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PubMed2004

Current man-made mineral fibers (MMMF) exposures among ontario construction workers.

Current occupational exposures to man-made mineral fibers (MMMF), including refractory ceramic fibers (RCF), were measured as part of an exposure assessment program for an epidemiological study pertaining to cancer and mortality patterns of Ontario construction workers. The assessments were carried out at commercial and residential sites. A total of 130 MMMF samples (104 personal and 26 area) was collected and included 21 RCF (16 personal and 5 area). The samples were analyzed by the World Health Organization method in which both respirable and nonrespirable airborne fibers are counted. The results show that Ontario construction workers' full-shift exposure to MMMF (excluding RCF) is generally lower than the American Conference of Governmental Industrial Hygienists' (ACGIH) recommended threshold limit value-time-weighted average (TLV-TWA) of 1 fibers/cc and thus should not present any significant hazard. However, approximately 40% of the occupational exposures to RCF are higher than ACGIH's TLV-TWA of 0.2 fibers/cc and present a significant potential hazard. Workers generally wore adequate approved respiratory protection, especially while performing particularly dusty tasks such as blowing, spraying, and cutting, so the actual exposure received by workers was lower than the reported values. Adequate control measures such as ventilation and respiratory protection should always be used when work involves RCF.

Air Pollutants, Occupational↗
PubMed2004

A simultaneous job- and task-based exposure evaluation of petroleum tanker drivers to benzene and total hydrocarbons.

A simultaneous job- and task-based exposure study was conducted for tanker drivers delivering petroleum products from several bulk terminals and an agency to retail outlets. Full-shift (job-based) samples and job component tasks samples were collected simultaneously. The tasks sampled included loading, unloading, and travel. Three hundred sixty-six personal charcoal tube samples were collected. Full-shift visual observations of work practices and real-time monitoring using a data logging hydrocarbon analyzer were also conducted. Multiple measurements per worker were made, which permitted an assessment of sampling variability within and between workers. The highest exposures for drivers occurred during unloading at the agency. The mean benzene exposure for agency drivers was 0.88 ppm for full-shift time-weighted average, 2.86 ppm for unloading, and 0.54 ppm for loading. For bulk terminal drivers, the mean benzene level without vapor control was 0.12 ppm for time weighted average, 0.24 ppm for unloading, and 0.33 ppm for loading. The time-weighted average exposure of the agency and bulk terminal drivers based on the data collected and the lognormal model can be expected to exceed threshold limit value-time weighted average of 0.5 ppm for benzene about 70 and 2% of the time, respectively. Agency drivers' unloading and loading tasks accounted for approximately 30% and 7% of the total time, and 95% and 4% of total exposure, respectively. For the bulk terminal drivers, mean unloading and loading tasks constituted 24% and 12% of the total time, and 68% and 19% of the total exposure, respectively. Travel activity accounted for an average of 63% of the total time for agency and 64% for bulk terminal drivers, but only contributed < 1 and 13% of the total exposure, respectively. The actual job-based time-weighted average concentration and the calculated time-weighted average derived from the time-weighted summation of the components tasks are in very good agreement. Within-worker variability was generally higher than between-worker variability. Exposure control strategies are required primarily for unloading at the agencies. Vapor control technology at the terminal effectively reduces exposure (by almost 50%) and fugitive emissions.

Automobile Driving↗
PubMed2005

Asbestos exposures to truck drivers during World Trade Center cleanup operations.

