Neuropsychological symptoms and occupational exposure to anaesthetics.

OBJECTIVE--To analyse the relation between symptoms regularly reported by hospital personnel and exposure to anaesthetics. SETTING--Personnel of 18 hospitals in Paris from 1987 to 1989. DESIGN--An exposed group that included all operating theatre members except for doctors, and which was divided into three subgroups depending on the degree of exposure--exposure was measured by the frequency of the use of the scavenging system--and a control group that included other hospital personnel matched by hospital, sex, occupation, age, and duration of service. SUBJECTS--557 exposed workers and 566 unexposed workers. MAIN OUTCOME MEASURES--The groups were compared according to the crude rates of regular symptoms. Adjusted odds ratios were calculated to estimate the risks associated with exposure to anaesthetic gas. Liver transaminase activities (alanine aminotransferase, aspartate aminotransferase (s-ASAT, and gamma-glutamyl transpeptidase) were measured and compared between groups of exposure. RESULTS--After controlling for working conditions and matching factors, neuropsychological symptoms and tiredness were reported more by workers in less often scavenged theatres than by controls. No difference was found between workers of the well scavenged theatres and controls. Among the exposed workers, the members of paediatric surgical staffs reported a higher rate of neurological complaints (tingling, numbness, cramps) and tiredness than the members of the other surgical staffs. They had a high value of s-ASAT more frequently than the other exposed workers. CONCLUSION--These results strengthen the hypothesis of a causal relation between exposure to anaesthetics and neuropsychological symptoms, and show a dose-response effect. They suggest that the use of ventilating systems in operating rooms is an effective means of prevention.     

Neuropsychological symptoms among tanker drivers with exposure to solvents

The purpose of this study was to measure the exposure of roadtanker drivers to organic solvents at work, and to study, usingquestionnaires, how many symptoms drivers have which might becaused by exposure to solvents. The target group for the studywas all the road tanker drivers of a Finnish oil firm (n=61men). There were two control groups from the same firm. Onecontrol group included workers who were occasionally exposedto solvents at work (n=56 men). The other group included workerswho had no exposure to solvents (n=31 men). Industrial hygienemeasurements were made in two oil depots (n=20). The drivers'personal exposures to organic solvents during loading of roadtankers were remarkable. In seven measurements (50%) duringtop loading, the exposure exceeded the Swedish TLV(8 h). Insymptom questionnaires, the drivers had more acute symptomswhich might be caused by solvent exposure compared to the controlgroup who had no exposure. The most remarkable differences werein the symptoms of fatigue, depression, hostility, listlessnessand uncertainty. Drivers had fewer symptoms which might be causedby long-term exposure to solvents than control groups. Furthermore,the differences between groups were not statistically significant.     

Neuropsychological test results and symptoms among workers with well-defined long-term exposure to lead.

Lead intoxication is a classical environmental hazard that can cause encephalopathy. During recent years several studies have suggested poor performances in psychological tests and increased numbers of subjective symptoms among workers with comparatively low blood lead concentrations. Forty-nine long-term lead-exposed male workers with time-weighted average blood lead concentrations between 1.3 and 3.3 mumol/l calculated from at least seven years' results have been compared with a referent group of 27 male industrial workers with normal blood lead concentrations and comparable intellectual backgrounds. Several indices of exposure were used. Both groups were examined with neuropsychological tests and a questionnaire covering neuropsychiatric symptoms. The exposed group performed less well in 11 of 14 non-verbal tests, and there were significant differences in tests of memory and reaction time. A non-linear dose-effect trend was indicated. The results are in accordance with those found in similar studies, and it is concluded that the blood lead concentration should be below 2.5 mumol/l to avoid the effects shown in this study.     

