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Concentrations of n-hexane greater than the threshold limit value (TLV) of 500 ppm are known to produce peripheral neuropathy. This report describes the case of a worker who developed peripheral neuropathy, with a histologic pattern characteristic of n-hexane toxicity, after chronic on-the-job exposure to n-hexane at concentrations less than 450 ppm. We suggest that the current TLV for n-hexane be reevaluated.
Exposure to silica dust among Danish stone workers was assessed from data collected in 1948-1980. After 1970, the exposure level was given in milligrams per cubic-meter and an exposure index (concentration of respirable dust divided by the threshold limit value for quartz) was calculated. The median index was 2.1 for the road and building material industry and 0.6 for the stonecutting industry. Crushing showed a median index of 2.6, compared to 1.0 for drilling, 0.9 for sieving, and 0.5 for cutting. The median index for the road and building material industry was higher for Bornholm than for other parts of Denmark. The median index of the stonecutting industry was 1.0 for Copenhagen and 0.5 for other parts of Denmark, and no data were available for Bornholm. Before 1970, the exposure level was given in particles per cubic meter, and few data were available on quartz content. Crushing showed the highest exposure before 1970.
In the present epidemiologic study 80 car or industrial spray painters with long-term low level exposure to organic solvents were examined and compared with two matched reference groups of nonexposed industrial workers (80 persons in each group). The aim of the study was to investigate the possible effects of the solvent exposure on health. The investigation included psychiatric interviews, psychometric tests, neurological, neurophysiological and ophthalmologic examinations, and computed tomography of the brain. The painters' previous and present exposure was carefully assessed by interviews and on-the-job measurements both at modern places of work and in a reconstructed model of a workshop from 1955. On the basis of the psychiatric interviews the psychiatric symptoms were rated according to a specially designed scale of 46 different items, graded in seven steps of increasing severity. The psychological performance was assessed by a battery of 18 tests. The neurological and neurophysiological examinations comprised visual evoked responses (VER), electroencephalography (EEG), and computerized EEG analysis (SPA) for the central nervous system and electroneurography (ENeG), the estimation of vibration sense thresholds, and a quantified neurological examination for the peripheral nervous system. The ophthamologic examination concentrated on the condition of the lens. Statistically significant differences between the exposed individuals and referents were found for psychiatric items indicative of a slight cerebral lesion (ie, a neurasthenic syndrome). The psychometric tests revealed statistically significant differences between the groups with respect to reaction time, manual dexterity, perceptual speed, and short-term memory. No differences were found with respect to performance on verbal, spatial, and reasoning tests. Significant differences between the groups were also found for the majority of the neurophysiological parameters measuring peripheral nerve functions, the most pronounced occurring in the long, sensory fibers. Moreover EEG and VER showed some differences between the groups, as did the results of the ophthalmologic examination and the computed tomography. Finally, it should be emphasized that the exposure levels, as measured at modern places of work and in the reconstructed workshop from 1955, were found to be considerably lower than the valid threshold limit values in Sweden.
Neurophysiological effects of long-term exposure to a mixture of organic solvents was studied among 102 car painters from 27 car repair garages in Helsinki. The reference group consisted of 102 age-matched railroad engineers from the Finnish State Railways. The mean age was 35 years and the exposure time ranged from 1 to 40 years (mean 14.8, SD 8.5). According to measurements the mean concentration of the solvent mixture was relatively low in the garages, namely, 31.8% of the Finnish threshold limit value (TLV), the range of separate components varying from 4 to 212% of the respective TLVs. The main components of about 20 organic solvents of the mixture were toluene, xylene, butyl acetate and white spirit. Electroencephalograms (EEGs) of all the 102 exposed and 102 nonexposed subjects were studied, but electroneuromyographic measurements were made of only 59 car painters and 53 referents with a similar age distribution. Motor (MCV and CVSF) and sensory conduction (SCV) velocities, as well as motor distal latencies, were recorded from nerves in the upper and lower extremities. Abnormal EEGs were encountered in 32 car painters and 37 referents. The frequency of abnormal EEGs was in both groups higher than expected on the basis of EEG literature (about 10%). Twenty-six car painters had a complex of four common symptoms of disturbances in the central nervous system; the same symptom complex was found in 12 engineers. Forty-six percent of the car painters with this symptom complex had an abnormal EEG, while only 26% of those without this symptom complex had an abnormal EEG. Railroad engineers did not show such a tendency. Abnormally slow MCVs or SCVs and/or prolonged motor distal latencies were found in 12 of the 59 car painters but in none of the 53 engineers studied. Other authors have stressed that many solvents primarily cause neuropathy, while objective signs of central nervous involvement have been minor, if any. Our findings are similar; they showed slight positive signs of slowed nerve conduction velocities among the car painters and no increase in EEG abnormalities in comparison to the reference group of railroad engineers.