This article presents results of asbestos air sampling conducted to assess the exposure to truck drivers working at the World Trade Center site. Sampling consisted of a combination of area and personal monitoring of 49 truck drivers and included optical and electron microscopic analyses. Three sampling periods were conducted: October 1-7, 2001, October 17-26, 2001, and April 13-23, 2002. Area sample locations were selected to estimate airborne concentrations around the perimeter of the site, on top of the pile, and in the pit. Air samples were collected using a 50-mm conductive cowl and a 25-mm mixed cellulose ester filter at flow rates ranging from 0.5-2 L/min. Samples were analyzed using a combination of phase contrast microscopy (PCM) NIOSH method 7400, transmission electron microscopy (TEM) NIOSH method 7402, and the direct method specified under the Asbestos Hazardous Emergency Response Act. Sample times and flow rates were adjusted to prevent overloading while maximizing sample volume. Personal sampling results suggest that asbestos fiber exposures to truck drivers at the site were low. Exposures based on TEM results generally ranged from less than detectable to 0.1 structures per cubic centimeter (s/cm(3)). TEM-based results further indicate that the majority of asbestos fibers were chrysotile and less than 5 microm in length. PCM-based estimates were generally higher than the TEM results. This is likely due to the counting of nonasbestos fibers. This conclusion is supported by the NIOSH 7402 TEM results, which did not detect asbestos fibers longer than 5 micro m. Area sample results were generally less than the personal results (except for the sample collected on top of the rubble pile) and decreased over the course of the cleanup. Our results show low airborne asbestos concentrations and a predominance of short fibers. Given these low concentrations, evidence of short fibers, and the short duration of the exposure (less than 10 months to complete the cleanup), it is likely that truck drivers working at the site are not at an increased risk for asbestos-related disease.

Asbestos↗
PubMed2005

A field study to assess the long-term sampling feasibility of evacuated canisters and the development of a mathematical model to analyze potential sampling bias.

Small, evacuated canisters (300 mL) equipped with a unique capillary flow controller were used to evaluate airborne concentrations of Stoddard solvent. The physical characteristics of the flow controller permitted the collection of air samples for a time period of 40 hours (5 consecutive work days). Long-term sampling (greater than 8 hours) is rarely performed in industrial hygiene due to limitations in current air sampling technology but may provide valuable information in characterizing worker cumulative exposures for some processes. A field study was performed to evaluate the feasibility of collecting a 40-hour area sample using the small canisters. Six canister samplers were used as area monitors to evaluate a cleaning operation for an entire workweek. For comparison, 30 diffusive badges (6 per day) were simultaneously used to monitor the same process. No statistical difference was found between the time-weighted average for the two sampling methods (p > 0.05). In addition, the canister samples integrate airborne concentrations for an entire workweek and therefore peak concentrations are not explicitly observed. Thus, an examination of peak exposures using simulated concentrations was conducted. A mathematical model was developed to determine whether a significant sampling bias was associated with long-term canister sampling when peak concentrations are present. The maximum possible bias was determined to be less than 9% for peak amplitudes having 10 times the background concentration and well below that for smaller amplitudes. Long-term sampling with the small, evacuated canisters was found to provide results comparable to sorbent sampling methods but with the added benefit of a significantly increased sampling time.

Adult↗
PubMed2006

Indoor and outdoor air quality assessment of four wastewater treatment plants.

The study assessed the air quality of four wastewater treatment plants (WWTPs) by monitoring levels of hydrogen sulfide (H2S) and endotoxin. Samples were taken over a 1-year period (2001-2002). The unit operations at each WWTP were categorized as: (a) grit removal, (b) primary clarification, (c) biological treatment, (d) secondary clarification, (e) sludge dewatering, and (f) digestion. Temperature and humidity were monitored simultaneously, whereas airborne H2S and endotoxin were monitored at each of the six unit operations in each plant. Carbonaceous biochemical oxygen demand (CBOD) and total incoming flow of the day of visit were also recorded. The geometric means of H2S concentration were less than 1 ppm and endotoxin ranged from 6-1247 EU/m3. A mixed model analysis of covariance (ANCOVA) was used for the statistical analysis. While temperature was not associated with the levels of both contaminants, humidity was influential on the level of H2S (p < 0.01) but not of endotoxin. CBOD did not affect the levels of either contaminant; however, incoming flows showed an association with the levels of H2S (p < 0.05). The concentrations of H2S in the six unit operations were statistically different, whereas endotoxin did not show any differences in concentrations between units. Individual comparisons proved that concentrations of H2S in the grit removal and sludge dewatering unit operations were statistically higher than the other operations. Overall, the concentrations of H2S varied depending on total incoming flow, humidity, and different unit operations. This trend was not observed for endotoxin. The results showed that the factors analyzed affected concentrations of H2S and endotoxin differently. Therefore, different control methods for endotoxin and H2S need to be considered to effectively reduce their concentrations at WWTPs.

