m3), the remaining lung parenchyma segments (high exposure -- 300 mg/m3). In addition, disturbances in acid-base equilibrium in form of compensated metabolic alkalosis (75 mg/m3) and compensated metabolic acidosis (300 mg/m3) have occurred. The obtained results demonstrate toxic effects of kerosene hydrocarbons on the function and structure of lungs.

Acid Phosphatase↗

PubMed2006

Petroleum pollutant degradation by surface water microorganisms.

BACKGROUND, AIMS AND SCOPE: It is well known that the composition of petroleum or some of its processing products changes in the environment mostly under the influence of microorganisms. A series of experiments was conducted in order to define the optimum conditions for an efficient biodegradation of petroleum pollutant, or bioremediation of different segments of the environment. The aim of these investigations was to show to what extent the hydrocarbons of a petroleum pollutant are degraded by microbial cultures which were isolated as dominant microorganisms from a surface water of a wastewater canal of an oil refinery and a nitrogen plant. Biodegradation experiments were conducted on one paraffinic, and one naphthenic type of petroleum during a three month period under aerobic conditions, varying the following parameters: Inorganic (Kp) or an organic medium (Bh) with or without exposition to light. METHODS: Microorganisms were analyzed in a surface water sample from a canal (Pancevo, Serbia), into which wastewater from an oil refinery and a nitrogen plant is released. The consortia of microorganisms were isolated from the water sample (most abundant species: Phormidium foveolarum--filamentous Cyanobacteria, blue-green algae and Achanthes minutissima, diatoms, algae). The simulation experiments of biodegradation were conducted with the biomass suspension and crude oils Sirakovo (Sir, paraffinic type) and Velebit (Ve, naphthenic type). After a three month period, organic substance was extracted by means of chloroform. In the extracts, the content of saturated hydrocarbons, aromatic hydrocarbons, alcohols and fatty acids was determined (the group composition). n-Alkanes and isoprenoid aliphatic alkanes, pristane and phytane, in the aliphatic fractions, were analyzed using gas chromatography (GC). Total isoprenoid aliphatic alkanes and polycyclic alkanes of sterane and triterpane types were analyzed by GC-MS. RESULTS AND DISCUSSION: Paraffinic type petroleums have a significant loss of saturated hydrocarbons. For naphthenic type petroleum, such a trend has not been observed. The most intensive degradation of n-alkanes and isoprenoid aliphatic alkanes (in paraffinic oil) and isoprenoids (in naphthenic oil) was observed using the inorganic medium Kp in the light; the microbial conversion is somewhat lower with Kp in the dark; with organic medium Bh in the light the degradation is of low intensity; with the same medium in the dark the degradation is hardly to be seen. Steranes and triterpanes were not affected by microbial degradation under the conditions used in our experiments. Obviously, the petroleum biodegradation was restricted to the acyclic aliphatics (n-alkanes and isoprenoids). CONCLUSION: Phormidium foveolarum (filamentous Cyanobacteria--blue-green algae) and Achanthes minutissima (diatoms, algae), microbial cultures isolated as dominant algae from a surface water in a wastewater canal of an oil refinery and a nitrogen plant, have degradable effects dominantly involving petroleum hydocarbons. Petroleum microbiological degradation is more intensive when inorganic medium (in the light) is applied. Having in mind that the inorganic pollutants have been released into the canal as well, this medium reflects more the natural environmental conditions. Polycyclic alkanes of sterane and triterpane type, in spite of the fact that these compounds could be degraded, have remained unchanged regarding abundance and distribution. Since this is the case even for naphthenic type petroleum (which is depleted in n-alkanes), it can be concluded that the biodegradation of petroleum type pollutants, under natural conditions, will be restrained to the n-alkane and isoprenoid degradation. RECOMMENDATION AND OUTLOOK: Performed experiments and simulations of petroleum microbiological degradation may serve for the prediction of the fate of petroleum type pollutants, as well as for definition of conditions for bioremediation of some environmental segments.

