Showing papers in "American Industrial Hygiene Association Journal in 1984"

Application of gas adsorption kinetics. I. A theoretical model for respirator cartridge service life.

Abstract: Using the principles of gas adsorption kinetics, we have developed a new theoretical model addressing the adsorption and breakthrough of contaminant vapors or gases with respect to solid sorbents. Specifically, we have applied the theory to predict respirator cartridge service life in connection with individual contaminant exposure to toluene, vinyl chloride, ethyl acetate, and each of several different trichlorinated hydrocarbons at several levels of concentration. Theoretical expressions and contaminant breakthrough curves derived from our new approach are compared with those published previously by Mecklenburg and by Wheeler. The breakthrough curves derived by Mecklenburg and by Wheeler have approximately the same shape as the corresponding experimental curves for 0% to 40% breakthrough. However, these curves deviate in varying degrees from the experimental data at breakthrough values exceeding 40%. By contrast, our new theory agrees with published experimental results over the entire range of 0% to 10...

Application of Gas Adsorption Kinetics — II. A Theoretical Model for Respirator Cartridge Service Life and Its Practical Applications

Abstract: A previously introduced theoretical model addressing respirator cartridge contaminant breakthrough was further developed in this study. This development involved the introduction of a new theoretical parameter, a, to complement the parameters k′ and τ employed in the initial theoretical approach. The extension of the theory permits the theoretical investigation of the following: (1) the effect of contaminant concentration on breakthrough time; (2) the effect of flow rate on breakthrough time; (3) the influence of contaminant concentration on percentage of breakthrough; and (4) the effect of contaminant concentration on the weight of adsorbed contaminant at a given time. We also compared new theoretical expressions with previously published empirical equations. Utilizing the parameter a, we derived a set of equations of significant practical value. These equations relate the ratio of two contaminant concentrations (one experimental reference concentration and any other concentration of interest) to either ...

Inhalation Exposure to Formaldehyde: An Overview of Its Toxicology, Epidemiology, Monitoring, and Control

Abstract: Increasing production and use of formaldehyde in consumer products have resulted in widespread recognition of its acute irritant effects at exposure levels below the current occupational health standard [3 parts per million parts of air (ppm)]. Formaldehyde is an allergic (immunologically mediated) skin sensitizer which may also cause or exacerbate respiratory distress in individuals with preexisting or formaldehyde-induced bronchial hyperreactivity. Formaldehyde gas is a very reactive alkylating agent which is mutagenic in several in vitro test systems. At exposure levels less than one order of magnitude greater than those often found in human occupational and nonoccupational environments, it induces squamous cell carcinomas in the nasal cavity of rats. Recent reviews suggest that formaldhyde exposure should be treated as though it poses a carcinogenic risk to humans and should be reduced to the lowest feasible level. This report reviews information on the epidemiologic evaluation of health effects which...

Environmental Study of Poultry Confinement Buildings

Abstract: Environmental measurements were made in three poultry confinement buildings in order to characterize gas and particulate contaminants. Levels of total and respirable dust averaged 4.4 and 0.24 mg/m3, respectively. Particle size distribution as measured by cascade impactors was similar in the three confinement houses with a mass median aerodynamic diameter of about 15 µm and a geometric standard deviation of about 2.2. Ammonia levels measured in the active areas of the buildings averaged about 25 ppm. Ammonia concentration was quite high, however, in an unused and unventilated portion of one of the buildings (). CO2 levels ranged from 0.05–0.1%. Levels of CO, H2S, NO2, NOx, CH4, mercaptan, formaldehyde, and hydrocarbons were all below the limit of detection for indicator tubes. Concentrations of airborne bacteria and fungi were on average about 1.5×105 and 1.0×104 colony-forming units/m3, respectively. Endotoxin analysis was also performed on the total and respirable dust samples. Endotoxih levels (express...

Cancer Mortality and Solvent Exposures in the Rubber Industry

Abstract: Some evidence suggests that solvent exposures to rubber industry workers may be associated with excess cancer mortality, but most studies of rubber workers lack information about specific chemical exposures. In one large rubber and tire-manufacturing plant, however, historical documents allowed a classification of jobs based on potential exposures to all solvents that were authorized for use in the plant. A case-control analysis of a 6678 member cohort compared the solvent exposure histories of a 20% age-stratified random sample of the cohort with those of cohort members who died during 1964–1973 from stomach cancer, respiratory system cancer, prostate cancer, lymphosarcoma, or lymphatic leukemia. Of these cancers, only lymphosarcoma and lymphatic leukemia showed significant positive associations with any of the potential solvent exposures. Lymphatic leukemia was especially strongly related to carbon tetrachloride (OR=15.3, p<.0001) and carbon disulfide (OR=8.9, p=.0003). Lymphosarcoma showed similar, but...

