Neurobehavioral changes among shipyard painters exposed to solvents

Painters in three shipyards, exposed to a wide variety of solvents, were examined. A short battery of performance tests, a detailed occupational history, and a special questionnaire to assess acute (prenarcotic, transitory) and chronic (persistent) neurologic symptoms was administered. The results of the neurobehavioral performance tests demonstrated decrements in central nervous system function in painters when compared with a control group matched for age, sex, race, and education. The prevalence of reported acute neurological symptoms among painters was increased significantly compared to other occupational groups in the same yards; for chronic, persistent symptoms the difference was not statistically significant. Performance test scores were significantly, negatively correlated with chronic symptoms but not with acute symptoms. No significant correlations between performance test scores and duration of solvent exposure or between symptoms and duration of solvent exposure were observed. The reversibility of such symptoms and of decrements in central nervous system function after cessation of exposure is still uncertain.     

Long-term follow up of workers exposed to solvents

Long term occupational exposure to organic solvents may cause adverse effects to the central nervous system. This collaborative study between six Swedish departments of occupational medicine examines the overall prognosis in terms of working capacity, symptoms, and psychometric test performance for individuals occupationally exposed to organic solvents. After re-analyses of the data from an initial clinical investigation of 111 men, the subjects were divided into two subgroups: one group of 65 with symptoms but no impairment on the tests and one group of 46 with toxic encephalopathy (symptoms and test impairment). At least five years after the initial examination the subjects were asked to attend a re-examination that included a structured medical interview and a psychometric investigation. The results indicate that effects on the central nervous system persist even when exposure has ceased. In the group of 46 more men had stopped working and were receiving sickness or early retirement pensions. This group also had reduced activity levels with regard to everyday life, leisure activities, and education or training and more neuropsychiatric symptoms. There was no support for the view that a solvent induced toxic encephalopathy is a progressive disease comparable with presenile dementia such as Alzheimer's disease or Pick's disease. If a worker was removed from exposure when he presented symptoms without signs of impairment in intellectual function recovery was seen in most cases.     

Long-term follow up of workers exposed to solvents.

Long term occupational exposure to organic solvents may cause adverse effects to the central nervous system. This collaborative study between six Swedish departments of occupational medicine examines the overall prognosis in terms of working capacity, symptoms, and psychometric test performance for individuals occupationally exposed to organic solvents. After re-analyses of the data from an initial clinical investigation of 111 men, the subjects were divided into two subgroups: one group of 65 with symptoms but no impairment on the tests and one group of 46 with toxic encephalopathy (symptoms and test impairment). At least five years after the initial examination the subjects were asked to attend a re-examination that included a structured medical interview and a psychometric investigation. The results indicate that effects on the central nervous system persist even when exposure has ceased. In the group of 46 more men had stopped working and were receiving sickness or early retirement pensions. This group also had reduced activity levels with regard to everyday life, leisure activities, and education or training and more neuropsychiatric symptoms. There was no support for the view that a solvent induced toxic encephalopathy is a progressive disease comparable with presenile dementia such as Alzheimer's disease or Pick's disease. If a worker was removed from exposure when he presented symptoms without signs of impairment in intellectual function recovery was seen in most cases.     

Neurobehavioral changes of shipyard painters exposed to mixed organic solvents

This study was conducted to evaluate neurobehavioral changes arising from occupational exposure to organic solvents among shipyard painters and to establish whether a dose-effect relation existed where there was any observed impairment of neurobehavioral performance by running the test of Simple Reaction Time (SRT), Symbol Digit Substitution (SD), and Finger Tapping Speed (FT) with a computer-assisted neurobehavioral test battery. The study group consisted of 180 shipyard painters and 60 reference workers. The workers answered a self-administered questionnaire on occupational, medical history, and demographic characteristics including age, work duration, education level, and quantity and frequency of alcohol and smoking, and performed three psychometric tests on the Korean Computerized Neurobehavioral tests. To estimate cumulative exposure level, samples of ambient air on 61 painters were analyzed using a gas chromatograph. Shipyard painters and the reference group showed significant differences in the results of test of SD, FT of dominant hand, and FT of non-dominant hand. The test results of SD of shipyard painters also showed significant difference by duration of work. This suggests that occupational exposure of organic solvent could induce neurobehavioral changes in the shipyard painters. Therefore an objective neurobehavioral tests recommended on evaluating neurobehavioral performance of long-term solvent-exposed shipyard workers.     