Air Pollutants↗
PubMed2005

RCF exposure data.

Explore the source record for details and available documents.

Air Pollutants, Occupational↗
PubMed2006

Metalworking fluid mist occupational exposure limits: a discussion of alternative methods.

NIOSH published a recommended exposure limit (REL) for metalworking fluids (MWF) in 1998 that was designed to prevent respiratory disorders associated with these industrial lubricants. The REL of 0.4 mg/m(3) (as a time-weighted average for up to 10 hours) was for the fraction of aerosol corresponding to deposition in the thoracic region of the lungs. This nonregulatory occupational exposure limit (OEL) corresponded to approximately 0.5 mg/m(3) for total particulate mass. Although this REL was designed to prevent respiratory disorders from MWF exposures, NIOSH acknowledged that exposures below the REL may still result in occupational asthma and hypersensitivity pneumonitis--two of the most significant respiratory illnesses associated with MWF. In the 8 years since the publication of the NIOSH MWF REL, neither the Occupational Safety and Health Administration (OSHA) nor the American Conference of Governmental Industrial Hygienists (ACGIH) has recommended an exposure limit for water-soluble MWF specifically, other than their previous exposure limits for mineral oil. An informal effort to benchmark companies involved in the manufacture of automobiles and automotive parts in North America indicated that most companies are using the NIOSH MWF REL as a guide for the purchase of new equipment. Furthermore, most companies have adopted a goal to limit exposures to below 1.0 mg/m3. We failed to find any company that has strictly enforced an OEL of 1.0 mg/m(3) through the use of either administrative controls or personal protective equipment, when engineering controls failed to bring the exposures to below this limit. We also found that most companies have failed to implement specific medical surveillance programs for those employees exposed to MWF mist above 1.0 mg/m(3). Organization Resources Counselors (ORC) published in 1999 (on their website) a "best practices" manual for maintaining MWF systems and reducing the likelihood of MWF-related illnesses. The emphasis of this approach was on control techniques, and there was no assignment of a specific OEL for MWF due to the wide variety of fluids that exist. The ORC did suggest that maintaining exposure levels to below 2.0 mg/m(3) would assist in minimizing upper respiratory complaints associated with MWF. Although the ORC manual indicated that MWF vary in composition and no single OEL is likely to be appropriate for all such fluids, it adopted a very similar concept to control banding, placing all MWF operations into a single band using similar (if not identical) controls. OSHA, in lieu of adopting a 6B health standard for MWF, has also published a voluntary "best practices" manual on their website. Their document drew heavily from the work of ORC and also incorporated information from the 1998 NIOSH MWF criteria document. Industrial users of MWF need to have guidance, such as an OEL, to determine when either engineering, administrative controls, or personal protective equipment must be implemented to protect their employees. The purpose of this article is to explore various approaches that might be taken to result in a single or multiple limits for exposures to MWF and its components. Approaches such as control banding are discussed in terms of an alternative to the use of an OEL.

Aerosols↗
PubMed2001

Bacterial contamination associated with electronic faucets: a new risk for healthcare facilities.