The effect of exposure to the solvent trichloroethylene (TRI) on the performance of tests of numerical ability, reaction time (simple and choice), and short-term memory was studied in 15 healthy male subjects. The subjects were tested individually on three different occasions during exposure to 540 and 1,080 mg/m3 of TRI in inspiratory air and under control conditions, respectively. At predetermined times during the three 70-min exposure periods, samples were taken of the subjects' alveolar air. Neither the reaction time tests nor the short-term memory test showed any signs of performance decrement during exposure to TRI as compared to those administered under control conditions. However, a statistically significant decrement in performance was obtained on the test of numerical ability during exposure to TRI. The results as a whole indicate that there should not be any risk of an acute effect on central nervous functions at concentrations which do not considerably exceed the Swedish threshold limit value for the solvent (160 mg/m3).
The behavioral effects of long-term exposure to a mixture of organic solvents were investigated in a comparison of the test results of 100 car painters with those of a reference group. The test battery included tests for intelligence, memory, psychomotor performances, and personality. In addition to the comparison of the mean results, two discriminant function analyses were made. In one, only the performance test variables were used, but in the other personality variables were also included. The results indicated impairments in psychological performances, as well as personality changes in the exposed group. Impairments in visual intelligence and verbal memory and a reduction of emotional reactivity were the central features of the adverse effects of solvent exposure, but the behavioral disturbances also involved several other functions, including performance on a verbal intelligence test. The possible role of the differences in the initial intelligence levels were controlled with a separate comparison of the test results of 33 pairs of exposed and nonexposed subjects who were matched for age and for their intelligence level, measured during the military service. The discriminant function analyses were based on the results of these matched subgroups and tested in the rest of the material. According to the results the sensitivity of the psychological test methods was high, but the specificity somewhat low, with regard to solvent exposure. The concentration of various solvents included in the exposure of car painters were low, the summated exposure corresponding corresponding to 32% of the Finnish threshold limit value. The possible role of a potentiating effect of the solvent in the development of behavioral disturbances is discussed.
The relationship between long-term occupational styrene exposure and disturbances in psychological functions was studied. The exposed group consisted of 98 male workers exposed to styrene in the manufacture of polyester plastic products, and the comparison group comprised 43 concrete reinforcement workers. The duration of exposure in years and the mean mandelic acid concentration in urine (five determinations during 5 weeks before the clinical examination) and the cumulative dose of exposure were used as the indicators of exposure. The psychological functions studied were intelligence, visuomotor speed, visuomotor accuracy, memory, vigilance, and psychomotor performance. Some personality test variables were also included. In a group comparison two variables (visuomotor inaccuracy and poor psychomotor performance) out of 20 showed statistically significant differences and characterized the styrene exposed group. These findings were confirmed when workers with low and high styrene exposure were compared. One variable measuring visuomotor speed and another measuring visual memory were related to the duration of exposure (R = 0.28, p less than 0.05). In a multiple regression analysis disturbances in visuomotor accuracy, poor psychomotor performance, and lowered vigilance proved to have some connection with a high mandelic acid concentration (R = 0.49, p less than 0.01). In addition workers with disturbances in visuomotor accuracy and slight disturbances in virumotor speed had higher mandelic acid concentrations when compared with those workers without any deterioration. The results indicate that disturbances in visuomotor accuracy and, to a lesser degree, in psychomotor performance are the main findings measured by test methods used in this study and related to one indicator of styrene exposure, mandelic acid concentration. The psychological methods used revealed subclinical symptoms related to exposure, and they should aid in making group diagnoses, e.g., when additional information is needed for the determination of the threshold limit value. The deterioration found in visuomotor accuracy could be related to lowered safety in work and traffic.