Exposure to Hydrogen Sulfide, Mercaptans and Sulfur Dioxide in Pulp Industry

Abstract: An hygienic survey for hydrogen sulfide, methyl mercaptan and its derivatives and sulfur dioxide in kraft mills and in sulfite mills revealed concentrations varying from 0 to 20 ppm hydrogen sulfide, 0 to 15 ppm methyl mercaptan and comparable amounts of dimethyl sulfide with dimethyl disulfide up to 1.5 ppm. The greatest emissions were detected at chip chutes and evaporation vacuum pumps. Batch operations yielded clearly higher sulfur dioxide concentrations (up to 20 ppm) as compared to a continuous ammonia-base digester. Furthermore, there was a strong correlation with the season in the sulfite mills where higher concentrations were found in the winter when natural ventilation was poorer. As to the health effects, the exposed workers complained of headaches and a decrease in concentration capacity more often than matched controls. The number of sick leaves was greater in the exposed workers than among the controls.

Characterization of diesel exhaust in a chronic inhalation study.

Abstract: We describe characterization of the exposure atmosphere in a life-span study of rats and mice exposed to chronic inhalation of diluted diesel exhaust. Diesel exhaust was generated by one of two General Motors 1980 Model, 5.7-liter V8 diesel engines connected to an eddy current dynamometer/flywheel system and operated on the Federal Test Procedure urban driving cycle. Animals were exposed 7 hours/day, 5 days/week to exhaust at particle concentrations of approximately 7000, 3500, and 350 µg/m3 or to clean air. Throughout the 24-month study, the mean particle mass concentration remained within 5% of the target values. Measured gas concentrations of CO, CO2, NO, NO2, and hydrocarbons were roughly proportional to the dilution ratio. A combination of a Lovelace Multijet cascade impactor followed by a parallel flow diffusion battery gave mass median diameters of 0.23 to 0.26 µm averaged over complete cycles and geometric standard deviations larger than 4. The aerosol concentration profile was associated with the...

Dose-dependent effects of submicrometer sulfuric acid aerosol on particle clearance from ciliated human lung airways

Abstract: We previously showed that 1 hr exposures to submicrometer sulfuric acid (H2SO4) aerosol at 100 and 1000µg/m3 altered the bronchial mucociliary clearance of monodisperse 7.6 µm MMAD99mTc-labelled ferric oxide (Fe2O3) in healthy, nonsmoking humans. The 7.6 µm particles were primarily deposited in the larger bronchial airways, where submicrometer H2SO4 has very little deposition. To determine the extent that submicrometer H2SO4 aerosol affects clearance from the more distal ciliated airways, we measured the clearance of a monodisperse 4.2 µm MMAD Fe2O3 aerosol in eight other healthy nonsmoking subjects. A greater fraction of 4.2 µm particles deposited in distal conductive airways. Bronchial mucociliary clearance was slower following 1 h nasal H2SO4 inhalations at 100,300 and 1000 µg/m3 than after sham exposures, while mucociliary transport rates within the trachea and indices of respiratory mechanics were unchanged. A comparison of the effects of 1 h exposures at 100 µg/m3 on the clearance of 7.6 and 4.2 µm ...

Occupational exposure of herbicide applicators to herbicides used along electric power transmission line right-of-way.

Abstract: Occupational exposures to herbicides were measured among 12 applicators in 1979 and 24 applicators in 1980, who were applying the three herbicides, 2,4-D, dichloroprop and picloram to electric power transmission rights of ways. In 1979 only urine was analyzed but in 1980 both breathing-zone air samples and urine were analyzed for herbicide residues. Dermal absorption was found to be the major absorption route being up to 50 times greater than exposure by the inhalation route when using a hand gun sprayer. Even with the mist blower herbicide application method, dermal absorption was 4 and 11 times greater than exposure by the inhalation route. Worker education on hazards of skin contact and improved protective equipment significantly reduced the 1980 urine concentrations of herbicide residues. A model is presented to relate the urinary concentrations to equivalent daily exposure levels.

