Medial plantar nerve conduction velocities among patients with vibration syndrome due to rock-drill work

OBJECTIVE: The present study was aimed at clarifying the effect of vibration syndrome (VS) on the peripheral nervous system in the lower extremities of patients with VS due to rock-drill work. METHODS: Fifty-three patients with VS due to previous exposure to vibration from rock-drilling work and 55 age-matched controls were examined for sensory nerve conduction velocities in the medial plantar nerve (SCV-P). The patient group was divided into three subgroups, outdoor rock-drill workers with vibration-induced white finger (VWF) (N = 10), tunnel workers with VWF (N = 27) and tunnel workers without VWF (N = 16). RESULTS: ANOVA of SCV-P for the four groups showed F = 3.23 (dF = 3, 104, p = 0.0253). A significant difference was found between the controls and outdoor rock-drill workers with VWF group (p = 0.0261) by multiple comparison using Scheffe's method. CONCLUSION: These findings suggest that peripheral nervous system function in the lower extremities of patient with VS is affected by cold exposure and circulatory disturbance manifested as VWF.     

The mechanism of a human reaction to vibration stress by palmar sweating in relation to autonomic nerve tone

Objectives: To clarify the mechanism of a human reaction to vibration stress by palmar sweating in relation to the autonomic nerve tone. Methods: The autonomic nerve tone was divided into four types by using digital photoelectroplethysmography (PTG) with auditory stimuli: normal (N), hyperreactive (I and D), and hyporeactive (P) types. Palmar sweating and digital PTG were simultaneously measured on the right palm and middle finger, respectively, in 20 healthy men. The left hand gripping the handle with a grasp strength of 49 N was exposed to vibration at a frequency of 125 Hz and acceleration magnitudes of 0 m/s² (as a control), 30 m/s², or 50 m/s² for 3 min. The volume of palmar sweating was recorded before, during, and 30 min after vibration load. Three kinds of drugs related to the autonomic nervous system were orally administered to the subjects. Then 80 min after administration, the experiments were repeated. Results: Of 20 subjects, 17 showed normal autonomic nerve tone (N type), and 3 hyperreactive (I type). The palmar sweating reaction to vibration in I-type subjects was greater and lasted longer than that in N-type subjects. Vibration with an acceleration of 50 m/s² produced the greatest reaction which was about 7 times larger than that at 0 m/s² and 2.5 times that at 30 m/s² (P < 0.01). Sulpiride decreased palmar sweating during vibration, while prazosin and scopolamine inhibited it. Conclusions: The palmar sweating reaction to vibration stress was related to the background level of the autonomic nerve tone. The sweating volume was in direct proportion to the acceleration magnitude of vibration. The reaction of palmar sweating to vibration stress may be mediated through both the adrenergic and cholinergic fibers of the autonomic nervous system. Received: 18 September 1998 / Accepted: 10 July 1999     

A prospective study of the cold response of digital vessels in forestry workers exposed to saw vibration

Objectives: To investigate the occurrence of vibration-induced white finger (VWF) and the cold response of digital vessels in a group of 68 forestry workers who underwent a first clinical examination in 1990 and were then reexamined in 1995. Methods: The forestry workers were divided into three groups: group A (n = 27), active workers who did not have VWF in␣1990 and continued to use chain saws; group B (n = 29), workers who did not have VWF in 1990 and retired before 1995; and group C (n = 12), active or retired workers who had VWF in 1990. The subjects underwent a medical interview, a complete physical examination, and a cold provocation test, which were performed by the same physicians at both surveys. The cold test consisted of measurement of the finger systolic blood pressure (FSBP) after local cooling to 10 °C, expressed as a percentage of the pressure recorded at 30 °C (FSBP%_10°). Results: Three new cases of VWF occurred during the follow-up period among workers who had used only antivibration (AV) chain saws. The vasoconstrictor response to cold was unchanged in group A and improved in group B (P < 0.001). A significant decrease in VWF symptoms and abnormal response to cold was observed in group C (P < 0.05). As a result of preventive measures curtailing saw usage time in the VWF workers, the daily vibration exposure in group C was lower in 1995 than in 1990 (P = 0.02). In the retired workers, FSBP%_10° was positively related to the time since the cessation of work with chain saws (P < 0.01). Conclusions: The findings of this follow-up study indicate that a reduction in or cessation of exposure to vibration has a beneficial effect on finger-blanching symptoms and the cold response of digital vessels. The occurrence of new cases of VWF in subjects whose work experience was limited to AV chain saws argues for the maintenance of health surveillance in these workers. Received: 16 March 1998 / Accepted: 12 June 1998     

