Annals of Occupational Hygiene - recent issues

How Safe is Control Banding? Integrated Evaluation by Comparing OELs with Measurement Data and Using Monte Carlo Simulation

Tischer, M., Bredendiek-KAmper, S., Poppek, U., Packroff, R. — 2009-07-03

The present study aims to explore the protection level that can be achieved by the German control banding (CB) tool Einfaches Massnahmenkonzept Gefahrstoffe, ‘Easy-to-use workplace control scheme for hazardous substances’. The rationale of our integrated approach is based on the Bewertungsindex (BWI), which is the quotient of the exposure level and the occupational exposure limit (OEL), with BWI <1 indicating compliance. The frequency distributions of the BWI were calculated in order to reflect statistically the variability of workplace conditions. The corresponding statistical values of the frequency distributions (percentiles etc.) are interpreted as an indicator of the level of protection that is achieved.

The occupational exposure data sets used in the calculation of the BWI frequency distribution were mainly collected from Bundesanstalt für Arbeitsschutz und Arbeitsmedizin field studies. The data sets taken into account were selected according to the criteria ‘hazard band, exposure potential, control approach’. Such a combination is called the ‘control banding scenario’ (CBS). Measurement data are only available for two CBS: in the case of the CBS ‘hazard band A, EPL3, CS1’ the only data that are available (n = 220) relate to propane-2-ol as used in the area of offset printing. Only 0.4 % of the BWI are above 1, this indicating a high level of compliance. In the case of the CBS ‘Hazard band B, EPL2, CS1’, exposure data are available from screen-printing firms (n = 50), optician workshops (n = 49), and from the area of furniture production (n = 13). The frequency distributions of the BWI reveal almost no instances of values being exceeded in the three branches.

In a subsequent step, a Monte Carlo Simulation was employed to explore whether the BWI frequency distributions can be generalized using a probabilistic model. The frequency distributions of the exposure levels and the OELs were used as the input data for the model. The simulation results show that the model distribution, called Modellierter Bewertungsindex distribution, can reproduce the BWI distribution if the data basis is homogeneous (data from one branch) and less correlated. In case of a heterogeneous data set (pooled data from different branches), the simulation results can be interpreted as generic statements about the attainable protection level. It was found that CB does not (at least potentially) guarantee compliance in either case. On the other hand, the generic simulation showed that compliance was high for volatile liquids used in closed systems (CBS: ‘hazard band C, EPL3, CS3’) and for solids in the presence of local exhaust ventilation (CBS: ‘hazard band B, EPS3, CS2’).

Evaluation of COSHH Essentials: Methylene Chloride, Isopropanol, and Acetone Exposures in a Small Printing Plant

Lee, E. G., Harper, M., Bowen, R. B., Slaven, J. — 2009-07-03

The current study evaluated the Control of Substances Hazardous to Health (COSHH) Essentials model for short-term task-based exposures and full-shift exposures using measured concentrations of three volatile organic chemicals at a small printing plant. A total of 188 exposure measurements of isopropanol and 187 measurements of acetone were collected and each measurement took ~60 min. Historically, collected time-weighted average concentrations (seven results) were evaluated for methylene chloride. The COSHH Essentials model recommended general ventilation control for both isopropanol and acetone. There was good agreement between the task-based exposure measurements and the COSHH Essentials predicted exposure range (PER) for cleaning and print preparation with isopropanol and for cleaning with acetone. For the other tasks and for full-shift exposures, agreement between the exposure measurements and the PER was either moderate or poor. However, for both isopropanol and acetone, our findings suggested that the COSHH Essentials model worked reasonably well because the probabilities of short-term exposure measurements exceeding short-term occupational exposure limits (OELs) or full-shift exposures exceeding the corresponding full-shift OELs were <0.05 under the recommended control strategy. For methylene chloride, the COSHH Essentials recommended containment control but a follow-up study was not able to be performed because it had already been replaced with a less hazardous substance (acetone). This was considered a more acceptable alternative to increasing the level of control.

Ultrafine Particle Characteristics in Seven Industrial Plants

Elihn, K., Berg, P. — 2009-07-03

Ultrafine particles are considered as a possible cause of some of the adverse health effects caused by airborne particles. In this study, the particle characteristics were measured in seven Swedish industrial plants, with a special focus on the ultrafine particle fraction. Number concentration, size distribution, surface area concentration, and mass concentration were measured at 10 different job activities, including fettling, laser cutting, welding, smelting, core making, moulding, concreting, grinding, sieving powders, and washing machine goods. A thorough particle characterization is necessary in workplaces since it is not clear yet which choice of ultrafine particle metric is the best to measure in relation to health effects. Job activities were given a different order of rank depending on what particle metric was measured. An especially high number concentration (130 x 10³ cm^–3) and percentage of ultrafine particles (96%) were found at fettling of aluminium, whereas the highest surface area concentration (up to 3800 µm² cm^–3) as well as high PM10 (up to 1 mg m^–3) and PM1 (up to 0.8 mg m^–3) were found at welding and laser cutting of steel. The smallest geometric mean diameter (22 nm) was found at core making (geometric standard deviation: 1.9).

Exposure to Hazardous Substances in a Standard Molecular Biology Laboratory Environment: Evaluation of Exposures in IARC Laboratories

Chapot, B., Secretan, B., Robert, A., Hainaut, P. — 2009-07-03

Working in a molecular biology laboratory environment implies regular exposure to a wide range of hazardous substances. Several recent studies have shown that laboratory workers may have an elevated risk of certain cancers. Data on the nature and frequency of exposures in such settings are scanty. The frequency of use of 163 agents by staff working in molecular biology laboratories was evaluated over a period of 4 years by self-administered questionnaire. Of the agents listed, ethanol was used by the largest proportion of staff (70%), followed by ethidium bromide (55%). Individual patterns of use showed three patterns, namely (i) frequent use of a narrow range of products, (ii) occasional use of a wide range of products, and (iii) frequent and occasional use of an intermediate range of products. Among known or suspected carcinogens (International Agency for Research on Cancer Group 1 and 2A, respectively), those most frequently used included formaldehyde (17%), oncogenic viruses (4%), and acrylamide (32%). The type of exposure encountered in research laboratories is extremely diverse. Few carcinogenic agents are used frequently but many laboratory workers may be exposed occasionally to known human carcinogens. In addition, many of the chemicals handled by staff represent a health hazard. The results enabled the staff physician to develop an individual approach to medical surveillance and to draw a personal history of occupational exposures for laboratory staff.

Role of Associated Mineral Fibres in Chrysotile Asbestos Health Effects: The Case of Balangeroite

Turci, F., Tomatis, M., Compagnoni, R., Fubini, B. — 2009-07-03

Objectives: To evaluate the biodurability of balangeroite, present as contaminant of chrysotile asbestos in the Balangero mine, in order to have indication whether it might have been a confounding factor in the association of the mesothelioma cases reported among mine workers and employees.