A Review of World Literature Finds Iron Oxides Noncarcinogenic

Abstract: Iron oxide appeared in the first list of 154 Threshold Limit Values adopted by the American Conference of Governmental Industrial Hygienists at its April 1949 annual meeting. It was set to control dust and fume at the recommended value of 15 mg/M3, at the time, the limit for an inert or "nuisance" dust, and was based on studies of welders made earlier by the U.S. Dept. of Labor and by Drinker and Nelson. By 1964, the TLV was tentatively reduced to 10 mg/M3 after a considerable body of literature had accumulated not only on the health experience of welders, but of other occupations involving iron oxides as well. As a group, these studies indicated that 15 mg/M3 permitted too great accumulations of iron pigmentation in the lung whose chronic retention effects were not known with certainty. Also, an occasional report of cancer of the lungs appeared particularly among British hematite miners, although these findings were immediately questioned on statistical grounds. In seeming confirmation of these early reports of cancer, an alarming number of reports of cancer of the lung and respiratory tract among welders and foundrymen began to appear by 1970, reaching a crescendo by the end of that decade. As past chairman of the TLV Committee, I decided to examine the bases of these findings. This review is the result of this examination.

Estimation of long term dust exposures in the Vermont granite sheds.

Abstract: Analysis of variance models were used to analyze 1153 personal samples of respirable granite dust collected in the Vermont granite sheds in 1970 and 1976. The best fitting model described dust concentrations in terms of job, shed, season, survey year, and included interaction terms between shed, season, and survey. This model explained 46% of the total variability in dust levels, and was used to estimate median annual dust concentrations for every job and shed in the industry. The analysis of variance suggested that dust levels varied more between sheds than between jobs within a shed, and that winter dust levels were significantly higher than summer levels. Dust levels in the 1970s were estimated by the average of the seasonally adjusted levels in the two surveys. Dust estimates in each job and shed were combined with personal work histories, and three procedures for estimating each worker's lifetime exposure were evaluated. The cumulative exposure index with uniform weights for each dust year of exposur...

A Diffusive Sampler Evaluation Protocol

Abstract: An integral part of any new development in sampling or analysis must be an evaluation of its performance both in laboratory and field trials. However, the evaluation protocol generally used for dynamic sampling (the NIOSH Standards Completion Program) does not apply to diffusive sampling, so that a new approach is required. The main features of the diffusive sampler protocol developed by the authors are: 1) Emphasis on the determination of the accuracy of the standard atmosphere used to calibrate the samplers; 2) Emphasis on field testing the samplers in a variety of occupational environments; 3) Omission of acceptance criteria based solely on accuracy.

The Development and Use of a Universal Model to Predict Tree Crop Harvester Pesticide Exposure

Abstract: A simple regression model is presented for predicting the transfer of residual foliar applied pesticide to the body of a Florida citrus harvester. This model is dependent on work rate and residue concentration and agrees with an earlier model derived from similar data taken from a California study. This suggests that observed regional differences in the morbidity of harvesters in treated fields may be due to regional differences in foliar pesticide residue levels rather than regional differences in transport mechanisms of pesticide from foliage to worker. Eventual metabolite output in worker urine is also predicted.

Reconstruction of silica exposure in the North Carolina dusty trades.

Abstract: The current occupational standard for quartz exposure is largely drawn from studies of the granite workers at Barre, Vermont. Since 1935, the North Carolina Dusty Trades program has accumulated data on work-place environmental conditions, occupational history and health status for persons exposed to silica in a broad range of mineral industries, including granite dimension stone. The environmental data have been collected with Greenburg-Smith and midget impingers and the respirable mass dust sampler. A procedure is presented to combine the results of these sampling methods and estimate exposure at the various jobs at each dusty trades plant. From an individual's occupational history, the environmental exposure estimates are used to formulate personal lifetime exposure summaries. The results of this procedure in the North Carolina granite industry compared well with historical data from Vermont granite sheds.