Assessment of autonomic nervous activity in hand-arm vibration syndrome patients using time- and frequency-domain analyses of heart rate variation

Objectives: The aim of the present study was to non-invasively assess autonomic nervous activity, using time- and frequency-domain analyses of heart rate variation (HRV), and to investigate the relationship between indices of HRV and duration of exposure to vibration (DEV), time since retirement from work involving vibration (TR) and time undergoing treatment (TT) in a group of patients with hand-arm vibration syndrome (HAVS). Subjects and methods: Twenty one HAVS patients who were no longer exposed to vibration and were undergoing standard treatment for HAVS, and 10 healthy control subjects, similar to the patients in age, height, weight and number of current smokers and drinkers, volunteered for this study. Indices of HRV [time-domain indices (the mean of R-R intervals, standard deviation and coefficient of variation) and normalized units of frequency-domain indices [low frequency (LF) and high frequency (HF) components], indicating parasympathetic nervous activity, were calculated from 2 min electrocardiographic data recorded during spontaneous breathing by subjects in supine rest. Results: The LF and HF components of the patients were significantly lower than those of the healthy controls (P < 0.05). When Pearson correlation analysis was applied for the patient group, using indices of HRV with age, weight, height, DEV, TR and TT, the LF components positively related to TR and TT (P < 0.01). The patients were thus divided into three groups as follows, according to TR: group A (≤1 year), group B (>1 to <5 years) and group C (≥5 to ≤10  years), or according to TT: group X (≤1 year), group Y (>1 to <5 years) and group Z (≥5 to ≤10  years). The LF components of the groups A and X were significantly lower than that of the healthy controls (P < 0.01). The HF components of the groups A and X were also significantly lower than that of the healthy controls (P < 0.05). Conclusions: The findings of the present study indicate decreased cardiac parasympathetic activity in the HAVS patients in comparison to the healthy controls. The TT and TR significantly influenced the HRV results in these patients; however, the DEV did not. The findings also indicate that treatment and cessation of exposure to vibration might have a beneficial effect on the cardiac parasympathetic activity in HAVS patients. Received: 18 March 1999 / Accepted: 14 June 1999     

Seroprevalence of hepatitis A markers in subjects exposed to biological risk

Objectives: The seroprevalence of hepatitis A virus antibodies was investigated in a population of 1051 subjects, of whom 376 were controls and 675 were exposed to different degrees of biological risk. Methods: The exposed group was subdivided into subjects at low (242), intermediate (265), and high (168) biological hazard; all subjects were employed in the biomedical field. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were also determined. Results: The seroprevalence of positive hepatitis A antibodies was 44.9% in all subjects but was significantly higher in males (50.6%) than in females (34.2%) and increased according to age (25.9% in subjects aged ≤40 years and 62.2% in subjects aged >40 years). No difference related to exposure to the biological risk was observed. The prevalence of transaminases at levels above normal values (χ²= 4.079, P < 0.05 for AST and χ²= 4.806, P < 0.05 for ALT) and mean values (AST P < 0.05; ALT P < 0.001) appeared significant in hepatitis A virus-positive subjects. On the other hand, excluding individuals with positive hepatitis C virus antibodies (16) and positive hepatitis B virus surface antigen (12), a prevalence of transaminase alterations was not observed, but mean levels of ALT lasted significantly longer in subjects with positive hepatitis A virus antibodies (P < 0.01). Conclusions: The results confirm that hepatitis A virus is not a risk for employees in the biomedical field, but the presence of hepatitis A virus antibodies suggests a possible, though not clinically evident, liver involvement. Received: 15 June 1998 / Accepted: 23 October 1998     

Assessment of biological chromium among stainless steel and mild steel welders in relation to welding processes