Prenarcotic and neuraesthenic symptoms among Dutch workers exposed to organic solvents

A population of 379 Dutch workers exposed to organic solvents was compared with a non-exposed population of 443 workers with regard to the prevalence of prenarcotic and neuraesthenic symptoms. Participants completed a questionnaire to collect information about their occupational history, exposure to organic solvents, and the occurrence of symptoms. The results of the study indicated that workers exposed to solvents have a higher reporting rate of prenarcotic symptoms than workers not exposed to solvents. The prevalence of chronic neurotoxic effects, however, in the form of neuraesthenic symptoms was only weakly associated with reported exposure to organic solvents. The influence of work stress in the development of these symptoms is perhaps more important than the role of exposure to organic solvents. It is concluded that the organic solvent syndrome type I, as defined by an international workshop, is not an important health hazard among Dutch painters.     

Prenarcotic and neuraesthenic symptoms among Dutch workers exposed to organic solvents.

A population of 379 Dutch workers exposed to organic solvents was compared with a non-exposed population of 443 workers with regard to the prevalence of prenarcotic and neuraesthenic symptoms. Participants completed a questionnaire to collect information about their occupational history, exposure to organic solvents, and the occurrence of symptoms. The results of the study indicated that workers exposed to solvents have a higher reporting rate of prenarcotic symptoms than workers not exposed to solvents. The prevalence of chronic neurotoxic effects, however, in the form of neuraesthenic symptoms was only weakly associated with reported exposure to organic solvents. The influence of work stress in the development of these symptoms is perhaps more important than the role of exposure to organic solvents. It is concluded that the organic solvent syndrome type I, as defined by an international workshop, is not an important health hazard among Dutch painters.     

Impairment of neurobehavioral function and color vision loss among workers exposed to low concentration of styrene--a review of literatures

Recently many studies on the health effects of workers who exposed to low-concentration styrene have been published. In this paper firstly we mentioned the reasons why nervous system was critical organ for evaluating the toxicity of organic solvents both in the acute and chronic exposure phases. Then we indicated how neurobehavioral test batteries were useful to detect subclinical adverse health effects of workers exposed to organic solvents. Secondly we reviewed many epidemiological studies on the impairment of neurobehavioral function, i.e., perceptual speed, memory, cognition, personality and mood, and the loss of color vision among styrene workers. Finally, we showed our recent data on the relationship between color vision loss and the concentration of urine metabolites among styrene workers. It can conclude that styrene may cause damage on nervous system, even at the low exposure level such as 50 ppm which used to be the Threshold Limit Value (TLV) recommended by Japan Society for Occupational Health (until 1999) and American Conference of Industrial Hygienists (until 1997).     

Hearing loss among workers exposed to moderate concentrations of solvents.

OBJECTIVES: It is known that some industrial organic solvents are ototoxic. This study was aimed at evaluating the hearing effects of a mixture of organic solvents alone or in combination with noise on employees in paint and lacquer enterprises. The concentration of solvents was below the occupational exposure limits (OEL) for most of the subjects. METHODS: Altogether 517 subjects were divided into the following three groups: persons with no risk due to noise or organic solvent exposure at the workplace, workers exposed to organic solvents only, and workers exposed to both organic solvents and noise. RESULTS: The relative risk (RR) of hearing loss in the solvent-only exposure group was significantly increased (RR 4.4 and RR 2.8 for noise exposure of < 80 dB-A and < 85 dB-A, respectively) in a wide range of frequencies (2-8 kHz). No additional risk in the solvent + noise exposure group was found (RR 2.8). Hearing thresholds were significantly poorer in a wide range of frequencies (1-8 kHz) for both groups exposed to solvents, when compared with the reference group. The mean hearing thresholds at frequencies of 2-4 kHz were poorer for workers exposed to solvents + noise than for the solvent-only group; this finding suggests an additional effect for noise. However, there was no correlation between hearing loss and the extent of solvent exposure. CONCLUSIONS: The results indicate that occupational organic solvent exposure at moderate concentrations increases the risk of hearing loss, and the ototoxic effects should be considered when the health effects of exposed workers are monitored.     

