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The use of hand-held vibrating tools may lead to hand-arm vibration syndrome (HAVS), a condition with vascular, neurological and musculoskeletal symptoms. Vibrating tools are used in several occupations in which women can be found, e.g. by metal- and wood workers, drivers, and dental personnel. The risk of women developing HAVS is hard to estimate, as little research has been done on women exposed to hand-arm vibration. The overall aim of this thesis has been to fill this gap of knowledge. It is based upon one questionnaire study and one interview study on women who have reported an occupational injury related to hand-arm vibration. The thesis also comprises two laboratory studies of female and male subjects exposed to hand-arm vibration from a handle.

The questionnaire and the interview study showed that the women had a high prevalence of symptoms, such as numbness, weakness, pain and white fingers. Neurological symptoms were more common and developed after shorter time of exposure compared to vascular symptoms. The symptoms had a considerable impact on all domains of the women’s lives, not only on their physical functioning, such as the ability to work, to participate in leisure activities and to do household activities, but also on their relationships and identity. Forty per cent of the women had retired or retrained due to the injury. Dental personnel had the highest relative risk of vibration injuries.

In one of the laboratory studies 12 female and 12 male subjects were exposed to vibration in two vibration directions, (Xh and Zh) and at two vibration levels. The absorbed power was higher in the Zh direction and at the higher vibration level. The volumes of the subjects’ arms affected the power absorption in the Zh direction. There were no indications of a gender difference in the absorption of power.

In the other laboratory study, the effect of handle size, vibration level, anthropometric measures and maximal grip force on the ability to perform a precision task was studied in 20 female and 20 male subjects. Ratings of difficulty and discomfort were made after each test round. The results indicate that the male subjects performed better in all the tests, but no gender difference was seen in the ratings. The higher vibration level resulted in higher ratings of discomfort. In the female subjects, the handle size, the anthropometric measures and maximal grip force affected both the performance and the ratings.

In conclusion, the studies indicate that vibration injuries are severely disabling and influence many parts of the sufferer’s life. Vibration injuries are preventable, and the extensive consequences found underscore the importance of preventive action. This can be done by informing employees about the risks, and by giving them the opportunity to choose suitable machines and to practice work tasks when starting a new job.

The aim of this study was to describe the symptoms and the prognosis of vibration injuries in women. The investigation was based on a study of 374 women who had reported an injury due to hand-arm vibration to the Social Insurance Office or had received financial compensation from the Swedish Labor Market Insurance scheme during 1988-1997. Information on, for example, self-rated health symptoms and vibration exposure was collected by means of a questionnaire. On average, the first symptoms started after 7 yr of exposure and the first visit to a doctor took place after 11 yr. Neurological symptoms developed after a shorter period of exposure compared to vascular symptoms, 6.8 and 9.2 yr, respectively. The prevalence of numbness at the time of reporting the injury was 91% and the prevalence of white fingers was reported by 54%. The occupational group with the highest prevalence of vibration injuries was dental technicians. Two thirds of the women had stopped using vibrating machines in their work. Among the women who suffered from white fingers when they reported the injury, 50% declared impairment or no improvement of the symptoms. One woman in five was retired and the same number of women had retrained due to the occupational injury.

It is not unusual for old data to be used in epidemiological studies. Recently developed instruments for measuring work-related stress did not exist when the data collection was carried out. Therefore, approximate questions are sometimes used. An apparent problem is the lack of validation of proxy questions. The aim of this study was to compare the original questions for measuring Effort-Reward Imbalance (ERI) with approximate questions. The study population corresponded with a subgroup in the WOLF-n (WOrk, Lipids, Fibrinogen-north) cohort study of cardiovascular risk in a working population in the north of Sweden: 655 men and 178 women. The agreement in exposure between the original and the approximate ERI single questions was relatively low throughout, whereas the correlation between the ERI subscales and the ERI ratios was reasonable. The latter agreement between the original and the approximate ERI ratio indicates that the approximate measures might have been useful in the past. Yet, whenever possible the implementation of the original questionnaire in study protocols is recommended since a complete measurement of ERI might help to further improve the internal consistency and the predictive validity of this exposure to effort-reward imbalance.