OBJECTIVE: To investigate the safety of the hospital water supply following a major flood. DESIGN: Surveillance was conducted of the hospital water supply as it entered the hospital and at randomly selected water faucets throughout the facility. SETTING: A newly constructed surgical critical-care unit in a 265-bed community hospital that had to be evacuated and was out of operation for 6 weeks following a major flood of the city. METHODS: Random water samples throughout the facility were analyzed for heterotrophic plate counts (HPCs), chlorine, and coliforms utilizing standard methods. RESULTS: Water samples entering the hospital met appropriate standards, indicating the city water distribution system was not contaminated. Of 169 faucets tested, 13 (22%) of 59 electronic faucets exceeded the HPC threshold, and 12 (11%) of 110 manual faucets exceeded the HPC threshold (P<.14). A comparison of two brands of electronic faucets with manual faucets and with each other revealed that the HPC threshold was exceeded by 11 (32%) of 34 brand A faucets as compared to 12 (11%) of 110 manual faucets (P<.006). The HPC threshold was exceeded by 2 (8%) of 25 brand B faucets compared to 12 (11%) of 110 manual faucets (P<.94). Contamination rates of brand A and brand B faucets differed significantly (P<.003). Similar testing 2 months after hyperchlorination of the water supply indicated that the HPC threshold was exceeded by 16 (52%) of 31 brand A faucets compared to 10 (9.%) of 110 manual faucets (P<.0000003) and by 2 (18%) of 25 brand B faucets compared to 10 (9%) of 110 manual faucets (P=1.0). CONCLUSIONS: A certain brand of electronic water faucet used in the hospital was associated with unacceptable levels of microbial growth in water and was a continuing source of bacteria potentially hazardous to patients.

Chlorine↗
PubMed2003

A contribution to the linear no-threshold discussion.

The paper approaches the linear no-threshold (LNT) hypothesis, currently used as the basis for recommendations in radiological protection, from the point of view of the radiation mechanism. All considerations of the validity of the LNT hypothesis based on experiment or epidemiology are dismissed because of the impossibility of deriving statistically significant data at very low doses. Instead, the LNT hypothesis is assessed from a consideration of the mechanism of radiation action. The DNA double-strand break is proposed to be the crucial radiation-induced molecular lesion. A trace is made using a series of correlations that link the DNA double-strand break to effects at the cellular level and these cellular effects are linked to the induction of cancer. Multistep modelling of carcinogenesis is used to take the link through to a consideration of radiation risk. It is concluded that, from the point of view of radiation mechanism, at very low doses the LNT hypothesis of radiation action is valid, that is, the risk function has a positive slope from zero dose.

Cell Death↗
PubMed2005

Exposure to low molecular weight isocyanates and formaldehyde in foundries using hot box core binders.

Emissions from a chemical core binder system (Hot Box) based on a formaldehyde-carbamide resin have been investigated. The binder is used in some Swedish die-casting foundries. During core-making and casting, low molecular monoisocyanates, in particular methyl isocyanate (MIC) and isocyanic acid (ICA), were identified. Exposure to air concentrations of MIC, ICA and formaldehyde were subsequently determined in all Swedish foundries using the Hot Box binder, and involved three brass and one grey iron foundry. The survey was carried out in the winter period of 2001, and involved core-makers, casters and fettlers in the brass foundries, whereas only core-makers were included in the grey iron foundry. For each worker, four to five short-term samples of isocyanates (n = 298) and one 8 h sample of formaldehyde (n = 64) were collected during one shift for 15 die-casters, 39 core-makers and 10 other workers in the foundry. The air concentrations of the MIC short-term samples varied between <4 and 68 microg m(-3), with corresponding ICA levels between <4 and 280 microg m(-3). Calculated 8 h time weighted average air concentrations of MIC, based on short-term samples for each individual, varied between <4 and 31 microg m(-3); for ICA the corresponding levels varied from <4 to 190 microg m(-3). The formaldehyde time weighted average concentration levels ranged from 14 to 1600 microg m(-3), and the Swedish occupational exposure limit (600 microg m(-3)) was exceeded only in 3% of the samples. In general, the core-makers were exposed to higher average formaldehyde levels compared to the casters, the latter being more exposed to monoisocyanates. During core-making and die-casting, low molecular monoisocyanates, in particular MIC and ICA, were identified. Compared to the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value-time weighted average (TLV-TWA) for MIC, the exposures were low. The lack of toxicological and human data for ICA and the relatively high air concentrations call for medical examination and preventive measures in production, ventilation and the use of personal safety equipment in the investigated foundries.

Air Pollutants, Occupational↗
PubMed2006

Relationship between genotoxicity biomarkers in somatic and germ cells: findings from a biomonitoring study.