Methods: The modifications taking place following incubation of the fibres in simulated phagolysosomal fluids have been measured on balangeroite, on one pure chrysotile sample (Val Malenco), on one chrysotile from Balangero with some associated balangeroite, and on two tremolite samples.

Results: The incubation modifies both chrysotile and balangeroite with substantial release in the medium of the metal ions which occupy the octahedral site in the mineral structure of the fibre while tremolite is virtually unaffected.

Conclusions: Considering the profound differences between the structure of balangeroite and amphiboles, previous results and observations on the poor ecopersistence of balangeroite, and the present data, we conclude that balangeroite traces may contribute to the overall toxicity of the airborne fibres in Balangero, but may not be compared to tremolite nor considered the sole responsible for the excess of mesothelioma found in Balangero.

A Survey of Occupational Exposure to 4,4'-methylene-bis (2-chloroaniline) (MbOCA) in the UK

Cocker, J., Cain, J. R., Baldwin, P., McNally, K., Jones, K. — 2009-07-03

Objectives: The main objective of the study was to gather information about the current controls and levels of exposure to 4,4'-methylene-bis (2-chloroaniline) (MbOCA) in a representative cross section of workplaces that use it to manufacture polyurethane elastomers. The study also aimed to investigate whether controls and guidance could be improved and to investigate exposure to isocyanates in these workplaces using biological monitoring.

Methods: An occupational hygienist and a field scientist visited the two UK suppliers and 20 out of the 25 workplaces known to be using MbOCA in the UK during 2005 and 2006. They collected air samples, surface wipes, gloves, and urine samples and made observations to assess exposure and the adequacy of controls. All samples were analysed for MbOCA and urine samples were additionally analysed for isocyanate metabolites. A statistical analysis was made of the results.

Results: Only 2.5% of the 80 personal inhalation exposures to MbOCA exceeded the workplace exposure limit of 5 µg m^–3 8-h time-weighted average and 84% were below the limit of detection (LOD). Surface samples (n = 334) were collected from MbOCA users and suppliers and 60% had detectable levels of MbOCA ranging from 0.019 to 400 µg cm^–2. The highest levels were around a hopper, ovens, and the weighing and pouring areas. MbOCA was also detected in 8 of the 75 samples collected from areas not likely to be in contact with MbOCA. At the two suppliers, samples (n = 28) were collected from the outside surfaces of recently imported kegs, pallets, and the floor around kegs. Six samples had detectable levels and four of these (0.2, 0.8, 1, and 6 µg cm^–2) were from the floor and pallets in both suppliers. The other two positive results were found on the outside rim (18 µg cm^–2) and side (23 µg cm^–2) of a keg at one supplier indicating contamination by the manufacturer. Urine samples (n = 79) were collected and 49% were below the LOD for MbOCA and only three samples had levels of MbOCA that exceeded the biological monitoring guidance value (BMGV) of 15 µmol mol^–1 creatinine. The highest urinary MbOCA concentrations were in samples from workers casting and moulding. The 90th percentile of the urine MbOCA results was 8.6 µmol MbOCA per mol creatinine. Urine samples were also analysed for the diamine metabolites of toluene diisocyanate and hexamethylene diisocyanate and 33% had detectable levels with 22 and 13% of results, respectively, above the BMGV for isocyanates (1 µmol isocyanate-derived diamine per mol creatinine). The maximum urinary concentration of toluene diamine and hexane diamine were 15.6 and 10.1 µmol mol^–1 creatinine, respectively.

Conclusions: The survey found that the measures used to control exposure to MbOCA could be improved. Although air levels of MbOCA were generally low, there was evidence of spread of surface contamination and poor maintenance of controls such as local exhaust ventilation. A BMGV based on the 90th percentile of data from workplaces with good control would be less than the 90% value of 8.6 µmol mol^–1 creatinine found in this study and suggests that the current BMGV of 15 µmol mol^–1 creatinine is no longer acting as a stimulus to reduce exposure. The metabolites of isocyanates found in urine samples in this study could arise from inhalation exposure to isocyanates or from dermal exposure to either isocyanates or their diamine breakdown product and need further investigation.

Sampling Strategies for Occupational Exposure Assessment under Generalized Linear Model

Chen, C.-C., Chuang, C.-L., Wu, K.-Y., Chan, C.-C. — 2009-07-03

Objectives: Occupational exposure assessment is a major task in industrial hygiene studies. Although statistical analyses for magnitudes and variations of exposures to various types of working populations based on existing data sets are extensive, relatively few discussions on study designs appear in the literature, especially for sample size determination and number of repeated measurements.

Methods: In this paper, we propose a general framework of sampling strategies on sample size requirement together with the number of repeated measurements using the mixed-effects generalized linear model (GLM). As illustrative examples, we discuss sampling strategies separately under the log-normal assumption for hypotheses testing on (i) mean exposure differences of multiple worker groups and (ii) presence of a long-term exposure trend.

Results: Given a specified alternative hypothesis, the desired significance level and statistical power, the number of repeated measurements, within-worker and between-worker variances, and a correlation structure, we have derived and tabulated an explicit sample size requirement of the two hypothetical cases under log-normal distribution assumption.

Conclusions: On the basis of the tabulated outcomes, the sample size requirement is much more dominant than the number of repeated measurements for a group exposure comparison. Thus, in this case, recruiting more workers with fewer repeated measurements may be more economical than the opposite approach. For testing the presence of a long-term exposure trend, the sample size required decreases substantially with the number of repeated measurements. Also, equally spaced sampling times would be optimal because the effect of between-worker variance is algebraically cancelled out in sample size calculations.

The Evaluation of CBRN Canisters for Use by Firefighters during Overhaul

Currie, J., Caseman, D., Anthony, T. R. — 2009-07-03

Air-purifying respirators (APRs) have been proposed to provide an additional respiratory protection option for structural firefighters involved in overhaul operations and wildland firefighters, where particulate and aldehyde exposures have been documented. Previous studies (Anthony et al., 2007) developed test methods to evaluate APR cartridges and canisters for use in overhaul activities, where initial findings indicated that multi-gas cartridges may not be effective. This study evaluated the performance of three chemical, biological, radiological, and nuclear (CBRN) canisters (MSA, 3M, and Scott) and one multi-gas canister similar in appearance to CBRN canisters but without CBRN certification (3M FR-64040). Challenge concentrations typical of overhaul exposures were generated by combusting common household materials. Twelve tests were conducted, using random canister selection, where challenge air and air filtered by the canisters were tested. All tests examined penetration of CO; NO₂; SO₂; respirable dust; aldehydes, including formaldehyde, acrolein, and glutaraldehyde; and hydrogen cyanide. Six of the tests also investigated naphthalene, benzene, and hydrogen chloride, but challenge concentrations from the simulated overhaul smoke were near the limit of detection (LOD) and were two orders of magnitude below short-term or ceiling concentrations of concern and were eliminated from further study with the combustion materials used in this study. In all tests, an irritant index was computed to evaluate the aggregate penetration of contaminants in the smoke mixture, using 15- and 30-min occupational exposure limits as well as assessing individual penetrations. In all cases, the challenge concentration irritant index exceeded unity, ranging from 2.3 to 21. For all 12 tests, the APR canister reduced the overall irritant index to levels below unity, indicating that these canisters would provide protection for firefighters working in overhaul environments. However, in some tests, levels of carbon monoxide were higher than recommended for persons wearing APRs. Since these canisters do not protect against carbon monoxide, firefighters must still rely on direct reading warning to indicate high CO levels, indicating the need to leave the area if wearing an APR, as these APR canisters would be inappropriate.