Biodegradation, Environmental↗

PubMed1995

Cell-type-specific leukemia analyses in a combined cohort of more than 208,000 petroleum workers in the United States and the United Kingdom, 1937-1989.

A large number of epidemiologic studies of workers in the petroleum industry have been conducted to investigate the carcinogenic and other health effects of exposure to petroleum products during manufacture and distribution. Of particular interest is the relationship between exposure to benzene or benzene-containing liquids in the petroleum industry and leukemia risk. However, few studies have investigated cell-type-specific leukemia risk. In the present investigation, all cohort studies of petroleum workers in the United States and the United Kingdom were combined into a single database for cell-type-specific leukemia analysis. The majority of these workers were petroleum refinery employees, but production, pipeline, and distribution workers in the petroleum industry were also included. The combined cohort consisted of 208,741 petroleum workers. Between 1937 and 1989, these workers contributed a total of 4,665,361 person-years of observation. More than 56 thousand deaths were reported among these workers during the 53 years of observation. Cell-type-specific leukemia risks were calculated using a meta-analysis procedure appropriate for combining occupational cohort studies. These risks were expressed in terms of cell-type-specific leukemia standardized mortality ratios (meta-SMRs). The meta-SMR for acute myelogenous leukemia was 0.96. The lack of an increase of acute myelogenous leukemia was attributed to the low levels of benzene exposure in the petroleum industry, particularly in comparison to benzene exposure levels in some previous studies of workers in other industries, who had been found to experience increased risk of acute myelogenous leukemia. Similarly, no increase in chronic myelogenous, acute lymphocytic, or chronic lymphocytic leukemias was found in petroleum workers (meta-SMRs of 0.89, 1.16, and 0.84, respectively). Meta-analyses restricted to refinery studies or to studies with at least 15 years of follow-up yielded similar results. The findings of the present investigation are consistent with those from several recent case-control studies.

Benzene↗

PubMed2003

Intrinsic bioremediation of a petroleum-impacted wetland.

Following the 1994 San Jacinto River flood and oil spill in southeast Texas, a petroleum-contaminated wetland was reserved for a long-term research program to evaluate bioremediation as a viable spill response tool. The first phase of this program, presented in this paper, evaluated the intrinsic biodegradation of petroleum in the contaminated wetland. Sediment samples from six test plots were collected 11 times over an 11-month period to assess the temporal and spatial petroleum concentrations. Petroleum concentrations were evaluated using gas chromatography-mass spectrometer analyses of specific target compounds normalized to the conservative biological marker, C(30)17alpha,21beta(H)-hopane. The analyses of specific target compounds were able to characterize that significant petroleum biodegradation had occurred at the site over the one-year period. Total resolved saturate and total resolved aromatic hydrocarbon data indicated the petroleum was degraded more than 95%. In addition, first-order biodegradation rate constants were calculated for the hopane-normalized target compounds and supported expected biodegradation patterns. The rapid degradation rates of the petroleum hydrocarbons are attributed to conditions favorable to biodegradation. Elevated nutrient levels from the flood deposition and the unconsolidated nature of the freshly deposited sediment possibly provided a nutrient rich, oxic environment. Additionally, it is suggested that an active and capable microbial community was present due to prior exposure to petroleum. These factors provided an environment conducive for the rapid bioremediation of the petroleum in the contaminated wetland.

Accidents↗

PubMed1996

Leukemia mortality by cell type in petroleum workers with potential exposure to benzene.

