Breathing Zone Of Workers Research Articles

Influenza virus emitted by naturally-infected hosts in a healthcare setting

BackgroundThe emergence of novel respiratory viruses such as avian influenza A(H7N9) virus and the Middle East Respiratory Syndrome Coronavirus (MERS-CoV) highlights the importance of understanding determinants of transmission to healthcare workers (HCWs) and the public. ObjectivesWe aim to determine the viral content of the air emitted by symptomatic inpatients or long-term care residents with laboratory-confirmed influenza virus infection (emitters), and in the breathing zones of healthcare workers who attend to them. DesignA prospective pilot study of patients with laboratory-confirmed influenza virus infection was undertaken. Air within 1m of the patient was sampled using a high volume air sampler. In addition, a lower volume air sampler was placed <1m from the patient, with another >1m from the patient. Viral RNA was recovered from the samplers and submitted for quantitative real time PCR. In addition, personal button samplers were provided to HCWs. ResultsThe air emitted by 15 participants with laboratory-confirmed influenza virus infection was sampled. Of the patients infected with influenza A, viral RNA was recovered from the air emitted by 9/12 patients using the low-volume sampler; no viral RNA was detected from air emitted by patients with influenza B (n=3). Influenza virus RNA was recovered from one HCW’s sampler. ConclusionsPatients with respiratory virus infection emit virus into the air which disperses to >1m and may reach the breathing zone of a HCW. This pilot study highlights the feasibility and importance of conducting a larger-scale study to identify determinants of exposure and transmission from patient to HCW.

Performance of particulate containment at nanotechnology workplaces

The evaluation of engineering controls for the production or use of carbon nanotubes (CNTs) was investigated at two facilities. These controls assessments are necessary to evaluate the current status of control performance and to develop proper control strategies for these workplaces. The control systems evaluated in these studies included ventilated enclosures, exterior hoods, and exhaust filtration systems. Activity-based monitoring with direct-reading instruments and filter sampling for microscopy analysis were used to evaluate the effectiveness of control measures at study sites. Our study results showed that weighing CNTs inside the biological safety cabinet can have a 37% reduction on the particle concentration in the worker's breathing zone, and produce a 42% lower area concentration outside the enclosure. The ventilated enclosures used to reduce fugitive emissions from the production furnaces exhibited good containment characteristics when closed, but they failed to contain emissions effectively when opened during product removal/harvesting. The exhaust filtration systems employed for exhausting these ventilated enclosures did not provide promised collection efficiencies for removing engineered nanomaterials from furnace exhaust. The exterior hoods were found to be a challenge for controlling emissions from machining nanocomposites: the downdraft hood effectively contained and removed particles released from the manual cutting process, but using the canopy hood for powered cutting of nanocomposites created 15%-20% higher ultrafine (<500 nm) particle concentrations at the source and at the worker's breathing zone. The microscopy analysis showed that CNTs can only be found at production sources but not at the worker breathing zones during the tasks monitored.

Silica Exposures in Artisanal Small-Scale Gold Mining in Tanzania and Implications for Tuberculosis Prevention

Gold miners exposed to crystalline silica are at risk of silicosis, lung cancer, and experience higher incidence rates of pulmonary tuberculosis (TB). Although the hazards associated with mercury exposure in artisanal small-scale gold mining (ASGM) have been well documented, no published data was available on crystalline silica exposures in this population. Air sampling was conducted in the breathing zone of workers in five villages in Tanzania with battery-operated sampling pumps and bulk samples were collected to measure the type and concentration of crystalline silica in the ore. Samples were analyzed at an accredited laboratory with X-ray diffraction. Airborne crystalline silica exposures exceeded recommended limits for all tasks monitored with an average exposure of 16.85 mg/m3 for underground drilling that was 337 fold greater than the recommended exposure limit (REL) published by the U.S. National Institute for Occupational Safety and Health (NIOSH) and 0.19 mg/m3 for aboveground operations or 4-fold greater than the REL. The exposures measured raise concern for possible acute and chronic silicosis and are known to significantly contribute to TB incidence rates in mining communities. The use of wet methods could greatly reduce exposures and the risk of TB and silicosis in ASGM. Ongoing efforts to address mercury and other hazards in ASGM should incorporate crystalline silica dust controls.