Neuropsychological function in retired workers with previous long-term occupational exposure to solvents

OBJECTIVES: It is plausible that neurodegenerative processes of aging might have a contributing role in the development of chronic effects of exposure to organic solvents. This study evaluated the risk for neuropsychological deficits among retired workers, relative to their histories of exposure to occupational solvents. METHODS: This cross sectional study evaluated retired male workers, 62-74 years of age, including 89 people with previous long-term occupational exposure to solvents (67 retired painters and 22 retired aerospace manufacturing workers), and 126 retired carpenters with relatively minimal previous exposure to solvents. Subjects completed a standardised neuropsychological evaluation and psychiatric interview, structured interviews for histories of occupational exposure and alcohol consumption, and questionnaires assessing neurological and depressive symptoms. RESULTS: By comparison with the carpenters, the painters on average reported greater cumulative alcohol consumption and had lower scores on the WAIS-R vocabulary subtest, usually presumed to reflect premorbid intellectual functioning. These findings, however, were not sufficient to account for the other study findings. Controlling for age, education, vocabulary score, and alcohol use, the painters had lower mean scores on test measures of motor, memory, and reasoning ability; and a subgroup of aerospace workers with moderate to high cumulative exposure to solvents (n = 8) had lower mean scores on measures of visuomotor speed, and motor, attention, memory, and reasoning ability. Subjects were more likely to have an increased number of relatively abnormal test scores (three or more outlier scores on 17 test measures) among both the painter group (odds ratio (OR), 3.1; 95% confidence interval (95% CI) 1.5 to 6.2) and the subgroup of aerospace workers with higher cumulative exposure (OR 5.6; 95% CI 1.0 to 38). The painters, but not the aerospace workers, reported significantly more neurological and depressive symptoms. CONCLUSIONS: The findings are consistent with residual central nervous system dysfunction from long-term exposure to organic solvents, persisting years after the end of exposure.

 

     

Monitoring occupational exposure to volatile anaesthetics in the operating theatre: environmental and biological measurements

Concentrations of nitrous oxide (N2O) and isoflurane were measured in environmental and urinary samples from subjects occupationally exposed to volatile anaesthetics in operating theatres in a hospital in northern Italy. The aim was to establish whether: an automatic analyzer (Brüel & Kjaer 1302 spectrometer) can be used for fixed position sampling ("anaesthetist zone" and "surgeon/instrument nurse zone"); periodic monitoring of anaesthetics will reduce exposure; exposure to N2O and isoflurane is within legal limits; exposure differs between anaesthetists and surgeons/instrument nurses. Exposure to anaesthetics was monitored twice at six-month intervals. In the first test time spent in the operating theatre was noted and exposure levels were measured automatically. In the second test levels were monitored with passive personal sampling devices. Environmental concentrations of N2O determined by the spectrometer were correlated to urinary levels. Urinary levels of N2O calculated from the regression line were the same as those obtained with the personal samplers. Environmental and urinary levels of N2O decreased significantly from the first to second test. In the second sampling 70% of subjects had levels of exposure to N2O and isoflurane within prescribed environmental limits (50 ppm for N2O and 0.5 ppm for isoflurane). At the first test anaesthetists had significantly higher levels of exposure to N2O than surgeons/instrument nurses. The survey demonstrated that: fixed position sampling data related to time spent in the operating theatre can be used to gauge individual exposure levels; exposure levels decrease after tests following implementation of preventive measures; monitoring needs to be repeated because exposure levels often exceed legal limits; occupational exposure decreases when pollution in the anaesthetic zone is reduced.     

Eye and airway symptoms in low occupational exposure to toluene diisocyanate

OBJECTIVES: Exposure to diisocyanates is a well known occupational hazard. The objective of this study was to determine the possibility of an association between low exposure to toluene diisocyanate (TDI) (airborne isocyanates and biomarkers of isocyanates in plasma and urine) and symptoms of the eyes and upper and lower airways. METHODS: Altogether 136 workers occupationally exposed to TDI and 118 unexposed employees were studied. A physician compiled thorough medical and occupational histories and registered symptoms, total and work-related, of the eyes, nose, and lower airways. The exposure was assessed with personal air measurements and with biomarkers of exposure in plasma and urine. The average exposure in the ambient air at the workplace of the exposed participants was below 1 ppb. RESULTS: Compared with the unexposed group, the exposed workers reported more total symptoms of the eyes and lower airways, as well as nose bleeding. A similar pattern, with even higher odds ratios, was observed for work-related symptoms. However, only eye symptoms proved to be significantly associated with the exposure, notably with all of the exposure measures. The risk was more pronounced for exposure to 2,4-TDI than for exposure to 2,6-TDI. CONCLUSIONS: Even very low exposure to TDI is related to negative health effects on exposed workers. Clear dose-response relationships were observed between three different measures of exposure and symptoms of the eyes.     