Furfuryl alcohol and formaldehyde concentrations in the air of coremaking areas of 10 iron and steel foundries were measured. The mean concentration of furfuryl alcohol and formaldehyde was 4.3 cm3/m3 and 2.7 cm3/m3, respectively. Furfuryl alcohol exceeded its threshold limit value (TLV) of 5 cm3/m3 in 22% of the determinations; and formaldehyde (TLV=2 cm3/m3) in 38%. In addition phenol concentration was determined in one foundry; and phosphoric acid concentration, in two foundries. The concentrations of phenol and phosphoric acid were far lower than their TLVs. The question is raised as to whether exposure to furfuryl alcohol and formaldehyde in foundries in combination with exposure to dust and smoking can increase the risk of chronic bronchitis.
OBJECTIVES: This study followed 279 auto assembly workers over 1 year to identify which factors influenced whether a worker would visit the plant medical department because of an upper-extremity musculoskeletal problem. METHODS: Incident cases were defined as involving workers who had not gone to the plant medical department in the preceding 6 months and then subsequently visited the medical department with a work-related musculoskeletal disorder that was potentially due to repetitive work activity (acute fractures or lacerations were excluded). RESULTS: There were 45 cases identified during the study period. Based on Cox regression analysis, significant predictors for visiting a medical department included exceeding the threshold limit value for hand activity and peak force, a history of diabetes, a current diagnosis of carpal tunnel syndrome, elbow tendonitis, and age under 40 years. CONCLUSIONS: The results of this study are consistent with those of other prospective studies that showed that both ergonomic and past medical history are risk factors for an upper-extremity musculoskeletal disorder and suggests that there is a healthy worker or survivor effect among older workers.
Eight-choice reaction time studies were carried out on women using trichloroethylene (TCE) as an industrial solvent, and simultaneous tests were performed on control subjects. The women exposed to TCE showed an increase in choice reaction time compared with the control subjects. This divergent trend was substantial at a factory where TCE levels exceeded the recommended threshold limit value (TLV). The divergence was less pronounced, but still clearly evident at another factory where TLV was not exceeded.
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.
INTRODUCTION: Medical staff working in surgical wards of hospitals, people that work on transport or storaging of gases and liquids, employees working on gas tanks and gas installations, mechanics for anesthetic devices and employees in the process of production of these substances are professionally exposed to anesthetic gases or and fumes that are released in their working environment. It has been confirmed that there were some deviations of indicators of the liver function after a long term exposure of the medical staff (surgeons, anesthesiologists, instrument nurses and anesthetists) to halothane and it has been notified that the level of wasted-halothane in the indoor air of the surgical theaters should be measured in order to get a correct and complete evaluation of the professional risk. The term "wasted-halothane" in this research means fumes of halothane that leave a closed circle: anesthetic device--respiratory organs (patient)--indoor air of the workplace (operating room). MATERIALS AND METHODS: Tests were done in the theaters of the surgical wards of the Department of Gynecology and Obstetrics of Novi Sad. During the testing period no ventilation system was used in any of the theaters. Tested groups included anesthesiologists, instrument nurses and anesthetists who were the members of the surgical team. Tests have not been done on same individuals, but the same workplace. Samples were taken using the "individual sample" method from the breathing zone of the tested person using a rubber pipe fixed on the shoulder. Pumps (personal samplers--"Casella") were set to absorb 0.2 liters of air per minute. Laboratory analyses of these samples were done using a method of desorption of the halothane fumes from the active coal with benzyl-alcohol, and their evaluation on gaschromatograph (Electron-Capture-Detector). The threshold Limit Value (TLV) of halothane fumes at the workplace is 40 mg/m3. RESULTS: During three days of sampling 32 samples of indoor air were taken from the surgical wards of the Department. 