Airborne Exposures to Polycyclic Aromatic Compounds Among Workers in Asphalt Roofing Manufacturing Facilities

We studied exposure of 151 workers to polycyclic aromatic compounds and asphalt emissions during the manufacturing of asphalt roofing products—including 64 workers from 10 asphalt plants producing oxidized, straight-run, cutback, and wax- or polymer-modified asphalts, and 87 workers from 11 roofing plants producing asphalt shingles and granulated roll roofing. The facilities were located throughout the United States and used asphalt from many refiners and crude oils. This article helps fill a gap in exposure data for asphalt roofing manufacturing workers by using a fluorescence technique that targets biologically active 4–6 ring polycyclic aromatic compounds and is strongly correlated with carcinogenic activity in animal studies. Worker exposures to polycyclic aromatic compounds were compared between manufacturing plants, at different temperatures and using different raw materials, and to important external benchmarks. High levels of fine limestone particulate in the plant air during roofing manufacturing increased polycyclic aromatic compound exposure, resulting in the hypothesis that the particulate brought adsorbed polycyclic aromatic compounds to the worker breathing zone. Elevated asphalt temperatures increased exposures during the pouring of asphalt. Co-exposures in these workplaces which act as confounders for both the measurement of total organic matter and fluorescence were detected and their influence discussed. Exposures to polycyclic aromatic compounds in asphalt roofing manufacturing facilities were lower than or similar to those reported in hot-mix paving application studies, and much below those reported in studies of hot application of built-up roofing asphalt. These relatively low exposures in manufacturing are primarily attributed to air emission controls in the facilities, and the relatively moderate temperatures, compared to built-up roofing, used in these facilities for oxidized asphalt. The exposure to polycyclic aromatic compounds was a very small part of the overall worker exposure to asphalt fume, on average less than 0.07% of the benzene-soluble fraction. Measurements of benzene-soluble fraction were uniformly below the American Conference of Governmental Industrial Hygienists' Threshold Limit Value for asphalt fume.

Silica exposure in the glass industry and human health risk assessment

Introduction: Among adverse effects in mines and industries, silica dust often been the subject of many controversies. Its severe and incurable side effects call for special attention to as well as assessment and control in workplaces. This study aims to determine the rate of silica concentration in the breathing zones of the glass industry in a comparison to standard limits in order to improve the safety of workers exposed to these particles. Materials and Methods: Being conducted in a glass factory in Tehran, this research employed a sampling method to measure the silica dust diffusion in six consecutive years from 2005 to 2010. The most effective method of dust level measurement in a workplace is to take samples in the breathing zone of workers exposed to it. In the subject factory, the sampling was performed in four sectors with the highest level of occupational exposure to the respirable dust. (1) Material charging unit, Excavator Operator. (2) Miscellaneous material weighing Operator (mixer). (3) Material charging, loading unit Operator. (4) Discharge (unloading) zone. The silica compound sampling and measur was conducted via the method by National Institute of US Occupational Health and Safety (NIOSH). By this method, the silica particles in the air were collected on the sorbent tube containing activated carbon (coconut shell) SKC-USA No. 226-01 and the sampling pump Model 222 ml/count, SKC with a flow rate of two liters per minute in the active method for 30 minutes. Then, observing necessary conditions and the chain of cold (Stored at 4΀C), the samples were transferred to the laboratory. The breathing zone samples were also collected from the four mentioned sectors by the sampling pump. Samples were analyzed with the Flame Ionization Detector, when they were transferred to the laboratory by Gas Chromatography Apparatus with the Flame. Results: Time-weighted a Average (TWA) exposure was at its highest level in 2009 and at its lowest level in 2008. Findings of the study also revealed that the amount of environmental silica dust threshold limit value in the material charging Unit of loading and Excavator Operators in the discharge zone was higher than the threshold limit value. After determining the dispersion density of suspended silica particles, TLV, TWA, and the non-cancer risk ratio of the particles in the mentioned sectors, control strategies and corrective suggestions were proposed. Conclusions: Results showed that, the silica concentration in the breathing zone of the glass industry was higher than the threshold limit value. Silica is a carcinogenic material causes chronic respiratory diseases and silicosis, therefore it is recommended to observe the safety principles and use wet silica in stead. The concentration of silica is at its highest level in the loading and unloading units, thus the engineering and managing controls should be utilized to avoid the direct exposure to these suspended particles. Moreover, the workers in these sectors should be well-trained regarding the exposure to silica and use of individual protective equipment.

