Nocturnal oxygen desaturation,as assessed by home oximetry,in long-term solvent-exposed workers

Recent studies have suggested that occupational exposure to solvents may be a cause of sleep apnea. Digital oximetry during one night was performed in solvent-exposed offset printers (n = 21) and in a control group (n = 21), using a Palco 400 Pulse Oximeter. The threshold for recording was set at an arterial oxygen saturation (SaO₂) of 90%. Furthermore, computerized neurobehavioral tests (NES) and a solvent-related complaints questionnaire (NSC-60) were administered. The mean exposure time was 15 years (SD = 10). Hygiene measurements revealed a large number of different solvents and a cumulative exposure between 15% and 97% of the “cumulative TLV.” The exposed workers had more solvent-related complaints, especially regarding mood (analysis of covariance, P = 0.02), than the nonexposed workers. The neurobehavioral tests indicated that hand-eye coordination was significantly worse in the exposed group (analysis of covariance, P = 0.03). The frequency of nocturnal desaturation was significantly higher in the printers (1.7 events/hr ± SD = 1.5) than in the controls (0.6 events/hr ± SD = 1.3) (Mann-Whitney test, P < 0.01). Also, the duration of desaturation was longer in the exposed workers: 3.2 min/hr (SD = 3.2) vs 1.2 min/hr (SD = 2.3) (Mann-Whitney test, P < 0.01). In the analysis of covariance, exposure (P = 0.04) and the interaction between smoking and exposure (P = 0.02) were shown to contribute significantly to the excess of nocturnal desaturation in the exposed. The same was true for the mean duration of desaturation (exposure: P = 0.02 and interaction exposure smoking: P = 0.02). The significant interaction was due to a more pronounced effect of solvent exposure among the nonsmoker group. No relation was found between the excess of complaints or the neuroperformance effects and the oximetry data. These data reinforce the presumption that occupational solvent exposure might contribute to sleep-disordered breathing. Am. J. Ind. Med. 32:656–664, 1997. © 1997 Wiley-Liss, Inc.     

Comparison of neurobehavioral function in workers exposed to a mixture of organic and inorganic lead and in workers exposed to solvents

The neurobehavioral effects of lead (organic and inorganic) and organic solvents were compared in 386 U.S. workers (52 reference, 190 lead, and 144 solvent workers). The association between neurobehavioral test performance and duration of exposure to lead or solvents was also examined and compared. The neurobehavioral test battery consisted of examiner and computer-administered neurobehavioral tests, a test of olfactory function, and questionnaires that assessed neuropsychiatric symptoms. Adjusted mean differences on the neurobehavioral test scores were estimated by comparing the exposed group to the referent group using linear regression and adjusting for premorbid intellectual ability, age, and race. Both lead and solvents were associated with diminished neurobehavioral performance in all neurobehavioral areas tested. Specifically, while lead and solvent exposure had the same magnitude of adverse effects on tests of manual dexterity, lead exposure was associated with greater adverse effects on memory and learning tests but with less adverse effects on executive/motor tests and on a test of olfaction than solvent exposure. An elevated number of neuropsychiatric symptoms was reported by 7% of the referent group, 43% of the lead group, and 15% of the solvent group. For exposure duration of ?10 years, more neurobehavioral decrements were found in the solvent group relative to the lead group. However, for exposure duration of ?18 years, the lead group showed more decrements than the solvent group. Overall, these data suggest differences in neurobehavioral functioning between the lead (organic and inorganic) and solvent exposed workers examined in this study.     

职业性混苯暴露工人神经行为功能改变

利用世界卫生组织（ＷＨＯ）推荐的神经行为核心测试组合（ＮＣＴＢ）对１０３名职业性混苯暴露工人,以及７２名无职业性有害因素接触的同厂工人进行测试。结果发现：暴露组在情感状态（ＰＯＭＳ）、手工敏捷度、数字广度、数字译码、目标追踪等项目得分都低于对照组,其中优势手手工敏捷度、目标追踪两项得分差异具显著性。按车间混苯浓度分为高暴露组和低暴露组,多因素分析发现：高暴露组情感状态（ＰＯＭＳ）中的抑郁－沮丧和有力－好动、数字广度、手工敏捷度（优势手和非优势手）、数字译码、目标追踪等项显著低于对照组和低暴露组。提示混苯暴露使工人神经行为功能表现某些方面的改变,如心情趋于抑郁、缺乏活动性,短时记忆力、理解力、运动速度、协调性等方面表现较差。     

Dose-related subclinical neurobehavioral effects of chronic exposure to low levels of organic solvents.

