American Conference Of Governmental Industrial Hygienists Threshold Limit Value Research Articles

The ACGIH TLV for lifting: Estimated TLVs for torso asymmetry beyond 30 degrees.

The American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLVs) for Lifting is a manual material handling (MMH) assessment method to identify weight limits that nearly all workers may be exposed to without developing work-related low back disorders (LBD). However, this assessment method only applies to lifting with the torso within 30° asymmetry of the sagittal plane. Estimate TLV weight limits while lifting with torso asymmetry greater than 30° beyond the sagittal plane. Lifting tasks were performed from various horizontal and vertical locations, at torso asymmetry angles of 0°, 15°, 30°, 45°, 60°, 75° and 90°, using ACGIH identified TLVs. Validated MMH assessment methods (NIOSH Lifting Equation, Ohio State University LBD Risk Model) were utilized to estimate TLVs at torso asymmetries greater than 30°. The current ACGIH TLVs resulted in low- to moderate-risk risk levels for torso asymmetries from 0° to 30°, and the risk incrementally increased as torso asymmetry increased to 90°. With the intention to keep the risk levels to that found at 30° torso asymmetry, lower TLV weight limits in the vertical and horizontal zones investigated were estimated for torso asymmetries from 45° to 90°. The resulting adjusted TLVs were consistent with weight limits identified for similar lifting conditions from other assessment methods that account for torso asymmetry. This research found current ACGIH-defined TLVs possess less than high-risk for LBD, and provided guidance to practitioners for reduced TLVs when torso asymmetry is greater than 30° from the sagittal plane.

Gasoline Generators and their Effects on Air Quality of Some Selected Business Centers in Tertiary Institutions in Rivers State

This study considered gasoline generators and their effects on air quality of some selected business centers in tertiary institutions in Rivers State. Air quality monitor was positioned 1.5m above the floor to determine the concentration levels of CO, CO2 and O2. The measurements were done on a daily for a period of three weeks. At FCE (T), Omoku, the mean concentration values of CO for Business and Institution’s generators were 109.2ppm and 62.3ppm; CO2 283.6ppm and 27.4ppm and O2 185.8% and 192.1% respectively. At IAUE, Port-Harcourt, CO for Business and Institution’s generators had mean concentration values of 144.7ppm and 89.6ppm; CO2 210.9 ppm and 188.8ppm, and for O2, 225.4% and 239.2% respectively. Similarly, for RSU, Port-Harcourt, the mean concentration of CO for Business and Institution’s generators were 144.8ppm and 84.5ppm; CO2 171.1ppm and 124.ppm; and for O2, 196.8% and 164.3%. respectively. CEAP, Port-Harcourt, CO had mean concentration values of 215.3ppm and light 92.2ppm, CO2 226.2ppm and 109.2ppm, whileO2 mean concentration values of 120.1% and 198.2% respectively. The concentration levels of CO, CO2 for business generators were much higher compared to when Institutions’ generators were used. The mean values of CO concentrations for the selected institutions for the period under study were higher than OSHA permissible exposure limit (PEL) of 50ppm (55mg/m3), NIOSH recommended exposure limit (REL) of 35ppm (40 mg/m3) and ACGIH threshold limit value (TLV) of 25ppm (28.6mg/m3), while that of CO2 concentration levels were less than OSHA’s established permissible limit of 5000ppm, and American Conference of Governmental Industrial Hygienists(ACGIH) threshold limit value (TLV) of 25ppm. It was also observed that as the concentrations of CO and CO2 increase, the O2 levels also decrease. It is therefore, very important to state that tertiary institutions’ managements in Nigeria should consider the provision of regular power supply on

163 Nitrous Oxide Exposure in Emergency Medical Services Providers: A Novel Direct Measurement Approach With Concerning Preliminary Findings