An empirical study on the wake around a squatting worker in a confined space.

When an air current flows from behind a worker, the contaminant level in the breathing zone may increase due to the wake around the worker. Researchers have been investigating about this wake, and much knowledge has been provided about the wake that appears around a standing worker. However, the wake around a squatting worker has not been addressed. This study aimed to describe the wake in front of a worker squatting in a confined space by using a model worker and a chamber and investigate the conditions in which this wake develops easily. A mannequin was employed as a model worker and was placed in the chamber to simulate a squatting worker in a confined space. Then, air was sent from behind under various conditions with a fan, and the wake was observed. A wake appeared when smoke was emitted at 0-0.1 m from the point just below the breathing zone, and most of the wake region was in the range between the point just below the model worker's breathing zone and body. A wake did not appear when a fan of 0.15 m in diameter was used. The flow rate and velocity of the airflow were almost irrelevant with respect to wake development. The following are recommended based on the results of the present study. i) The distance between a source of contaminants and the point just below the breathing zone should be more than 0.2 m. ii) An air duct with a cross-section of less than 0.02 m(2) is desirable to avoid producing a wake.

Application of good practices as described by the NEPSI agreement coincides with a strong decline in the exposure to respiratory crystalline silica in Finnish workplaces.

To protect the health of those occupationally exposed to respirable crystalline silica, the main industries in European Union associated with exposure to respirable silica, agreed on appropriate measures for the improvement of working conditions through the application of good practices, as part of 'The Agreement on Workers Health Protection through the Good Handling and Use of Crystalline Silica and Products Containing it' (NEPSI agreement), signed in April 2006. The present paper examines trends in exposure to respirable crystalline silica in Finland prior to and following the implementation of the NEPSI agreement and includes a working example of the NEPSI approach in the concrete industry. Data derived from workplace exposure assessments during the years 1994-2013 are presented, including 2556 air samples collected mostly indoors, from either the breathing zone of workers or from stationary points usually at a height of 1.5 m above the floor, with the aim to estimate average exposure of workers to respiratory crystalline silica during an 8-h working day. The aim was, to find out how effective this unique approach has been in the management of one of the major occupational hazards in the concerned industries. Application of good practices as described by the NEPSI agreement coincides with a strong decline in the exposure to respirable crystalline silica in Finnish workplaces, as represented by the clientele of Finnish Institute of Occupational Health. During the years followed in the present study, we see a >10-fold decrease in the average and median exposures to respirable silica. Prior to the implementation of the NEPSI agreement, >50% of the workplace measurements yielded results above the OEL8 h (0.2mg m(-3)). As of present (2013), circa 10% of the measurements are above of or identical to the OEL8 h (0.05mg m(-3)).

0195 Carbon nanotube exposure assessment for a study on early biological effects; the CANTES study

ObjectivesTo assess personal exposure to carbon nanotubes for a study of early effect biomarkers among workers exposed to carbon nanotubes (CNTs).MethodThree major job categories were identified in the exposed factory:...