Workers in the petroleum industry are potentially exposed to a variety of petrochemicals, including benzene or benzene-containing liquids. Although a large number of studies of petroleum workers have been conducted to examine leukemia and other cancer risks, few existing studies have investigated cell-type-specific leukemias. One of the major reasons for the lack of cell-type-specific analysis was the small number of deaths by cell type in individual studies. In the present investigation, all cohort studies of petroleum workers in the United States and the United Kingdom were combined into a single database for cell-type-specific leukemia analysis. The majority of these workers were petroleum refinery employees, but production, pipeline, and distribution workers in the petroleum industry were also included. The combined cohort consisted of more than 208,000 petroleum workers, who contributed more than 4.6 million person-years of observation. Based on a meta-analysis of the combined data, cell-type-specific leukemia risks were expressed in terms of standardized mortality ratios (meta-SMRs). The meta-SMR for acute myeloid leukemia was 0.96. The lack of an increase of acute myeloid leukemia was attributed to the low levels of benzene exposure in the petroleum industry, particularly in comparison to benzene exposure levels in some previous studies of workers in other industries, who had been found to experience an increased risk of acute myeloid leukemia. Similarly, no increase in chronic myeloid, acute lymphocytic, or chronic lymphocytic leukemias was found in petroleum workers (meta-SMRs of 0.89, 1.16, and 0.84, respectively). Stratified meta-analyses restricted to refinery studies or to studies with at least 15 years of follow-up yielded similar results. The findings of the present investigation are consistent with those from several recent case-control studies of cell-type-specific leukemia. Patterns and levels of benzene exposure in the petroleum industry are reviewed. The results of the present epidemiologic investigation are discussed in conjunction with recent advances in leukemogenesis from other scientific disciplines.

Benzene↗

PubMed1989

Toxicology of oil field wastes. Hazards to livestock associated with the petroleum industry.

In oil-producing states, the proximity of livestock to drilling operations and production sites often results in poisoning of animals from ingestion of crude oil, condensate, salt water, heavy metals, and caustic chemicals. The heavy metals encountered most frequently are lead from pipe joint compound and arsenicals and chromates used as corrosion inhibitors. Numerous toxic and caustic chemicals are used in drilling muds and fluids. Crude oil and salt water spills are common occurrences around production sites. Pipeline breaks may result in exposure of livestock to crude oil or refined petroleum hydrocarbons. Ingestion of petroleum hydrocarbons may result in sudden death from peracute bloat. The most common cause of illness or death following exposure to petroleum hydrocarbons is aspiration pneumonia, which may cause a chronic progressive deterioration of health, with death after several days or weeks. Cases in which livestock are exposed to oil, salt water, or caustic chemicals, but do not die acutely or from aspiration pneumonia are more frustrating to diagnose. In these cases, parasitism, poor nutrition, and other debilitating diseases must be considered. Anorexia, weight loss, and decreased rumen motility may be caused by a disruption of normal rumen function. Petroleum hydrocarbons, salt water, and caustic chemicals have the potential of altering rumen flora and enzymatic processes as well as damaging the ruminal and gastrointestinal epithelium. The toxicity of petroleum hydrocarbons appears to be related more closely to the volatility and viscosity of the product than to other factors. The more volatile straight chain and aromatic petroleum hydrocarbons have a greater potential for aspiration pneumonia and may produce an anesthetic-like action if absorbed systemically. The more volatile petroleum hydrocarbons also are more irritating to skin and mucous membranes and appear to be more damaging to rumen flora. Treatment of petroleum hydrocarbon ingestion is aimed at preventing aspiration pneumonia and the animal's absorption of highly volatile components. Activated charcoal slurries and, in some instances, vegetable oil may be used to absorb the ingested petroleum or alter its viscosity to minimize absorption and aspiration. These procedures should be followed by the administration of rumenatories or saline cathartics to hasten the evacuation of the gastrointestinal tract. Chronic poor performance animals with anorexia and rumen dysfunction may respond to fresh rumen inoculant, intravenous glucose, and B-complex vitamins. Prognosis primarily hinges on whether or not aspiration pneumonia has occurred. Treatment of aspiration pneumonia rarely is effe

Animals↗

PubMed2000

Non-Hodgkin's lymphoma and exposure to benzene in a multinational cohort of more than 308,000 petroleum workers, 1937 to 1996.

