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BACKGROUND: No previous research has been performed into neck pain among forklift operators. This is a common complaint among these workers, who number around 150,000 in Sweden and six million in Europe. The aim of the study was to examine long-term exposure to unnatural neck positions among forklift operators as a risk factor for neck pain. METHODS: A retrospective cohort study was conducted of all eligible employees at a high-level warehouse. Forklift operators and office workers answered an 18-page questionnaire comprising questions about joint pain, work tasks, work postures and year of start for all items. By using person years in the exposed and less-exposed groups before start of neck pain we were able to calculate Incident Rate ratios for various exposures. RESULTS: Forty nine percent of the forklift operators reported having experienced neck pain compared to 30 % of office workers. Being a forklift operator was associated with an increased risk of neck pain (OR = 5.1, 95% CI 1.4-18.2). Holding the head in an unnatural position resulted in significantly increased risks for neck pain, irrespective of type of position. The risks for neck pain remained after taking other ergonomic exposures and psychosocial aspects into consideration. CONCLUSIONS: This is the first published study showing that forklift operators have an increased risk of neck pain. The results are therefore of significance for improving work schedules, the adjustment of work tasks for these workers and the design of the vehicles.

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Upper airway irritation is common among individuals working in moldy and damp buildings. The aim of this study was to investigate effects on the protein composition of the nasal lining fluid. The prevalence of symptoms in relation to work environment was examined in 37 individuals working in two damp buildings. Microbial growth was confirmed in one of the buildings. Nasal lavage fluid was collected from 29 of the exposed subjects and 13 controls, not working in a damp building. Protein profiles were investigated with a proteomic approach and evaluated by multivariate statistical models. Subjects from both workplaces reported upper airway and ocular symptoms. Based on protein profiles, symptomatic subjects in the two workplaces were discriminated from each other and separated from healthy controls. The groups differed in proteins involved in inflammation and host defense. Measurements of innate immunity proteins showed a significant increase in protein S100-A8 and decrease in SPLUNC1 in subjects from one workplace, while alpha-1-antitrypsin was elevated in subjects from the other workplace, compared with healthy controls. The results show that protein profiles in nasal lavage fluid can be used to monitor airway mucosal effects in personnel working in damp buildings and indicate that the profile may be separated when the dampness is associated with the presence of molds.

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BACKGROUND: Previous studies have suggested that exposure to organic solvents, including volatile anaesthetic agents, may be a risk factor for multiple sclerosis (MS), possibly in combination with genetic and other environmental factors. AIMS: To further investigate the role of volatile anaesthetic agents having similar acute toxic effects to other organic solvents. METHODS: Female nurse anaesthetists, other female nurses, and female teachers from middle and upper compulsory school levels were identified and retrieved from the 1985 census, Statistics Sweden. By means of the unique personal identity number in Sweden, these individuals were linked with the disability pension registers at The National Social Insurance Board and also with data on hospital care 1985-2000 at The National Board of Health and Welfare. RESULTS: The cumulative incidence rate ratio of MS was found to be increased in female nurse anaesthetists in relation to other nurses (statistically not significant) and teachers (statistically significant), respectively. CONCLUSIONS: These findings give some support to previous findings of an increased risk for MS in nurse anaesthetists. This is interesting in the context of previous observations of organic solvents in general as a potential risk factor in MS.

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OBJECTIVE: The aim of this study was to elucidate further whether occupational exposure to non-sensitising air pollution at workplaces increases the risk of adult onset asthma. METHODS: One hundred and twenty persons with asthma diagnosed by general practitioners, aged 20-65 years, were compared with 446 referents matched for age and gender and living in the same community as the cases. Information about occupation, exposure to specific allergens, smoking habits, dwellings and atopy was obtained from a postal questionnaire. The subjects' occupations were categorised as clean or polluted, based on the judgement of the referents on their respective occupations. RESULTS: Three years or more of work in air-polluted workplaces resulted in an odds ratio of 1.7 (95% confidence interval 1.0-2.7). Stratification of the material on smoking habits, gender or atopy did not alter the results, nor did exclusion of subjects exposed to specific allergens of statistical significance in this material, e.g. flour dust. Smoking per se did not bring any risk of asthma. Working in buildings affected by dampness and mould brought a fourfold significant risk. CONCLUSION: In this study occupational exposure to unspecific air pollution at workplaces was associated with an increased risk of adult-onset asthma.