The use of inhaled nitrous oxide (N2O) as a pain control agent by emergency medical services (EMS) has notably increased nationwide in recent years. N2O offers numerous benefits as a out-of-hospital analgesic but is also exhaled unmetabolized by patients and accumulates in confined areas, with potential for chronic health implications or acute intoxication at high levels. While there is a wealth of literature addressing occupational N2O exposure in hospital and outpatient settings, the literature on out-of-hospital provider exposure is outdated and inadequate. This ongoing study is the first to measure levels of EMS provider exposure to N2O during actual (non-simulated) patient encounters. The primary study objective is to obtain an average value of ambient N2O concentration during a typical EMS patient encounter in which N2O is used, and to compare this sample mean to national standards for safe exposure limits. Ambient N2O concentrations were directly sampled via externally validated dosimeter badges (Kem Medical Products Corp.) worn in the breathing zone of EMS providers while caring for patients who met clinical criteria for (and were subsequently given) N2O, on-scene and/or during transport, as dictated by existing statewide EMS protocols for pain control. The primary provider of participating EMS crews unsealed and donned a dosimeter badge when N2O was started and wore the badge until care was transferred at the hospital. The delivery system (Nitronox) provided N2O with oxygen in a fixed 50/50 mix; patients self-administered ad libitum via a hand-held mouthpiece, with flow regulated via a demand valve. Per state protocol, crews were always required to open a patient compartment window and utilize the exhaust fan during N2O administration. Used badges were immediately re-sealed and later shipped for lab analysis by the supplier. Additional data including total exposure time were gathered for each call. Enrollment was started on a continuous basis at three 911 agencies within a single EMS district containing both urban and rural service areas in late March 2019. At the time of abstract submission, lab analysis was complete for three dosimeters, with a fourth pending. The average ambient N2O concentration over the three corresponding patient encounters was calculated to be 275 parts per million (ppm) as a time-weighted average (TWA). This preliminary sample mean exceeds the National Institute of Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL) of 25 ppm as a TWA, as well as the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) of 50 ppm as a TWA. Of note, during the only patient encounter in which N2O was used as the exclusive pain control agent for the duration of transport, ambient concentrations exceeded the validated limit of the dosimeter (N2O >700 ppm as a TWA). Preliminary findings suggest EMS providers in the study area may be unintentionally exposed to ambient N2O concentrations in excess of the NIOSH REL and ACGIH TLV during administration for out-of-hospital analgesia; however, no conclusions may be drawn yet given the current n of 3. Data collection was ongoing at the time of submission; if further data suggests excessive exposure, it may prompt early study termination and reassessment of EMS N2O protocols or delivery systems.

Sound Level Measurements in Berthing Areas of an Aircraft Carrier

Personnel assigned to aircraft carriers work and live in environments where hazardous noise areas and hearing recovery spaces such as sleeping areas are in close proximity to one another. Hazardous noise exposure occurring during on-duty time periods and elevated noise levels during off-duty periods in sleeping areas may be prohibiting adequate hearing recovery, thus potentially leading to hearing loss and may lead to adverse effects on sleep, leading to crew-member fatigue. This investigation characterizes Equivalent sound level (Leq) and standardized octave band center frequency noise levels according to berthing (sleeping) area location during flight operation and nonflight operation time periods on a US Navy aircraft carrier. In addition, the investigation compares noise measurements in sleeping areas to noise levels associated with auditory rest and poor sleep quality and quantity. Noise levels were measured in berthing areas aboard a US Navy Nimitz-class aircraft carrier during a routine at-sea period. Sixty noise measurements were taken in eight sleeping locations. Leq in decibels 'A' weighted (dBA) and noise levels from 16 to 16 000 Hz in (dB) were measured during flight operations [Leq (flt ops)] and nonflight operations [Leq (nonflt ops)]. Leq was also measured according to sleep area shipboard locations of forward (FWD) Leq (FWD), middle (MID) Leq (MID), and rear (AFT) Leq (AFT). These data were compared to the 70 dBA American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) for effective quiet areas. In addition, these data were compared to noise levels associated with hearing loss and sleep parameters. Statistical analysis was conducted with R version 3.5.2 using an alpha level of 0.05. Leq (flt ops) in sleeping areas was a statistically significant (P < 0.05) 6.4 dBA higher than the Leq (nonflt ops). Leq (FWD) and Leq (MID) in sleeping areas was a statistically significant (P < 0.05) 15.2 and 15.0 dBA higher, respectively, than the Leq (AFT) noise levels. Mean noise levels at standardized center (1/1) octave bands were highest between 500 and 4000 Hz, ranging from 65.2 to 69.8 dB. A total of 72% of all area Leq measurements exceeded the 70 dBA ACGIH TLV classified as effective quiet to allow for temporary threshold shift recovery. All noise measurements exceeded the World Health Organization's noise threshold where adverse effects on sleep begin. Results suggest that sleeping area location in close proximity to relatively high noise sources and activities occurring on an aircraft carrier (i.e. flight operations) increase noise levels in sleeping areas. These findings raise serious concerns since high noise exposures both on duty and during off-duty/sleeping periods may inhibit auditory recovery from hazardous noise exposures. In addition, results suggest noise levels in sleeping areas are high enough to evoke negative sleep effects.