Petroleum workers are exposed to benzene or benzene-containing petroleum products. As such, studies of these workers provide an opportunity for investigating the relationship between benzene and non-Hodgkin's lymphoma (NHL). However, few cohort studies of petroleum workers report results of NHL separately. One reason is that NHL is usually grouped with other lymphopoietic cancers in the analysis. Another reason is the relatively small number of NHL cases in some studies. To determine the risk of NHL in petroleum workers, we identified 26 cohorts of petroleum workers in the United States, the United Kingdom, Canada, Australia, Italy, and Finland. Authors of the original studies were contacted, and data on the number of observed deaths and person-years of observation were requested. Data from these studies were reviewed individually as well as combined in a pooled analysis (meta-analysis). In particular, results for individual cohorts, most of which had never been reported before, were presented. The combined multinational cohort consisted of more than 308,000 petroleum workers (6.6 million person-years), and the observation period covered an interval of 60 years from 1937 to 1996. A total of 506 NHL deaths were observed, compared with 561.68 expected. The standardized mortality ratio was 0.90 and the 95% confidence interval was 0.82 to 0.98. Analyses were performed by type of facility and industrial process. Stratum-specific standardized mortality ratios (95% confidence intervals) were 0.96 (0.86 to 1.07) for US refinery workers, 1.12 (0.90 to 1.37) for non-US refinery workers, 0.64 (0.50 to 0.82) for product (gasoline) distribution workers, and 0.68 (0.47 to 0.95) for crude oil workers. When individual cohorts were stratified by length of observation, no pattern was detected. In general, exposure levels before 1950 were much higher than thereafter. However, analysis of workers by hire date (< 1950, > or = 1950) revealed no difference in NHL mortality. Furthermore, none of the individual studies showed significant exposure-response relations. In summary, results from individual studies, as well as from the pooled analysis, indicated that petroleum workers were not at an increased risk of NHL as a result of their exposure to benzene or other benzene-containing petroleum products in their work environment. This conclusion was supported by cohort studies of workers in other industries who were exposed to benzene as well as by population-based case-control studies of NHL and occupational exposures.

Benzene↗

PubMed2005

[Study on the groundwater petroleum contaminant biodegradation by high efficient microorganism].

The groundwater petroleum contaminant biodegradation effect by high efficient hybrid microorganism was. investigated and the groundwater contaminant biodegradation transportation mathematical model was established in this study. The high efficient bacteria was separated and filtrated from the soil contaminated by petroleum hydrocarbon, and it was identified as Pseudomonas, Flavobacterium and Micrococcus. The petroleum degradation rates by these three kinds microorganism were 62%, 56% and 62% respectively in 24 h, and the high petroleum biodegradation rate 85% could be achieved by the hybrid microorganism constituted by these three kinds of microorganism, which was higher than that of any other each single bacteria community. The hybrid microorganism in-flowed into the reactor imitating the aquifer media with the petroleum wastewater, and it could form a steady microorganism zone in the foreside of the reactor. The petroleum biodegradation rate could achieve 60% when the petroleum wastewater flowed through this microorganism zone and the average petroleum biodegradation rate could reach up to 90% in the effluent. The groundwater contaminant biodegradation transportation mathematical model can predict the biodegradation of the wastewater through the microorganism zone effectively, of which the calculating values have good relativity with those of measurement.

Bacteria↗

PubMed1982

Neurotoxicity of petroleum benzine compared with n-hexane.