Air and biological monitoring were used for assessing external and internal chromium exposure among 116 stainless steel welders (SS welders) using manual metal arc (MMA), metal inert gas (MIG) and tungsten inert gas (TIG) welding processes (MMA: n = 57; MIG: n = 37; TIG: n = 22) and 30 mild steel welders (MS welders) using MMA and MIG welding processes (MMA: n = 14; MIG: n = 16). The levels of atmospheric total chromium were evaluated after personal air monitoring. The mean values for the different groups of SS welders were 201 μg/m³ (MMA) and 185 μg/m³ (MIG), 52 μg/m³ (TIG) and for MS welders 8.1 μg/m³ (MMA) and 7.3 μg/m³ (MIG). The curve of cumulative frequency distribution from biological monitoring among SS welders showed chromium geometric mean concentrations in whole blood of 3.6 μg/l (95th percentile = 19.9), in plasma of 3.3 μg/l (95th percentile = 21.0) and in urine samples of 6.2 μg/l (95th percentile = 58.0). Among MS welders, mean values in whole blood and plasma were rather more scattered (1.8 μg/l, 95th percentile = 9.3 and 1.3 μg/l, 95th percentile = 8.4, respectively) and in urine the value was 2.4 μg/l (95th percentile = 13.3). The analysis of variance of chromium concentrations in plasma previously showed a metal effect (F = 29.7, P < 0.001), a process effect (F = 22.2, P < 0.0001) but no metal–process interaction (F = 1.3, P = 0.25). Concerning urinary chromium concentration, the analysis of variance also showed a metal effect (F = 30, P < 0.0001), a process effect (F = 72, P < 0.0001) as well as a metal–process interaction (F = 13.2, P = 0.0004). Throughout the study we noted any significant differences between smokers and non-smokers among welders. Taking in account the relationships between chromium concentrations in whole, plasma or urine and the different welding processes, MMA-SS is definitely different from other processes because the biological values are clearly higher. These higher levels are due to the very significant concentrations of total soluble chromium, mainly hexa- valent chromium, in welding fumes. Received: 9 May 1996 / Accepted: 14 March 1997     

Benzene in environmental air and human blood

To study the blood benzene levels resulting from environmental and occupational benzene exposure. Methods: Benzene in venous blood was measured in 243 nonoccupationally exposed subjects (“normal” people) and in 167 workers occupationally exposed to benzene. All exposed workers gave blood samples at the end of the work shift and on the following morning before resuming work. Blood benzene was assayed by gas chromatography (GC)-mass spectrometry. Occupational benzene exposure was monitored by environmental personal samplers and measured by GC analysis. Results: The mean occupational benzene exposure for all 167 workers studied was 186 ng/l (58 ppb; range 5–1535 ng/l, 2–500 ppb). Overall, the mean blood benzene level of all workers was 420 ng/l at the end of the shift and 287 ng/l on the morning thereafter. The blood benzene levels measured the morning after turned out to be significantly lower (t = 3.6; P < 0.0001) than those measured at the end of the shift. The mean blood benzene level of the 243 “normal” subjects was 165 ng/l, which was significantly lower than that measured in the workers on the morning thereafter (t=5.8; P < 0.0000001). The mean blood benzene concentration was significantly higher in smokers than in nonsmokers in both the general population (264 versus 123 ng/l) and in the exposed workers. In the group of nonsmoking workers, whose workplace exposure to benzene was lower than 100 ng/l, blood benzene levels were similar (210–202 ng/l) to those measured in the nonsmoking general population (165 ng/l). End-of-shift blood benzene correlated significantly with environmental exposure (y=0.91x + 251; r=0.581; n=162; P < 0.00001). Finally, there was also a significant correlation between blood benzene measured at the end of the shift and that determined on the morning thereafter (y=0.45x + 109; r=0.572; n=156; P < 0.00001). Conclusion: Nonsmoking workers occupationally exposed to benzene at environmental levels lower than 100 ng/l (mean 35 ng/l) and the nonsmoking general population exposed to ubiquitous benzene pollution have similar blood benzene concentrations. This suggests that it is impossible to distinguish between occupational and environmental exposure when the benzene level in the workplace is less than 100 ng/l. Received: 31 December 1997 / Accepted: 4 August 1998     

Biological monitoring of occupational exposure to N,N -dimethylformamide – the effects of co-exposure to toluene or dermal exposure