One hundred eight-seven workers (mean age +/- SD; 42 +/- 8.8 years) in two paint manufacturing plants were examined to determine if sustained low-level exposure to mixed organic solvents resulted in the painters' syndrome (a psycho-organic syndrome). The test battery consisted of a medical and occupational questionnaire, the Present State Examination, the Zung Depression Scale, the Scandinavian Questionnaire 16, a neuropsychological battery, and vibration thresholds. Solvent exposure, expressed as total hydrocarbon of combined selected solvents, was quantitated using 13-15 years of personal breathing zone samplings. Linear regression analysis controlling for several confounding variables demonstrated significant correlations between increasing exposure to mixed organic solvents and neurobehavioral performance for vibration threshold and several neuropsychological tests. Dose-related effects of chronic solvent exposure on neurobehavioral outcomes (all subclinical) were shown, but "typical" symptoms characteristic of the painter's syndrome were not found.     

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.     

Neurobehavioral evaluation of venezuelan workers exposed to organic solvent mixtures

To assess the applicability of the World Health Organization (WHO) Neurobehavioral Core Test Battery (NCTB), we evaluated 53 male and 29 female Venezuelan workers exposed to mixtures of organic solvents in an adhesive factory, and 56 male and 11 female workers unexposed to any type of neurotoxic chemical. The average age of unexposed workers was 30 years and 33 years for those exposed, average schooling for both groups was 8 years, and the mean duration of exposure was 7 years. The NCTB, which assesses central nervous system functions, is composed of seven tests that measure simple motor function, short-term memory, eye-hand coordination, affective behavior, and psychomotor perception and speed. The battery includes: profile of mood states (POMS); Simple Reaction Time for attention and response speed; Digit Span for auditory memory; Santa Ana manual dexterity; Digit-Symbol for perceptual motor speed; the Benton visual retention for visual perception and memory; and Pursuit Aiming II for motor steadiness. In each of 13 subtests, the exposed group had a poorer performance than the nonexposed group. The range of differences in mean performance was between 5% and 89%. particularly in POMS (tension-anxiety, anger-hostility, depression-rejection, fatigue-inertia, confusion-bewilderment), Simple Reaction Time, Digit-Symbol, and Santa Ana Pegboard (p < .05). In multivariate regression analyses, controlling for the effects of age, sex, and education, significantly poorer performance in the exposed was found for tension-anxiety, hostility, depression, and confusion moods in the POMS, and in digit-symbol and simple reaction time (p < .05). These alterations were also dose-related using years of exposure in analyses of covariance. Compared to the nonexposed, the exposed subjects demonstrated an increased frequency of subjective symptoms of fatigue, difficulties with memory, confusion, paresthesias in upper and lower extremities, and sleep disturbances. We conclude that the methodology is applicable to the population studied. The tests of the NCTB were accepted by the subjects and were administered satisfactorily, except for occasional difficulties in verbal comprehension in subtests of POMS, which is the only test that requires more demanding verbal skills. The magnitude of the behavioral deficits is consistent with the probable high level of exposure and with the range of deficits previously reported in workers with long-term solvent exposures.     

Occupational solvent exposure and brain function: an fMRI study

Background: Deficits in cognitive function have been demonstrated among workers chronically exposed to solvents, but the neural basis for these deficits has not been shown.Objectives: We used functional magnetic resonance imaging (fMRI) to compare pathophysiological changes in brain function between solvent-exposed and control workers.Methods: Painters, drywall tapers, and carpenters were recruited from the International Union of Painters and Allied Trades, District Council 9 in New York City and District Council 21 in Philadelphia, Pennsylvania, and from the Carpenters Union in New Jersey. Twenty-seven solvent-exposed and 27 control subjects of similar age, education, and occupational status completed the N-Back working memory test during fMRI. After controlling for confounders (age; lifetime marijuana, cocaine, and alcohol use; blood lead; symptoms of depression; verbal intelligence), voxelwise group analysis and regional activation levels were compared and then correlated with an index of lifetime solvent exposure.Results: Solvent-exposed workers’ performance on the N-Back was significantly worse than that of controls. Activation of the anterior cingulate, prefrontal, and parietal cortices—areas serving working memory function and attention—was also significantly lower for solvent-exposed workers relative to controls. After controlling for confounders, we observed a negative correlation between lifetime solvent exposure and activation in these same regions among the solvent-exposed workers.Conclusions: This study is one of the few to document neural structures affected by exposure to solvents. Our findings provide a biological mechanism for the neurobehavioral deficits in working memory and attention that have previously been reported by other groups studying the effects of chronic exposure to solvents. These imaging markers, which are consistent with the neurobehavioral measures in our subject population, are consistent with altered brain pathology caused by prolonged exposure to solvent mixtures during construction work.     