Gram-Negative Bacterial Endotoxins in Grain Elevator Dusts

Abstract: Twenty settled and 69 respirable grain dust samples were collected from 5 grain elevators along the lower Mississippi River. Studies were performed on 2-keto-3-deoxyoctonate (KDO) concentrations, total bacterial plate counts, gram-negative bacteria (GNB) count, identification of GNB, and endotoxin levels. KDO values were 52.1–510.0 ng/mg. A new method involving gas liquid chromatography was developed to analyze for KDO. No correlation could be made between KDO and endotoxin levels. Total bacterial plate counts for settled dusts ranged from 1.9 to 53.4 million/g, while the GNB count was 0.1–50.0 million/g. Two hundred and thirty GNB were isolated from all samples and identified. Sixty-one percent were Enterobacter agglomerans, followed by species of Pseudomonas (9.1%), Serratia (6.9%), Actinetobacter (6.9%) and other genera (16.2%). All but four of the airborne samples had no significant bacterial population. Twenty-three of sixty-nine airborne samples contained 0.6 ng of endotoxin while 3 filters had 6.0 ...

Evaluation of total isocyanate-in-air method using 1-(2-methoxyphenyl)piperazine and HPLC.

Abstract: The United Kingdom Health and Safety Commission has set a ‘common control limit’ for workplace exposure to all isocyanates. This limit replaces the previous United Kingdom threshold limit values, which were set for just four species of monomeric isocyanate compounds. This new control limit is set at 20 µg of isocyanate group per cubic meter of air expressed as an eight-hour weighted average, and 70 µg of isocyanate group per cubic meter of air as a 10-minute weighted average. These new control limits make it necessary that analytical methods should be capable of measuring total isocyanate concentration, including monomers and prepolymers. A previously available method for determining isocyanate monomers using l-(2-methoxyphenyl)piperazine with high performance liquid chromatography (HPLC) has been modified to measure both monomer and prepolymer. A dual detection system employing electrochemical and ultra-violet detectors is used to identify isocyanate-derived HPLC peaks which are then quantified by refere...

Field comparison between two nitrous oxide (N2O) passive monitors and conventional sampling methods.

Abstract: Field tests conducted over the range of 4–330 ppm nitrous oxide in hospital operating rooms as well as dental and veterinary clinics showed a prototype of the Landauer NITROX® passive monitor compared more favorably with a Miran 1-A® IR gas analyzer than either the Solid State Sensor® or bag samples. All methods were tested simultaneously in a chamber designed to produce uniform real-time monitoring.

Personal air samplers for measuring occupational exposures to biological hazards.

Abstract: Microbiological air samplers, designed to be worn as personal samplers, were evaluated for studying occupational exposures to aerosols of infectious and allergenic materials. Gelatin filter media, an impinger sampler, and spiral and cascade impactors were tested for collection efficiency for small (≤2 µm) latex spheres and for recovery of bacterial aerosols. Only 20% of an aerosol of 0.8 µm latex particles passed through the impinger uncollected, while recovery of bacteria equalled or exceeded collection in an all-glass impinger. Gelatin filters matched the collection efficiency of membrane filters, but were unsatisfactory for the isolation of bacteria sensitive to dehydration. The spiral sampler and the cascade impactor provide information on the size distribution of collected particles, although, at present, collection efficiencies for very small particles are too low for rigorously quantitative studies. Methods of collection, and sampling strategies for biological aerosols are similar to those used for...

Workplace Protection Factor Measurements on Powered Air-Purifying Respirators at a Secondary Lead Smelter: Results and Discussion

Abstract: A study was conducted at a secondary lead smelter to evaluate the workplace performance of the 3 M W-344 and Racal AH3 powered air-purifying respirators equipped with helmets and high efficiency filters. The research protocol developed for the study has been described in a companion paper. The results of the study indicate that the mean lead concentrations, measured inside the facepiece of both PAPRs, were significantly less than the OSHA lead exposure limit of 50 µg/m3. The means of the workplace protection factor measurements on both PAPRs were significantly less than the PAPR selection guide protection factor classification of 1000. Correlation analysis of preshift quantitative fit factors and corresponding workplace protection factors indicated no linear association between these two measures of performance. This finding suggests that for PAPRs equipped with helmets and high efficiency filters quantitative fit factors as presently determined are not indicative of the workplace protection which the res...

Deposition and retention of inhaled aggregate 67Ga2O3 particles in beagle dogs, Fischer-344 rats, and CD-1 mice.