Objectives: The objective of this study is to assess the exposure and intake dose of N,N-dimethylformamide (DMF) and the correlation between them, according to the type of exposure for the workers in the DMF industry. Methods: We monitored 345 workers occupationally exposed to DMF, from 15 workshops in the synthetic fiber, fiber coating, synthetic leather and paint manufacturing industries. Ambient monitoring was carried out with personal samplers to monitor the external exposure. Biological monitoring was done to determine the internal dose by analyzing N-methylformamide (NMF) in end-shift urine. Work procedure and exposure type of each DMF workshop was carefully surveyed, to classify workers by exposure type according to work details. Workers were classified into three groups (Group A: continuous and direct exposure through inhalation and skin; Group B: intermittent and short-term exposure through inhalation and skin; Group C: continuous and indirect exposure mostly through inhalation). Results: Geometric mean of DMF concentration in air was 2.62 (GSD 5.30) ppm and that of NMF in urine was 14.50 (GSD 3.89) mg/l. In the case of continuous absorption through inhalation and dermal exposure (Group A), the value of NMF in urine corresponding to 10 ppm of DMF was 45.3 mg/l (r=0.524, n=178), 39.1 mg/g creatinine (r=0.424), while it was 37.7 mg/l (r=0.788, n=37), 24.2 mg/g creatinine (r=0.743) in the case of absorption mostly through inhalation (Group C). Creatinine correction reduced the correlation between two parameters. Conclusion: The NMF in urine corresponding to 10 ppm DMF, of the dermal and inhalation exposure group was 39.1 mg/g creatinine (r=0.424, n=178), while that of the inhalation exposure-only group was 24.2 mg/g creatinine (r=0.743, n=37). Co-exposure with toluene reduced the NMF excretion in urine. Received: 4 October 1999 / Accepted: 25 April 2000     

Calcium disodium ethylenediaminetetraacetate-chelated lead as a predictor for subclinical lead neurotoxicity: follow-up study on gun-metal foundry workers

Objectives: To examine if chelated lead was a more predictive indicator of the subclinical effect of lead on conduction velocities of faster or slower nerve fibers as compared with blood lead (BPb). Methods: Distribution of conduction velocities (DCV) in large myelinated fibers of the sensory median nerve was measured twice at a 1-year interval in 17 male gun-metal foundry workers with BPb concentrations of 22–59 (mean 40.2) μg/dl and a mobilization yield of lead into urine (MPb) by calcium disodium ethylenediaminetetraacetate of 0.15–2.09 (mean 1.19) mg/24 h for the 1st year and in 20 healthy males (controls). Results: Yearly changes in the conduction velocities of faster fibers were significantly correlated with the corresponding change in MPb (P < 0.05) but not with that in BPb (P > 0.05). In ten workers showing an increase in MPb during the 1-year period (0.44 mg/24 h on average) the conduction velocities of faster fibers were decreased significantly, resulting in the values being significantly lower in all the workers combined than in the controls (P < 0.05). On the other hand, in the remaining workers, who showed a lesser extent of reduction in MPb (0.08 mg/24 h on average), the DCV did not change (P > 0.05). Conclusion: Chelated lead might be a more predictive indicator of the effect of lead on the conduction velocities of faster fibers than blood lead. Received: 12 January 1998 / Accepted: 21 April 1998     

Suppressive mechanism of gastric motility by whole-body vibration

Objective: To investigate the mechanism of gastric motility suppression by exposure to whole-body vibration (WBV). Methods: The gastric motility was evaluated by electrogastrography (EGG) under food intake and autonomic nerve blocking agents in ten healthy volunteers. Sinusoidal vertical vibration with a frequency of 4 Hz (1.0 ms⁻² rms) was given to the subject for 10 min. Results: The amplitude of EGG wave and the power spectrum corresponding to the slow wave component was remarkably decreased by vibration exposure. Food intake enhanced the gastric motility about 2.5-fold in the power spectral density. During and after vibration exposure, the response mode was similar to those at fasting states. Under the influence of anticholinergic (scopolamine) and alpha-adrenergic blocking agents (prazosin), the power spectra were decreased. A further decrease was observed during vibration exposure. A beta-adrenergic blocking agent (propranolol) led to a marked increase in the amplitude of EGG and its power spectrum. With pretreatment by a beta-adrenergic blocking agent, however, vibration exposure reduced both of them. Conclusions: These results suggest that short-term exposure to WBV can suppress the gastric myoelectric activity, the responses on which may be mediating by neurohumoral effects as well as the mechanical effect of WBV. Received: 7 September 1998 / Accepted: 9 May 1999     

Exposure assessment and sensitisation in workers exposed to organic acid anhydrides