Petroleum benzine is one of the mixtures of organic solvents containing n-hexane. The occurrence of polyneuropathy in the workers using petroleum benzines is attributed mainly to n-hexane, though other hydrocarbons present are also suspected of having some neurotoxicity or some potential which could modify the neurotoxicity of n-hexane. The present experiment was performed in order to clarify the toxicity of petroleum benzine to the peripheral nerve and compare it with that of n-hexane. Forty rats were randomly divided into five groups. The groups were exposed to 200 ppm n-hexane, 500 ppm n-hexane, and petroleum benzine vapor containing 200 ppm n-hexane or 500 ppm n-hexane, together with aliphatic and aromatic hydrocarbons for 12 h a day for 24 weeks. The body weight, motor nerve conduction velocity, motor distal latency, and mixed nerve conduction velocities were measured before exposure and every 4 weeks of exposure. A rat from each exposed group was histopathologically examined after 24 weeks' exposure. The function of the peripheral nerve was conspicuously impaired by 500 ppm n-hexane, slightly impaired by 200 ppm n-hexane and petroleum benzine containing 500 ppm n-hexane, and even less impaired by petroleum benzine containing 200 ppm n-hexane. Degenerations of the myelin sheaths and axons were demonstrated in all exposed groups upon examination of the revealed tail nerves. Thus, the experiment revealed that petroleum benzine could impair the peripheral nerves, while some components of petroleum benzine were considered to inhibit the neurotoxicity of n-hexane.

Alkanes↗

PubMed1999

Petroleum jelly is an ideal contact medium for pain reduction and successful treatment with extracorporeal shock wave lithotripsy.

PURPOSE: Various minimally invasive approaches to reduce pain during extracorporeal shock wave lithotripsy (ESWL) have been described. We compared petroleum jelly (Vaselinet) and ultrasound gel in vitro as a contact medium based on the stone fragmentation rate. The analgesic effect of cutaneous petroleum jelly was tested against eutectic mixture of local anesthesia. We also evaluated the outcome of ESWL in a large group of patients treated with petroleum jelly. MATERIALS AND METHODS: In vitro 3 artificial stones were completely fragmented with a MFL 5000* lithotriptor using petroleum jelly or ultrasound gel as a contact medium. A total of 110 patients (group 1) received petroleum jelly before treatment with the same lithotriptor. After retrospective analysis of group 1 we matched 32 patients (group 2) receiving cutaneous eutectic mixture of local anesthesia. Because of the favorable results with petroleum jelly, we used it in another 148 patients, for a total of 258 patients (group V). Treatment dependent pain was scored using a questionnaire as 1--no, 2--minor, 3--tolerable and 4--intolerable. ESWL without additional analgesics had a pain score of 1 to 3. RESULTS: In vitro petroleum jelly had a superior fragmentation rate compared to ultrasound gel. Our long-term experience with the lithotriptor indicated that only 30% of patients required no additional analgesics with cutaneous ultrasound gel. In contrast, no additional analgesics were needed in only 38% of group 2 compared to 81.8% of group V. The stone fragmentation rate did not differ statistically between groups. CONCLUSIONS: Cutaneous petroleum jelly offers a noninvasive, highly effective, inexpensive treatment modality with no side effects and significant reduction in pain. This ointment is our contact medium of choice.

Anesthetics, Local↗

PubMed1986

In vitro genotoxicity studies using complex hydrophobic mixtures: efficient delivery of a petroleum sample to cultured C3H/10T1/2 cells via lipid vesicle incorporation.