Living at Work: 24-hour Noise Exposure Aboard US Navy Aircraft Carriers.

Personnel assigned to aircraft carriers are exposed to a variety of noise sources from equipment and flight deck operations for durations >12 h. Personnel work and live in environments where hazardous noise areas and hearing recovery spaces such as sleeping and relaxation areas are in proximity to one another which provides little recovery time from hazardous noise. This investigation describes noise levels measured over a 24-h period on a US Navy aircraft carrier during flight operations for different populations of aircraft carrier personnel. Personal noise monitoring occurred from 23 to 28 January 2014 aboard a US Navy Nimitz-class aircraft carrier during a routine at-sea period. Fifty-nine study volunteers were assigned to similar exposure groups (SEGs). The SEGs were compared to determine which groups were at greatest risk of hazardous noise exposure. Statistical analysis was conducted with SPSS version 24 using an alpha level of 0.05. Mean 24-h equivalent continuous sound levels Leq(24-h) and on-duty time weighted averages (TWA(on-duty)) ranged from 71 to 127 decibels A weighted (dBA). The 80 dBA American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) for 24-h noise exposure was exceeded by 93% of the study volunteers. The 85 dBA ACGIH TLV and Department of Defense Occupational exposure limit for 8-h noise exposures was exceeded by 68% of the population. Leq(off-duty) ranged from 38 to 102 dBA with 61% of the population exceeding the 70 dBA ACGIH TLV classified as effective quiet to allow for temporary threshold shift recovery. SEG 2 Flight Deck Launch and Recovery had significantly higher 24-h noise exposures than SEG 3 Damage Control Maintenance and Repair (P = 0.01), SEG 5 Supply (P = 0.01), and SEG 7 Administrative/Professional (P = 0.009). Similar results were found for TWA(on-duty) noise exposures. Median TWA(on-duty) and Leq(24-h) for SEG 2 were 16-21 dB higher than SEG 3, 5, and 7. There were no significant differences between off-duty Leq noise exposures according to SEG. SEGs located on the flight deck (SEGs 1 and 2) and SEGs responsible for maintenance and repair activities (SEGs 3 and 4) supporting flight operations had the highest TWA(on-duty) and Leq(24-h). These findings raise serious concerns because high noise exposures both on- and off-duty may result in immediate acoustic trauma and development of temporary threshold shifts, which, if unresolved with auditory rest, may lead to permanent hearing loss.

Occupational Mercury Exposure at a Fluorescent Lamp Recycling Facility - Wisconsin, 2017.

On May 9, 2017, Public Health Madison & Dane County contacted the Wisconsin Division of Public Health for assistance with investigation of mercury exposure among workers at a fluorescent lamp recycling facility. Public Health Madison & Dane County had been contacted by the Wisconsin Department of Natural Resources as part of an investigation of potential environmental contamination at the facility. Fluorescent lamps are composed of a phosphor-coated glass tube containing mercury vapor and argon. During the recycling process, lamps are crushed, releasing mercury vapor and mercury-containing dusts. State and county health officials, in collaboration with Wisconsin Department of Natural Resources, conducted an investigation of mercury exposure of workers and an environmental assessment of the facility, surrounding areas, and worker vehicles. All five workers who were tested had urine mercury levels exceeding the American Conference of Governmental Industrial Hygienists (ACGIH) biologic exposure index of 20.0 μg/g creatinine, and two had tremor on physical exam. Workers wore inadequate personal protective equipment (PPE). Mercury levels in indoor air varied within the building, with a maximum of 207.4 μg/m3 at floor level on the crushing platform, approximately eightfold higher than the ACGIH threshold limit value of 25 μg/m3 (1). Mercury also was found in workers' vehicles, indicating risk for take-home exposure. Workers at risk for mercury exposure need to have access to and consistently wear National Institute of Occupational Safety and Health (NIOSH)-approved respiratory protection for mercury vapor, nitrile or other suitable gloves to prevent contact exposure, and disposable suits with booties and change shoes before leaving the worksite to prevent take-home exposures.