Objectives: To clarify whether the intensity of exposure to organic acid anhydrides (OAAs) is associated with the risk of sensitisation to these allergens. Methods: The investigations were carried out in three different manufacturing plants (A, B, and C) where OAAs were used in the production of epoxy resins. Methyltetrahydrophthalic acid anhydride (MTHPA) was used in all three plants. The exposure assessment included stationary and ambient air monitoring (OAAs in the air) and biological monitoring (metabolites in urine). In plant A 20, in plant B 86 and in plant C 113 employees were examined by a physician (anamnesis, skin-prick test, specific IgE, spirometry). In plants B and C, the exposure areas were classified as high, medium, and low, without the results of the exposure assessment being known. Results: The ambient air concentrations (in μg/m³) of MTHPA were 37.2 and 58.5 in plant A (number of samples n=2), ranged from <0.5–26.2 in plant B (n=5) and from 2.1–57.9 in plant C (n=3) with stationary air collecting, and from 8–45 (n=6), from <4.7–35.7 (n=3) and from 2–37.8 (n=3) with personal air collection. The metabolites of OAAs in urine (in nmol/mmol creatinine) ranged from 5.7–645 (median of MTHPA: 346) in plant A, from <1–213 (median of MTHPA: 10.1) in plant B and from 0.1–830 (median of the sum of the OOA metabolites: 108.6) in plant C. The prevalence of sensitisation was 35% in plant A, 21% in plant B and 29% in plant C. A higher prevalence in the highly exposed areas, however, could not be seen. Levels of IgE specific for conjugates of MTHPA were not associated with the metabolites in the end of shift urine. Levels of IgG specific for conjugates of MTHPA, however, were associated with the metabolites in the end of shift urine. Conclusions: The data showed that biological monitoring is a useful tool in the exposure assessment of OAAs. Comparing the prevalence of sensitisation and the results of biological monitoring, between the three plants, we found that sensitisation increased with increasing exposure. Within a plant a higher risk of sensitisation in persons working in highly exposed areas at the time of the examination could not be seen, possibly due to frequent job rotation. Received: 2 August 1999 / Accepted: 29 January 2000     

Occupational determinants of heart rate variability

Objectives: Analysis of HRV has been suggested as a way to study the effects of work-related stresses on cardiovascular autonomic regulation. The aim of this study was to evaluate the use of HRV in the investigation of work-related stressors. Methods: Cross-sectional data from an ongoing cohort study were used to analyse the relationship of the potential workplace stressors of job-strain, noise and shift work, with HRV. Mean HRV values during sleep and work were calculated in 135 24-h EKG recordings. Results: Shift workers displayed significantly decreased SDNNi levels during sleep, compared with those of the daytime workers (adjusted least square mean values: 69.3 and 85.8 ms, respectively, P < 0.05). Compared with the control group reporting low job demands and high work control (mean: 73.2), we found significantly elevated %LF means during work adjusted for sleep in the low demands, low control group (77.9, P < 0.01), high demands, high control group (77.7, P < 0.05) and high demands, low control group (77.7, P < 0.05). Workers reporting a high noise level compared with a low work noise level also displayed an elevated adjusted mean %LF during work (78.0 and 75.3 respectively, P < 0.06). Conclusions: The finding of a decreased SDNNi level during sleep in shift workers compared with day workers indicated a less favourable cardiovascular autonomic regulation, which may explain in part the excess cardiovascular disease risk in shift workers. The elevated %LF during work in employees exposed to high job strain or high noise levels indicated a direct shift in the autonomic cardiac balance towards sympathetic dominance. We concluded that the analysis of HRV may provide a useful tool in the study of the physiological effects of work-related stresses. Received: 22 July 1999 / Accepted: 4 December 1999     