Petroleum fractions are a diverse group of extremely hydrophobic mixtures, some of which display strong carcinogenicity in animal skin painting experiments. Interpretation of in vitro genotoxicity experiments with these samples is complicated by inefficient delivery of these hydrophobic substances inside target cells. We therefore developed methods to assess and improve the efficiency of delivering a petroleum sample (Matrix, A.P.I. 81-17) to cultured C3H/10T1/2 cells for genotoxicity studies via lipid vesicle incorporation. Three radiolabeled compounds (14C-benzo(a)pyrene, 14C-decane, and 14C-naphthalene) of widely differing volatilities, broadly representative of the spectrum of compounds in petroleum samples, were separately added to Matrix. Lipid vesicles containing Matrix and radiolabeled compounds were prepared by the classical methods for preparing neutral, positive, and negatively charged multilamellar and unilamellar liposomes. Of these, the classical methods for preparing neutral unilamellar liposomes were the most successful for delivering radiolabeled compounds in Matrix to cells. Vesicles optimal for the delivery of tracers in Matrix were prepared with DSPC:cholesterol:lyso-PC (8.8:0.8:0.4, molar ratio) in a Matrix to lipid ratio of 31:69 (w/w). This new method of delivery resulted in proportional, dose-dependent, and reproducible uptake of all tracers. Further, cells treated with this preparation took up 2.5-fold more 14C-decane, 1.5-fold more 14C-BaP, and 18-fold more 14C-naphthalene added to Matrix than did cells treated with Matrix emulsified in tissue culture medium. In contrast, tracers were not taken up in a proportional or reproducible manner when emulsions were used, and in fact, uptake of 14C-naphthalene was consistently very small. Two petroleum fractions, C(2)029188 and C(3)029194, were 4- and 6-fold more cytotoxic, respectively, when delivered to C3H/10T1/2 cells by lipid vesicles than emulsions. The carcinogenic petroleum fraction C(5)0292202 induces type II transformed foci in C3H/10T1/2 cells when cells were treated with C(5)0292202 incorporated into lipid vesicles. The methods for lipid vesicle incorporation described here are effective in delivering hydrophobic petroleum fractions to cells and provide an alternative to the current inefficient and artifactual methods of emulsification currently used. With further validation and standardization, lipid vesicle incorporation of petroleum fractions and treatment of cells with these vesicles should be useful for studying the genotoxicity of complex hydrophobic mixtures in cell culture systems.

Acetone↗

PubMed1997

Multiple myeloma and benzene exposure in a multinational cohort of more than 250,000 petroleum workers.

Case reports have suggested an association between benzene exposure and multiple myeloma. Because petroleum workers are exposed to benzene or benzene-containing liquids, studies of these workers provide an opportunity for investigating the relationship between benzene and multiple myeloma. A large number of cohort studies of petroleum workers have been conducted. However, few of them have reported results of multiple myeloma separately. One reason is that multiple myeloma is usually grouped with other lymphopoietic cancers in the analysis. Another reason is that multiple myeloma is relatively rare, and few individual studies are large enough to provide reliable risk estimates. To determine the risk of multiple myeloma in petroleum (refinery, distribution, production, and pipeline) workers, we have identified 22 cohort mortality studies of petroleum workers in the United States, the United Kingdom, Canada, and Australia. Authors of these studies were contacted, and data on the number of observed deaths and age-specific person-years of observation were requested. Data from individual studies were combined in a pooled analysis (meta-analysis). In addition to the pooled analyses, results for individual cohorts, most of which have never been reported before, are also presented. The combined multinational cohort consisted of more than 250,000 petroleum workers, and the observation period covered an interval of 55 years from 1937 to 1991. A total of 205 deaths from multiple myeloma were observed, compared to 220.93 expected, a total derived from respective national mortality rates. The corresponding standardized mortality ratio (SMR) was 0.93 and the 95% confidence interval (95% CI) was 0.81-1.07. Additional analyses were performed by type of facility and industrial process. Stratum-specific SMRs (95% CIs) were 0.92 (0.77-1.09) for refinery workers and 0.93 (0.69-1.23) for distribution workers. When individual cohorts were stratified by length of observation, no pattern was detected. The pooled analysis indicates that petroleum workers are not at an increased risk of multiple myeloma as a result of their exposure to benzene, benzene-containing liquids, or other petroleum products in their work environment. This conclusion is supported by cohort studies of workers in other industries who were exposed to benzene as well as by population-based case-control studies of multiple myeloma and occupational exposures.

Australia↗

PubMed2000

A critical review of cancer epidemiology in the petroleum industry, with a meta-analysis of a combined database of more than 350,000 workers.

