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PubMed1983

Epidemiologic health study of workers in an aluminum smelter in British Columbia. Effects on the respiratory system.

A health survey was carried out on all white males in an aluminum smelter in British Columbia. The survey consisted of a medical-occupational questionnaire, spirometry, chest radiography, and environmental monitoring. We have compared the results of a respiratory survey in 713 workers in the office and casting department with no significant exposure to air contaminants (control workers) with those of 797 potroom workers: 495 who spent more than 50% of their working time in the potroom (high exposure) and 302 workers who spent less than 50% of their working time in the potroom (medium exposure). Potroom workers (high) had a significantly greater prevalence of cough and wheeze than did those in the control group, and they had significantly lower mean forced expiratory volume in one second and maximal midexpiratory flow rate than did those in the control group after adjustment had been made for differences in age, height, and smoking habits. Potroom workers (medium) had a slightly greater prevalence of respiratory symptoms and lower lung function than did workers in the control group, but the differences were not significant. We were unable to demonstrate potroom asthma. The levels of total fluoride, gaseous fluoride, particulate fluoride, sulphur dioxide, and total particulates found in the potroom at the time of the study were below the currently accepted threshold limit values, but the levels of benzo-alpha-pyrene were high.

Adult↗
PubMed1983

Airway responses to sulfate and sulfuric acid aerosols in asthmatics. An exposure-response relationship.

Epidemiologic studies support an association between elevated levels of sulfates and increased symptoms in asthmatics. To determine if these pollutants produce airway responses, 17 asthmatics inhaled the following sulfates: sodium bisulfate, ammonium sulfate, ammonium bisulfate (NH4HSO4), or sulfuric acid (H2SO4) aerosols with an aerodynamic diameter of 0.80 micron at concentrations of 100 micrograms/m3, 450 micrograms/m3, and 1,000 micrograms/m3. A sodium chloride (NaCl) aerosol of similar characteristics, administered by double-blind randomization, served as a control. Subjects breathed these aerosols for a 16-minute period via a mouthpiece. Deposition studies showed 54 to 65% retention of the inhaled aerosols. At the 1,000 micrograms/m3 concentration, the Threshold Limit Value for occupational exposure, H2SO4 and NH4HSO4 inhalation produced significant reductions in specific airway conductance (SGaw) (p less than 0.05) and forced expiratory volume in one second (p less than 0.01) compared with NaCl or pre-exposure values. At the 450 micrograms/m3 concentration, only H2SO4 inhalation produced a significant reduction in SGaw (p less than 0.01). At 100 micrograms/m3, a level 3 to 5 times greater than peak urban levels, no significant change in airway function occurred after any sulfate exposure. These data indicate that asthmatics demonstrate bronchoconstriction after brief exposure to common acidic sulfate pollutants.

Adult↗
PubMed1983

Synergistic effects on rat lungs of mixtures of oxidant air pollutants (ozone or nitrogen dioxide) and respirable aerosols.

A hitherto unexpected synergism between the oxidant air pollutants ozone or nitrogen dioxide and a respirable-sized aerosol of ammonium sulfate was observed during controlled exposures of rats to these substances. Response of rat lungs to these pollutants was quantitated by measurement of apparent collagen synthesis rates in vitro by lung minces from exposed animals. Dose-response curves to either O3 or NO2 were altered in the presence of 5 mg/m3 of (NH4)2SO4 aerosol. Morphometric and histologic observations of lungs from rats exposed to high levels of ozone, with and without concurrent exposure to the (NH4)2SO4 particles, confirmed such synergistic effects. In a separate set of experiments, rats were exposed at near ambient levels to mixtures of ozone and sulfuric acid aerosol (submicron-sized aerosol). Potentiation of ozone effects on lung collagen synthesis rates was also observed in these experiments. These observations may have broad implications for the appropriate evaluation of laboratory data in the setting of ambient air quality standards and/or threshold limit values for occupational safety.

Aerosols↗
PubMed1985

Serial measurements of intra-oral air mercury: estimation of daily dose from dental amalgam.

Serial measurements of Hg concentration in intra-oral air were made during and after chewing stimulation in 35 subjects with occlusal amalgam restorations. Hg concentrations remained elevated during 30 min of continuous chewing and declined slowly over 90 min after cessation of chewing. By curve-fitting and integration analysis of data during these time periods (including corrections for respiratory volume, retention rate of inspired Hg, oral-to-nasal breathing ratios, and consumption of three meals and three snacks per day), we calculated that all subjects received an average daily Hg dose of approximately 20 micrograms. Subjects with 12 or more occlusal amalgam surfaces were estimated to receive a daily Hg dose of 29 micrograms, whereas in subjects with four or fewer occlusal amalgam surfaces, the dose was 8 micrograms. These Hg dosages from dental amalgam were as much as 18-fold the allowable daily limits established by some countries for Hg exposure from all sources in the environment. The results demonstrate that the amount of elemental Hg released from dental amalgam exceeds or comprises a major percentage of internationally accepted threshold limit values for environmental Hg exposure. It is concluded that dental amalgam Hg makes a major contribution to total daily dose.