Nasal symptoms and indices of nasal inflammation in flour-dust-exposed bakers

To analyze whether indices of nasal airway inflammation in bakers were related to nasal symptoms and exposure to airborne flour dust. Methods: A cross-sectional study was performed in 12 currently flour-exposed bakers. They were examined by nasal lavage (NAL), visual inspection, a test of mucociliary clearance, and nasal peak expiratory flow (nasal PEF). NAL fluid was analyzed according to the inflammatory markers eosinophil cationic protein (ECP), indicating eosinophilic activity; myeloperoxidase (MPO), indicating active neutrophils; hyaluronic acid (HA) from active fibroblasts; tryptase, indicating activation of mast cells; and albumin, indicating plasma exudation. The bakers were also questioned about respiratory symptoms and working history. Their current and cumulative exposure to inhalable flour dust was estimated after exposure measurements and information about earlier work tasks. Office workers (n = 16) without occupational exposure to dust or any other known nasal irritant or sensitizer served as controls. Results: Personal inhalable dust measurements among the bakers working as dough makers or bread formers ranged from 1.0 to 3.8 mg/m³. Of the 12 bakers, 10 reported at least 1 nasal symptom (crusts, blockage, or a runny nose), a proportion significantly greater than that of the controls (P = 0.009). Bakers with nasal symptoms had higher concentrations of markers of inflammation in their NALs as compared with nonsymptomatic bakers. The difference was significant for MPO (P = 0.02) and HA (P = 0.04) in relation to a runny nose. Tryptase was detected in only one NAL of the bakers. There was a positive correlation between the cumulative dose of inhalable flour dust and concentrations of MPO and HA in NAL. Two bakers were sensitized to wheat; they had the highest NAL concentrations of inflammatory markers. Conclusions: Our results indicate that flour dust exposure in bakers at levels below the current occupational exposure limit causes nasal mucosal inflammation, which, in turn, is related to nasal symptoms. We propose that the inflammation may be nonallergic, characterized by activation of neutrophils and fibroblasts. Received: 16 September 1997 / Accepted: 16 May 1998     

Occupational exposure to low concentrations of carbon disulfide as a risk factor for hypercholesterolaemia

Objective: The objective of this study was to investigate the effect of occupational exposure to carbon disulfide (CS₂) concentrations below threshold limit value (TLV)-time-weighted average (TWA) (31 mg/m³) on total cholesterol, blood pressure and the prevalence of coronary heart disease (CHD). Methods: A cross-sectional study involving 141 viscose rayon workers (64 men), and 141 age- and gender-matched controls without occupational contact with noxious chemicals, was carried out. The probability for CHD was determined by means of the WHO questionnaire and was 12-lead electrocardiography-coded using Minnesota criteria. Blood pressure was measured by the standardized method of the WHO and blood was examined for total cholesterol. A cumulative exposure index (CS₂ index) was calculated for each worker by multiplying the number of years held in a particular job, by the CS₂ concentrations in that job-environment. According to the CS₂ index, the exposed workers were distributed into two groups: group 1 (CS₂ index <100) and group 2 (CS₂ index ≥100). Results: Depending on the job and specific work place the CS₂ concentrations were between 1 and 30 mg/m³. Cholesterol levels were significantly higher in the exposed group (4.9 ± 0.7) compared with the controls (4.6 ± 0.7). Adjustment for age, smoking, body-mass index (BMI) and gender showed the significant effect of the CS₂ index on the total cholesterol (P < 0.001). The prevalence of hypercholesterolaemia was significantly higher in the exposed group (42.6%), compared with the controls (26.2%); odds ratio (OR) (adjusted for potential confounders) was 2.56, 95% CI 1.47–4.46. Logistic regression showed a significantly increased risk for elevated cholesterol in group 2 (OR 5.52; 95% CI 2.81–10.83). No significant effect of CS₂ index on blood pressure and CHD prevalence was found. Conclusions: The results of our study show that occupational exposure to CS₂ concentrations below 31 mg/m³ and a CS₂ index >100 may increase total cholesterol. Our results imply that even the CS₂ concentrations below TLV-TWA may produce morbid changes, and suggest the mechanism of the effect of CS₂, leading to lipid metabolism disturbances and acceleration of atherosclerosis. Received: 1 February 2000 / Accepted: 24 June 2000     

Urinary nickel as bioindicator of workers' Ni exposure in a galvanizing plant in Brazil

Objectives: We measured urinary nickel (U-Ni) in ten workers (97 samples) from a galvanizing plant that uses nickel sulfate, and in ten control subjects (55 samples) to examine the association between occupational exposure to airborne Ni and Ni absorption. Methods: Samples from the exposed group were taken before and after the work shift on 5 successive workdays. At the same time airborne Ni (A-Ni) was measured using personal samplers. Ni levels in biological material and in the airborne were determined by a graphite furnace atomic absorption spectrometry validated method. In the control group the urine samples were collected twice a day, in the before and after the work shift, on 3 successive days. Results: Ni exposure low to moderate was detected in all the examined places in the plant, the airborne levels varying between 2.8 and 116.7 μg/m³ and the urine levels, from samples taken postshift, between 4.5 and 43.2 μg/g creatinine (mean 14.7 μg/g creatinine). Significant differences in U-Ni creatinine were seen between the exposed and control groups (Student's t test, P ≤ 0.01). A significant correlation between U-Ni and A-Ni (r = 0.96; P ≤ 0.001) was detected. No statistical difference was observed in U-Ni collected from exposed workers in the 5 successive days, but significant difference was observed between pre- and postshift samples. Conclusions: Urinary nickel may be used as a reliable internal dose bioindicator in biological monitoring of workers exposed to Ni sulfate in galvanizing plants regardless of the day of the workweek on which the samples are collected. Received: 28 January 1999 / Accepted: 10 July 1999     