Increase in neuropsychiatric symptoms after occupational exposure to low levels of styrene.

The results of this study suggest that exposure to styrene below the current Swedish permissible exposure limit of 20 ppm induces neurotoxic effects expressed as an increased number of neuropsychiatric symptoms. Twenty men exposed to styrene at a plastics factory participated. The reference group included 20 non-exposed men matched for age, working schedule, and physical work load. Exposure to styrene during one workday was assessed by personal air monitoring and biological monitoring. To evaluate the physical work load the pulse(heart) rate was measured. One week before the study each man completed a neuropsychiatric symptom questionnaire containing 16 items. Also 17 questions regarding acute symptoms of local irritation and symptoms of the central nervous system were presented after the psychometric tests were performed. The tests were simple reaction time, colour word vigilance, and symbol digit. A follow up with regard to the symptoms among the exposed men was done after their summer vacation, about two to five weeks after their last exposure. The mean eight hour time weighted average (TWA) concentration of styrene in air, measured by passive dosimetry was 8.6 ppm (range 0.04-50.4 ppm). The exposed men had significantly more symptoms than the referents although there were no significant differences for the psychometric tests. At the follow up the exposed men reported fewer symptoms. This study indicates that symptoms are earlier indicators of adverse effects than complex tests and underlines the importance of regular follow up of people exposed to styrene (and probably organic solvents in general).     

Respiratory symptoms and intensity of occupational dust exposure

Objectives: Occupational exposure to dusts may result in chronic respiratory symptoms. Methods: To investigate the utility of obtaining a history of occupational exposure to dust in US veterans, a respiratory health survey was conducted between 1988 and 1992 in a community-based cohort of US veterans in southeastern Massachusetts that were eligible for Veterans Affairs (VA) healthcare benefits but were not regular users. A mail questionnaire was used to obtain a history of cough, phlegm, and wheeze, work in a dusty job, and duration, type, and intensity of dust exposure. Information on cigarette use and other possible confounders was obtained. Results: In 2,617 white men, after the data had been adjusted for cigarette smoking, age, distance to the nearest major roadway, and chronic respiratory disease, the relative odds of chronic cough, chronic phlegm, and persistent wheeze attributable to occupational dust exposure was increased twofold. Risk also increased, based on exposure intensity. For heavy dust exposure the OR was 1.98 (95% CI 1.39–2.81) for chronic cough, 2.82 (95% CI 2.03–3.93) for chronic phlegm, and 2.70 (95% CI 1.95–3.75) for persistent wheeze. Conclusions: After active cigarette smoking and other possible confounders had been considered, it was found that dust exposure was related to respiratory symptoms in US veterans and that the greatest risk was attributable to heavy intensity exposure.Presented in abstract form at the 1994 annual meeting of the American Thoracic Society.     

A follow-up study on occupational exposure to inhaled anaesthetics in Eastern European surgeons and circulating nurses

Objective: Although no dose-response relationship exists for the health risks associated with the occupational exposure to inhaled anaesthetics, public health authorities recommend threshold values. The aim of the present study was to assess whether and to what extent these threshold values are exceeded in surgeons and circulating nurses of an Eastern European university hospital, before and after measures had been taken to reduce occupational exposure. Methods: At nine workplaces, occupational exposure to nitrous oxide and the volatile anaesthetic used (halothane or isoflurane) was measured within the breathing zones of surgeons and circulating nurses by means of photoacoustic infrared spectrometry. The measurements were carried out in 1996 and were repeated in 1997 after the installation of active scavenging devices at five workplaces, and an air-conditioning system at one workplace. Results: Occupational exposure to nitrous oxide and halothane or isoflurane was lower in 1997 compared with that of 1996. In 1996, 89% of the nitrous oxide values were above the European threshold value of 100 ppm, whereas in 1997 approximately 50% were above this limit. In 1996 the majority of the measurements for the volatile anaesthetics were already below 5 ppm halothane and 10 ppm isoflurane and the number of measurements exceeding these limits was further reduced in 1997. Conclusion: The measures taken were effective in reducing waste gas exposure. Nevertheless, further efforts are necessary, especially for nitrous oxide, to reach Western European standards and to minimise possible health risks. These efforts comprise the installation of (active) scavenging devices, air-conditioning systems and new anaesthesia machines at all workplaces, the use of low-flow anaesthesia, the replacement of inhaled anaesthetics by intravenous anaesthetics and an appropriate working technique. Received: 27 April 2000 / Accepted: 26 July 2000     