Air↗
PubMedDate not supplied

Olfactory neuron loss in adult male CD rats following subchronic inhalation exposure to hydrogen sulfide.

Dysosmia and anosmia are reported to occur following human exposure to hydrogen sulfide (H2S) gas. The clinical association between H2S exposure and olfactory dysfunction in humans necessitates evaluation of the nasal cavity and olfactory system in experimental animals used to study H2S toxicity. The purpose of this study was to subchronically expose 10-week-old male CD rats to relatively low concentrations of H2S and to histologically evaluate the nasal cavity for exposure-related lesions. Rats (n = 12/group) were exposed via inhalation to 0, 10, 30, or 80 ppm H2S 6 h/d and 7 d/wk for 10 weeks. Following exposure to 30 and 80 ppm H2S, a significant increase in nasal lesions limited to the olfactory mucosa was observed. The lesions, which consisted of olfactory neuron loss and basal cell hyperplasia, were multifocal, bilaterally symmetrical, and had a characteristic rostrocaudal distribution pattern. Regions of the nasal cavity affected included the dorsal medial meatus and the dorsal and medial portions of the ethmoid recess. The no observed adverse effect level for olfactory lesions in this study was 10 ppm. For perspective, the American Conference of Governmental Industrial Hygienists threshold limit value (TLV) recommendation for H2S is currently 10 ppm (proposed revision: 5 ppm), so the concentrations employed in the present study were 3 and 8 times the TLV. These findings suggest that subchronic inhalation exposure to a relatively low level of H2S (30 ppm) can result in olfactory toxicity in rats. However, because of differences in the breathing style and nasal anatomy of rats and humans, additional research is required to determine the significance of these results for human health risk assessment.

Administration, Inhalation↗
PubMed1989

Tropospheric ozone: the dynamics of human exposure.

The conditions in the ambient atmosphere conducive to ozone exposure are examined, and placed into a context of the time and locations where individuals would be expected to be affected by high ozone. This is done for both 1 h and 8 h averaging times. Concentrations of ozone in the ambient atmosphere can violate the National Ambient Air Quality Standard (NAAQS) and also the Time Weighted Average-Threshold Limit Value (TWA-TLV) for workers. Exposures that occurred in a 1982 episode associated with a health effects study are described in detail. The effective dose received by a camper at a children's summer camp appeared to be similar to that delivered to volunteers during a controlled human exposure study in which effects on pulmonary function were observed.

Environmental Exposure↗
PubMedDate not supplied

Multi-route exposure assessment and biological monitoring of urban pesticide applicators during structural control treatments with chlorpyrifos.

A preliminary study of dermal and respiratory exposure to chlorpyrifos (Dursban TC) during structural treatments was conducted with eight workers from a commercial pest control company. The compound was applied by sub-slab and soil injection to four houses, with each application involving two workers. Crawl space applications were included in three of the jobs. Field sampling extended over the entire workday, and included personal air samples and dermal exposure evaluation with patches and handwashes. A fluorescent tracer was added to the formulation for qualitative determination of skin deposition patterns. Pre-exposure and complete 72 hour urine samples were also collected. Total dermal exposure averaged 5.94 mg/hr. The major contributors were the upper legs (38%) and the forearms (34%). Accidents occurred during two of the four applications observed, and the two workers involved in the accidents were the most highly exposed individuals. The mean estimated absorbed daily dose was 9.5 ug/kg/day, with approximately 73% contributed by the dermal route. Thus, under these work conditions the Threshold Limit Value is not an appropriate guide for worker safety. The principal urinary metabolite of chlorpyrifos, 3,5,6-trichloro-2-pyridinol, was found in measurable quantities in all urine samples. Urinary metabolite levels collected 24-48 hr postexposure were highly correlated (R2 = 0.86) with total absorbed dose estimates. The high variability among individual excretion patterns suggests against the use of urine spot sampling, but longer collections may prove useful in the development of a Biological Exposure Index for chlorpyrifos.

Absorption↗
PubMed1986

Effects of human exposure to atmospheric epsilon-caprolactam.