Hand-arm vibration syndrome with use of anti-vibration chain saws: 19-year follow-up study of forestry workers

Objectives: Hand-arm vibration syndrome (HAVS) consists of vascular and neurological component. Musculoskeletal component has not been delineated yet. In the present follow-up study, we evaluated the prevalence of HAVS and the cumulative exposure to vibration among a cohort of forestry workers. Special interest was given to numbness and musculoskeletal disorders of upper extremity and neck in forestry workers. Methods: A follow-up study starting from 1976 was conducted among forestry workers in Suomussalmi in Finland. Total exposure of hand-arm vibration was recorded during 11 cross-sectional surveys. The last study was carried out in 1995. The lifetime dose of vibration energy was calculated. A cohort of 52 forest workers participated to all 11 cross-sectional surveys 1976–1995. HAVS and musculoskeletal disorders were evaluated. Results: The prevalence of active vibration white finger (VWF) decreased from 13 to 4% in the cross-sectional study. In the cohort VWF decreased from 17 to 8% and numbness increased from 23 to 40%. Rotator cuff syndrome (P=0.034) and epicondylitis (P=0.004) associated with numbness. Regional neck pain was diagnosed in 38% of workers and associated with low back pain. In modeling VWF, the lifelong vibration energy (OR 1.03, CI 1.01–1.05), and smoking (OR 7.36, CI 1.07–50.76) were significant. Numbness was modeled by pain in upper extremities (OR 12.43, CI 2.42–63.80) and neck pain (5.97, CI 1.25–28.39), not by lifelong vibration energy. Right rotator cuff syndrome was modeled by age (OR 2.58, CI 1.04–6.41) and lifelong vibration energy (OR 1.04, CI 1.00–1.07). Conclusions: The prevalence of VWF constantly decreased. Numbness did not follow the vibration exposure profile. Numbness also associated with upper extremity musculoskeletal disorders. Hand-arm vibration associated with the right rotator cuff syndrome in forestry workers.     

Comparison between blood and urinary toluene as biomarkers of exposure to toluene

Objectives: To compare blood toluene (TOL-B) and urinary toluene (TOL-U) as biomarkers of occupational exposure to toluene, and to set a suitable procedure for collection and handling of specimens. Method: An assay based on headspace solid-phase microextraction (SPME) was used both for the determination of toluene urine/air partition coefficient (λ_urine/air) and for the biological monitoring of exposure to toluene in 31 workers (group A) and in 116 non-occupationally exposed subjects (group B). Environmental toluene (TOL-A) was sampled during the work shift (group A) or during the 24 h before specimen collection (group B). Blood and urine specimens were collected at the end of the shift (group A) or in the morning (group B) and toluene was measured. Results: Toluene λ_urine/air was 3.3 ± 0.9. Based on the specimen/air partition coefficient, it was calculated that the vial in which the sample is collected had to be filled up to 85% of its volume with urine and 50% with blood in order to limit the loss of toluene in the air above the specimen to less than 5%. Environmental and biological monitoring of workers showed that the median personal exposure to toluene (TOL-A) during the work-shift was 80 mg/m³, the corresponding TOL-B was 82 μg/l and TOL-U was 13 μg/l. Personal exposure to toluene in environmentally exposed subjects was 0.05 mg/m³, TOL-B was 0.36 μg/l and TOL-U was 0.20 μg/l. A significant correlation (P < 0.05) was observed between TOL-B or TOL-U and TOL-A (Pearson's r=0.782 and 0.754) in workers, but not in controls. A significant correlation was found between TOL-U and TOL-B both in workers and in controls (r=0.845 and 0.681). Conclusion: The comparative evaluation of TOL-B and TOL-U showed that they can be considered to be equivalent biomarkers as regards their capacity to distinguish workers and controls and to correlate with exposure. However, considering that TOL-U does not require an invasive specimen collection, it appears to be a more convenient tool for the biological monitoring of exposure to toluene. Received: 20 October 1999 / Accepted: 4 March 2000     