A neurological evaluation of workers exposed to mixtures of organic solvents

Workers with long term exposure to mixtures of organic solvents below regulatory limits have been reported to experience mild, but clinically detectable, sensory or sensorimotor polyneuropathies. In conjuction with a cross sectional study of behavioural performance a clinical neurological evaluation was conducted among printers and spray painters to examine dose response relations. All 240 subjects completed an occupational history and symptom questionnaire and underwent a clinical neurological examination. On average, subjects had been employed on their current job for six years. Classification of solvent exposure for each subject was based on exposed versus non-exposed job titles and observations during an industrial hygiene walk-through or on the measured concentration of solvents in full shift personal air samples. The average full shift solvent concentration was 302 ppm for printing plant workers and 6-13 ppm for workers at other plants. Isopropanol and hexane were the major constituents. Neurological abnormalities consistent with mild polyneuropathy were found in 16% of subjects; none was clinically significant. Exposed/non-exposed comparisons showed slightly higher frequency of symptoms in the exposed subjects which was not related to solvent level. Subjects categorised as exposed during the walk- through survey also had poorer vibratory sensation measured at the foot and diminished ankle reflexes. In multiple linear regression models, however, controlling for age, sex, alcohol intake, and examiner, no significant (p less than 0.05) relation was found between solvent concentration and poor neurological function except for two point discrimination measured at the foot. This investigation has not provided evidence for dose related adverse neurological effects from exposure to moderately low levels of solvent mixtures for a relatively short duration, although this may be due to the shortness of exposure duration, the type of solvent exposure, or to selection factors.     

Neurotoxic effects of organic solvents in exposed workers: an occupational, neuropsychological, and neurological investigation

Ninety-eight workers, 65 exposed to organic solvents and 33 unexposed, were examined in order to assess possible neurotoxic signs and symptoms related to solvent exposure. The study group, who were selected according to the type of exposure in a given work process, had been exposed to various types of solvents. The groups were comparable in regard to age, the history of brain traumas and other neurological diseases, and alcohol consumption. The exposed workers had more symptoms of intellectual impairment, poorer performances in psychological tests, and more often signs of cerebral asthenopia. Symptoms and signs of peripheral neuropathy were not significantly increased. Solvent exposure and neurotoxic signs and symptoms were mildly correlated in the study group. Such dose-effect correlations have previously been proved only in a few epidemiological studies. This warrants reevaluation of the risk of developing toxic encephalopathy during prolonged occupational exposure to solvents.     

A neurological evaluation of workers exposed to mixtures of organic solvents.

Workers with long term exposure to mixtures of organic solvents below regulatory limits have been reported to experience mild, but clinically detectable, sensory or sensorimotor polyneuropathies. In conjuction with a cross sectional study of behavioural performance a clinical neurological evaluation was conducted among printers and spray painters to examine dose response relations. All 240 subjects completed an occupational history and symptom questionnaire and underwent a clinical neurological examination. On average, subjects had been employed on their current job for six years. Classification of solvent exposure for each subject was based on exposed versus non-exposed job titles and observations during an industrial hygiene walk-through or on the measured concentration of solvents in full shift personal air samples. The average full shift solvent concentration was 302 ppm for printing plant workers and 6-13 ppm for workers at other plants. Isopropanol and hexane were the major constituents. Neurological abnormalities consistent with mild polyneuropathy were found in 16% of subjects; none was clinically significant. Exposed/non-exposed comparisons showed slightly higher frequency of symptoms in the exposed subjects which was not related to solvent level. Subjects categorised as exposed during the walk- through survey also had poorer vibratory sensation measured at the foot and diminished ankle reflexes. In multiple linear regression models, however, controlling for age, sex, alcohol intake, and examiner, no significant (p less than 0.05) relation was found between solvent concentration and poor neurological function except for two point discrimination measured at the foot. This investigation has not provided evidence for dose related adverse neurological effects from exposure to moderately low levels of solvent mixtures for a relatively short duration, although this may be due to the shortness of exposure duration, the type of solvent exposure, or to selection factors.     