Abstract: Deposition and retention of inhaled 67Ga2O3 aerosols were measured in ten beagle dogs to provide reasonable estimates for human deposition and in Fischer-344 rats and CD-I mice to estimate lung burdens in small animals frequently used in toxicological evaluations. Aggregated particles of 67Ga2O3, 0.1 µm mass median diameter (MMD), were produced using heat treatment of 67Ga tetramethylheptanedione. Whole-body counting and gamma camera imaging were used to measure deposition. Pulmonary deposition in dogs was measured as 25% of the inhaled particles for the 0.1 µm particles. Tracheobronchial and nasopharyngeal deposition were much lower, 7% and 7% respectively. Pulmonary deposition of 0.1 µm (MMD) particles was calculated as 10% and 11% of inhaled particles in Fischer-344 rats and 15 and 20% in mice for two separate nose-only exposures of each species.

Study and Models of Total Lead Exposures of Battery Workers

Abstract: In an attempt to establish a more realistic and reliable model for relating environmental exposure measurements to the biological indices of exposure, a study was undertaken to quantify the total sources of lead exposure among lead storage battery workers. In addition to the usual personal and area lead air sampling, quantitative and repeatable measurements of removable lead from work surfaces and the workers' hands and faces were obtained daily for ten consecutive work days in the pasting and battery assembly departments. Mathematical correlations of blood lead and zinc protoporphyrin (ZPP) levels as the dependent variable with the lead exposure sources were derived and demonstrated most strongly as log-log relationships. Statistical analyses by computer programming indicated that the airborne, hand, facial and work surface levels have a high degree of inter-correlation with a very significant positive individual correlation with blood lead levels and a somewhat lower correlation with ZPP. The results su...

Exposure of embalmers to formaldehyde and other chemicals

Abstract: Seven funeral homes were surveyed in 1980 to determine the magnitude of embalmers' exposure to formaldehyde, other chemical vapors, and total and respirable particulates. Air was monitored for formaldehyde by personal and area samples, and assayed using the chromotropic acid method. Personal sampling revealed time-weighted average formaldehyde concentrations which ranged from 0.1 to 0.4 ppm (mean 0.3 ppm) and 0.5 to 1.2 ppm (mean 0.9 ppm) during the embalming of intact and autopsied bodies, respectively. Concentrations of other airborne chemicals and of particulates were negligible. In preparing autopsied bodies, embalming technique and condition of the body itself appeared to be major determinants of formaldehyde exposure.

A laboratory evaluation of wipe testing based on lead oxide surface contamination.

Abstract: Although wipe testing has been used extensively as a measure of surface contamination in industrial hygiene, few scientific studies have been reported to validate the procedure with respect to quantitative recovery, repeatability or methodology. Consequently, a laboratory evaluation of wipe testing with particular attention to the OSHA procedure was undertaken using lead oxide dust as the test contaminant. A dust dispersion system was devised using a Wright dust feeder to produce relatively uniform surface concentrations in an aerosol chamber. Wipe materials included moistened filter paper, commercial paper towels, adhesive paper labels and adhesive tape. The quantitative recovery and repeatability of the wipe procedures were related to surface concentrations and the operational and material variables. Significant improvements in recoveries of up to 90% can be obtained with good repeatability for removable lead oxide dust on non-porous surfaces using moist paper on a fixed test surface area. For porous surfaces, which show significantly lower recovery by all methods, adhesive sampling materials applied at maximum pressure provided an optimum recovery of 77%. The importance of reliable surface contamination measurements in assessing potential health hazards underscores the desirability of improving the demonstrated deficiencies of the OSHA and other wipe sampling procedures.

Gas Phase Reaction of Toluene Diisocyanate with Water Vapor

Abstract: A study of the gas phase reaction of toluene diisocyanate (TDI) with water vapor has been conducted in a large (17.3 m3) environmental chamber. A number of analytical procedures were employed to follow the decay of TDI and to search for toluene diamine (TDA) and other reaction products. Experiments were conducted at ambient temperatures (27±1°C); relative humidity was varied from 7 to 70 percent. Four TDI concentrations were examined i.e. 0.6,0.2,0.1 and 0.05 ppm. No evidence was found for a gas phase reaction between TDI and H2O. This finding appears to contradict earlier studies of the reaction of TDI with water vapor. The observed TDI loss rate in the present study has been ascribed to physical removal process i.e. surface adsorption onto the walls of the environmental chamber. The results of this study cannot exclude the possibility that TDI reacts slowly with water vapor, but under the conditions of these experiments, adsorption on the wall surfaces takes place first. TDA and TDI-urea were searched f...