The relationship between blood lead levels and neurobehavioral test performance in NHANES III and related occupational studies

OBJECTIVES: The goals of this study were two-fold: (1) to assess the relationship between blood lead levels and neurobehavioral test performance in a nationally sample of adults from the third National Health and Nutrition Evaluation Survey and (2) to analyze the results from previously published studies of occupational lead exposure that used the same neurobehavioral tests as those included in the survey. METHODS: Regression models were used to test and estimate the relationships between measurements of blood lead and performance on a simple reaction time, a symbol-digit substitution, and a serial digit learning test in adults aged 20-59 years who participated the survey. Mixed models were used to analyze the data from the occupational studies. RESULTS: The blood lead levels of those participating in the survey ranged from 0.7 to 41.8 microg/dl. The estimated geometric mean was 2.51 microg/dl, and the estimated arithmetic mean was 3.30 microg/dl. In the survey, no statistically significant relationships were found between blood lead concentration and performance on the three neurobehavioral tests when adjusted for covariates. In the occupational studies, the groups exposed to lead consistently performed worse than control groups on the simple reaction time and digit-symbol substitution tests. CONCLUSIONS: The results from the survey and the occupational studies do not provide evidence for impairment of neurobehavioral test performance at levels below 25 microg/dl, the concentration that the Centers for Disease Control and Prevention define as elevated in adults. The average blood lead level of the exposed groups in the occupational studies was 41.07 microg/dl, less than 50 microg/dl, the minimum concentration that the Occupational Safety and Health Administration requires for medical removal from the workplace. Given the evidence of impaired neurobehavioral performance in these groups, the 50 microg/dl limit should be reevaluated.     

Neurologic function among termiticide applicators exposed to chlorpyrifos

Chlorpyrifos is a moderately toxic organophosphate pesticide. Houses and lawns in the United States receive a total of approximately 20 million annual chlorpyrifos treatments, and 82% of U.S. adults have detectable levels of a chlorpyrifos metabolite (3,5, 6-trichloro-2-pyridinol; TCP) in the urine. The U.S. Environmental Protection Agency has estimated that there are 5,000 yearly reported cases of accidental chlorpyrifos poisoning, and approximately one-fourth of these cases exhibit symptoms. Organophosphates affect the nervous system, but there are few epidemiologic data on chlorpyrifos neurotoxicity. We studied neurologic function in 191 current and former termiticide applicators who had an average of 2.4 years applying chlorpyrifos and 2.5 years applying other pesticides, and we compared them to 189 nonexposed controls. The average urinary TCP level for 65 recently exposed applicators was 629.5 microg/L, as compared to 4.5 microg/L for the general U.S. population. The exposed group did not differ significantly from the nonexposed group for any test in the clinical examination. Few significant differences were found in nerve conduction velocity, arm/hand tremor, vibrotactile sensitivity, vision, smell, visual/motor skills, or neurobehavioral skills. The exposed group did not perform as well as the nonexposed group in pegboard turning tests and some postural sway tests. The exposed subjects also reported significantly more symptoms, including memory problems, emotional states, fatigue, and loss of muscle strength; our more quantitative tests may not have been adequate to detect these symptoms. Eight men who reported past chlorpyrifos poisoning had a pattern of low performance on a number of tests, which is consistent with prior reports of chronic effects of organophosphate poisoning. Overall, the lack of exposure effects on the clinical examination was reassuring. The findings for self-reported symptoms raise some concern, as does the finding of low performance for those reporting prior poisoning. Although this was a relatively large study based on a well-defined target population, the workers we studied may not be representative of all exposed workers, and caution should be exercised in generalizing our results.     