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.     

Behavioural evaluation of workers exposed to mixtures of organic solvents

Reports from Scandinavia have suggested behavioural impairment among long term workers exposed to solvents below regulatory standards. A cross sectional study of behavioural performance was conducted among printers and spray painters exposed to mixtures of organic solvents to replicate the Scandinavian studies and to examine dose-response relationships. Eligible subjects consisted of 640 hourly workers from four midwestern United States companies. Of these, 269 responded to requests to participate and 240 were selected for study based on restrictions for age, sex, education, and other potentially confounding variables. The subjects tested had been employed on average for six years. Each subject completed an occupational history, underwent a medical examination, and completed a battery of behavioural tests. These included the Fitts law psychomotor task, the Stroop colour-word test, the Sternberg short term memory scanning test, the short term memory span test, and the continuous recognition memory test. Solvent exposure for each subject was defined as an exposed or non-exposed category based on a plant industrial hygiene walk-through and the concentration of solvents based on an analysis of full shift personal air samples by gas chromatography. The first definition was used to maintain consistency with Scandinavian studies, but the second was considered to be more accurate. The average full shift solvent concentration was 302 ppm for the printing plant workers and 6-13 ppm for the workers at other plants. Isopropanol and hexane were the major components, compared with toluene in Scandinavian studies. Performance on behavioural tests was analysed using multiple linear regression with solvent concentration as an independent variable. Other relevant demographic variables were also considered for inclusion. No significant (p greater than 0.05) relation between solvent concentration and impairment on any of the 10 behavioural variables was observed after controlling for confounding variables. Exposed/non-exposed comparisons showed a significantly poorer digit span among those exposed, but this has not been generally reported in the Scandinavian studies. The medical examination showed no abnormalities of clinical significance. The inability to replicate the findings of the Scandinavian studies could have been due to the shortness of the duration of workers' exposure, the type of solvents in the mixtures, use of different behavioural tests, or to selection factors.     

Neurobehavioral performance among agricultural workers and pesticide applicators: a meta-analytic study

Chronic low level exposure of agricultural workers and applicators to pesticides has been found to be associated with different degrees of decrement in cognitive and psychomotor functions. The goal of this study was to use meta-analysis to (1) identify and quantify neurobehavioral deficits among agricultural workers and pesticide applicators, and (2) analyse the potential confounders or moderators of these neurobehavioral deficits. Seventeen studies, reporting on 21 independent cohort groups, were included in the meta-analysis. These studies involved 16 neuropsychological tests providing 23 different performance measures that constitute the neurobehavioral constructs. All tests and measures of the neurobehavioral functions of attention, visuomotor integration, verbal abstraction and perception constructs showed significant decrements for exposed participants. One out of three tests of memory, two of five tests of sustained attention, and four of eight tests of motor speed constructs also showed significant decrements. Nine out of these 15 effect size distributions demonstrated significant heterogeneity across cohorts. A search for cohort-level variables (eg, agricultural workers vs applicators, duration of exposure, age and percentage of male participants) to explain this heterogeneity was largely unsuccessful. However, for one test, Block Design, the duration of exposure was positively associated with performance decrements. Furthermore, it was also found that performance decrements on this test were smaller for older participants. Increasing the number of studies and using more consistent methodologies in field studies are needed.     