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Several studies have indicated an association between MS and organic solvent exposure. Our objective was to analyse differences regarding cerebrospinal fluid (CSF) properties, magnetic resonance imaging (MRI) features and cerebral metabolites, measured by proton spectroscopy (1H-MRS), in 20 patients with spontaneous multiple sclerosis (MS) and in 20 patients with MS after solvent exposure; 15 healthy subjects served as controls. CSF examinations were retrospectively reviewed from the medical files. There were no significant differences in the CSF regarding pleocytosis, spinal-serum albumin ratio or mean extended IgG index. However, T2-weighted images of the solvent-exposed MS patients showed more hypointenseareas in the basal ganglia. Hypointensity on T2-weighted images of the basal ganglia in the solvent-exposed MS patients may correspond to neurodegeneration and could be an early event in MS.

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BACKGROUND: Volatile anaesthetics are chemically related to organic solvents used in industry. Exposure to industrial solvents may increase the incidence of multiple sclerosis (MS). AIM: To examine the risk among nurse anaesthetists of contracting MS. METHODS: Nurses with MS were identified by an appeal in the monthly magazine of the Swedish Nurse Union and a magazine of the Neurological Patients Association in Sweden. Ninety nurses with MS responded and contacted our clinic. They were given a questionnaire, which was filled in by 85 subjects; 13 of these were nurse anaesthetists. The questionnaire requested information about work tasks, exposure, diagnosis, symptoms, and year. The number of active nurse anaesthetists was estimated based on information from the National Board of Health and Welfare and The Nurse Union. Incidence data for women in the region of Gothenburg and Denmark were used as the reference to estimate the risk by calculation of the standardised incidence ratio (SIR). RESULTS: Eleven of the 13 nurse anaesthetists were exposed to anaesthetic gases before onset of MS. Mean duration of exposure before diagnosis was 14.4 years (range 4-27 years). Ten cases were diagnosed in the study period 1980-99, resulting in significantly increased SIRs of 2.9 and 2.8 with the Gothenburg and the Danish reference data, respectively. CONCLUSION: Although based on crude data and a somewhat approximate analysis, this study provides preliminary evidence for an excess risk of MS in nurse anaesthetists. The risk may be even greater than observed, as the case ascertainment might have been incomplete because of the crude method applied. Further studies in this respect are clearly required to more definitely assess the risk.

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The etiology of multiple sclerosis (MS) may involve exposure to infectious, chemical or physical agents damaging the blood-brain barrier and an autoimmune reaction against myelin breakdown products. Here we report a pooled analysis of 174 MS cases and 815 population controls from two case-control studies with regard to such a potentially damaging exposure, namely X-ray examinations, radiological work and treatment with ionizing radiation. Exposure was assessed by questionnaires to the subjects. We obtained odds ratios of 4.4 (95% confidence interval, CI, 1.6-11.6) and 1.8 (95% CI 1.2-2.6) for radiological work and X-ray examinations, respectively; 5 cases, but no controls, in one of the studies had been treated with ionizing radiation. Our data and some other observations reported in the literature suggest a contributory role for ionizing radiation to the development of MS in some cases.