Developmental Fluoride Neurotoxicity: A Systematic Review and Meta-Analysis

Background: Although fluoride may cause neurotoxicity in animal models and acute fluoride poisoning causes neurotoxicity in adults, very little is known of its effects on children’s neurodevelopment.Objective: We performed a systematic review and meta-analysis of published studies to investigate the effects of increased fluoride exposure and delayed neurobehavioral development.Methods: We searched the MEDLINE, EMBASE, Water Resources Abstracts, and TOXNET databases through 2011 for eligible studies. We also searched the China National Knowledge Infrastructure (CNKI) database, because many studies on fluoride neurotoxicity have been published in Chinese journals only. In total, we identified 27 eligible epidemiological studies with high and reference exposures, end points of IQ scores, or related cognitive function measures with means and variances for the two exposure groups. Using random-effects models, we estimated the standardized mean difference between exposed and reference groups across all studies. We conducted sensitivity analyses restricted to studies using the same outcome assessment and having drinking-water fluoride as the only exposure. We performed the Cochran test for heterogeneity between studies, Begg’s funnel plot, and Egger test to assess publication bias, and conducted meta-regressions to explore sources of variation in mean differences among the studies.Results: The standardized weighted mean difference in IQ score between exposed and reference populations was –0.45 (95% confidence interval: –0.56, –0.35) using a random-effects model. Thus, children in high-fluoride areas had significantly lower IQ scores than those who lived in low-fluoride areas. Subgroup and sensitivity analyses also indicated inverse associations, although the substantial heterogeneity did not appear to decrease.Conclusions: The results support the possibility of an adverse effect of high fluoride exposure on children’s neurodevelopment. Future research should include detailed individual-level information on prenatal exposure, neurobehavioral performance, and covariates for adjustment.     

Comparison of patella lead with blood lead and tibia lead and their associations with neurobehavioral test scores

OBJECTIVE: Lead exposure in adults is associated with worse cognitive function in cross-sectional and longitudinal studies. Previous studies have mainly examined relations with blood lead or cortical bone lead; few have examined trabecular bone lead. METHODS: We performed a cross-sectional analysis of the relations of patella lead and other lead biomarkers with measures of neurobehavioral and peripheral nervous system function in 652 lead workers. RESULTS: Patella lead was found to be associated with worse performance on seven of 19 tests of manual dexterity, sensory vibration threshold, and depressive symptoms. The associations of patella lead with cognitive function were essentially similar to those with blood lead or tibia lead but of somewhat lower magnitude. CONCLUSIONS: In this study, measurement of patella lead did not aid causal inference regarding cognitive effects when compared with blood lead and tibia lead.     

低水平铅暴露对印刷厂工人神经行为的影响评价

为评价低水平铅暴露对神经行为的影响，用世界卫生组织推荐的神经行为核心测试组合（ＮＣＴＢ）方法对２８名印刷厂排字工人和４６名大学三年级学生进行测试。测试项目包括：（１）情感状态，（２）简单反应时，（３）数字跨度，（４）手敏捷度，（５）数字译码，（６）视觉保留。测试结果表明在所有的测试项目中，未见两组间得分有显著性差异。多元逐步回归分析提示在很低暴露水平情况下，铅与神经行为得分间存在联系     

Neurobehavioral effects of acute and chronic mixed-solvent exposure in the screen printing industry

This 2-year prospective study examined the neurobehavioral effects of acute and chronic exposure to mixed solvents in workers in a screen printing business. A total of 30 subjects participated in the study in two field testings over a 12 month period. Each subject completed a detailed medical and occupational questionnaire, had a neurological examination, and underwent a battery of neuropsychological tests. Industrial hygiene investigation identified the following chemical exposures as present: toluene, methyl ethyl ketone, mineral spirits, β-ether, methylene chloride, and acetic acid. Different departments and jobs had varying degrees of exposure to these chemicals, the highest exposures being in the ink mix area and the screen washroom area. However, all exposure levels were below recommended threshold limit values. Persons categorized as having higher acute exposure demonstrated significantly impaired test performance on tasks involving manual dexterity, visual memory, and mood. Those with higher chronic exposure demonstrated significantly poorer performance on visual memory tasks and mood. Results suggest that the mixed solvents used in the screen printing industy have an effect on central nervous system functioning in the absence of obvious clinical disease.     