Vibrotactile Perception and Effects of Short-Term Exposure to Hand-Arm Vibration

Burstrom, L., Lundstrom, R., Hagberg, M., Nilsson, T. — 2009-07-03

This study clarifies whether the established frequency weighting procedure for evaluating exposure to hand-transmitted vibration can effectively evaluate the temporary changes in vibrotactile perception thresholds due to pre-exposure to vibration. In addition, this study investigates the relationship between changes of the vibrotactile perception thresholds and the normalized energy-equivalent frequency-weighted acceleration. The fingers of 10 healthy subjects, five male and five female, were exposed to vibration under 16 conditions with a combination of different frequencies, intensities, and exposure times. The vibration frequencies were 31.5 and 125 Hz and exposure lasted between 2 and 16 min. According to International Organization for Standardization (ISO) 5349-1, the energy-equivalent frequency-weighted acceleration for the experimental time of 16 min is 2.5 or 5.0 m s^–2 root-mean-square, corresponding to a 8-h equivalent acceleration, A(8), of ~0.5 and 0.9 m s^–2, respectively. A measure of the vibrotactile perception thresholds was conducted before the different exposures to vibration. Immediately after the vibration exposure, the acute effect was measured continuously on the exposed index finger for the first 75 s, followed by 30 s of measures every minute for a maximum of 10 min. If the subject's thresholds had not recovered, the measures continued for a maximum of 30 min with measurements taken every 5 min. Pre-exposure to vibration significantly influenced vibrotactile thresholds. This study concludes that the influence on the thresholds depends on the frequency of the vibration stimuli. Increased equivalent frequency-weighted acceleration resulted in a significant change in threshold, but the thresholds were unaffected when changes in the vibration magnitude were expressed as the frequency-weighted acceleration or the unweighted acceleration. Moreover, the frequency of the pre-vibration exposure significantly influenced (up to 25 min after exposure) recovery time of the vibrotactile thresholds. This study shows that the frequency weighting procedure in ISO 5349-1 is unable to predict the produced acute changes in the vibrotactile perception. Moreover, the results imply that the calculation of the ‘energy-equivalent’ frequency-weighted acceleration does not reflect the acute changes of the vibration perception thresholds due to pre-exposure to vibration. Furthermore, when testing for the vibrotactile thresholds, exposure to vibration on the day of a test might influence the results. Until further knowledge is obtained, the previous practice of 3 h avoidance of vibration exposure before assessment is recommended.

NIOSH Definition of Closed-System Drug-Transfer Devices

Nygren, O., Olofsson, E., Johannson, L. — 2009-07-03

Canadian Chrysotile Report Released--At Last

Ogden, T. L. — 2009-06-03

Occupational Exposure Decisions: Can Limited Data Interpretation Training Help Improve Accuracy?

Logan, P., Ramachandran, G., Mulhausen, J., Hewett, P. — 2009-06-03

Accurate exposure assessments are critical for ensuring that potentially hazardous exposures are properly identified and controlled. The availability and accuracy of exposure assessments can determine whether resources are appropriately allocated to engineering and administrative controls, medical surveillance, personal protective equipment and other programs designed to protect workers. A desktop study was performed using videos, task information and sampling data to evaluate the accuracy and potential bias of participants’ exposure judgments. Desktop exposure judgments were obtained from occupational hygienists for material handling jobs with small air sampling data sets (0–8 samples) and without the aid of computers. In addition, data interpretation tests (DITs) were administered to participants where they were asked to estimate the 95th percentile of an underlying log-normal exposure distribution from small data sets. Participants were presented with an exposure data interpretation or rule of thumb training which included a simple set of rules for estimating 95th percentiles for small data sets from a log-normal population. DIT was given to each participant before and after the rule of thumb training. Results of each DIT and qualitative and quantitative exposure judgments were compared with a reference judgment obtained through a Bayesian probabilistic analysis of the sampling data to investigate overall judgment accuracy and bias. There were a total of 4386 participant–task–chemical judgments for all data collections: 552 qualitative judgments made without sampling data and 3834 quantitative judgments with sampling data. The DITs and quantitative judgments were significantly better than random chance and much improved by the rule of thumb training. In addition, the rule of thumb training reduced the amount of bias in the DITs and quantitative judgments. The mean DIT % correct scores increased from 47 to 64% after the rule of thumb training (P < 0.001). The accuracy for quantitative desktop judgments increased from 43 to 63% correct after the rule of thumb training (P < 0.001). The rule of thumb training did not significantly impact accuracy for qualitative desktop judgments. The finding that even some simple statistical rules of thumb improve judgment accuracy significantly suggests that hygienists need to routinely use statistical tools while making exposure judgments using monitoring data.

Classification of Thermal Environments for Comfort Assessment

Lenzuni, P., Freda, D., Del Gaudio, M. — 2009-06-03

According to ISO 7730:2005, classification is a mandatory precondition for thermal comfort assessment since the appropriate criterion depends on which category the specific work situation (SWS) investigated belongs to. Unfortunately, while the standard does include three different comfort criteria, it does not indicate how the appropriate criterion should be selected. This paper presents a classification scheme that allows thermal comfort assessment to be reliably performed in any environment. The model is based on an algorithm that calculates a score by means of a weighted product of three quantities, each one taking care of a specific, highly relevant element: the subject's thermal sensitivity, the accuracy required for carrying out the task and the practicality of thermal control. The scheme's simple modular structure can easily accommodate both changes and additions, should other hypothetical elements be identified to be as relevant to the classification scheme. The model presented allows a modulation of comfort levels across different social groups. It is so possible to provide extra care for children, elderly, pregnant women, disabled and other ‘weak’ categories, as required by ISO/TS 14415:2005, by setting the highest comfort level. Finally, it also widens the options for simultaneously establishing comfort conditions for different individuals performing different tasks in the same area and clarifies whose comfort should be pursued with the highest priority.