Improving the ACGIH threshold limit value (TLV) process

The intent of this manuscript is to elucidate needed improvements in American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) deliberations. More broadly, irreproducibility and bias adversely impact the collection, interpretation, statistical analysis, presentation, and reporting of results in many fields. In 2012, Begley and Ellis reported that scientists at Amgen had attempted to confirm published findings related to research topics of possible interest to Amgen. Fifty-three papers were deemed “landmark” studies. The authors were “shocked” when scientific findings were confirmed in only 6 (11%) cases. Many studies have confirmed that the peer-reviewed literature in biomedicine is in the midst of an irreproducibility crisis. Compounding the irreproducibility crisis is the existence of a significant bias against the publication of negative results. In the toxicology setting, negative toxicity test results are infrequently published as compared with reports that a chemical possesses a particular toxicity in a given test. Despite these deficiencies, the ACGIH states that “…the TLV®-CS Committee preferably relies on published, peer reviewed literature available in the public domain.” The primarily academic studies published in the peer-reviewed literature upon which ACGIH relies to determine TLVs rarely report raw data not already statistically transformed that are thus incalculable. In contrast, consideration of unpublished studies funded by industry, the vast majority of which are good laboratory practice-conducted contract lab studies, is only acceptable to ACGIH if the data owner provides the raw data to third parties upon request. This asymmetry in both the source of data emphasized, and inability to independently statistically analyze findings reported in the published academic literature, introduces a strong skew toward reliance on unverifiable although published measurements in the TLV process. Since Occupational Safety and Health Administration (OSHA) recommends that workplaces rely on ACGIH TLVs and National Institute for Occupational Safety and Health recommended exposure limits rather than older OSHA permissible exposure limit values to optimize worker safety, ACGIH should adopt a more transparent and science-based process.

The neuro-ophthalmological effects related to long-term occupational exposure to organic solvents in painters.

Organic solvents are widely used in many industries, and usually, exposure occurs with mixtures of solvents. Organic solvent mixtures are known for their ability to affect tissues of high lipid content including the myelin sheath in the nervous system. The purpose of this work was to study the evidence that long-term (more than 10 years) exposure to organic solvent mixtures among painters can induce neuro-ophthalmological effects on the function of retinal ganglion cells and the optic tract. Twenty workers with long-term occupational exposure to mixed organic solvents were compared to 40 control subjects. The controls were matched for age, gender, and demographic characteristics but were not occupationally exposed to any known organic solvents, using the following comparators: visual evoked potential (VEP), electroretinogram (ERG), color vision (CV), and contrast sensitivity (CS) testing. Environmental monitoring was done in the work environment with consideration to the American Conference of Governmental Industrial Hygienists Threshold Limit Values (ACGIH-TLVs). The exposed group had significantly longer latency and higher amplitude of VEP waves especially P100, higher Color Confusion Index (CCI), especially affecting the blue-yellow spectrum, and lower Log CS. There was no significant difference between exposed and nonexposed groups in full-field flash ERG response; however, in the pattern ERG, the exposed group had significantly longer latency of P50, which reflects changes in the retinal ganglion cell. Long-term occupational exposure to mixed organic solvents appeared to affect the optic tract functions in the form of increasing latency of VEP response, affecting the quality of CV and decreasing CS. It also affects the retinal ganglion cell layer with increased latency of P50 of the pattern ERG response.

Carpal tunnel syndrome and manual work: the OCTOPUS cohort, results of a ten-year longitudinal study.

The American Conference of Governmental Industrial Hygienists (ACGIH) proposed a method to assess the hand, wrist and forearm biomechanical overload based on exertions frequency (hand-activity level) and force use (normalized peak force). We applied the ACGIH threshold limit value (TLV)® method to a large occupational cohort to assess its ability to predict carpal tunnel syndrome (CTS) onset. A cohort of industrial and service workers was followed-up between 2000 and 2011. We investigated the incidence of CTS symptoms and CTS confirmed by nerve conduction studies (NCS). We then classified exposure with respect to action limit (AL) and TLV. Cox regression models including age, gender, body mass index, and presence of predisposing pathologies were conducted to estimate hazard ratios (HR) of CTS and population attributable fractions. We analyzed data from 3131 workers [females, N=2032 (65%); mean age at baseline 39.3, standard deviation (SD) 9.4 years]. We observed 431 incident cases of CTS symptoms in 8000 person-years and 126 cases of CTS confirmed by NCS in 8883 person-years. The ACGIH TLV® method predicted both CTS symptoms [HR between AL and TLV 2.18, 95% confidence interval (95% CI) 1.86-2.56; above TLV 2.07, 95% CI 1.52-2.81] and CTS confirmed by NCS (HR between AL and TLV 1.93, 95% CI 1.38-2.71; above TLV 1.95, 95% CI 1.27-3.00). About one third of CTS cases were attributable to exposure levels above the AL. The ACGIH TLV® method predicted the risk of CTS, but the dose-response was flat above the AL; a fine-tuning of the proposed thresholds should be considered.