In 1989 we published a critical review of cancer epidemiology in petroleum workers, which included as a component of the review a meta-analysis by cancer site. Subsequently we have completed three additional reviews and meta-analyses on cell-type-specific leukemias (1995), multiple myeloma (1997), and non-Hodgkin's lymphoma (2000). The objective of the present investigation was to update our 1989 review and meta-analysis of nonlymphohematopoietic cancers in cohort studies of petroleum workers. Included in the present investigation were cohort studies of petroleum workers from the United States, the United Kingdom, Canada, Australia, Finland, Sweden, and Italy. Individual studies were reviewed with regard to specific cancer sites. For each cancer of interest, risk ratios from the individual studies were presented. In some studies, subcohort analyses stratified by exposure parameters such as length of employment, job category, and hire year were also reported. These subcohort or stratified analyses were reviewed and the results of these analyses were taken into consideration in our interpretation. In addition to the qualitative review of individual studies, a meta-analysis was performed to combine data from individual cohort studies of petroleum workers. The primary purpose of the meta-analysis was to provide a summary measure of risk for each cancer site. Based on a review and meta-analyses of cohort studies of more than 350,000 petroleum workers in the United States, the United Kingdom, Canada, Australia, Finland, Sweden, and Italy, we concluded that there was no increased mortality from digestive cancers (stomach, large intestine, liver, or pancreas), lung cancer, bladder cancer, kidney cancer, or brain cancer. The summary standardized mortality ratios for these cancer sites were all below unity. Significant increases of melanoma mortality were reported in some small groups of refinery workers in the United Kingdom and upstream operation workers in Canada, but no responsible agent(s) had been identified. The observed mortality from skin cancer in all other studies was similar to the expected. In particular, no significant increase of skin cancer mortality was reported in any of the U.S. studies. Elevated mortality from prostate cancer was noted in short-term workers at a U.S. refinery and in short-term workers employed in certain crafts at U.S. crude oil operations. However, the absence of an upward trend by length of employment in these workers argued against an association between exposure to petroleum products and prostate cancer. For all petroleum workers as a whole, mortality from prostate cancer was as expected.

Australia↗

PubMed2003

The microbiology of hydrocarbon degradation in subsurface petroleum reservoirs: perspectives and prospects.

The majority of the Earth's petroleum resource is partly biodegraded. This is of considerable practical significance and can limit economic exploitation of petroleum reserves and lead to problems during petroleum production. Knowledge of the microorganisms present in petroleum reservoirs, their physiological properties and the biochemical potential for hydrocarbon degradation benefits successful petroleum exploration. Anaerobic conditions prevail in petroleum reservoirs and biological hydrocarbon degradation is apparently inhibited at temperatures above 80-90 degrees C. We summarise available knowledge and conjecture on the dominant biological processes active during subsurface petroleum biodegradation.

Aerobiosis↗

PubMed2003

Recent advances in petroleum microbiology.

Recent advances in molecular biology have extended our understanding of the metabolic processes related to microbial transformation of petroleum hydrocarbons. The physiological responses of microorganisms to the presence of hydrocarbons, including cell surface alterations and adaptive mechanisms for uptake and efflux of these substrates, have been characterized. New molecular techniques have enhanced our ability to investigate the dynamics of microbial communities in petroleum-impacted ecosystems. By establishing conditions which maximize rates and extents of microbial growth, hydrocarbon access, and transformation, highly accelerated and bioreactor-based petroleum waste degradation processes have been implemented. Biofilters capable of removing and biodegrading volatile petroleum contaminants in air streams with short substrate-microbe contact times (<60 s) are being used effectively. Microbes are being injected into partially spent petroleum reservoirs to enhance oil recovery. However, these microbial processes have not exhibited consistent and effective performance, primarily because of our inability to control conditions in the subsurface environment. Microbes may be exploited to break stable oilfield emulsions to produce pipeline quality oil. There is interest in replacing physical oil desulfurization processes with biodesulfurization methods through promotion of selective sulfur removal without degradation of associated carbon moieties. However, since microbes require an environment containing some water, a two-phase oil-water system must be established to optimize contact between the microbes and the hydrocarbon, and such an emulsion is not easily created with viscous crude oil. This challenge may be circumvented by application of the technology to more refined gasoline and diesel substrates, where aqueous-hydrocarbon emulsions are more easily generated. Molecular approaches are being used to broaden the substrate specificity and increase the rates and extents of desulfurization. Bacterial processes are being commercialized for removal of H(2)S and sulfoxides from petrochemical waste streams. Microbes also have potential for use in removal of nitrogen from crude oil leading to reduced nitric oxide emissions provided that technical problems similar to those experienced in biodesulfurization can be solved. Enzymes are being exploited to produce added-value products from petroleum substrates, and bacterial biosensors are being used to analyze petroleum-contaminated environments.