Use of Direct Reading and Short Term Sampling of Indoor Air Quality in a Veterans Affairs Dental Clinic Laboratory for Select Air Contaminants

This screening survey was conducted to assess the concentrations of select airborne contaminants in a Veterans Affairs Medical Center Dental Laboratory. Airborne concentrations were measured for the following contaminants: ni- trous oxide (N2O), carbon dioxide (CO2), sulfur dioxide (SO2), and airborne particles or particulate matter (PM). The PM was measured and classified by the aerodynamic diameter of the particulates; specifically as PM0.3, PM0.5, PM1.0, PM2.0, PM5.0 and PM10.0.The gases were measured with a Miran Sapphire, portable infrared analyzer. The particulates were measured using the Fluke 983 Particle Counter. Using these instruments, area monitoring was conducted for concentra- tions of gases and aerosols as a result of releases from dental activities such as waxing and grinding of dental models. All area monitoring samples were collected within approximately one foot of the breathing zone of dental workers. The re- sults of this survey found the air quality in the dental laboratory was within the regulatory limits for these agents. How- ever, the concentration of SO2 was found to exceed the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLV) on more than one occasion. This was potentially due to room ventilation inade- quacies. It is recommended that the dental laboratory's ventilation system be modified and operated to assure more effec- tive dilution and removal of air contaminants.

DNA Damage and Susceptibility Assessment in Industrial Workers Exposed to Styrene

Styrene is a widely used chemical in the manufacture of synthetic rubber, resins, polyesters, and plastics. The highest levels of human exposure to styrene occur during the production of reinforced plastic products. The objective of this study was to examine occupational exposure to styrene in a multistage approach, in order to integrate the following endpoints: styrene in workplace air, mandelic and phenylglyoxylic acids (MA + PGA) in urine, sister chromatid exchanges (SCE), micronuclei (MN), DNA damage (comet assay), and genetic polymorphisms of metabolizing enzymes (CYP2E1, EPHX1, GSTM1, GSTT1, and GSTP1). Seventy-five workers from a fiberglass-reinforced plastics factory and 77 unexposed controls took part in the study. The mean air concentration of styrene in the breathing zone of workers (30.4 ppm) and the mean concentration of urinary metabolites (MA + PGA = 443 ± 44 mg/g creatinine) exceeded the threshold limit value (TLV) and the biological exposure index (BEI). Significantly higher SCE frequency rate and DNA damage were observed in exposed workers, but MN frequency was not markedly modified by exposure. With respect to the effect of genetic polymorphisms on different exposure and effect biomarkers studied, an increase in SCE levels with elevated microsomal epoxide hydrolase activity was noted in exposed workers, suggesting a possible exposure–genotype interaction.

Gaseous Contaminant Distribution in the Breathing Zone

Conventionally, the "breathing zone" is defined as the zone within a 0.3 m (or 10 inches) radius of a worker's nose and mouth, and it has been generally assumed that a contaminant in the breathing zone is homogeneous and its concentration is equivalent to the concentration inhaled by the worker. However, several studies have mentioned that the concentration is not uniform in the breathing zone when a worker is close to the contaminant source. In order to examine the spatial variability of contaminant concentrations in a worker's breathing zone, comparative measurements of personal exposure were carried out in a laboratory. In experiment, ethanol vapor was released in front of a model worker (human subject and mockup mannequin) and the vapor concentrations were measured at two different sampling points, at the nose and at the chest, in the breathing zone. Then, the effects of the sampling location and the body temperature on the exposure were observed. The ratios of nose concentration to chest concentration for the human subject and the mannequin were 0-0.2 and 0.12, respectively. The exposure level of the mannequin was about 5.5-9.3 times higher than that of the human subject.

An electrical sensor for long-term monitoring of ultrafine particles in workplaces