Occupational exposures to radiofrequency fields: results of an Israeli national survey

Relatively high exposures to radiofrequency (RF) fields can occur in the broadcast, medical, and communications industries, as well in occupations that use RF emitting equipment (e.g. law enforcement). Information on exposure to workers employed in these industries and occupations is limited. We present results of an Israeli National Survey of occupational RF field levels at frequencies between ~100 kHz and 40 GHz, representing Industrial Heating, Communications, Radar, Research, and Medicine. Almost 4300 measurements from 900 sources across 25 occupations were recorded and categorised as ‘routine’, ‘incidental’, or ‘unintended’. The occupation-specific geometric means (GMs) of the percentage of the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit values (TLVs) for each of the three exposure scenarios are presented together with the geometric standard deviation (GSD). Additionally, we present estimates of occupation-specific annual personal exposures and collective exposures. The vast majority of the GM of routine exposures ranged from a fraction to less than 1% of ACGIH TLVs, except for Walkie-Talkie (GM 94% of ACGIH), Induction Heating (17%), Plastic Welding (11%), Industrial Heating (6%) and Diathermy (6%). The GM of incidental and unintended exposures exceeded the TLV for one and 14 occupations, respectively. In many cases, the within-occupation GSD was very large, and though the medians remained below TLV, variable fractions of these occupations were projected to exceed the TLV. In rank order, Walkie-Talkie, Plastic Welding, and Induction Heating workers had the highest annual cumulative personal exposure. For cumulative collective exposures within an occupation, Walkie-Talkie dominated with 96.3% of the total, reflecting both large population and high personal exposure. A brief exceedance of the TLV does not automatically translate to hazard as RF exposure limits (issued by various bodies, including ACGIH) include a 10-fold safety factor relative to thermal thresholds and are based on a 6 min averaging period.

Suggested safe harbor limit for titanium dioxide: an exposure level which protects consumers from cancer incidence.

Suggested safe harbor limit for titanium dioxide: an exposure level which protects consumers from cancer incidence.

Penetration patterns of monomeric and polymeric 1,6-hexamethylene diisocyanate monomer in human skin

We investigated penetration patterns of monomeric and polymeric 1,6-hexamethylene diisocyanate (HDI), experimentally and as part of commercial products, in excised full-thickness human skin at 5, 10, 30, or 60 min after exposure. We observed that both monomeric and polymeric HDI were readily absorbed into the skin and that the clearcoat composition affects the penetration rate of the individual isocyanates. The short-term absorption rates for HDI monomer, biuret, and isocyanurate were determined and used to estimate the exposure time required to reach a body burden equal to the American Conference of Governmental Industrial Hygienists (ACGIH) inhalation threshold limit value (TLV) or Oregon State occupational exposure limit (OEL). Oregon is the only government entity in the United States to promulgate a short-term exposure limit (STEL) for HDI-based polyisocyanates biuret and isocyanurate. Based on these absorption rates for a slow-drying clearcoat after 10 min (1.33 μg cm(-2) h(-1)) or 60 min (0.219 μg cm(-2) h(-1)), we calculated that 6.5 and 40 min dermal exposure, respectively, is required to achieve a dose of HDI equivalent to the ACGIH TLV. For biuret, the time to achieve a dose equivalent to the Oregon OEL for slow-drying clearcoat was much shorter (<31 min) than that for fast-drying clearcoat (618 min). Isocyanurate had the shortest skin absorption times regardless of clearcoat formulation (14 s-1.7 min). These results indicate that the dose received through dermal exposure to HDI-containing clearcoats has a significant potential to exceed the dose equivalent to that received through inhalation exposure at established regulatory limits. A critical need exists to monitor dermal exposure quantitatively in exposed workers, to use proper protective equipment to reduce dermal exposure, and to re-evaluate regulatory exposure limits for isocyanates.