Critical Evaluation of Sequential Leaching Procedures for the Determination of Ni and Mn Species in Welding Fumes

Berlinger, B., Naray, M., Sajo, I., Zaray, G. — 2009-06-03

In this work, welding fume samples were collected in a welding plant, where corrosion-resistant steel and unalloyed structural steel were welded by gas metal arc welding (GMAW) and manual metal arc welding (MMAW) techniques. The welding fumes were sampled with a fixed-point sampling strategy applying Higgins–Dewell cyclones. The following solutions were used to dissolve the different species of Ni and Mn: ammonium citrate solution [1.7% (m/v) diammonium hydrogen citrate and 0.5% (m/v) citric acid monohydrate] for ‘soluble’ Ni, 50:1 methanol–bromine solution for metallic Ni, 0.01 M ammonium acetate for soluble Mn, 25% acetic acid for Mn⁰ and Mn²⁺ and 0.5% hydroxylammonium chloride in 25% acetic acid for Mn³⁺ and Mn⁴⁺. ‘Insoluble’ Ni and Mn contents of the samples were determined after microwave-assisted digestion with the mixture of concentrated (cc). HNO₃, cc. HCl and cc. HF. The sample solutions were analysed by inductively coupled plasma quadrupole mass spectrometry and inductively coupled plasma atomic emission spectrometry. The levels of total Ni and Mn measured in the workplace air were different because of significant differences of the fume generation rates and the distributions of the components in the welding fumes between the welding processes. For quality control of the leaching process, dissolution of the pure stoichiometric Mn and Ni compounds and their mixtures weighing was investigated using the optimized leaching conditions. The results showed the adequacy of the procedure for the pure metal compounds. Based on the extraction procedures, the predominant oxidation states of Ni and Mn proved to be very different depending on the welding techniques and type of the welded steels. The largest amount of Mn in GMAW fumes were found as insoluble Mn (46 and 35% in case of corrosion-resistant steel and unalloyed structural steel, respectively), while MMAW fumes contain mainly soluble Mn, Mn⁰ and Mn²⁺ (78%) and Mn³⁺ and Mn⁴⁺ (54%) in case of corrosion-resistant steel and unalloyed structural steel, respectively. According to the results of the leaching procedures, GMAW fumes are rich in oxidic Ni (79%), while Ni compounds in welding fumes generated during MMAW are mainly in easily soluble form (44%). The crystalline phases were identified in each welding fume by X-ray powder diffraction (XRPD) technique as well. From the XRPD spectra, it is clear that GMAW fumes contain predominantly magnetite (FeFe₂O₄). In case of structural steel welding, there was a little amount of ferrite (-Fe) also found. Welding fume generated during MMAW of structural steel contained a complex alkali–alkali earth fluoride phase (KCaF₃–CaF₂) and some magnetite and jakobsite (MnFe₂O₄). The XRPD results did not fully confirm the ones obtained from the extraction experiments. However, some results, for example the rate of soluble Ni and Mn compounds compared to the total, can be useful for further investigations of welding fumes.

Selection of Nutrients for Prevention or Amelioration of Lead-Induced Learning and Memory Impairment in Rats

Fan, G., Feng, C., Li, Y., Wang, C., Yan, J., Li, W., Feng, J., Shi, X., Bi, Y. — 2009-06-03

Background: We carried out animal experiments based on the orthogonal design L₈(2⁷) setting seven factors with two different levels of each and 10 groups of rats. The nutrients tested were tyrosine, glycine, methionine, taurine, ascorbic acid, thiamine and zinc.

Objectives: The objective of this study was to explore the optimal combinations of nutrients for prevention or amelioration of lead-induced learning and memory impairment.

Methods: Rats were supplemented with nutrients by gavage once a day in two experiments: one was simultaneous nutrient supplementation with lead acetate administration (800 mg l^–1) for 8 weeks (prophylactic supplementation) and the other was nutrient supplementation for 4 weeks after the cessation of 4 weeks of lead administration (remedial supplementation). Morris water maze was initiated at ninth week. Rats were terminated for assays of levels of Pb in blood, activities of superoxide dismutase (SOD) and nitric oxide synthase (NOS) in hippocampus, levels of nitric oxide (NO) in hippocampus and expressions of Ca2+/calmodulin-dependent protein kinase II (CaMKII) and cyclic adenosine monophosphate (cAMP) response element-binding protein messenger RNA in hippocampus.

Results: Results showed that in prophylactic supplementation, methionine, taurine, zinc, ascorbic acid and glycine were the effective preventive factors for decreasing prolonged escape latency, increasing SOD and NOS activities and NO levels in the hippocampus, respectively. On the other hand, in remedial supplementation, taurine was the effective factor for reversing Pb-induced decrease in activities of SOD, NOS and levels of NO.

Conclusions: In conclusion, the optimum combinations of nutrients appear to be methionine, taurine, zinc, ascorbic acid and glycine for the prevention of learning and memory impairment, while taurine and thiamine appear to be the effective factors for reversing Pb neurotoxicity.

Solvent Removal of Beryllium from Surfaces of Equipment Made of Beryllium Copper

Dufresne, A., Turcotte, V., Golshahi, H., Viau, S., Perrault, G., Dion, C. — 2009-06-03

Exposure to beryllium compounds, both by inhalation and skin contact, may result in immune sensitization and chronic beryllium disease. The objective of the present research work was to study the feasibility of removing beryllium compounds from the surfaces of devices made of Be-Cu alloy and to estimate the frequency at which the surfaces had to be rubbed in order to evaluate the likelihood that beryllium can be removed from the surfaces by serial wipe sampling at concentrations exceeding the US Department of Energy (DOE) standard limit of 0.2 µg per 100 cm². The standard limit was exceeded after successive cleanings of moulds and plates made of Be-Cu alloy with solvents such Citranox^TM, an acidic solvent, Alconox^TM, Z-99^TM and Fantastik^TM, basic solvents, or more neutral solvents such as Luminox^TM and water. Citranox was the best solvent for extracting beryllium from the tested surfaces, while Alconox^TM seemed to be the second best one. In general, warm water, Luminox^TM and Z-99^TM seemed to be less efficient for extracting Be from all equipment. The results of the present study suggest that Ghost Wipes^TM, when passed across a surface under the firm pressure of an individual's hand, can be used to detect beryllium contamination. However, they seem to show low reliability for quantification. From a safety standpoint in occupational settings, workers should be offered skin protection and respiratory protection if they have to handle devices made of Be-Cu alloy.