There is little published information on the human toxicology of epsilon-caprolactam, the monomer precursor of nylon 6. This paper reports an investigation of a group of eight workers who had been chronically exposed to atmospheric caprolactam levels of around 70 times the current ACGIH threshold limit value (TLV). No evidence of systemic toxicity was found, although all workers showed a greater or lesser degree of skin change in the form of peeling and/or fissuring.

Adult↗
PubMed2001

Aerosol particle and organic vapor concentrations at industrial work sites in Malaysia.

The objective of this study was to establish baseline data about air pollutants potentially related to nasopharyngeal carcinoma (NPC) in the Federal Territory and Selangor, Malaysia. During 1991-1993, ambient air quality was monitored at 42 work sites representing ten industrial sectors: adhesive manufacturing, foundries, latex processing, metalworking, plywood/veneer milling, ricemilling, rubber tire manufacturing, sawmilling, shoemaking, and textile related industries. At each work site, aerosol particle size distributions and concentrations of formaldehyde, benzene, toluene, isopropyl alcohol, and furfural were measured. Mean aerosol particle concentrations ranged from 61 micrograms/m3 in foundries to 5,578 micrograms/m3 in ricemills, with five industries (adhesives, metalworking, ricemilling, sawmilling, and shoemaking) exceeding the US EPA 24-hr ambient air standard for PM-10. Formaldehyde concentrations exceeded the threshold limit value (TLV) in adhesives factories. Other vapours and elements measured were well below TLVs.

Aerosols↗
PubMed1995

An Epidemiologic Study of the Effects of Carbon Disulfide on the Peripheral Nerves.

Although the labor inspection had disclosed considerable exposure to carbon disulfide (CS&inf2;) in a Belgian viscose rayon factory, the company medical officer had not diagnosed any case of polyneuropathy in association with CS&inf2; exposure, although this finding had been extensively reported in the literature. Personal monitoring of CS&inf2; exposure was performed in 17 jobs. Because the working conditions in the factory had not changed since 1932, a CS&inf2; cumulative exposure index (CS&inf2; index) could be calculated for each individual. Examination of the exposed subjects (n = 111) included a self-administered questionnaire, a clinical neurologic examination, and electroneuromyography. Seventy-four workers from other plants, not exposed to CS&inf2; or to any other neurotoxic agent, served as referents. The average CS&inf2; exposures of the study group ranged from 4 to 112 mg/m(3). The data were analyzed with multiple regression methods, adjusting the effect of exposure for a number of possible confounders. Significant associations were found between the cumulative CS&inf2; index and symptoms consistent with polyneuropathy in the legs and with abnormal recruitment pattern and decrease of motor conduction velocities of the peroneal nerves. Exposures to CS&inf2; at levels below the present threshold limit value (31 mg/m(3)) were associated with significant decreases of motor conduction velocity.

Journal Article↗
PubMed1996

Lung Function in Woodworking Teachers in Sweden.

Work-related airways symptoms are common in woodworkers. To study possible work-related effects on lung function, 40 exposed woodworking teachers and 31 controls were examined by spirometry, diffusion-capacity and nitrogen-washout determinations, and methacholine challenge. Measured levels of total and respirable dust and terpene concentrations in the shops were below the Swedish threshold-limit values. Lung-function values on Monday morning were similar in the two groups. Slight obstructive impairments during the working week were found in both groups. In the woodworking teachers, small changes in lung function were related to measured total dust, use of process ventilation, and use of a broom to clean the benches. Their methacholine reactivity was slightly more pronounced compared with that of the controls, but the numbers of hyperreactive individuals (PC&inf20; < 8 mg/m(3)) were equal in the two groups. These facts might indicate small work-related effects on lung function, but some contradictory findings disturb this interpretation. The results are therefore inconclusive.

Journal Article↗
PubMedDate not supplied

Neuropsychological effects of occupational exposures to carbon disulfide and hydrogen sulfide.

In the framework of an extensive health survey of viscose rayon workers in Belgium, 187 workers underwent a neuropsychological examination. Of these, 120 had been exposed for at least a year to carbon disulfide (CS&inf2;) and hydrogen sulfide (H2S), and 67 served as a non-exposed control group. Measurements showed that many of the 17 jobs in the factory involved exposures to CS&inf2; ranging from 3 mg/m(3) (centrifuge operator) to 147 mg/m(3) (spinning cake regulator), far in excess of the threshold limit value (TLV) of 31 mg/m(3); H2S exposures remained below the recommended TLV of 14 mg/m(3). The neuropsychological investigation included subtests of the Wechsler Adult Intelligence Scale, the entire Wechsler Memory Scale, the Bourdon-Wiersma Test, the Santa Ana Dexterity Test, the Gibson Spiral Maze, and the Bimanual Sinusoidal Movement Test. Specific questions were included to account for the effects of age, educational level, eye complaints, alcohol consumption, medication intake, and test motivation. Only the group exposed to values exceeding three times the recommended TLV for CS2; had significant impairments in both the speed and the quality of psychomotor performance. Exposure to CS2; and H2S had no significant effect on memory and attention. Covariance analysis revealed the confounding influences of educational level and eye complaints for explaining observed "differences" in memory and attention tasks found by univariate analysis.