Increased acquired dyschromatopsia among solvent-exposed workers: an epidemiology study on 249 employees of an aluminum-foil printing factory

Objective: To analyze the effects on color vision of chronic exposure to mixtures of solvents including ethyl acetate, ethanol, and ketones among the workers of a large factory specializing in the manufacture of photoengraved aluminum packaging. Methods: We analyzed a group of 129 subjects who had been exposed to solvents for more than 3 years (mean age 40 years, range 25–59 years) and a nonexposed group of 120 subjects (mean age 41 years, range 21–57 years). The two groups had a similar length of service (17 and 19 years on average, respectively). The exposed subjects consumed more tobacco and alcohol than the nonexposed workers. The study involved administration of the Lanthony D-15 desaturated test. The subjects were classified as having or not having dyschromatopsia on the basis of Lanthony's criteria and the chromatic confusion index (CCI) was calculated according to Bowman's method. After observation of the work stations and analysis of an occupational questionnaire the findings were used to construct a cumulative exposure index covering the whole of each subject's working life. Air samples were taken at each work station and in each production sector to determine current exposure. Results: The average cumulative exposure index was 194 (median 174, range 27–513). The average hygienic effect index (according to ACGIH recommendations), regularly used for atmospheres containing mixtures of products, varied between 12% and 27% of the occupational limit values permitted under French legislation. As regards color vision, 23% of the exposed group had dyschromatopsia, as did 13% of the nonexposed group, with the odds ratio (OR) adjusted for age and consumption of tobacco and alcohol being 1.99 (1.02, 3.89). The analysis of the dose-response relationship according to the cumulative exposure index showed an OR of 1.59 for the lowly exposed group (index ≤174) and an OR of 2.40 for the highly exposed group (index >174) as compared with the nonexposed group. Subjects with complex color vision loss (n=23) had a significantly higher cumulative exposure index than those with blue-yellow loss (n=23; 232 versus 155; P=0.04). The CCI was on average higher in the exposed group, but the difference between the two groups was not significant. Conclusion: The results of this study are in favor of an increased risk for impairment of chromatic discrimination among workers exposed to mixtures of solvents including mainly ethyl acetate, ethanol, and ketones. Received: 10 September 1996 / Accepted: 12 December 1997     

Work-site clinical and neurobehavioral assessment of solvent-exposed microelectronics workers

Twenty-five workers, five currently and 20 formerly involved in the manufacture of hybrid microcircuits, underwent clinical evaluations at the request of a management-union committee concerned about chronic solvent exposures in a research and development laboratory. A battery of neurobehavioral tests was administered to compare the solvent-exposed group with 32 age-, gender-, ethnicity-, and education-matched controls. The tests included: MMPI-I, hand grip strength, tactile sensitivity, dexterity, color discrimination, visual acuity and contrast sensitivity, and tests selected from the computerized Neurobehavioral Evaluation System (NES2). Clinical narratives and retrospective exposure assessments in the study group suggested chronic low-level exposure to solvents, with intermittent acute excursions. Work-related diagnoses included upper respiratory mucosal irritation and sinusitis (44%), lower respiratory reactive airway-disease (12%), and dermatitis (5%). Three workers (12%) had findings consistent with a solvent-induced encephalopathy. Significant differences (after Bonferroni correction) were found between the two groups on 5 of 11 NES subtests: symptom scale, mood scale, finger tapping, simple reaction time, and symbol-digit substitution. Differences also reached significance for overall vibration sensitivity thresholds, visual contrast sensitivity, and grip strength. The MMPI average clinical scale elevation was significantly higher in the exposed group than controls. These results support an association between chronic low-dose solvent exposure and measurable neurobehavioral changes.     

Children of working low-income families in California: does parental work benefit children's insurance status,access, and utilization of primary health care?