Occupational Exposure to Beryllium in French Enterprises: A Survey of Airborne Exposure and Surface Levels

2009-06-03

An assessment survey of occupational exposure to beryllium (Be) was conducted in France between late 2004 and the end of 2006. Exposure estimates were based on the analytical results of samples collected from workplace air and from work surfaces in 95 facilities belonging to 37 sectors of activity. The results of this study indicated airborne Be concentrations in excess of the occupational exposure limit value of 2 µg m^–3 recommended in France. Metallurgy and electronic component manufacturing represented the activities and occupations where workers had the highest arithmetic mean exposures to Be. Surface contamination levels were also high and frequently exceeded thresholds recommended by different bodies. These results should prompt the development of prevention programmes that include Be substitution, process control and surface decontamination, in conjunction with suitable medical surveillance.

Historical Analysis of Airborne Beryllium Concentrations at a Copper Beryllium Machining Facility (1964-2000)

2009-06-03

Copper beryllium alloys are the most commonly used form of beryllium; however, there have been few studies assessing occupational exposure in facilities that worked exclusively with this alloy versus those where pure metal or beryllium oxide may also have been present. In this paper, we evaluated the airborne beryllium concentrations at a machining plant using historical industrial hygiene samples collected between 1964 and 2000. With the exception of a few projects conducted in the 1960s, it is believed that >95% of the operations used copper beryllium alloy exclusively. Long-term (>120 min) and short-term (<120 min) personal and area samples were collected during a variety of activities including machining of copper beryllium-containing parts, as well as finishing operations (e.g., deburring and polishing) and decontamination of machinery. A total of 580 beryllium air samples were analyzed (311 personal and 269 area samples). The average concentration based on area samples (1964–2000) was 0.021 µg m^–3 (SD 0.17 µg m^–3; range 0.00012–2.5 µg m^–3); 68.8% were below the analytical limit of detection (LOD). The average airborne beryllium concentration, based on all personal samples available from 1964 through the end of 2000 (n = 311), was 0.026 µg m^–3 (SD 0.059 µg m^–3; range 0.019–0.8 µg m^–3); 97.4% were below the LOD. Personal samples collected from machinists (n = 78) had an average airborne concentration of 0.021 µg m^–3 (SD 0.014 µg m^–3; range 0.019–0.14 µg m^–3); 97.4% were below the LOD. Airborne concentrations were consistently below the Occupational Safety and Health Administration permissible exposure limit for beryllium (2 µg m^–3). Overall, the data indicate that for machining operations involving copper beryllium, the airborne concentrations for >95% of the samples were below the contemporaneous occupational exposure limits or the 1999 Department of Energy action level of 0.2 µg m^–3 and, in most cases, were below the LOD.

Acute Health Effects on Planters of Conifer Seedlings Treated with Insecticides

Elfman, L., Hogstedt, C., Engvall, K., Lampa, E., Lindh, C. H. — 2009-06-03

Objectives: The aim of this study was to assess acute health effects on planters caused by planting conifer seedlings treated with two insecticides, with active ingredients imidacloprid and cypermethrin, in comparison with untreated seedlings.

Methods: The investigation was a double-blind crossover study, which included a follow-up of 19 planters over a 3-week period. During Week 1, the 19 planters handled untreated conifer seedlings while they planted imidacloprid- and cypermethrin-treated seedlings during study Week 2 and 3, respectively. Signs and symptoms of acute health effects were documented by a questionnaire, administered by the field staff, during these 3 weeks. Inflammation markers in the nasal mucous membrane were also measured as an objective test. Exposure to cypermethrin was further assessed by measuring 3-phenoxybenzoic acid (3-PBA) in urine. No validated biomarker was available to assess internal exposure to imidacloprid.

Results: No clear, acute adverse health effects could be found in planters during the week of exposure to conifer seedlings treated with imidacloprid (Merit Forest) or cypermethrin (Forester), as compared to during the week of planting untreated seedlings. During the week of cypermethrin exposure, the individuals had 3-PBA values that were 12–54% higher (P < 0.05), depending on the worker, than those observed during the untreated week. There were no statistically significant correlations between the raised levels of 3-PBA and self-reported health problems. These results have been obtained during planting in late summer/early autumn and with good use of protective clothing.

Conclusions: No clear, acute adverse health effects could be found in planters after exposure to conifer seedlings treated with imidacloprid (Merit Forest) or cypermethrin (Forester), as compared with planting untreated seedlings. The metabolite, 3-PBA, was found in low levels in urine and was increased after exposure to cypermethrin. However, no clear relationships could be found between exposure and reported symptoms or between elevated 3-PBA levels and reported symptoms.

Comparative Evaluation of Overexposure Potential Indices used in Solvent Substitution

Debia, M., Begin, D., Gerin, M. — 2009-06-03

Background: Overexposure potential indices (OPIs) can be defined as ratios between different measures of the volatility of a substance and its 8-h occupational exposure limit. Objectives: The overall objective of this study was to compare three OPIs, using a list of commonly used or recommended solvents as both single substances and mixtures. The three indices studied differ in the way they characterize volatility: vapour pressure for the vapour hazard ratio (VHR), calculated emission rate for the ‘SUBstitution FACtor’ (SUBFAC) index obtained from the former Danish SUBTEC software and discrete values based on relative evaporation rate for the Måleteknisk Arbejdshygiejnisk Luftbehov (MAL) index which is part of regulations in Denmark.

Methods: A list of 56 pure solvents and of 50 mixtures of solvents was used for the comparison. For mixtures, VHR was calculated both as VHR_mi, where the mixture is considered as ideal, and as VHR_mc (corrected) with the introduction of activity coefficients to take into account the nonideal behaviour of components. Activity coefficients were a standard feature of SUBFAC for mixtures (SUBFAC_m) but are not used when calculating MAL for mixtures (MAL_m).

Results: Pure solvents rank in overall similar order with the three systems and correlation was excellent between VHR and SUBFAC (R = 0.99) and good between VHR and MAL (R = 0.75). For solvent-based mixtures, correlation is excellent between VHR_mi and VHR_mc (R = 0.98) and between VHR_mc and SUBFAC_m (R = 0.98) but moderate between VHR_mi and MAL_m (R = 0.52). Ratios between VHR_mc and VHR_mi varied between 0.57 and 2.7, thus spanning an ~5-fold range, and averaged 1.2. Worse correlations involving the MAL index are attributed to the discrete nature of its numerator.

Conclusions: Overall, these results favour using the simple and more easily available VHR when comparing pure substances. In the case of mixtures, the effect of nonideality may be important in certain cases. As a precaution, since no integrated tool is available presently to easily calculate OPI values corrected for nonideality, substitution should be recommended only as long as the non-corrected VHR value for an alternative solvent is at least 5-fold less than that of the solvent to replace.

Quantitative Determination of Airborne Respirable Non-Fibrous {alpha}-Silicon Carbide by X-ray Powder Diffractometry

Bye, E., Foreland, S., Lundgren, L., Kruse, K., Ronning, R. — 2009-06-03

Objectives: The purpose of the present investigation was to establish a method for the determination of airborne respirable non-fibrous silicon carbide (SiC). The main application is within the industrial production of SiC.