30 samples were taken in the surgical theaters, one in the hall between surgical theaters, and one in the room for rest of the staff. Concentration of halothane fumes in the theatre No 1 was between 6.9 mg/m3 and 27.31 mg/m3 in anesthetists, between 33.08 mg/m3 and 37.62 mg/m3 in anesthesiologists and between 6.9 mg/m3 and 27.31 mg/m3 in instrument nurses. At the theatre No 2 concentration of halothane fumes was between 31.27 mg/m3 and 37.9 mg/m3 in anesthetists, between 3.56 mg/m3 and 91.7 mg/m3 in anesthesiologists and up to 95.5 mg/m3 in instrumenting nurses. Concentration of halothane fumes in the theatre No 3 were between 4.19 mg/m3 and 17.18 mg/m3 in anesthetics, between 6.23 mg/m3 and 37.62 mg/m3 in anesthesiologists and between 8.27 mg/m3 and 12.33 mg/m3 in instrument nurses. In the hall between these surgical theaters the concentration was 3.02 mg/m3 and 0.28 mg/m3 in the room for rest. DISCUSSION: Halothane fumes were present in the atmosphere of the working environment in significant quantities at all tested places Especially indicative were the results that showed that the concentration of halothane fumes in the theatre No 1, at the end of surgical operational program, was much higher than at the beginning, and what is even more important it was much higher than those in TLV in anesthesiologists and instrument nurses (more than twice higher). The differences of concentrations between specific occupations within the surgical team were also significant. Our results show that the most exposed were anesthesiologists and instrument nurses, who spent most time nearby the operation table. The anesthetists were much less exposed, due to the fact that they are assistants that often leave the surgical theater during the surgical interventions. Indicators illustrate that the increase of the concentration of halothane fumes depends on the length the surgical theaters were used. It shows an increase of halothane fumes co
Concurrently with the increase of air-conditioning, potentially severe or frequent new diseases have emerged, giving rise to social and economical consequences. The first part of this work is a state of the art review of the relationships between air-conditioning, airborne microorganisms and health, through a technical, metrological and medical approach. The second part presents four studies performed in this field. Two of them deal with the relationship between airborne microorganisms and technical features of air-conditioning. Measurements performed on actual sites demonstrated the benefit of using high efficiency filters and low risk components in air-conditioning systems. The third study was aimed to look for a relationship between airborne microorganisms and sick building syndrome symptoms. Statistical analyses of individual data revealed significant associations between airborne bacteria or fungi and symptoms. These results may be the first step in determining a dose-response relationship, in order to define threshold limit values in this field. In the fourth study, the contribution of particle counting in assessing exposure to airborne microorganisms was explored by monitoring simultaneous variations of microbial and particle concentrations. The results showed that associating particle counting may allow to detect microbial variations instantaneously, and therefore improve the assessment of exposure to airborne microorganisms.
In August of 1996, Sheriff's deputies investigated the deaths of three individuals suspected to have been overcome by phosphine gas. Phosphine is an extremely toxic gas, and is generally seen in the farming industry where it is used as a grain fumigant. It can also be generated as a by-product during the manufacturing of methamphetamine. Chemicals and equipment consistent with the manufacturing of methamphetamine were noted at the location, as well as an apparent reaction mixture heated to near dryness. Dräger tubes detected an atmospheric phosphine concentration in excess of 0.3 parts per million (ppm), the Threshold Limit Value. Deputies had initially assessed the scene with no protective equipment, raising concerns about phosphine toxicity and the effects of exposure. The objectives of this paper are to describe how phosphine is formed during the manufacture of methamphetamine, to review the toxicity, health effects and symptoms of exposure, to address the safety concerns regarding potential exposure to law enforcement personnel, and to describe the protective equipment available for personnel who respond to clandestine laboratories.
There is little doubt that heat stress affects many workers adversely and that protective clothing generally adds to the burden. The ACGIH threshold limit value for heat stress is the guiding document for evaluation of heat stress in the United States. Adjustment factors have been used to reflect the change in heat stress imposed by different clothing ensembles. While the first proposed factors started with limited experimental data and professional judgment, heat balance methods in the laboratory have yielded better estimates of adjustment factors and for a wider selection of ensembles. These same experiments have provided the starting point to accounting for nonporous clothing in heat balance evaluation schemes such as required sweat rate. Proposed changes to the ACGIH TLV have been mentioned and a framework for thinking about controls presented.