OBJECTIVE: To examine financial and nonfinancial access to care and utilization of primary health care services among children of working low-income families earning below 200 percent of the federal poverty level in California, and to compare them to children in nonworking low-income families and in families earning over 200 percent of poverty. DATA SOURCES/STUDY SETTING: The 1994 National Health Interview survey weighted to reflect population estimates for California. STUDY DESIGN: This cross-sectional study of 3,831 children under age 19 focuses on financial access, that is, the prevalence and continuity of health insurance coverage; structural access, including the presence of a usual source of care, the predominant care source, its responsiveness to patient's needs, and any indications of delayed or missed care; and utilization of health care measured by the presence of an outpatient doctor's visit and the mean number of visits relative to child health status. DATA COLLECTION: The study uses secondary analysis. FINDINGS: Compared to children of nonworking low-income parents and to nonpoor children, children of working low-income parents were more likely to be uninsured (32.1 percent versus 15.6 percent and 10.3 percent, p = .0001) and to experience disruptions in insurance coverage (p = .0009). These differences persisted after controlling for other covariates in multivariate analyses. Children of working low-income parents did not differ significantly from children of nonworking low-income parents on measures of structural access or utilization, after adjusting for other covariates. However, they differed significantly from nonpoor children on structural access and utilization, and these differences mostly persisted after adjusting for other covariates (odds ratios from 1.5 to 2.9). Similar patterns were observed when children of full-time, year-round working parents with low earnings were compared with the two reference populations. CONCLUSION: Children in working low-income families in California have some of the worst access problems. Even full attachment to the workforce does not guarantee health insurance benefits, access to care, or improved health care use for children of low-income parents. These children are not better off than other low-income children of nonworking parents and are much worse off than nonpoor children. Expansion of health insurance coverage through Healthy Families and Medi-Cal, and attention to nonfinancial barriers to care for working low-income families may help to reduce these disparities.     

Changes in psychological performances of solvent-poisoned and solvent-exposed workers

The changes in psychological performances associated with long-term exposure to organic solvents and solvent mixtures were studied in a group of 56 male workers diagnosed as having an occupational disease caused by solvents. Their mean duration of exposure was 9.1 ± SD 8.3 years, and they were exposed mainly to halogenated and aromatic hydrocarbons and to mixtures of paint solvents. The psychological performances of these solvent-exposed patients were compared with those of 98 styrene-exposed workers and a nonexposed group of 43 construction workers. The applied psychological test variables were factor analyzed, before other statistical analysis, in order to clarify what they measured in the present study. The solvent-exposed group was characterized by a decline in visuomotor performance and decreased freedom from distractibility. The poor visuomotor performances were also related to the long duration of solvent exposure in this group of patients. The index applied for the exposure level revealed no significant relationships to psychological performances among the solvent-exposed patients. The psychological performances of the styrene-exposed group differed only very slightly from those of the non-exposed workers.     

乙苯对职业人群神经行为的影响

目的 评价乙苯对职业人群神经行为的影响.方法 选择某石化公司苯乙烯合成原料车间246名乙苯上料工为接触组,相应的公司办公人员122名作为对照组,通过问卷调查,收集乙苯职业接触的基本信息.通过WHO神经行为核心测试组合(NCTB)法,测试对象的个体神经行为功能.结果 接触组和对照组的4项消极情绪状态(紧张、抑郁、愤怒、困惑)得分之间差异无统计学意义(P＞0.05),接触组的积极情绪状态(有力)得分(16.29±8.61)明显低于对照组(18.46±9.52),疲劳得分(9.23±1.27)明显高于对照组(7.16±1.15),(P＜0.05).接触组的平均反应时、数字广度得分明显高于对照组,手提转敏捷度、视觉记忆、目标追踪-Ⅱ正确打点数得分明显低于对照组,差异有统计学意义(P＜0.05).按不同的工龄分段,接触组各工龄段间视觉记忆、目标追踪-Ⅱ正确打点数得分的差异无统计学意义(P＞0.05),3～、4～和5～年工龄段的5项消极情绪状态(紧张、抑郁、愤怒、疲劳、困惑)得分及平均反应时得分均明显高于0～和2～年工龄段.3～、4～年工龄段的数字广度和3～、4～和5～年工龄段的手提转敏捷度、数字译码得分皆明显低于0～和2～年工龄段,差异均有统计学意义(P＜0.05).结论 乙苯可降低接触工人神经行为功能,工人神经行为功能在工龄为3年时发生了明显变化,工龄3年左右工人为乙苯神经行为损害的易感人群.