Methods: Due to the complex airborne aerosol mixture of crystalline compounds in the SiC industry, X-ray powder diffractometry was selected as the most appropriate method. Without any international standard material for the respirable fraction of non-fibrous SiC, pure and suitable products from three SiC plants in Norway were selected. These products have a median particle diameter in the range 4.4–5.1 µm. The method is based on thin sample technique, with the dust deposited on a polycarbonate filter. Absorption correction is done by standard procedures with the use of a silver filter, situated below the polycarbonate filter.

Results: The diffraction line used for quantitative determination was selected carefully. This was done to avoid interferences from quartz, cristobalite, and graphite, which all are airborne components present in the atmosphere during the industrial process. The instrumental limit of detection for the method is 12 µg.

Conclusions: This method has been used to determine airborne non-fibrous SiC in a comprehensive ongoing project in the Norwegian SiC industry for further epidemiological studies. The method is fully applicable for compliance work.

Bayesian Modeling of Exposure and Airflow Using Two-Zone Models

Zhang, Y., Banerjee, S., Yang, R., Lungu, C., Ramachandran, G. — 2009-06-03

Mathematical modeling is being increasingly used as a means for assessing occupational exposures. However, predicting exposure in real settings is constrained by lack of quantitative knowledge of exposure determinants. Validation of models in occupational settings is, therefore, a challenge. Not only do the model parameters need to be known, the models also need to predict the output with some degree of accuracy. In this paper, a Bayesian statistical framework is used for estimating model parameters and exposure concentrations for a two-zone model. The model predicts concentrations in a zone near the source and far away from the source as functions of the toluene generation rate, air ventilation rate through the chamber, and the airflow between near and far fields. The framework combines prior or expert information on the physical model along with the observed data. The framework is applied to simulated data as well as data obtained from the experiments conducted in a chamber. Toluene vapors are generated from a source under different conditions of airflow direction, the presence of a mannequin, and simulated body heat of the mannequin. The Bayesian framework accounts for uncertainty in measurement as well as in the unknown rate of airflow between the near and far fields. The results show that estimates of the interzonal airflow are always close to the estimated equilibrium solutions, which implies that the method works efficiently. The predictions of near-field concentration for both the simulated and real data show nice concordance with the true values, indicating that the two-zone model assumptions agree with the reality to a large extent and the model is suitable for predicting the contaminant concentration. Comparison of the estimated model and its margin of error with the experimental data thus enables validation of the physical model assumptions. The approach illustrates how exposure models and information on model parameters together with the knowledge of uncertainty and variability in these quantities can be used to not only provide better estimates of model outputs but also model parameters.

Flow and Performance of an Air-curtain Biological Safety Cabinet

Huang, R. F., Chou, C. I. — 2009-06-03

Using laser-assisted smoke flow visualization and tracer gas concentration detection techniques, this study examines aerodynamic flow properties and the characteristics of escape from containment, inward dispersion, and cross-cabinet contamination of a biological safety cabinet installed with an air curtain across the front aperture. The experimental method partially simulates the NSF/ANSI 49 standards with the difference that the biological tracer recommended by these standards is replaced by a mixture of 10% SF₆ in N₂. The air curtain is set up across the cabinet aperture plane by means of a narrow planar jet issued from the lower edge of the sash and a suction flow going through a suction slot installed at the front edge of the work surface. Varying the combination of jet velocity, suction flow velocity, and descending flow velocity reveals three types of characteristic flow modes: ‘straight curtain’, ‘slightly concave curtain’, and ‘severely concave curtain’. Operating the cabinet in the straight curtain mode causes the air curtain to impinge on the doorsill and therefore induces serious escape from containment. In the severely concave curtain mode, drastically large inward dispersion and cross-cabinet contamination were observed because environmental air entered into the cabinet and a three-dimensional vortical flow structure formed in the cabinet. The slightly concave curtain mode presents a smooth and two-dimensional flow pattern with an air curtain separating the outside atmosphere from the inside space of the cabinet, and therefore exhibited negligibly small escape from containment, inward dispersion, and cross-cabinet contamination.

Methods for Measuring Performance of Vehicle Cab Air Cleaning Systems Against Aerosols and Vapours

Bemer, D., Subra, I., Regnier, R. — 2009-06-03

Vehicle cabs equipped with an effective air cleaning and pressurization system, fitted to agricultural and off-road machineries, isolate drivers from the polluted environment, in which they are likely to work. These cabs provide protection against particulate and gaseous pollutants generated by these types of work activities. Two laboratory methods have been applied to determining the performance characteristics of two cabs of different design, namely, optical counting-based measurement of a potassium chloride (KCl) aerosol and fluorescein aerosol-based tracing. Results of cab confinement efficiency measurements agreed closely for these two methods implemented in the study. Measurements showed that high confinement efficiencies can be achieved with cabs, which are properly designed in ventilation/cleaning/airtightness terms. We also noted the importance of filter mounting airtightness, in which the smallest defect is reflected by significant degradation in cab performance. Determination of clean airflow rate by monitoring the decrease in test aerosol concentration in the test chamber gave excellent results. This method could represent an attractive alternative to methods involving gas tracing or air velocity measurement at blowing inlets.

Steve Bailey, President of BOHS, 2008-2009

2009-03-27

Annals of Occupational Hygiene Performance Indicators, 2008

Ogden, T. — 2009-03-27

Agreement between Task-Based Estimates of the Full-Shift Noise Exposure and the Full-Shift Noise Dosimetry

2009-03-27

Noise assessments have been conducted using full-shift dosimetry and short-term task-based measurements. Advantages of the task-based method include the opportunity to directly identify high-noise exposure tasks and to target control measures, as well as obtain estimates of task-based full-shift exposures; however, there is little empirical evidence comparing the two methods. National Institute for Occupational Safety and Health assessed noise exposures at three industrial facilities using dosimetry and task-based methods with the objective of comparing the two strategies and assessing the degree of agreement and causes of disagreement. Eight indices of task-based full-shift exposures were created from task-based sampling using three methods to assess time-at-task (direct observation by industrial hygienist, end-of-shift worker estimates and supervisor estimates) and three methods to assign noise levels to tasks [direct measurement, arithmetic mean (AM) and geometric mean (GM)]. We assessed aspects of agreement (precision, bias and absolute agreement) using Bland–Altman plots and concordance correlation coefficient (CCC). Overall, the task-based methods worked fairly well, with mean biases less than ±2.8 dBA and precision ranges of 3.3–4.4 dBA. By all measures, task-based full-shift estimates based on supervisor assessment of time-at-task agreed most poorly with the dosimetry data. The task-based full-shift estimates based on worker estimates of time-at-task generally agreed as well as those based on direct observation. For task noise level, task-based full-shift estimates based on directly measured task agreed the best with dosimetry data, while agreement for task-based indices based on task AM or GM was variable. Overall, the task-based full-shift estimates based on direct observation task and direct measured task noise level achieved the best agreement with the dosimetry data (CCC 0.84) with 95% of their differences being within 7.4 dBA and 56% of the differences <3 dBA. For this index, a high degree of accuracy was observed (accuracy coefficient = 0.96) with major cause of disagreement arising from a lack of precision (precision coefficient = 0.88). When the measurements were classified by job characteristics, significant improvements in the degree of agreement were observed in the low job mobility, low job complexity and low job variability categories. Our data suggest that a high degree of absolute agreement can be achieved between the task-based and dosimetry-based estimates of full-shift exposures. The task-based approach that uses worker reports combined with task AM or GM levels is similar to the more time-intensive direct observation method to estimate full-shift exposures.