Field evaluation of a passive sampler for the exposure assessment of 2-methoxyethanol

Objective: This paper presents a field evaluation of 3 M 3500 passive badges for measuring 2-methoxyethanol (ME) in a humid working environment. Methods: A total of 93 pairs of side-by-side active/passive samples, 48 pairs of duplicate active samples, 52 pairs of duplicate passive samples, and three groups of six replicate active/passive samples were compared. Three groups of six replicate active charcoal/active charcoal tube with drying tube samples were also compared to evaluate the humidity effect. Results: No statistical difference was found between the passive badges and active samplers. Linear regression showed the correlation to be high (r = 0.992, slope  =  0.973, n = 93) over the range of 0.17–163 ppm. The mean concentration difference was −0.34 ppm and the mean relative error was 3.50%. The intraclass correlation coefficients of 48 duplicate active samples and 52 duplicate passive samples were 0.994 and 0.989, respectively. The precision of replicate passive, active, and active/drying tube samples (n = 6) were 3.84%, 7.14%, and 5.12%, respectively. Conclusions: The humidity effect for active samples was insignificant at the low sampling rate (36.3 ml/min). It is therefore concluded that the use of the passive samplers to assess ME exposure produces comparable findings to that of active sampling. Received: 5 March 1999 / Accepted: 9 September 1999     

Housing as an Intervention on Hospital Use: Access among Chronically Homeless Persons with Disabilities

A study examining demographics and hospital utilization for chronically homeless persons with disabilities was conducted at pre-housing enrollment and at 6 months post-housing. Of the 20 participants, 70% (n = 14) were Black American and 30% (n = 6) were White; 100% (n = 20) were non-Hispanic; 90% (n = 18) were men; 40% (n = 8) were veterans; Median years since last permanent housing and total homelessness were 7 and 10.5 respectively. The following increases were observed: employment (0 to 1); income (20%, n = 4 to 35%, n = 7); primary care (25%, n = 5 to 95%, n = 19); and mental health service use (25%, n = 5 to 60%, n = 12). Known disabilities included HIV (15%, n = 3); hepatitis C (45%, n = 9); mental illness (60%, n = 12) and substance abuse (80%, n = 16) with 45% (n = 9) dually diagnosed. Over the course of the study, Emergency department visits and inpatient hospitalization use decreased. While these differences were not statistically significant (p = 0.14 and p = 0.31, respectively), they translate to an estimated $250,208 savings.     

High prevalence of K-ras-2 mutations in hepatocellular carcinomas in workers exposed to vinyl chloride

Objectives: Vinyl chloride (VC) and its metabolites are human carcinogens associated with liver angiosarcomas (LAS) and also with hepatocellular carcinomas (HCCs). In VC associated LAS mutations of the K-ras-2 gene have been reported; however, no data about the prevalence of such mutations in VC-associated HCCs are available. The aim of the study was to evaluate possible specific K-ras-2 oncogene mutations in the case of HCCs due to VC. Methods: The presence of K-ras-2 mutations was analysed in tissue from 12 patients with VC-associated HCCs. All patients had known long-term exposure to VC (average exposure amount: 9,942 ppm-years). Twenty patients with hepatocellular carcinoma due to hepatitis B (n=7), hepatitis C (n=5) and alcoholic liver cirrhosis (n=8) served as a control group. The specific mutations were determined by direct sequencing of codons 12 and 13 of the K-ras-2 gene in carcinomatous and adjacent non-neoplastic liver tissue after microdissection. Immunohistochemical analysis was performed to detect p21 ^ras protein. Results: K-ras-2 mutations were found in five of 12 (42%) examined HCCs and in three cases of adjacent non-neoplastic liver tissue (25%). There were three guanine to adenine (G → A) point mutations in the tumour tissue. All three mutations found in non-neoplastic liver from VC-exposed patients were also G → A point mutations (codon 12- and codon 13-aspartate mutations). Within the control group, K-ras-2 mutations were found in three of 20 (15%) examined HCCs. Conclusions: Mutations of the K-ras-2 gene in hepatocellular carcinomas associated with VC exposure are frequent events. We observed a K-ras-2 mutation pattern characteristic of chloroethylene oxide, one of the carcinogenic metabolites of VC analysed in animal models. Our results suggest that VC had direct toxic effects not only on endothelial cells but also on hepatocytes, as it was previously only described in animal models. Received: 5 December 2000 / Accepted: 17 April 2001