Investigation and control of occupational hazards associated with the use of spirit duplicators

Abstract: A Health Hazard Evaluation was conducted by the National Institute for Occupational Safety and Health (NIOSH) to determine if vapors from duplicating fluid (99% methyl alcohol) used in direct-process spirit duplicating machines were causing adverse health effects among teacher aides, or had been responsible for the deaths of three former teacher aides. Death certificates and autopsy data were obtained and evaluated. A self-administered symptom questionnaire was distributed to current teacher aides (exposed group) and to a comparison group of teachers. Fifteen-minute breathing zone air samples for methyl alcohol vapor were collected at operator stations using an infrared gas analyzer. No information supported the claim that the three deaths were related to methyl alcohol exposure. Teacher aides reported significantly more blurred vision, headache, dizziness, and nausea than the comparison group. Concentrations of airborne methyl alcohol ranged from 365 3080 ppm; 15 of 21 measurements exceeded the NIOSH-rec...

Airborne isocyanates in polyurethane spray painting: determination and respirator efficiency.

Abstract: The concentrations of airborne isocyanates were measured during spray painting with two-component polyurethane paint. The isocyanate component - hexamethylene-diisocyanate (HDI) and its prepolymer of the biuret type - were determined by high performance liquid chromatography after derivatization to stable urea derivatives with N-4-nitrobenzyl-N-n-propylamine. Samples were collected on reagent impregnated glassfiber filters, and the derivatives were eluted with the chromatographic eluent. An impregnation technique is reported; it facilitates the chromatographic separation and the subsequent quantitative determination. Recovery studies from filters were performed in the range of 0.05 to 30 µg for the HDI monomer, and 0.5 to 100 µg for the HDI oligomer on the same filter. Average recoveries of the monomer and the oligomer were 97±2% (standard deviation) and 92±4%, respectively. The concentrations of the isocyanate components, measured during spray painting, were very high. For example, the level of the monom...

Effects of respirators under heat/work conditions

Abstract: Physiological responses and perceived strain of five unacclimatized male subjects were studied. The subjects were exposed to heat during an exercise task and were evaluated while wearing half and full facepiece, cartridge-type, air-purifying respirators, and without a respirator. The exercise consisted of walking on a treadmill for a period of 1 hour in a controlled environmental chamber at each of two different energy expenditure levels (200 and 400 Kcal/hr) (≅58 and 116 Watts) and two different heat exposures (air temperatures of 25°C and 43.3°C). The results indicated that wearing a full facepiece respirator imposed significant physiological strain added to that caused by the heat and workloads used in the study. Five of the six physiological measures show this increased physiological strain: (1) heart rate; (2) minute ventilation; (3) oxygen consumption; (4) energy expenditure; and (5) oral temperature. There was no detectable effect on sweat rate. Although subjective ratings indicated more discomfort...

Isomeric Composition of Airborne TDI in the Polyurethane Foam Industry

Abstract: The isomeric composition of airborne toluene diisocyanate has been determined in two plants producing slab stock flexible polyurethane foam. The high performance liquid chromatographic technique used for analysis of the collected samples was optimized for the quantitative and qualitative determination of 2,4 and 2,6-TDI. The data indicates that there is a very large increase in the amount of airborne 2,6-TDI relative to the 2,4 isomer, as compared to the starting material used in the process. The magnitude of the increase was dependent on the stage of production. These results are consistent with the hypothesis of increased offgassing of 2,6-TDI, due to its lower reactivity.

In-Mask Aerosol Sampling For Powered Air Purifying Respirators

Abstract: A system for sampling aerosols in the facepiece of a powered air purifying respirator has been described. The system consists of a sampling inlet mounted on the respirator facepiece, a filter cassette and a personal sampling pump. The theoretical and practical considerations leading to the design of the sampling inlet have been discussed and experimental data presented showing the efficiency of the inlet as a function of particle size and sampling flow rate. The in-mask sampling system has been designed for powered air purifying respirators.

A manual materials handling study of bag lifting.

Abstract: Physiological and psychophysical research approaches were employed to determine the effects of two levels of fullness (70% and 95%) and the use of handles on bag lifting tasks. A comparison of bag lifting and box lifting was also conducted. Neither the level of bag fullness nor the availability of handles on the bag resulted in a significant change in physiological response for a 20.4 kg load. The maximum acceptable weight lifted was significantly higher when performing a bag lifting task either with handles or when the bag was 95% full. The maximum acceptable weight of lift for bag lifting tasks was higher (2.21 kg) than for box lifting tasks under the conditions of this experiment.