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OBJECTIVES: Acrylate-styrene copolymer polish has been used to protect the surface of linoleum flooring since the 1960s. Problems with powdering of floor polish were observed at an early stage. In a secondary school in Linköping, Sweden, this phenomenon occurred in the winter of 1994-1995 and the pupils frequently reported irritative symptoms from the eyes and airways. This study was undertaken to assess the potential effect of powdering floor polish on the mucous membranes of the eyes and respiratory tract. METHODS: Repeated questionnaire-based surveys were conducted with identical questions in the spring of 1995 (during the powdering period) and in the autumn of 1995 (after the polish was removed). The questions dealt with irritative symptoms from the nose, eye, throat and lower respiratory tract. RESULTS: A preventive effect related to the removal of polish was found for irritative symptoms in all locations mentioned above, but was particularly clear for the lower respiratory tract (prevalence rate ratio = 0.37, 95% CI = 0.23-0.59). CONCLUSIONS: The results of this study indicate that the powdering of floor polish may cause irritative symptoms from the eyes and airways in school children.

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OBJECTIVES: In most previous provocation studies subjects suffering from "electric hypersensitivity" have not been able to determine correctly whether or not they have been subjected to a sham or true provocation to magnetic or electric fields. However, an often-discussed weakness is that most of the earlier provocation studies have been performed in a laboratory situation, often with simulated fields, which may not be representative of conditions prevailing in the homes or workplaces of the patients. Criticism has also been put forth about neglect of the long latency period of symptoms. Therefore, a provocation study was performed in the homes or workplaces of the patients, where we also studied the symptoms and on-off answer 24 hours after the exposure. METHODS: Fifteen subjects selected as having fast and distinct reactions from electric equipment were provoked on 4 occasions: mainly 2 true and 2 sham provocations. The intervals between exposure were a few or more days in order to provide the subjects with an opportunity to recover before the next provocation. A control group of healthy subjects with normal hearing and vision verified that the provocations were performed in a blind manner. RESULTS: The patients suffering from "electric hypersensitivity" were no better than the control group in deciding whether or not they were exposed to electric and magnetic fields. CONCLUSIONS: Exposure to electric and magnetic fields per se does not seem to be a sufficient cause of the symptoms experienced by this patient group.

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BACKGROUND: Clinical experience of cases of fatty liver disease (FLD) with exposure to organic solvents suggested a possible risk. METHODS: Thirty male cases of FLD, ages 20-59 years, with biopsy records at departments of pathology in southeast Sweden were compared to 120 male controls randomly drawn from the study area population. Questionnaire information was obtained about job titles and specific occupational exposures; exposure level categories were then assessed blindly for both cases and controls. Medical records for cases were scrutinized to elucidate possible confounding and/or interacting effects from alcohol, the use of drugs, and other diseases. RESULTS: Moderately intense and mixed solvent exposure for more than 1 year within the last 15 years prior to diagnosis resulted in an age-adjusted Mantel-Haenszel odds ratio of 4.3 (95% confidence interval (CI), 1.2-15); for intense exposure, the odds ratio was 7.7 (95% CI 1.7-48). Confounding from alcohol, use of drugs, other diseases, and overweight could be ruled out with reasonable confidence. CONCLUSIONS: This study indicates that occupational exposure to organic solvents may play a role in the development of FLD, as indicated earlier in case reports and in one small case-control study.

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Sixty workers, consecutively admitted due to suspicion of solvent-induced chronic toxic encephalopathy (CTE), were investigated with pure-tone audiometry, determination of speech recognition of monosyllabic words and distorted speech and cortical response audiometry (CRA). Eighteen workers not exposed to occupational solvents and noise were also investigated. The scores in the distorted speech test were significantly lower and the CRA latencies were significantly longer in the solvent group than in the control group. There was no difference between the groups in the pure-tone and monosyllabic speech recognition tests. In the solvent group, 19 subjects had one or several pathological audiological test results (values exceeding the mean result of the control group by 2 SD). Independently of the audiological examination all the workers in the solvent group underwent the traditional clinical assessment of CTE, which is based on symptoms, history of exposure, clinical neurological examination and a neuropsychological investigation. They were classified in three groups--CTE, incipient CTE and non-CTE. There was no correlation between these groups and the audiological test results. A previous report on vestibular pathology in the same group of subjects and the present investigation on hearing deficits suggest that long-term exposure to solvents causes disturbances of the central pathways in the otovestibular system. Hitherto, no attention has been paid to these disturbances in the definition of the CTE syndrome.