Particulate exposures were assessed among construction workers engaged in hot processes in four jobs (boilermakers, ironworkers, pipefitters and welder-fitters) at nine sites in the U.S. After being trained by occupational hygienists, the workers obtained shift-long personal samples at each site for total particulates (TP). Selected samples were also assayed for manganese (Mn), nickel (Ni), and chromium (Cr). Workers provided information about process- and task-related covariates that were present on the days of monitoring. Data were investigated with mixed-model regression analyses that designated the jobs and covariates as fixed effects and the worker and error terms as random effects. Results indicated that the within-worker variance components, but not the between-worker variance components, could be pooled among jobs. Mean air levels for a given agent varied by roughly six to 100 fold among the jobs, with boilermakers and ironworkers experiencing much higher levels of TP and Mn than pipefitters and welder-fitters. Limited data also suggested that welder-fitters were exposed to greater levels of Ni and Cr than pipefitters. Sufficient sample sizes were available to evaluate the effects of covariates upon exposures to TP and Mn. As expected, processes involving more than 50% hot work led to substantially higher levels of TP and Mn than those involving shorter durations of hot work. Local-exhaust or mechanical ventilation reduced exposure to TP (but not Mn) by as much as 44%, and shielded or manual arc welding increased exposure to Mn (but not TP) by about 80%. Parameters estimated with these mixed models were used to calculate probabilities that workers were exposed at levels above U.S. occupational exposure limits (OELs). Regarding TP and Mn, these calculations suggested that 26-95% of exposures to boilermakers and pipefitters and 2-13% of exposures to pipefitters and welder-fitters exceeded the current Threshold Limit Values. Among welder-fitters, limited data also pointed to probabilities of 2-50% for exceeding particular OELs for Ni and Cr. Using the significance of the estimated random-worker effects as a gauge for the uniformity of exposure within a job, administrative or engineering changes appear appropriate for reducing exposures to boilermakers and ironworkers, while individual personal environments should be investigated for pipefitters and welder-fitters.
OBJECTIVES: In occupational medicine, blood concentrations are often measured to judge the internal burden of workers at work-place during exposure to a potentially hazardous substance. However, blood-withdrawals are invasive and can often not be taken at work-place due to hygienic reasons. Sampling of saliva is non-invasive and easy to perform even at workplace. In order to substitute blood analysis, analysis of saliva has to be as specific and sensitive as blood investigations. Therefore acetone-concentrations in blood and in saliva during exposure to isopropanol were compared. METHODS: 18 healthy non-smokers were exposed to 360 ppm isopropanol in an exposure chamber over 4 h. Once an hour during exposure and 30 min after, blood and saliva were sampled. Saliva was collected by a cotton plug over 10 minutes and stored in an airtight closed headspace tube. Concentrations of the metabolite acetone were measured by gas chromatography. - RESULTS: The concentrations of acetone in blood and saliva rose continually during exposure and dropped after exposure-cessation. High correlations between concentrations of acetone in blood and saliva were found for each individual and the entire group (entire group: r = 0.8568, p <0.0001, y = 0.8374x - 0.4404). CONCLUSIONS: Acetone-measurement in saliva is a non-invasive, easily conductable and reliable method for estimating the internal burden of isopropanol-exposure. Further studies for the standardization and validation are necessary to impose a threshold limit value on work-place isopropanol-exposure.
Available industry guidelines and federal standards have failed to fully protect workers from chemical toxicity: none exist for most chemicals, many are biased toward what can easily be achieved, and many were developed long after health consequences became evident. Limitations of occupational air contaminant standards in the United States are well illustrated by standard-setting for the neurotoxin n-hexane. In the 1940s, the American Conference of Governmental Industrial Hygienists (ACGIH) first promulgated industrial guidelines known as "threshold limit values" (TLVs), including an 8-hour time-weighted average of 500 ppm for inspired n-hexane. Despite subsequent recognition of the neurotoxicity of n-hexane with industrial outbreaks of polyneuropathy beginning in the 1960s, the TLV for n-hexane remained unchanged until 1976 when a value of 100 ppm was adopted. Because a growing number of clinical reports have identified clinical and subclinical neurotoxicity from n-hexane near, at, and below the current time-weighted average TLV of 50 ppm, even this level is too high to protect all workers. In part due to procedural and political constraints, the Occupational Safety and Health Administration (OSHA) has independently developed only a small number of exposure standards in the past 25 years, and has been incapable of providing needed revisions for existing standards. Most OSHA standards--including those for n-hexane--were adopted in 1971 from the 1968 ACGIH TLVs and have never been revised. From 1971 to 1989 the OSHA permissible exposure level (PEL) for n-hexane remained at 500 ppm, 5-10 times as great as other contemporary standards. To help correct its regulatory backlong, OSHA promulgated 375 new or revised PELs in 1989--including a new standard of 50 ppm for n-hexane--but all of these were vacated by the 11th U.S. Court of Appeals in 1992. As a result, the current OSHA PEL for n-hexane remains at the 500 ppm level adopted in 1971, which even then was too high based upon available scientific evidence. New information over this long period, including that obtained from industrial outbreaks of disease due to chemical exposures, has not been incorporated into revised federal standards.