A follow-up study on occupational exposure to inhaled anaesthetics in Eastern European surgeons and circulating nurses

OBJECTIVE: Although no dose-response relationship exists for the health risks associated with the occupational exposure to inhaled anaesthetics, public health authorities recommend threshold values. The aim of the present study was to assess whether and to what extent these threshold values are exceeded in surgeons and circulating nurses of an Eastern European university hospital, before and after measures had been taken to reduce occupational exposure. METHODS: At nine workplaces, occupational exposure to nitrous oxide and the volatile anaesthetic used (halothane or isoflurane) was measured within the breathing zones of surgeons and circulating nurses by means of photoacoustic infrared spectrometry. The measurements were carried out in 1996 and were repeated in 1997 after the installation of active scavenging devices at five workplaces, and an air-conditioning system at one workplace. RESULTS: Occupational exposure to nitrous oxide and halothane or isoflurane was lower in 1997 compared with that of 1996. In 1996, 89% of the nitrous oxide values were above the European threshold value of 100 ppm, whereas in 1997 approximately 50% were above this limit. In 1996 the majority of the measurements for the volatile anaesthetics were already below 5 ppm halothane and 10 ppm isoflurane and the number of measurements exceeding these limits was further reduced in 1997. CONCLUSION: The measures taken were effective in reducing waste gas exposure. Nevertheless, further efforts are necessary, especially for nitrous oxide, to reach Western European standards and to minimise possible health risks. These efforts comprise the installation of (active) scavenging devices, air-conditioning systems and new anaesthesia machines at all workplaces, the use of low-flow anaesthesia, the replacement of inhaled anaesthetics by intravenous anaesthetics and an appropriate working technique.     

Metallothionein and occupational exposure to cadmium.

The relationship between metallothionein (MT), chronic exposure to cadmium (Cd), and renal function was investigated in 53 men who were occupationally exposed to Cd. The aim was to determine if MT is a potential biological monitor for chronic exposure to Cd which would be useful for preventing Cd nephropathy. In this study MT excretion, serum MT, and serum creatinine concentrations were significantly higher in subjects with abnormal renal function who had been exposed to Cd. MT excretion was also linearly related on an individual basis to protein excretion, beta 2-microglobulin (beta 2-M) excretion, and cumulative time weighted exposure (dose). MT excretion was also a better predictor of dose than either beta 2-M excretion or Cd excretion. The findings suggest that MT is a potential biological monitor for chronic Cd exposure that would be useful for preventing Cd-induced nephropathy. Further studies of non-specific nephropathies and MT are needed to determine if MT is a specific indicator of proximal tubule function secondary to chronic exposure to Cd.     

Respiratory symptoms and pathophysiological effects of occupational exposure to formaldehyde and wood dust

The hazards of exposure to formaldehyde have been widely discussed in recent years on account of the health complaints of exposed persons. Both domestic and occupational exposure to formaldehyde is common. In the present study the effects of formaldehyde alone and in combination with wood dust, another nasal irritant, on the upper and lower respiratory tract have been investigated. The effects were correlated with the duration and degree of exposure. Discomfort from both the upper and lower airways was more frequent in the exposed group than in the unexposed group. Nasal obstruction among the exposed subjects in general could not be detected by rhinomanometric measurements, but, for the group exposed to formaldehyde alone and with a history of nasal blocking, there was significant nasal mucosal swelling. The nasal mucociliary clearance was significantly delayed, and the sense of smell was significantly reduced in the exposed groups when they were compared with the referents. Spirometry showed a significantly decreased forced vital capacity in the exposed groups. There were no signs in this investigation that duration of exposure or level of exposure to formaldehyde would have any influence on the severity of symptoms or the impairment of physiological conditions.     