Adult↗
PubMed2005

Sub-chronic inhalation of high concentrations of manganese sulfate induces lower airway pathology in rhesus monkeys.

BACKGROUND: Neurotoxicity and pulmonary dysfunction are well-recognized problems associated with prolonged human exposure to high concentrations of airborne manganese. Surprisingly, histological characterization of pulmonary responses induced by manganese remains incomplete. The primary objective of this study was to characterize histologic changes in the monkey respiratory tract following manganese inhalation. METHODS: Subchronic (6 hr/day, 5 days/week) inhalation exposure of young male rhesus monkeys to manganese sulfate was performed. One cohort of monkeys (n = 4-6 animals/exposure concentration) was exposed to air or manganese sulfate at 0.06, 0.3, or 1.5 mg Mn/m3 for 65 exposure days. Another eight monkeys were exposed to manganese sulfate at 1.5 mg Mn/m3 for 65 exposure days and held for 45 or 90 days before evaluation. A second cohort (n = 4 monkeys per time point) was exposed to manganese sulfate at 1.5 mg Mn/m3 and evaluated after 15 or 33 exposure days. Evaluations included measurement of lung manganese concentrations and evaluation of respiratory histologic changes. Tissue manganese concentrations were compared for the exposure and control groups by tests for homogeneity of variance, analysis of variance, followed by Dunnett's multiple comparison. Histopathological findings were evaluated using a Pearson's Chi-Square test. RESULTS: Animals exposed to manganese sulfate at > or = 0.3 mg Mn/m3 for 65 days had increased lung manganese concentrations. Exposure to manganese sulfate at 1.5 mg Mn/m3 for > or = 15 exposure days resulted in increased lung manganese concentrations, mild subacute bronchiolitis, alveolar duct inflammation, and proliferation of bronchus-associated lymphoid tissue. Bronchiolitis and alveolar duct inflammatory changes were absent 45 days post-exposure, suggesting that these lesions are reversible upon cessation of subchronic high-dose manganese exposure. CONCLUSION: High-dose subchronic manganese sulfate inhalation is associated with increased lung manganese concentrations and small airway inflammatory changes in the absence of observable clinical signs. Subchronic exposure to manganese sulfate at exposure concentrations (< or = 0.3 mg Mn/m3) similar to the current 8-hr occupational threshold limit value established for inhaled manganese was not associated with pulmonary pathology.

Acute Disease↗
PubMed1999

To what extent are biomonitoring data available in chemical risk assessment?

1. Chemical risk assessment integrates the identification of hazards and the human exposure levels which can be established from external and/or internal exposure data. 2. The availability of biomonitoring and metabolism animal data, the skin penetration ability, and the existence of atmospheric threshold limit values were examined for twelve substances of the European first list of priority existing substances. This investigation was focused on workplace exposures and on urinary biomarkers of exposure. Appropriate biomonitoring data appeared to be available for two substances: styrene and trichloroethylene. Some biomonitoring research has been conducted on acrylonitrile, buta-1,3-diene, cyclohexane, 1,4-dichlorobenzene, hydrogen fluoride, 2-(2-methoxyethoxy)ethanol, however additional studies could be usefully carried out. No biomonitoring data are available for alkanes, C10-13, chloro; benzene, C10-13-alkyl derivatives; bis(pentabromophenyl)ether; diphenylether, octabromo-derivative. 3. It was concluded that in some cases, biomonitoring data are either lacking or scarce. This is rather surprising since the selection of the substances of the priority list was based on high tonnage, widespread use, extent of human exposure, and toxicological concern. The development of biomonitoring information could be helpful in assessing individual or population chemical exposure whatever the source and route, and would result in both more realistic and more accurate risk assessments.

Acrylonitrile↗
PubMedDate not supplied

Particle size distribution and respiratory deposition estimates of beryllium aerosols in an extraction and processing plant.