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OBJECTIVES: The diagnosis of solvent-induced chronic toxic encephalopathy is commonly based on case histories of exposure to solvents, symptoms, and deficits on psychometric tests. It has previously been demonstrated that long-term solvent-exposed workers have disturbances of the equilibrium system. The correlation between these disturbances and the diagnosis of chronic toxic encephalopathy has been analyzed in the present study. MATERIAL AND METHODS: Sixty men, consecutively admitted due to the suspicion of this syndrome, were investigated and classified into 3 groups--solvent-induced chronic toxic encephalopathy, incipient chronic toxic encephalopathy and nonchronic toxic encephalopathy. They were all examined using an otoneurological test battery, including analysis of saccades, smooth pursuit, visual suppression of the vestibular ocular reflex, and dynamic posturography. RESULTS: Compared with healthy referents several of the subjects, even in the nonchronic toxic encephalopathy group, showed a reduced visual suppression ability, a prolonged latency of saccades, and pathological posturographic results. Some otoneurological tests correlated with the duration of exposure and the results of psychometric tests representing memory and perceptual skills. Nevertheless, there was no significant group correlation between the otoneurological findings and the diagnosis of chronic toxic encephalopathy. CONCLUSION: Disturbances revealed by an otoneurological investigation have so far not been considered in the diagnosis of chronic toxic encephalopathy. Our results indicate that an otoneurological test battery adds worthwhile information about lesions within the brainstem-cerebellar complex not revealed by a psychometric investigation.

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OBJECTIVES: This case-referent study was performed to investigate the possibility of nonspecific air pollution at workplaces increasing the risk of bronchial asthma for formerly healthy adults. METHODS: Seventy-nine cases of asthma, diagnosed at a lung clinic, among persons aged 20-65 years were compared with 304 referents drawn randomly from the population of the catchment area. Questionnaire information was obtained regarding occupation, exposure to suspect allergens, place of residence, smoking habits, and atopy. The subjects' occupations were categorized into four air pollution classes based on how the referents reported air pollution in their respective occupations. RESULTS: Three years or more of work in air-polluted occupations resulted in an odds ratio of 3.0 (OR) (95% confidence interval 1.5-6.1) in a comparison with work in occupations with slight or no air pollution. Stratification of the material for smoking habits or atopy did not alter the results. Nor did the exclusion of specific exposures to asthmatogenic agents such as ioscyanates, stainless steel welding, or aluminum salts change the effects of the nonspecific air pollution at workplaces. Smoking per se was associated with an almost doubled risk for asthma (OR 1.9, 95% confidence interval 1.1-3.4). CONCLUSION: The results of this study support an association between occupational exposure to nonspecific air pollution and the development of bronchial asthma.

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The incidence of neoplasms in childhood and adolescence in northern and central Sweden before and after the radioactive fallout from the Chernobyl accident was investigated in an ecologic study, 1978 to 1992. The study included all parishes in the six most contaminated counties classified after aerial mapping of ground radiation from 137Cs and investigated 746 cases of neoplasms in ages 0-19 y, diagnosed in the six counties. Incidence and relative risks of neoplasms were compared in areas with high, intermediate, and low contamination after versus before the Chernobyl accident in 1986. A continuous increase of brain tumor incidence in the ages 0-19 y during the period 1978-92 without clear relationship to the Chernobyl fallout was discovered. No clear relationship between the incidence of brain tumor and the exposure to varying levels of radiation from 137Cs was apparent. A somewhat decreased relative risk of acute lymphatic leukemia appeared in areas with increased exposure. Other neoplasms showed no changes in incidence over time or with regard to exposure. Until now, there is no indication that the Chernobyl accident has affected the incidence of childhood and adolescence neoplasms in Sweden, but it is still too early for any final conclusion about the effect of this event.