Health symptoms and occupational exposure to flea control products among California pet handlers

A statewide telephone survey of health symptoms associated with occupational exposure to flea control products among California pet handlers was conducted in 1987 following several reports of ill workers. The 696 employees interviewed worked at veterinary clinics, pet stores, pet boarding kennels, pet grooming shops, and animal control facilities. Symptom incidence and frequency and flea control product use were reported for the 3 months prior to interview. Eye and skin symptoms and unusual tiredness were elevated among workers who applied flea control products to animals or facilities. After adjustment for potential confounders, these symptoms were elevated 64% to 258% among applicators as compared to nonapplicators who worked in the same facilities. Workers who used protective clothing and equipment and followed some protective work practices were not at increased symptom risk. Some specific flea control active ingredients and application procedures were associated with respiratory effects and with symptoms suggesting systemic pesticide poisoning.     

Bladder cancer and occupational exposure to leather.

A large case-control study of bladder cancer (2982 cases; 5782 controls) included information about occupational exposure to leather. Occupational histories of exposed white study subjects were reviewed and 150 were determined to have had "true" on the job exposure to leather. The odds ratio estimate (OR) of bladder cancer associated with such exposure in white subjects (n = 8063) was 1.4 (95% confidence limits = 1.0, 1.9) after adjustment for sex, age, and cigarette smoking. The risk was highest in those first employed in a leather job before 1945, although no dose-response relation with duration of leather employment was found. Subjects employed in "dusty" leather jobs had a slightly higher risk than those with other types of leather jobs. Our results are consistent with reports of an increased risk of bladder cancer associated with exposure to leather. Although the agents responsible have not been identified, our findings of an increased risk associated with exposure in the earlier years of this century and in dusty jobs suggest that leather dusts may be important.     

Psychiatric disorders and occupational exposure to solvents.

Three hundred and eighty one men admitted to hospital for the first time with any psychiatric diagnosis were individually matched for age and year to patients admitted to general hospitals. An occupational history was obtained from 90% of this study group by telephone interview or mail. Exposure to solvents was assessed by three methods, individual rating of each job recorded, application of an exposure matrix based on job title, and assessment of lifetime job histories of selected case-referent pairs. A sample of individual ratings used in the analysis was compared with ratings made by five experts. The panel values tended to be lower but all six sets of ratings correlated well. There was no increased risk of psychiatric illness among subjects exposed to moderate or greater solvent concentrations for at least 10 years (odds ratio (OR) 1.0, 90% confidence interval (90% CI) 0.7-1.4, individual rating; OR 1.1, 90% CI 0.6-2.0, job title matrix; OR 0.9, 90% CI 0.5-1.7, lifetime assessments). At higher exposures the risk was increased--although not to a statistically significant degree--especially for cases with non-psychotic diagnoses (ICD-9 codes 300-316). This negative result, by all three methods of assessment of exposure, contrasted with that from a parallel investigation of cases of organic psychoses and cerebral degeneration.     

Psychiatric disorders and occupational exposure to solvents.

Three hundred and eighty one men admitted to hospital for the first time with any psychiatric diagnosis were individually matched for age and year to patients admitted to general hospitals. An occupational history was obtained from 90% of this study group by telephone interview or mail. Exposure to solvents was assessed by three methods, individual rating of each job recorded, application of an exposure matrix based on job title, and assessment of lifetime job histories of selected case-referent pairs. A sample of individual ratings used in the analysis was compared with ratings made by five experts. The panel values tended to be lower but all six sets of ratings correlated well. There was no increased risk of psychiatric illness among subjects exposed to moderate or greater solvent concentrations for at least 10 years (odds ratio (OR) 1.0, 90% confidence interval (90% CI) 0.7-1.4, individual rating; OR 1.1, 90% CI 0.6-2.0, job title matrix; OR 0.9, 90% CI 0.5-1.7, lifetime assessments). At higher exposures the risk was increased--although not to a statistically significant degree--especially for cases with non-psychotic diagnoses (ICD-9 codes 300-316). This negative result, by all three methods of assessment of exposure, contrasted with that from a parallel investigation of cases of organic psychoses and cerebral degeneration.     

Allergy and occupational exposure to hydroquinone and to methionine.