Pegasor Oy Ltd. (Finland) has developed a diffusion charging measurement device that enables continuous monitoring of fine particle concentration at a low initial and lifecycle cost. The innovation, for which an international process and apparatus patent has been applied for, opens doors for monitoring nanoparticle concentrations in workplaces.The Pegasor Particle Sensor (PPS) operates by electrostatically charging particles passing through the sensor and then measuring the current caused by the charged particles as they leave the sensor. The particles never touch the sensor and so never accumulate on its surfaces or need to be cleaned off. The sensor uses an ejector pump to draw a constant sample flow into the sensing area where it is mixed with the clean, charged pump flow air (provided by an external source). The sample flow containing charged particles passes through the sensor. The current generated by the charge leaving the detection volume is measured and related to the particle surface area. This system is extremely simple and reliable – no contact, no moving parts, and all critical parts of the sensor are constantly cleaned by a stream of fresh, filtered air. Due to the ejector pump, the sample flow, and respectively the sensor response is independent of the flow and pressure conditions around the sampling inlet.Tests with the Pegasor Particle Sensor have been conducted in a laboratory, and at a workplace producing nanoparticles for glass coatings. A new measurement protocol has been designed to ensure that process workers are not exposed to unusually high nanoparticle concentrations at any time during their working day. One sensor is placed inside the process line, and a light alarm system indicates the worker not to open any protective shielding or ventilation systems before concentration inside has reached background levels.The benefits of PPS in industrial hygiene are that the same monitoring technology can be used at the source as well as at the worker breathing zone. Up to eight sensors can be installed in series for centralized monitoring of the whole process in real time.

The Impact of Boundary Layer Separation on Local Exhaust Design and Worker Exposure

Abstract The phenomenon of boundary layer separation is an important factor in determining a worker's breathing zone concentration. This article presents the results of flow visualization and tracer gas studies, conducted in a wind tunnel with a mannequin, designed to examine this phenomenon. A simple conceptual model, based on mass transport by vortex shedding, provides a reasonable estimate of the mannequin's breathing zone concentration. An empirical model is developed which relates the measured concentration to the distance from the source to the breathing zone for the situation when the contaminant is released downstream in a uniform flow. Applications of the results are discussed.

Cytogenetic and DNA damage on workers exposed to styrene

Styrene is a commercially important chemical widely used in the manufacture of synthetic rubber, resins, polyesters and plastics. The highest levels of human exposure to styrene occur during the production of reinforced plastic products. The objective of this work was to evaluate both DNA and cytogenetic damage in styrene-exposed workers, analysing only non-smoker individuals. Environmental levels of styrene and urinary concentrations of mandelic and phenylglyoxylic acids were determined, and genetic damage was studied by means of micronucleus (MN) test, sister chromatid exchanges (SCEs) and comet assay. Fifty-two fibreglass-reinforced plastics workers and 54 controls took part in the study. The mean air concentration of styrene in the breathing zone of workers exceeded the threshold limit value, and 24 workers exceeded the biological exposure index. A strong and significant correlation was found between styrene environmental concentrations and urinary metabolites. Higher SCE rate (P<0.01) was observed in exposed workers than in controls. Besides, significant correlations were obtained for SCE rate with both environmental and internal exposure parameters (r=0.496, P<0.01 and r=0.511, P<0.01, respectively). Results from MN test and comet assay showed slight and non-significant increases related to the exposure. Our data seem to support previous studies reporting genotoxicity associated with occupational exposure to styrene, excluding the confounding influence of smoking, although caution must be taken in the interpretation of these results since the significance of an increase in SCE rate is still unclear.

Development of a Personal Sampler for Evaluating Exposure to Ultrafine Particles

Evaluation of the exposure of humans to ultrafine, airborne particles is an important aspect of health in the workplace, especially in cases where nano-particles are present. However, portable sampling devices for efficiently collecting ultrafine particles in a worker's breathing zone are not readily available. The present study describes the design and development of a portable sampler for collecting particulates in the breathing zone, as a possible tool for this purpose. The design is based on the use of an ”Inertial Filter” to separate various-sized nano-order particles. Inertial filters consisting of SUS fiber felt (fiber diameter 5.6-13.5 μm) placed in circular nozzles (3-6 mm diameter with 4.5 mm length) were used. To achieve the smallest dp50 under the allowable pressure drop of a portable pump, the influence of fiber loading on separation performance and pressure drop were investigated. The influence of particle loading was also examined in relation to pressure drop and separation performance. The smallest dp50 under the allowable pressure drop (5.7 kPa at 6 L/min) for the battery pump employed was ~140 and 200 nm respectively for SUS fibers of 5.6 and 9.8 μm diameter (particle volume fraction ~0.013). The change in separation performance due to particle loading was confirmed to be acceptable for use under the present conditions. Under these conditions, a sufficient amount of particles can be collected for chemical analyses, e.g., particle-bound PAHs after 6-8 hours of sampling. Hence, the developed sampler has the potential for use in evaluating exposure to ultrafine particles in the breathing zone in the workplace.