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OBJECTIVES: Exposure to organic solvents increases the risk of neuropsychiatric disability or chronic toxic encephalopathy (CTE). Polymorphisms in the biotransformation of xenobiotics and solvents may influence individual susceptibility to develop toxic effects. In this study the problem of whether there could be any association between the glutathione S-transferase M1 (GSTM1) null genotype and the risk for CTE, with regard to solvent exposure, was investigated. METHODS: Sixty patients referred to a clinic because of some degree of psychiatric or neurological symptoms, as well as exposure to solvents, were examined by means of a validated questionnaire and psychometric testing. The degree of exposure to solvents was assessed by a thorough interview. According to clinical findings, the patients were classified into three categories as those with solvent-induced CTE, those with incipient CTE, and those who were non-CTE patients. Afterwards, leukocyte DNA (deoxyribonucleic acid) was isolated and the GSTM1 null genotype was determined by an assay based on polymerase chain reaction, blindly with regard to both exposure and disease status. RESULTS: The relative proportion (RP) of GSTM1 null genotypes was significantly increased for patients with a diagnosed CTE when they were compared with non-CTE patients (RP 2.55, 95% confidence interval 1.0-6.2). Dichotomizing the patients by high and low exposure revealed an increased risk for both GSTM1 gene carriers and the GSTM1 null genotype in the high-exposure group, the relative risks (RR) being 4.5 and 7.9, respectively. The chi-square for the Mantel extension for trend was 6.2 (P = 0.025). CONCLUSIONS: The GSTM1 null genotype acts as a risk modifier for CTE among patients occupationally exposed to solvents. The risk seems to increase in a dose-dependent fashion.

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To evaluate the possible relation between exposure to organic solvents and the development of multiple sclerosis, we carried out a best-evidence synthesis of the available information. We found 13 studies with varying methodology that included information on solvent exposure. In 10 of the studies, there were indications of an increased risk of multiple sclerosis in relation to solvent exposure. We made three selections of studies for both pooled analyses and meta-analyses. The relative risk point estimates that we obtained varied from 1.7 to 2.6. Our evaluation is consistent with the hypothesis that organic solvents may be a cause of multiple sclerosis.

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PURPOSE: To use MR to examine patients with CNS symptoms indicating +chronic intoxication. MATERIAL AND METHODS: Thirty-two subjects exposed to industrial solvents for 5 to 28 years and 40 age-matched, healthy controls were examined. RESULTS: All patients showed decreased signal in the basal ganglia on T2-weighted images. In 11 of the patients the white matter showed diffuse hyperintensity with loss of the grey-white matter discrimination and with distinct periventricular hyperintensities in 5 of the patients. The controls had no pathological changes in the brain. CONCLUSION: Although the relatively small number of patients may obscure the significance, findings observed on T2-weighted images were patchy periventricular hyperintensities and hypointensities in the basal ganglia. Fast spin-echo is a good technique with fast acquisition of images with true spin-echo contrast features.

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The role of smoking and air pollution in bronchial asthma in otherwise healthy adults is still unclear. We compared 79 cases of asthma, diagnosed between ages 20 and 65 years, with 304 randomly drawn population controls of similar age from the same catchment area as the cases. The comparison involved questionnaire information on smoking habits, occupational exposures, dwelling conditions, various suspect allergenic exposures, and atopy. Those who had smoked for 3 years or more, present or past, were at increased risk for bronchial asthma (odds ratio = 1.9; 95% confidence interval = 1.1-3.3). Adjustment by multiple logistic regression for age and gender as well as atopy and air pollution at work did not change the relative risk estimate. Exposure to environmental tobacco smoke, or passive smoking, at work involved a slightly greater risk.

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