Respiratory manifestations have been reported after exposure to hydroquinone and to methionine. One hundred and three men in the same chemical plant were divided into three groups according to their exposure and compared by questionnaire, respiratory functional tests with methacholine then salbutamol challenges, and measurements of serum immunoglobulins G and E. Group H included 33 workers exposed to hydroquinone, trimethyl-hydroquinone, and retinene-hydroquinone. Group M included 15 workers exposed to methionine. Group C was a control group of 55 workers. The prevalence of respiratory symptoms was higher in the two exposed groups. Before challenges, pulmonary function values were significantly lower in groups H and M than those in group C. The challenges induced significant variations in the three groups but these variations were less pronounced in group M than in the other groups. The level of immunoglobulin G in group H (m +/- SD = 12.5 gram/liter +/- 2.6) was significantly higher than in group C (10.6 gram/liter +/- 2.4; p less than 0.002). The level of immunoglobulin E in group H (m = 140 IU/l) was also higher in group C (109 IU/l) but this difference was not significant. These findings suggest that exposure to methionine and to hydroquinone and its derivatives induce ventilatory impairment, perhaps by an immunological mechanism.     

Relationship of symptoms to occupational styrene exposure and to the findings of electroencephalographic and psychological examinations

Summary Ninety-eight male laminating workers occupationally exposed to styrene were clinically examined, and their symptoms were clarified with the aid of a questionnaire. The mandelic acid concentration in urine was used as the measure of current exposure. The median mandelic acid concentration (mean of five determinations) of the exposed group was 808 mg/l (Q₁ 439, Q₃ 1390). The symptoms of the exposed group were compared with those of unexposed men (n=98) and also correlated to the mandelic acid concentration. Symptoms of fatigue, difficulties in concentration and symptoms of irritation occurred statistiscally significantly more often in the exposed group than in the unexposed one (p < 0.01). During the workday irritation and prenarcotic symptoms, e.g., nausea, dizziness and a drunken feeling, were reported significantly more often (p < 0.001) in the exposed group. When the relationship between symptoms, and also symptom scores, and the mandelic acid concentration was examined, no statistically significant correlation was found. Also a comparison of symptoms of the most and least exposed groups revealed no statistically significant difference. Earlier abnormal electroencephalographic (EEG) findings and abnormal psychological functions (lowered psychomotor accuracy and speed) had been found to statistically significantly correlate with urinary mandelic acid concentration. In the present investigation the symptoms and symptom scores of the groups with abnormal EEGs or psychological functions were compared to the group with corresponding normal findings, and no statistically significant difference was found. The clinical examination did not reveal any neurological deficits. In an attempt to determine whether mandelic acid causes uroepithelial atypias, a urinary cytologic examination was made; none of the 35 specimens showed any suspicious cellular changes. The results of the symptom survey indicate that the presence of symptoms can not be used as a predictor of exposure or as a predictor of abnormal findings in psychological and EEG examinations. They might also indicate that the symptoms and the objective findings describe different aspects of the effects of styrene exposure.     

Neuropsychological effects of exposure to naphtha among automotive workers.

The association between exposure to naphtha and neurobehavioural measures was examined prospectively over one year among workers employed at an automotive plant that used naphtha to calibrate fuel injectors. The neurobehavioural tests included those that assess mood, basic intelligence, and functioning of the cerebral frontal lobes and limbic system and were designed so that acute, reversible, and chronic effects of solvent exposure could be assessed. Participants were 248 workers in June 1988, and the testing was repeated on 185 of these workers in 1989. Concentrations of naphtha at the plant ranged from six to 709 mg/m3, although exposure was greater in 1988 than in 1989. Duration of exposure for individual subjects ranged from 0.8 to 7.3 years. Cross sectional data analyses showed significant associations between level of exposure to naphtha and slower timed scores on trails A, and greater reports of negative affective symptoms on profile of mood states scales in 1988 but not 1989. Threshold model analyses of the 1989 data showed an association between score on visual reproductions immediate recall and daily exposure to naphtha at or above 1050 h x mg/m3. Models of chronic exposure showed no associations between chronic exposure and negative neurobehavioural outcome. Results suggest that naphtha produces mild acute reversible effects on function of the central nervous system at or above daily exposures of 540 h x mg/m3 (approximately 90 ppm/h).