Neurobehavioral and respiratory findings in jet engine repair workers: A comparison of exposed and unexposed volunteers

Workers repairing jet engines had respiratory, rheumatic, and neurobehavioral symptoms. They had welded and ground stainless steel parts using hard metal tools and cleaned metal with chlorinated and fluorinated organic solvents. We compared 154 workers and 112 unexposed subjects, all volunteers of similar ages and with similar educational levels, for abnormalities on chest radiographs, spirometric measurements, and questionnaires. Also appraised were performance of reaction time, balance, blink reflex latency, color discrimination, Culture Fair, vocabulary, slotted pegboard, trail making A and B, profile of mood states (POMS), and frequencies of 35 symptoms. Compared to unexposed subjects, workers had significantly more respiratory symptoms but no differences in pulmonary function. They had significantly prolonged simple and choice reaction time (P<0.0001), and abnormal balance with eyes open and eyes closed (P<0. 0001), and abnormal color discrimination. Blink reflex latency was abnormal in both exposed workers and in local unexposed compared to other reference groups. Focus of the inquiry on lung disease helped ensure that for neurobehavioral tests confounding factors were minimal and known biases were small. We tentatively attribute the neurobehavioral impairments and increased symptom frequencies to chlorinated solvent exposure. Excessive respiratory symptoms are attributed to welding stainless steel combined with cigarette smoking. Specifically, manganese exposure may have affected the respiratory and the central nervous systems.     

Behavioural evaluation of workers exposed to mixtures of organic solvents.

Reports from Scandinavia have suggested behavioural impairment among long term workers exposed to solvents below regulatory standards. A cross sectional study of behavioural performance was conducted among printers and spray painters exposed to mixtures of organic solvents to replicate the Scandinavian studies and to examine dose-response relationships. Eligible subjects consisted of 640 hourly workers from four midwestern United States companies. Of these, 269 responded to requests to participate and 240 were selected for study based on restrictions for age, sex, education, and other potentially confounding variables. The subjects tested had been employed on average for six years. Each subject completed an occupational history, underwent a medical examination, and completed a battery of behavioural tests. These included the Fitts law psychomotor task, the Stroop colour-word test, the Sternberg short term memory scanning test, the short term memory span test, and the continuous recognition memory test. Solvent exposure for each subject was defined as an exposed or non-exposed category based on a plant industrial hygiene walk-through and the concentration of solvents based on an analysis of full shift personal air samples by gas chromatography. The first definition was used to maintain consistency with Scandinavian studies, but the second was considered to be more accurate. The average full shift solvent concentration was 302 ppm for the printing plant workers and 6-13 ppm for the workers at other plants. Isopropanol and hexane were the major components, compared with toluene in Scandinavian studies. Performance on behavioural tests was analysed using multiple linear regression with solvent concentration as an independent variable. Other relevant demographic variables were also considered for inclusion. No significant (p greater than 0.05) relation between solvent concentration and impairment on any of the 10 behavioural variables was observed after controlling for confounding variables. Exposed/non-exposed comparisons showed a significantly poorer digit span among those exposed, but this has not been generally reported in the Scandinavian studies. The medical examination showed no abnormalities of clinical significance. The inability to replicate the findings of the Scandinavian studies could have been due to the shortness of the duration of workers' exposure, the type of solvents in the mixtures, use of different behavioural tests, or to selection factors.     

Neurotoxic effects of organic solvents in exposed workers: two controlled follow-up studies after 5.5 and 10.6 years

The findings of acute and/or chronic central and peripheral neurotoxic effects of organic solvents in workers from a previous controlled cross-sectional study (65 exposed and 33 unexposed) were re-assessed to ascertain whether the neurotoxic symptoms and signs had become chronic. These follow-ups were performed 5.5 years later by occupational medical and clinical neurological examination (59 exposed and 30 unexposed) and again 10.6 years later by a mailed questionnaire (53 exposed and 30 unexposed). Both follow-ups revealed more acute neurotoxic symptoms in the exposed workers than in the unexposed workers, but fewer than previously, and indeed, the current exposure to solvents had been reduced. However, at both follow-ups, the exposed workers showed significantly more symptoms of chronic encephalopathy, in particular, memory and concentration impairment. These latter symptoms had also significantly worsened in the workers who were still being exposed, while they were presently unchanged in the previously exposed workers who had been free of exposure for 6.6 years at the latter follow-up. On the other hand, symptoms of chronic encephalopathy had not appeared in the unexposed group. Among workers, both still and previously exposed, there were also social consequences in the form of occupational disqualification. According to the findings, long-term occupational exposure to organic solvents in concentrations that are not unusual at workplaces may lead to development of chronic neurotoxic symptoms.     