Presence of Tungsten-Containing Fibers in Tungsten Refining and Manufacturing Processes

Mckernan, J. L., Toraason, M. A., Fernback, J. E., Petersen, M. R. — 2009-03-27

In tungsten refining and manufacturing processes, a series of tungsten oxides are typically formed as intermediates in the production of tungsten powder. The present study was conducted to characterize airborne tungsten-containing fiber dimensions, elemental composition and concentrations in the US tungsten refining and manufacturing industry. During the course of normal employee work activities, seven personal breathing zone and 62 area air samples were collected and analyzed using National Institute for Occupational Safety and Health (NIOSH) fiber sampling and counting methods to determine dimensions, composition and airborne concentrations of fibers. Mixed models were used to identify relationships between potential determinants and airborne fiber concentrations. Results from transmission electron microscopy analyses indicated that airborne fibers with length >0.5 µm, diameter >0.01 µm and aspect ratios ≥3:1 were present on 35 of the 69 air samples collected. Overall, the airborne fibers detected had a geometric mean length 3 µm and diameter 0.3 µm. Ninety-seven percent of the airborne fibers identified were in the thoracic fraction (i.e. aerodynamic diameter ≤ 10 µm). Energy dispersive X-ray spectrometry results indicated that airborne fibers prior to the carburization process consisted primarily of tungsten and oxygen, with other elements being detected in trace quantities. Based on NIOSH fiber counting ‘B’ rules (length > 5 µm, diameter < 3 µm and aspect ratio ≥ 5:1), airborne fiber concentrations ranged from below the limit of detection to 0.085 fibers cm^–3, with calcining being associated with the highest airborne concentrations. The mixed model procedure indicated that process temperature had a marginally significant relationship to airborne fiber concentration. This finding was expected since heated processes such as calcining created the highest airborne fiber concentrations. The finding of airborne tungsten-containing fibers in this occupational setting needs to be confirmed in similar settings and demonstrates the need to obtain information on the durability and associated health effects of these fibers.

A Novel Size-Selective Airborne Particle Size Fractionating Instrument for Health Risk Evaluation

Gorbunov, B., Priest, N. D., Muir, R. B., Jackson, P. R., Gnewuch, H. — 2009-03-27

Health risks associated with the inhalation of airborne particles are known to be influenced by particle size. Studies have shown that certain nanoparticles, with diameters <100 nm, have increased toxicity relative to larger particles of the same substance. A reliable, size-resolving sampler able to collect a wide range of particle sizes, including particles with sizes in the nanometre range, would be beneficial in investigating health risks associated with the inhalation of airborne particles. A review of current aerosol samplers used for size-resolved collection of airborne particles highlighted a number of limitations. These could be overcome by combining an inertial deposition impactor with a diffusion collector in a single device. Verified theories of diffusion and inertial deposition suggested an optimal design and operational regime. The instrument was designed for analysing mass distribution functions. Calibration was carried out using a number of recognized techniques. The sampler was tested in the field by collecting size-resolved samples of lead containing aerosols present at workplaces in factories producing crystal glass. The mass deposited on each screen proved sufficient to be detected and measured by an appropriate analytical technique. Mass concentration distribution functions of lead were produced. The nanofraction of lead in air varied from 10 to 70% by weight of total lead.

A New Semivolatile Aerosol Dichotomous Sampler

Kim, S. W., Raynor, P. C. — 2009-03-27

This study reports the results of a numerical investigation and an experimental study on a round nozzle virtual impactor (VI) operated in two different modes. The newly proposed sampler, the semivolatile aerosol dichotomous sampler (SADS), was studied to overcome some of the problems of existing personal sampling methods such as evaporative loss during filter sampling. The main difference between VIs and the SADS was the inverted flow ratio between the major flow and the minor flow. Sampling in the SADS settings gives a lower cutsize in both numerical simulations and experimental results. Whereas the 50% separation efficiency for a VI occurred in numerical simulations when the square root of Stokes number equaled 0.97, the 50% efficiency for the same sampler run in the SADS settings occurred when the square root of the Stokes number was 0.27. The back pressure on each flow direction was studied and greater pressure drop was observed through the vapor flow in SADS settings. Sampling using a SADS was more effective than traditional filter methods because of its smaller cutsize, instant separation of vapor from particles and reduced particle losses.

Model-Based Imputation Approach for Data Analysis in the Presence of Non-detects

Krishnamoorthy, K., Mallick, A., Mathew, T. — 2009-03-27

A model-based multiple imputation approach for analyzing sample data with non-detects is proposed. The imputation approach involves randomly generating observations below the detection limit using the detected sample values and then analyzing the data using complete sample techniques, along with suitable adjustments to account for the imputation. The method is described for the normal case and is illustrated for making inferences for constructing prediction limits, tolerance limits, for setting an upper bound for an exceedance probability and for interval estimation of a log-normal mean. Two imputation approaches are investigated in the paper: one uses approximate maximum likelihood estimates (MLEs) of the parameters and a second approach uses simple ad hoc estimates that were developed for the specific purpose of imputations. The accuracy of the approaches is verified using Monte Carlo simulation. Simulation studies show that both approaches are very satisfactory for small to moderately large sample sizes, but only the MLE-based approach is satisfactory for large sample sizes. The MLE-based approach can be calibrated to perform very well for large samples. Applicability of the method to the log-normal distribution and the gamma distribution (via a cube root transformation) is outlined. Simulation studies also show that the imputation approach works well for constructing tolerance limits and prediction limits for a gamma distribution. The approach is illustrated using a few practical examples.