미술대학 조소작업 중 발생하는 분진 및 소음에 대한 노출평가

Objectives: A great number of hazardous agents can be emitted from various types of art-creation in a fine arts college, but little data on exposure assessment has been published. A variety of processes encompassing toxic or non-toxic materials, tools, and components are involved in a sculptor work at a fine art college. The aim of this study was to assess exposure levels to particulates and noise during sculpture classes in a college of fine arts. Methods: Students in sculpture classes participated in this study. Mass, number, and surface area concentrations of particulates, noise level, temperature and relative humidity were monitored by both personal and area sampling during the tasks of metal, wood, and stone sculpting. Results: The number and surface concentration of particulates was the highest in the task of wood sculpting, followed by metal and stone work. The mass concentration of particulates was the highest in stone sculpting (personal GM 3.0 mg/, GSD 3.0), followed by wood (personal GM 1.5 mg/, GSD 1.8) and metal work (personal GM 0.95 mg/, GSD 1.51) in that order. Occupational exposure limits (OEL) for particulates depends on the type of particulate. For wood dust, 86% (six subjects) of the personal samples and all area samples exceeded the Korean OEL for wood dust (1 mg/), while 20% (two subjects) among stone sculpting students were exposed above the Korean OEL (10 mg/). In contrast, metal sculpting did not exceed the OEL (5 mg/). For noise level, metal sculpting students (Leq 95.1 dB(A) in the morning, 85.3 dB(A) in the afternoon) were exposed the most, followed by stone sculpting (88.3 dB(A)), and wood sculpting (84.8 dB(A)) in that order. Compared with the 90 dB(A) of the Korean OEL and 85 dB(A) of the American Conference of Governmental Industrial Hygienists` threshold limit value (ACGIH-TLV) for noise, 100% of the subjects (five subjects) and area samples during metal sculpting in the morning session exceeded both OELs, but only three subjects (60%) exceeded the ACGIH-TLV in the afternoon session. For stone sculpting, 50% (one subject) and 100% (two subjects) exceeded the Korean OEL and ACGIH-TLV, respectively, but the area sample did not exceed either OEL. During wood sculpting, two subjects (40%) exceeded ACGIH TLV. Conclusions: This work evaluated the sculptors` exposure to particulate matter and noise in fine art college, and revealed a poor working environment for the participating students. Effective measures should be supplemented by the administration of colleges.

Assessment Of LBD Risk By Gender Using The ACGIH-TLV Lifting Assessment Method

The American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLV) assessment method was developed to identify safe weight limits for lifting based on horizontal and vertical locations of the object lift origin. However it is unknown if a difference in injury risk exists between genders at the safe lifting weights identified by the ACGIH TLV. PURPOSE: To assess Low Back Disorder (LBD) Risk using a validated risk model to determine if the ACGIH TLV assessment is appropriate irrespective of gender. METHODS: 24 subjects (12 male, 12 female) acquired and replaced a box of ACGIH TLV safe weights from 2 vertical zones and 4 horizontal lifting distances. EMG determined muscle activity of the rectus abdominis, deltoid, trapezius, and erector spinae. A Lumbar Motion Monitor was utilized to quantify torso kinematics. External moment was measured for each lift phase. Lift rate, torso kinematics, and external moment were used to determine LBD Risk. RESULTS: LBD Risk: LBD Risk for the MidShin to Knuckle zone was not significantly affected by gender (p=0.16). LBD Risk varied significantly by horizontal distance (p<0.0001). For Knuckle to Shoulder zone, LBD Risk varied significantly by gender (p=0.01). Females demonstrated higher LBD Risk (22.3%) than males (20.9%). LBD Risk varied significantly by horizontal distance (p<0.0001). EMG: For MidShin to Knuckle zone the trapezius had a significant distance by gender effect (p<0.0004) where differences between genders in %MVC were larger in the Mid2 distance (female 47.1, male 20.5) compared to the Far1 distance (female 22.7, male 14.2). For Knuckle to Shoulder zone, significant horizontal distance effects (p<0.003) exist for all muscles, only in the deltoid and erector spinae were the differences large 30.8 (Far2) to 12.3 (Mid1) for the deltoid and 35.8 (Far2) to 27.7 (Far1) for the erector spinae. The trapezius also had a significant distance by gender effect (p<0.0057) where differences between genders in %MVC were larger in the Far2 zone (female 43.2, male 17.6). CONCLUSIONS: While the LBD Risk model estimates the ACGIH identified safe weights for all lifting zones to be of low to moderate risk for both genders, EMG results indicate gender differences in lifting mechanics may exist in the upper extremity, with females demonstrating greater muscle activity.