Aerobiosis↗

PubMedDate not supplied

Phytoremediation of aged petroleum sludge: effect of irrigation techniques and scheduling.

The use of higher plants to accelerate the remediation of petroleum contaminants in soil is limited by, among other factors, rooting depth and the delivery of nutrients to the microsites at which remediation occurs. The objective of this study was to test methods of enhancing root growth and remediation in the subsurface of a contaminated petroleum sludge. The phytoremediation of highly contaminated petroleum sludge (total petroleum hydrocarbons >35 g kg(-1) was tested in the greenhouse as a function of the frequency and the depth of irrigation and fertilization. Water and dissolved plant nutrients were added to the soil surface or at a depth of 30 cm, either daily or weekly. Equivalent quantities of water and nutrients were added in all cases. Daily irrigation at a depth of 30 cm invoked greater root growth and enhanced contaminant degradation relative to all other treatments. In the absence of plants, residual concentrations of petroleum hydrocarbons after 7 mo were higher than with plants. The presence of plant roots clearly improved the physical structure of the soil and increased microbial populations. Thus, the plant roots in conjunction with daily additions of soluble N and P appeared to enhance oxygen transport to greater depths in the soil, stimulate petroleum-degrading microorganisms, and provide microbial access to soil micropores. Subsurface irrigation with frequent, small amounts of water and nutrients could significantly accelerate phytoremediation of field soils contaminated with petroleum hydrocarbons.

Agriculture↗

PubMed1999

Petroleum biodegradation in marine environments.

Petroleum-based products are the major source of energy for industry and daily life. Petroleum is also the raw material for many chemical products such as plastics, paints, and cosmetics. The transport of petroleum across the world is frequent, and the amounts of petroleum stocks in developed countries are enormous. Consequently, the potential for oil spills is significant, and research on the fate of petroleum in a marine environment is important to evaluate the environmental threat of oil spills, and to develop biotechnology to cope with them. Crude oil is constituted from thousands of components which are separated into saturates, aromatics, resins and asphaltenes. Upon discharge into the sea, crude oil is subjected to weathering, the process caused by the combined effects of physical, chemical and biological modification. Saturates, especially those of smaller molecular weight, are readily biodegraded in marine environments. Aromatics with one, two or three aromatic rings are also efficiently biodegraded; however, those with four or more aromatic ring are quite resistant to biodegradation. The asphaltene and resin fractions contain higher molecular weight compounds whose chemical structures have not yet been resolved. The biodegradability of these compounds is not yet known. It is known that the concentrations of available nitrogen and phosphorus in seawater limit the growth and activities of hydrocarbon-degrading microorganisms in a marine environment. In other words, the addition of nitrogen and phosphorus fertilizers to an oil-contaminated marine environment can stimulate the biodegradation of spilled oil. This notion was confirmed in the large-scale operation for bioremediation after the oil spill from the Exxon Valdez in Alaska. Many microorganisms capable of degrading petroleum components have been isolated. However, few of them seem to be important for petroleum biodegradation in natural environments. One group of bacteria belonging to the genus Alcanivorax does become predominant in an oil-contaminated marine environment, especially when nitrogen and phosphorus fertilizers are added to stimulate the growth of endogenous microorganisms.

Biodegradation, Environmental↗