A biomonitoring study to evaluate chromosome and DNA damage respectively in somatic and germ cells of a group of male workers exposed to styrene by using biomarkers of genotoxicity was carried out. Styrene-exposed workers from three different areas of Tuscany and healthy subjects, of comparable mean age, sex and lifestyle characteristics, as a control group not exposed to chemicals, have been enrolled. In addition to previous reports [L. Migliore, A. Naccarati, A. Zanello, R. Scarpato, L. Bramanti and M. Mariani (2002) Hum. Reprod., 17, 2912-2918; L. Migliore, A. Naccarati, F. Coppedè et al. (2006) Pharmacogenet. Genomics, 16, 87-99] we present now data on a cross-sectional investigation involving a homogeneous group of subjects for which data on both somatic and germ cells have been obtained from individuals (42 exposed and 25 controls). Somatic cell genotoxicity was assessed by analysing the frequency of micronucleated binucleated cells (MNBN) in blood lymphocytes. The micronucleus assay was coupled with centromeric fluorescence in situ hybridization (FISH) analysis. Primary DNA damage in germ cells was evaluated by alkaline single-cell gel electrophoresis (Comet assay) and the percentage of the tail DNA (%TD) was used as parameter of Comet evaluation. Moreover, to investigate the frequencies of aneuploidy and diploidy in sperm, we performed multicolour FISH, using DNA probes specific for the centromeric regions of sex chromosomes and chromosome 2, in decondensed sperm nuclei of samples with normal semen parameters in a subgroup of individuals. Mandelic and phenylglyoxylic acids (MAPGA) in end of shift samples were determined as biomarkers of internal dose. MAPGA excretion was consistent with an exposure to styrene above the threshold limit value-time weighted average concentration of 20 p.p.m. Styrene workers showed significantly higher frequency of MNBN as compared to controls (13.8 +/- 5.2 versus 6.2 +/- 5.1; P < 0.001), due to higher proportions of both micronuclei (MN) arising from chromosomal breakage (C-MN) and harbouring whole chromosomes (C+MN). DNA damage in sperm cells was also higher among styrene-exposed, the %TD being 11.02 +/- 2.99 versus 7.42 +/- 2.30 in controls (P < 0.001). The incidence of aneuploidy and diploidy for the tested chromosomes in sperm did not show a statistically significant difference between workers and controls. However, a positive correlation was found between genotoxic damage detected in somatic and in germ cells, even after removing the effect of age (r = 0.475; P < 0.001). Although cytogenetic biomarkers detected both in somatic and germ cells were interrelated, no relationships were apparent with exposure parameters. Styrene exposure may increase the likelihood of both chromosome and DNA damage in somatic and germ cells, thus supporting the hypothesis of an interference on reproductive capacity among exposed workers. This is the first time that a field study shows a correlation between two biomarkers of genotoxicity evaluated at the same time in somatic and germ cells.

Biomarkers↗
PubMed2001

Decreased carotid artery distensibility as a sign of early atherosclerosis in viscose rayon workers.

Carbon disulphide (CS(2)) is known to accelerate atherosclerosis and to increase the risk for cardiovascular diseases. To assess the effect of CS(2) on the functional (distensibility and compliance) and the structural (intima media thickness) properties of the common carotid artery, and blood pressure and lipid metabolism parameters, a cross-sectional study on 85 workers from a viscose rayon factory and 37 controls was carried out. Exposure to CS(2) was assessed by personal monitoring and was well below the threshold limit value-time weighted average. Carotid arterial wall properties were determined using a non-invasive ultrasound wall movement detector system. No significant effect of CS(2) on blood pressure, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol or triglycerides was found. Among the vascular parameters studied, only distensibility was significantly lower and heart rate was significantly higher in exposed subjects compared with the controls. In conclusion, occupational exposure to CS(2) may cause early alterations in arterial elastic properties in young individuals, and even before lipid and clinical findings have occurred, important functional changes in the vessel wall are present.

Adult↗