Assessment of airborne asbestos exposure at an asbestos cement sheet and pipe factory in Iran

Iran imports nearly 55,000 metric tons of asbestos per year, and asbestos cement (AC) plants contribute nearly 94% of the total national usage. In the present study, asbestos fiber concentrations during AC sheet and pipe manufacturing were measured by phase-contrast microscopy (PCM) and polarized light microscopy (PLM) in 98 personal air samples. The fiber type and its chemical composition were also evaluated by scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). Personal monitoring of fiber levels indicated a range from 0.02 to 0.55 PCM f/ml (0.02–0.69 PLM f/ml). The AC workers’ geometric mean asbestos exposure was 0.09 PCM f/ml (0.11 PLM f/ml), with arithmetic mean of 0.13 PCM f/ml (0.16 PLM f/ml). The observed fiber concentrations in many processes were higher than the threshold limit value (TLV) proposed by the American Conference of Governmental Industrial Hygienists (ACGIH), which is 0.1 f/ml. Based on these findings, the PLM values were approximately 25% higher than PCM values. The SEM data demonstrate that fibrous particles contained chrysotile. The thinnest fiber recognized by SEM had a diameter of 0.2 μm. Mean exposure exceeded the TLV for asbestos in pipe molding and finishing (100%) as well as sheet molding and finishing (45.5–83.3%). In conclusion exposure control may be needed to be in compliance with the ACGIH TLV and other guidance levels. Also, with regard to PCM limitations for airborne fiber analysis, the use of microscopic methods other than PCM can be used to improve the techniques used presently.

Preliminary Study of Propyl Bromide Exposure among New Jersey Dry Cleaners as a Result of a Pending Ban on Perchloroethylene

Many states are considering, and some states have actively pursued, banning the use of perchloroethylene (PERC) in dry cleaning establishments. Proposed legislation has led many dry cleaners to consider the use of products that contain greater than 90% n-propyl bromide (n-PB; also called 1-bromopropane or 1-BP). Very little information is known about toxicity and exposure to n-PB. Some n-PB-containing products are marketed as nonhazardous and “green” or “organic.” This has resulted in some users perceiving the solvent as nontoxic and has resulted in at least one significant poisoning incident in New Jersey. In addition, many dry cleaning operators may not realize that the machine components and settings must be changed when converting from PERC to n-PB containing products. Not performing these modifications may result in overheating and significant leaks in the dry cleaning equipment. A preliminary investigation was conducted of the potential exposures to n-PB and isopropyl bromide (iso-PB; also called 2-bromopropane or 2-BP) among dry cleaners in New Jersey who have converted their machines from PERC to these new solvent products. Personal breathing zone and area samples were collected using the National Institute for Occupational Safety and Health Sampling and Analytical Method 1025, with a slight modification to gas chromatography conditions to facilitate better separation of n-PB from iso-PB. During the preliminary investigation, exposures to n-PB among some workers in two of three shops were measured that were greater than the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) for n-PB. The highest exposure measured among a dry cleaning machine operator was 54 parts per million (ppm) as an 8-hr time-weighted average, which is more than 5 times the ACGIH TLV of 10 ppm. The preliminary investigation also found that the work tasks most likely to result in the highest short-term exposures included the introduction of solvent to the machine, maintenance of the machine, unloading and handling of recently cleaned clothes, and interrupting the wash cycle of the machine. In addition, this assessment suggested that leaks may have contributed to exposure and may have resulted from normal machine wear over time, ineffective maintenance, and from the incompatibility of n-PB with gasket materials.

Exposure assessment of carbon nanotube manufacturing workplaces

Seven CNT (carbon nanotube) handling workplaces were investigated for exposure assessment. Personal sampling, area sampling, and real-time monitoring using an SMPS (scanning mobility particle sizer), dust monitor, and aethalometer were performed to characterize the mass exposure, particle size distribution, and particle number exposure. No workplace was found to exceed the current ACGIH (American Conference of Governmental Industrial Hygienists) TLVs (threshold limit values) and OELs (occupational exposure levels) set by the Korean Ministry of Labor for carbon black (3.5 mg/m3), PNOS (particles not otherwise specified; 3 mg/m3), and asbestos (0.1 fiber/cc). Nanoparticles and fine particles were most frequently released after opening the CVD (chemical vapor deposition) cover, followed by catalyst preparation. Other work processes that prompted nanoparticle release included spraying, CNT preparation, ultrasonic dispersion, wafer heating, and opening the water bath cover. All these operation processes could be effectively controlled with the implementation of exposure mitigation, such as engineering control, except at one workplace where only natural ventilation was used.