Adverse effects in workers exposed to inorganic lead

This paper describes a retrospective cohort study comparing 60 workers occupationally exposed to inorganic lead and 60 matched controls. All subjects were assessed using data obtained from a specially designed Questionnaire for lead exposure and toxic effects assessment, physical examination, spirometry, ECG, and laboratory tests including blood lead level (BLL) and biomarkers of lead toxic effects. Muscle pain, droopiness, and work-related nasal symptoms were significantly more frequent in lead workers. The prevalence of lung symptoms was higher in lead workers than in controls, but not significantly (20 % vs. 6.6 %, respectively). Mean values of BLL and delta-aminolevulinic acid (ALA) were significantly higher in lead workers. The activity of delta-aminolevulinic acid dehydratase (ALAD) in lead workers was significantly lower than in controls. Abnormal of BLL, ALAD, and ALA were more frequent in lead workers, with statistical difference for BLL and ALAD. Inverse correlation was found between BLL and ALAD, and positive correlation between BLL and age, years of employment, and years of exposure. Inverse correlation was found between ALAD and age, years of employment, years of exposure, blood pressure, alcohol consumption, and years of alcohol consumption. Changes in spirometry correlated inversely with BLL. A positive correlation was found between BLL and erythrocyte count and haemoglobin concentration, whereas it was inverse for ALAD and haemoglobin concentration. A significant difference was found for BLL and ALAD, with a very high odds ratio (14.64 and 7.23, respectively) and high relative risk (4.18 and 3.08, respectively). Our data have confirmed the association between occupational lead exposure and deviation in specific biological markers of lead effect and between the role of occupational exposure in the development of adverse effects.     

高频作业工人地为功能改变的观察

探讨神经行为功能检测在高频辐射职业危害中的应用价值。采用ＷＨＯ神经行为核心测试组合中４项神经行为功能测试方法，观察工业高频电磁场对作业工人神经行为的影响。结果 高频作业工人各项指标得分均显低于对照组，并与作业工人神经衰弱的检出结果有一定的关系。     

Prevalence of self-reported health complaints among shoe workers of small workshop exposed to organic solvents in Hebron City, West Bank: a cross-sectional survey

The study was conducted to estimate the prevalences of neurological disorders and mucous membrane irritation complaints among workers of shoe workshops in Hebron City, in particular to measure the associations between the occurrence of symptoms indicating polyneuropathy among workers and exposure to organic solvents in the glueing tasks. A group of 103 male workers from 30 workshops, exposed to organic solvents for more than one year were recruited to the study during the years 1996-1997. A validated Swedish neuropsychiatric questionnaire which contained questions on neurological and mucous irritation symptoms was used. Prevalence ratios were used as an indicator for relative risk. The overall prevalence of painful tingling of limbs (used as indicator of polyneuropathy) was high among the workshop workers (40%) and was significantly associated with long term exposure to organic solvents in glueing tasks (PR 2.8: 95% CI 1.0-8.3). Moderate associations were seen in other tasks. Headache and mental irritability did not show any association with organic solvent exposure in the workshop tasks. Breathing difficulty showed a moderate non-significant association with long term exposure to organic solvents (72 months) in cleaning tasks (1.9,0.7-4.8), while sore eyes also showed a moderate non-significant association with exposure to organic solvents for 25-72 months in the glueing tasks. Long term exposure to n-hexane (mainly found in the glues) could be the main cause of polyneuropathy among the workers of Hebron shoe workshops. The absence of effective ventilation systems and personal protective equipment might increase the prevalence of polyneuropathy among these workers. In conclusion, glues containing high concentrations of n-hexane are still in use in many shoe workshops in Hebron City (as well as in other developing countries), and long term exposure to n-hexane in glueing compounds could result in polyneuropathy among the workers. However, in the absence of objective measurements our results must be interpreted with caution. Well planned longitudinal studies with objective measures of exposure and disease are important for future research in developing countries.