Measurement Error and Model Specification in Determining How Duration of Tasks Affects Level of Occupational Exposure

Burstyn, I. — 2009-03-27

Statistical modeling of determinants of exposure ascertained in large-scale surveys is an increasingly popular approach to both (i) identifying effective occupational exposure controls that arise in ‘natural experiments’ and (ii) predicting how altering some working conditions may impact exposure levels. This paper sheds light on two underappreciated methodological challenges of such studies. First, I examine the impact of measurement error in the observed determinant of exposure on an investigator's ability to correctly rank the determinants of exposure in terms of their exposure rate (one aspect of how important a give determinant is). Simultaneously, I consider the issue of whether empirical models fitted for the sake of statistical convenience actually reflect the physical reality that is being modeled and how this may affect the answer to the question about ranking determinants of exposure. These general issues are examined in the context of the ‘time per task’ determinant of exposure and true exposure model that states that exposure is equal to product of exposure rate and duration of a task. Simulation studies were conducted and their conclusions applied in re-examining the data on the impact of duration of some key task on exposure levels to flour dust among bakers. The simulation study demonstrated that bias due to measurement error in observed effects can be either positive or negative. The main conclusion is that the correct ranking of exposure rates can be obtained from both true and poorly specified exposure models, but can be severely distorted by errors in estimates of the duration of tasks performed.

Determinants of Exposure to Metalworking Fluid Aerosols: A Literature Review and Analysis of Reported Measurements

Park, D., Stewart, P. A., Coble, J. B. — 2009-03-27

An extensive literature review of published metalworking fluid (MWF) aerosol measurement data was conducted to identify the major determinants that may affect exposure to aerosol fractions (total or inhalable, thoracic and respirable) and mass median diameters (MMDs). The identification of determinants was conducted through published studies and analysis of published measurement levels. For the latter, weighted arithmetic means (WAMs) by number of measurements were calculated and compared using analysis of variance and t-tests. The literature review found that the major factors affecting aerosol exposure levels were, primarily, decade, type of industry, operation and fluid and engineering control measures. Our analysis of total aerosol levels found a significant decline in measured levels from an average of 5.36 mg m^–3 prior to the 1970s and 2.52 mg m^–3 in the 1970s to 1.21 mg m^–3 in the 1980s, 0.50 mg m^–3 in the 1990s and 0.55 mg m^–3 in the 2000s. Significant declines from the 1990s to the 2000s also were found in thoracic fraction levels (0.48 versus 0.40 mg m^–3), but not for the respirable fraction. The WAMs for the auto (1.47 mg m^–3) and auto parts manufacturing industry (1.83 mg m^–3) were significantly higher than that for small-job machine shops (0.68 mg m^–3). In addition, a significant difference in the thoracic WAM was found between the automotive industry (0.46 mg m^–3) and small-job machine shops (0.32 mg m^–3). Operation type, in particular, grinding, was a significant factor affecting the total aerosol fraction [grinding operations (1.75 mg m^–3) versus other machining (0.95 mg m^–3)], but the levels associated with these operations were not statistically different for either the thoracic or the respirable fractions. Across all decades, the total aerosol fraction for straight oils (1.49 mg m^–3) was higher than for other fluid types (soluble = 1.08 mg m^–3, synthetic = 0.52 mg m^–3 and semisynthetic = 0.50 mg m^–3). Fluid type was also found to be partly associated with differences in the respirable fraction level. We found that the total aerosols were measured by a variety of sampling media, devices and analytical methods. This diversity of approaches makes interpretation of the study results difficult. In conclusion, both the literature review and the measurement data analyzed found that decade and type of industry, operation and fluid were important determinants of total aerosol exposure. Industry type and fluid type were associated with differences in exposure to the thoracic and respirable fraction levels, respectively.

Permeation of Hair Dye Ingredients, p-Phenylenediamine and Aminophenol Isomers, through Protective Gloves

Lee, H.-S., Lin, Y.-W. — 2009-03-27

Skin irritation and contact allergies are skin disorders common to hairdressers. The predominant oxidative hair dye components, such as p-phenylenediamine (PPD) and aminophenol isomers, can cause contact dermatitis. Use of protective gloves can prevent dermal contact with skin irritants. This study investigates the permeation behaviors of p-aminophenol (PAP), m-aminophenol (MAP), o-aminophenol (OAP) and PPD in single and mixed challenge solutions with disposable natural rubber latex (NRL) gloves, disposable polyvinylchloride (PVC) gloves and neoprene (NP) gloves. The challenge solutions were 4% PPD (w/v), 3% OAP (w/v), 2% PAP (w/v) and 2% MAP (w/v) in ethanol or 12% hydrogen peroxide solutions. The cocktail solutions of the four chemicals were also tested. An American Society for Testing and Materials type permeation cell, ethanol liquid collection and gas chromatography–flame ionization detection of samples taken from the collection medium every 10 min facilitated determination of breakthrough times (BTs), cumulative permeated masses and steady-state permeation rates (SSPRs). Experiments were 4 h long for the NRL and PVC gloves and 8 h for NP gloves. No chemicals tested broke through the NP gloves when exposed for 8 h. In the ethanol solution, PPD and OAP started breaking through the PVC gloves at 40 min. The SSPRs of PVC gloves were higher than those for NRL gloves in all challenge conditions for both single chemicals and mixtures. No tested chemicals in hydrogen peroxide solutions permeated the gloves during the 4-h tests. The chemical composition of the challenge solution was a main effecter of BTs and SSPRs for the NRL glove. For disposable PVC gloves, the main factors of BTs were molecular size [molar volume (MV)] and polarity (logK_ow), and the primary factors of SSPRs were concentration, MV and logK_ow. In conclusion, disposable NRL gloves and disposable PVC gloves should not be used repeatedly for handling the hair dye products. Hydrogen peroxide did not accelerate chemical breakthrough. The compositions of the challenge solutions and physical and chemical properties (MV and logK_ow) affected permeation behaviors for different gloves.

New Respirator Fit Test Panels Representing the Current Chinese Civilian Workers

2009-03-27

Respirator fit test panels provide an objective tool for selecting representative human test subjects based upon their facial characteristics for use in research, product development, testing and certification. Fit test panels were typically based upon anthropometric data such as the 1967–1968 survey of American military personnel. In this study, the objectives were to: (i) evaluate the applicability of the recently developed National Institute for Occupational Safety and Health (NIOSH) respirator fit test panels for Chinese workers and (ii) develop new respirator fit test panels using the Chinese survey data. Overall, 95% of the workers in the Chinese survey fall within the NIOSH bivariate and principal component analysis (PCA) panels, suggesting that these panels would also be appropriate for the Chinese population. However, distribution of the subject across the panels was not uniform; only 6.3% of survey participants fell into five cells of the bivariate panel and only 7.2% were found within three cells of the PCA panel. Therefore, new respirator fit test panels with subject dimensions and distributions specific to Chinese workers may be beneficial for certain applications. Two new respirator fit test panels were developed with the same techniques used to create the NIOSH panels. All measurements were weighted to match age and gender distributions of the Chinese population from the 2005 census. The bivariate approach used face length and face width measurements, and the PCA panel was developed using the first two principal components obtained from a set of 10 facial dimensions. Respirators designed to fit these Chinese worker-specific panels are also likely to accommodate >95% of Chinese workers.