Abstract：

Objective To evaluate the influence of ethylbenzene on the neurobehavior of occupationally exposed workers. Methods The exposure group consisted of 246 workers occupationally exposed to ethylbenzene and 172 staffs from the offices served as controls. The basic information on ethylbenzene exposure was collected by the questionnaire. The nervous behavior and function of workers were evaluated by Neurobehavioral Core Test Battery (NCTB). Results There were no differences of the scores for four emotional states (tension, depression, angry and bewilderment) between exposure group and control group (P＞0.05). The score of emotion (vigor) in exposure group was significantly lower than that in control group (P＜0.05), but the fatigue score in exposure group was significantly higher than that in control group (P＜0.05).The score of mean reaction time in exposure group was significantly higher than that in control group (P＜0.05), the scores of digital span, manual dexterity, visual retention and target tracking in exposure group were significantly lower than those in control group (P＜0.05). The exposure group was divided into 5 sub-groups,according to working duration. There were no differences for the scores of visual retention and target tracking among 5 sub-groups (P＞0.05). The scores of five emotional states (tension, depression, angry, fatigue and bewilderment) in 3 sub-groups exposed to ethylbenzene for 3～, 4～ and 5～ years were significantly higher than those in 2 sub-groups exposed to ethylbenzene for 0～ and 2 ～ years (P＜0.05). The scores of digital span in 2 sub-groups exposed to ethylbenzene for 3～ or 4～ years and the scores of manual dexterity and digital symbol in 3 sub-groups exposed to ethylbenzene for 3 ～, 4～ and 5～ years were significantly lower than those in 2 subgroups exposed to ethylbenzene for 0～ and 2 ～ years (P＜0.05). Conclusion Ethylbenzene can depress the neurobehavioral functions of exposed workers. The neurobehavioral functions of workers exposed to ethylbenzene for 3 years changed significantly. The workers exposed to ethylbenzene for 3 years may be the susceptible population of neurobehavioral function impairment.     

Protein kinase C activity and the relations between blood lead and neurobehavioral function in lead workers

At picomolar concentrations, lead activates protein kinase C (PKC). This activation has been implicated in the neurotoxicity of lead. No prior study has evaluated the association of PKC activity with neurobehavioral function in humans. The purpose of this study was to determine whether PKC activity is associated with neurobehavioral function or modifies the relationship between blood lead levels and neurobehavioral test scores. In this cross-sectional study of 212 current lead workers in the Republic of Korea, we assessed blood lead levels, neurobehavioral test scores, and PKC activity. PKC activity was determined by measuring the levels of phosphorylation of three erythrocyte membrane proteins (spectrin and the 52-kDa and 48-kDa subunits of band 4.9), using an in vitro back-phosphorylation assay. When linear regression was used to control for confounding variables, blood lead was a significant predictor of decrements in performance on tests of psychomotor function, manual dexterity, and executive ability. In linear regression models, back-phosphorylation levels were not associated with neurobehavioral test scores, but when dichotomized at the median, back-phosphorylation levels modified the relationship between blood lead and test scores. For spectrin and the 52-kDa and 48-kDa subunits of band 4.9, 5, 2, and 5 of 14 interaction terms, respectively, had associated p-values less than 0.10, all with positive signs, indicating that blood lead was associated with worse test scores only in subjects with lower back-phosphorylation levels. These data indicate that blood lead levels are associated with decrements in neurobehavioral test scores, mainly in the domains of manual dexterity and psychomotor function, but only in subjects with lower in vitro back-phosphorylation levels, which is equivalent to higher in vivo PKC activity. We hypothesize that subjects with higher PKC activity in the presence of lead may be more susceptible to the health effects of lead.     

Occupational exposure to solvents and cerebellar,brainstem and vestibular functions

Summary Forty-eight persons (age 44, SD 9 years) exposed to paint solvents and 40 nonexposed referents (age 45, SD 9 years) were examined. The duration of exposure was 4 to 30 (mean 20) years and the life-time exposure level was estimated to have been 10 to 330 (mean 60%) of the hygienic standard. The methods used were a neurological examination, electroencephalography, brainstem auditory-evoked potentials, electronystagmography, and posturography. Lifetime exposure was estimated on the basis of a detailed occupational history and environmental measurements made at the work places over several years. The average weekly alcohol consumption was established in a detailed interview. Due to the small number of subjects examined, the study was inconclusive. The findings classified as abnormal were slightly more common in the exposed than in the referents, and in the persons who used alcohol than in the non-users. The differences were not statistically significant, and no exposure-response relationships were found.