Reassessment of occupational exposure limits

Although the Netherlands currently has its own procedure for evaluating chemical compounds and setting occupational exposure limits (OELs), most of these limits were originally adopted in the 1970s from threshold limit values (TLVs) set by the American Conference of Governmental Industrial Hygienists (ACGIH). However, beginning in the late 1980s, criticism about non-scientific considerations being used to set TLV's suggested that TLVs might not offer sufficient health protection to workers. This situation prompted the Dutch Ministry of Social Affairs and Employment to request that the Health Council of the Netherlands reassess the health protection of MAC values that were contained in the 1994 Dutch MAC list. Criteria documents were prepared for 161 compounds. They were evaluated by a committee of the Health Council of the Netherlands consisting of international experts who reassessed the toxicological hazards of these substances and recommended, whenever possible, health-based OELs. The results of the reassessment by the Health Council were compared with the MAC values of the 1994 Dutch MAC list, ACGIH TLVs, and existing German OELs. The toxicological database met the committee's criteria for a health-based OEL for only about 40% of the compounds. Many older MAC values were either too high or not scientifically supported and therefore not health-based.

Status of Worker Exposure to Asphalt Paving Fumes with the Use of Engineering Controls

Since 1996, industry, labor, and government have partnered to minimize workers' exposure to asphalt fumes using engineering controls. The objective of this study was to determine the use after some years of experience and to benchmark the effectiveness of the engineering controls as compared to the current exposure limits. To accomplish this objective, the current highway class pavers equipped with controls to reduce asphalt fumes, occupational exposure levels, and ventilation flow rates were monitored, and a user acceptance survey was conducted. Personal breathing-zone sampling was administered to determine concentrations of total particulate matter (TPM) and benzene soluble matter (BSM). Personal monitoring of workers yielded a BSM arithmetic mean of 0.13 mg/m3 (95% confidence limits (0.07, 0.43) mg/m3). All site average worker BSM values are below the American Conference of Governmental Industrial Hygienists (ACGIH) adopted threshold limit value (TLV) time weighted average (TWA) of 0.5 mg/m3 as benzene soluble inhalable particulate, although five sites contained 95% confidence limits slightly above the ACGIH TLV. The TPM arithmetic mean was 0.35 mg/m3 (95% confidence limits (0.27, 0.69) mg/m3). All sites showed average worker and area TPM values below NIOSH's recommended exposure limit for asphalt fumes (5 mg/m3, 15 min). One screed area sample and one operator area sample were also taken each day. Area samples followed a similar pattern to the worker breathing zone samples, but were generally slightly higher in TPM and BSM concentration. The effect of work practices and application temperatures appears to have an impact on the ability of the engineering controls to keep exposure below the TLV for BSM. To gain a better understanding of the aerodynamic properties of asphalt fumes, particle size and airborne concentrations were also monitored using a TSI model 3320 aerodynamic particle sizer spectrometer. The geometric mean particle size was between 0.64 and 0.98 micrometers for the worker breathing zone samples, with a geometric mean of 0.73 micrometers for all sites. Total airborne concentrations were typically higher for the asphalt fume exposed groups than for the background samples. During high fume events, four 15-minute samples were taken each day. Only one 15-minute sample was above the limit of quantification. Stack flow rates were measured, and results are discussed and compared to the manufacturers' nominal values. Survey results were generally positive, with recommendations discussed for continuous improvement.

吸入性粉じんの管理濃度と遊離けい酸分析

In Japan, there are two commonly used regulations on respirable dust concentration: the Occupational Exposure Limit (OEL), recommended by the Japan Society for Occupational Health, and the Administrative Control Level (ACL). Both depend on the crystalline silica content in dust. Until 2004, the ACL for respirable dust conformed to the OEL. However, the ACL was revised in 2005 in light of the OEL and the American Conference of Governmental Industrial Hygienists (ACGIH)'s Threshold Limit Value (TLV), same value as National Institute for Occupational Safety and Health (NIOSH)'s Recommended Exposure Limit (REL). In this paper, the author intends to clarify the stringency of the current ACL by comparing it with the OEL and the ACGIH's TLV. In addition, the effect of the analytical error due to the phosphoric acid method in the current and former ACLs is shown.