The mass size distribution of beryllium aerosols generated in the various operational areas of a typical extraction and processing plant was studied using an eight-stage impactor sampler. The total concentration of beryllium in the plant was found to be well below the threshold limit value. The mean value of mass median aerodynamic diameter of beryllium particles observed for various operations ranged from 5.0-9.5 microm. The alveolar deposition for various operational areas was estimated to be 3-5% for nasal breathing and 9-13% for oral breathing based on the International Commission on Radiological Protection (ICRP) human respiratory tract model. Deposition during oral breathing was higher than during nasal breathing by approximately a factor of two to three. This study on exposure characterization was useful for reducing the respirable fraction of beryllium aerosol by optimizing the capture velocity and improving the quality of other control measures.

Aerosols↗
PubMedDate not supplied

Workplace exposure to submicron particle mass and number concentrations from manual arc welding of carbon steel.

Particle emissions from manual shielded metal arc welding of carbon steel were sampled in a typical industrial maintenance and metal fabrication workplace environment. Particle number measurements over the size range from 14 nm to 10 microm using a scanning mobility particle sizer and an optical particle counter showed that welding produced an approximately lognormal particle mode with a 120 nm count median and a geometric standard deviation of 2.07. This study produced welding particle number concentrations on the order of 2 x 10(5)/cm(3) in the building air 8.5 m away from the welding. Workplace exposure samples were below the current 8-hour American Conference of Governmental Industrial Hygienists mass concentration threshold limit value of 5 mg/m(3). Submicron particles comprised 80% of the total aerosol mass collected by a cascade impactor during welding. The concentration of larger particles was indistinguishable from indoor background. Microscopy showed that the welding emissions are dominated by clusters formed from <0.1 microm primary spheres. These data on the particles resulting from aerosol transformation by natural dilution inside an industrial building can be compared with laboratory-scale studies of welding particulate. The particle number characteristics observed in this study are significant because toxicological hypotheses suggest that number or surface area may be a better metric than mass when evaluating the health effects of fine particles.

Environmental Monitoring↗
PubMedDate not supplied

Exposure to diesel exhaust emissions on board locomotives.

Measurements of diesel exhaust emissions (DEEs) were taken in the cabs of leading and trailing locomotives on 48 runs, under winter and summer conditions, on 9 different routes. The cab windows were kept open during the summer runs and closed during the winter runs. The average measurement duration was 9.5 hours. There was virtually no exposure to DEEs in the lead locomotives during winter or summer and very little in the trailing locomotives during winter. The average elemental carbon (EC) concentration in the trailing units of the summer trials was greater than or equal to the proposed American Conference of Governmental Industrial Hygienists' threshold limit value/time-weighted average of 20 microg/m(3) on 26% of the runs, and was greater than or equal to 10 microg/m(3) on 63%. The concentrations of the gaseous components (nitric oxide, nitrogen dioxide, and carbon monoxide) were from 10 to 20 times below their respective threshold limit values. Mean EC concentration was 2.9 microg/m(3) (detection limit 2 microg/m(3)) during the winter runs and 17.1 microg/m(3) during summer. DEEs appeared to be fairly uniformly distributed in the trailing cabs. Configuration of the locomotives had a major impact on EC concentration, with the mean concentration being nearly three times higher in the forward-backward mode than in the forward-forward mode. Descriptive statistics such as means, medians, standard deviations, and so forth, are provided. Various types of statistical comparisons are reported. Recommendations for controlling exposure are made.

Carbon↗
PubMedDate not supplied

Strength capabilities and subjective limits in repetitive manual exertions: task and hand dominance effects.

Strength and subjectively determined exertion limits are used widely for ergonomic evaluation. Although compilations of such data for the hand and finger exist, several important limitations include the use of inexperienced participants and constrained postures. In this study both strength and maximum acceptable limits (MAL, 2-hour duration) were obtained from both industrial workers and inexperienced volunteers in 10 simulated hand-intensive automotive assembly tasks. To expand the applicability of the results, the effects of hand-dominance were also determined. Results were compared with existing recommendations (by Kodak and the American Conference of Governmental Industrial Hygienists threshold limit value for hand-intensive activities), and showed that across the diverse tasks the former yields values slightly below the 1st percentile of MAL, whereas the latter values are slightly higher than the 25th percentile. MALs were found to be approximately 50% of strength, consistent with earlier reports, and suggesting that acceptable limits are strongly influenced by physical capacity. Substantial differences ( approximately 30%) in strength and MALs were found between the two participant groups, emphasizing that participants should resemble the target population. Hand-dominance effects were statistically significant though of moderate size ( approximately 5%). Strength and MAL distributions are provided that can be used for evaluation and design of a variety of hand-intensive occupational tasks.

Adult↗