Assessment of the Total Inflammatory Potential of Bioaerosols by Using a Granulocyte Assay

Occupational health symptoms related to bioaerosol exposure have been observed in a variety of working environments. Bioaerosols contain microorganisms and microbial components. The aim of this study was to estimate the total inflammatory potential (TIP) of bioaerosols using an in vitro assay based on granulocyte-like cells. A total of 129 bioaerosol samples were collected in the breathing zone of workers during their daily working routine at 22 biofuel plants. The samples were analyzed by traditional assays for dust, endotoxin, fungal spores, (1-->3)-beta-d-glucan, total number of bacteria, the enzyme N-acetyl-beta-d-glucosaminidase (NAGase; primarily originating from fungi), Aspergillus fumigatus, and mesophilic and thermophilic actinomycetes; the samples were also assayed for TIP. In a multilinear regression four factors were significant for the TIP values obtained: endotoxin (P < 0.0001), fungal spores (P < 0.0001), (1-->3)-beta-d-glucan (P = 0.0005), and mesophilic actinomycetes (P = 0.0063). Using this model to estimate TIP values on the basis of microbial composition, the correlation to the measured values was r = 0.91. When TIP values obtained in the granulocyte assay were related to the primary working area, we found that bioaerosol samples from personnel working in straw storage facilities showed high TIP values ( approximately 50 times the TIP of unstimulated controls). In contrast, bioaerosol samples from personnel with work functions in offices or laboratories showed low TIP values ( approximately 5 times the TIP of the unstimulated control). This indicates, as expected, that these areas were less contaminated. In conclusion, the granulocyte assay reacts to multiple contaminants in the environmental samples and can be used to obtain a measurement of TIP. Therefore, potential occupational health effects related to inflammation of the airways in a working environment can be estimated using this assay.

Relevance of aerosol dynamics and dustiness for personal exposure to manufactured nanoparticles

Production and handling of manufactured nanoparticles (MNP) may result in unwanted worker exposure. The size distribution and structure of MNP in the breathing zone of workers will differ from the primary MNP produced. Homogeneous coagulation, scavenging by background aerosols, and surface deposition losses are determinants of this change during transport from source to the breathing zone, and to a degree depending on the relative time scale of these processes. Modeling and experimental studies suggest that in MNP production scenarios, workers are most likely exposed to MNP agglomerates or MNP attached to other particles. Surfaces can become contaminated by MNP, which constitute potential secondary sources of airborne MNP-containing particles. Dustiness testing can provide insight into the state of agglomeration of particles released during handling of bulk MNP powder. Test results, supported by field data, suggest that the particles released from powder handling occur in distinct size modes and that the smallest mode can be expected to have a geometric mean diameter >100 nm. The dominating presence of MNP agglomerates or MNP attached to background particles in the air during production and use of MNP implies that size alone cannot, in general, be used to demonstrate presence or absence of MNP in the breathing zone of workers. The entire respirable size fraction should be assessed for risk from inhalation exposure to MNP.

The Challenges of Controlling Organic Solvents in a Paint Factory due to Solvent Impurity

In this study, several exhaust ventilation systems were designed and implemented in a paint manufacturing factory, using ACGIH recommendations. The personal exposure of workers to solvents used in the factory was evaluated to examine the role of implemented standard ventilation system. For this purpose, Toluene and Xylene concentration were monitored before and after the application of ventilation systems. Personal samples and subsequent analysis were conducted according to OSHA's method No: 12. Samples were analyzed, using Gas Chromatography. The results showed that the ventilation standards recommended by ACGIH were able to control Toluene and Xylene vapors successfully below the recommended TLVs (e.g. 44.49 ppm and 97.73 ppm respectively). It was also discovered that although Benzene was not reported as a component of the paint, its concentration in breathing zone of workers were much higher than the respective TLV (e.g. 4.5 ppm). This could be from the impurity of solvents used in paint factories which raises new questions. According to IRIS epidemiologic information, it was found that implementation of industrial ventilation systems decrease the relative risk (RR) of leukemia due to exposure to benzene, from 66.4 to 3.2 cases per work life, in this factory. Finally it was deduced that solvents impurities such as Benzene should be seriously considered as a major problem that may not be controlled using ventilation standards recommended by ACGIH for paint mixing and storing process.

Environmental exposure to xylenes in drivers and petrol station workers by urinary methylhippuric Acid.

The aims of this study were evaluation of exposed to xylenes in low concentration and compare urinary level of methyl hippuric acid in taxi drivers and petrol stations workers in West of Iran. This observation study was carried out on samples of the exposed men to xylenes in two occupational groups in Hamadan City (west of Iran) from March 2003 to March 2004. Subjects included 45 taxi drivers and 25 petrol station workers. The study group was selected from 54 workers at petrol stations and 300 drivers by simple random sampling. Xylenes was analyzed using gas chromatography equipped with a Flame Ionization Detector (FID). The urinary methyl hippuric acid (MHA) was analyzed with High performance Liquid Chromatography (HPLC) equipped with an ultraviolet (UV) detector. Total xylene exposure was 1.05±0.55 ppm (mean±SD) with a range of 0.20-2.55 ppm that was about 4 times more than taxi drivers' exposure. The poor correlation coefficient was seen between xylenes concentration and urinary MHA for drivers (r2= 0.09 to 0.42) but significant associations were noted between urinary MHA and xylene in the breathing zone of petrol station workers (r2= 0.69 to 0.77; P< 0.05). High xylenes levels are emitted in petrol stations at Iran. Urinary MHA level has a poor correlation with exposure to xylenes in drivers but has good correlation in petrol station workers.

Genotoxic damage in pathology anatomy laboratory workers exposed to formaldehyde

Formaldehyde (FA) is a chemical traditionally used in pathology and anatomy laboratories as a tissue preservative. Several epidemiological studies of occupational exposure to FA have indicated an increased risk of nasopharyngeal cancers in industrial workers, embalmers and pathology anatomists. There is also a clear evidence of nasal squamous cell carcinomas from inhalation studies in the rat. The postulated mode of action for nasal tumours in rats was considered biologically plausible and considered likely to be relevant to humans. Based on the available data IARC, the International Agency for Research on Cancer, has recently classified FA as a human carcinogen. Although the in vitro genotoxic as well as the in vivo carcinogenic potentials of FA are well documented in mammalian cells and in rodents, evidence for genotoxic effects and carcinogenic properties in humans is insufficient and conflicting thus remains to be more documented. To evaluate the genetic effects of long-term occupational exposure to FA a group of 30 Pathological Anatomy laboratory workers was tested for a variety of biological endpoints, cytogenetic tests (micronuclei, MN; sister chromatid exchange, SCE) and comet assay. The level of exposure to FA was evaluated near the breathing zone of workers, time weighted average of exposure was calculated for each subject. The association between the biomarkers and polymorphic genes of xenobiotic metabolising and DNA repair enzymes was also assessed. The mean level of exposure was 0.44 ± 0.08 ppm (0.04–1.58 ppm). MN frequency was significantly higher ( p = 0.003) in the exposed subjects (5.47 ± 0.76) when compared with controls (3.27 ± 0.69). SCE mean value was significantly higher ( p < 0.05) among the exposed group (6.13 ± 0.29) compared with control group (4.49 ± 0.16). Comet assay data showed a significant increase ( p < 0.05) of TL in FA-exposed workers (60.00 ± 2.31) with respect to the control group (41.85 ± 1.97). A positive correlation was found between FA exposure levels and MN frequency ( r = 0.384, p = 0.001) and TL ( r = 0.333, p = 0.005). Regarding the genetic polymorphisms studied, no significant effect was found on the genotoxic endpoints. The results of the present biomonitoring study emphasize the need to develop safety programs.