Transcranial magnetic stimulation or repetitive transcranial magnetic stimulation (TMS/rTMS) is currently being used in treatments of the central nervous system diseases, for instance, depressive states. The principles of localized magnetic stimulation are summarized and the risk and level of occupational field exposure of the therapeutic staff is analyzed with reference to lCNIRP guidelines for pulses below 100 kHz. Measurements and analysis of the occupational exposure to magnetic fields of the staff working with TMS/rTMS are presented.

An increased risk for coronary heart disease among shift workers is earlier shown in the epidemiological literature. The aim of this thesis has been to penetrate metabolic disturbances and obesity among shift workers compared to day workers, and to compare if there are differences in total mortality or cause specific mortality of coronary heart disease (CHD), diabetes or ischaemic stroke in between the two groups.

In an intervention study on female nurses (N=11), on night schedules in Umeå hospital, the highest peak value of glucose and insulin after meal ingestion was seen in the late evening (23:30). The post-prandial area under curve (AUC) of glucose and insulin was correspondingly largest after meal ingestion the same clock hour compared to meal ingestion other clock times.

In two different cross-sectional studies Västerbotten Inventory Study (VIP) (N= 27,485) and in a subset of Work, Lipids and Fibrinogen Study (WOLF) (N= 1,324) metabolic differences in between shift and day workers has been evaluated. In both studies have obesity, high triglycerides and low HDL-cholesterol been more prevalent among the shift-working group compared to the day-working group. After adjustments for age and socio-economic factors in the VIP-study obesity and high triglycerides remained as risk factors in shift workers in both men and women. After directly age standardisation, a clustering effect, simultaneously, of two or more metabolic risk factors (obesity, hypertension, and high triglycerides) was seen in both genders among the shift workers compared to the day workers. Correspondingly, in the Wolf study low HDL-cholesterol and high triglycerides remained as significant risk factors after adjustments of confounders as age, socio-economic group, physical activity, current smoking, low social support and high job strain.

In a cohort study from one company (MoDo) with two plants in the pulp and paper industry 2,354 male shift workers and 3,088 male day workers were followed from January 1, 1952 to December 31, 2001 regarding total and cause specific mortality due to CHD, diabetes and ischaemic stroke. Groups of workers defined by different duration of shift exposure were compared with day workers by calculating standardised relative rates (SRR). No increased risk of total mortality was seen among shift workers compared to day workers. Higher duration of shift work was associated with increased risk for CHD, and shift workers with 30 years or more had the highest risk. Diabetes was more common with increasing number of shift year exposure. Compared to day workers shift workers had also an increased risk to die because of ischaemic stroke, with the highest relative difference in the least shift exposed group (< 5 years).

Objectives: The aim of the present study was to investigate the relationship between important metabolic risk factors for coronary heart disease (CHD) and type 2 diabetes in shift workers and day workers.

Methods: Cross-sectional data from a sub-population in the WOLF study consisting of 665 day workers and 659 three-shift workers in two plants were analysed.

Results: A higher proportion of shift workers than day workers had high triglyceride levels (‡1.7 mmol/l), low levels of HDL-cholesterol (<0.9 mmol/l) and abdominal obesity (waist/hip ratio>0.9). The risk of low HDLcholesterol was doubled in shift workers, (odds ratio (OR): 2.02, 95% confidence interval (95% CI): 1.24– 3.28) after being adjusted for age, socio-economic factors, physical activity, current smoking, social support and job strain. High levels of triglycerides were also significantly associated with shift work (OR: 1.40, 95% CI: 1.08–1.83). The OR for abdominal obesity was 1.19, (95% CI: 0.92–1.56). The prevalence of hyperglycaemia (serum glucose ‡7.0 mmol/l) was similar in day and shift workers. No significant interaction was seen between shift work and abdominal obesity with regard to the associations with triglycerides and HDL-cholesterol.

Conclusions: We found a significant association between shift work and lipid disturbances (i.e. low HDL-cholesterol and high triglyceride levels). We did not find any association with hyperglycaemia.

OBJECTIVES To explore how metabolic risk factors for cardiovascular disease (CVD) differ between shift workers and day workers in a defined population. Shift work has been associated with an increased risk of CVD. Risk factors and causal pathways for this association are only partly known.

METHODS A working population of 27 485 people from the Västerbotten intervention program (VIP) has been analysed. Cross sectional data, including blood sampling and questionnaires were collected in a health survey.

RESULTS Obesity was more prevalent among shift workers in all age strata of women, but only in two out of four age groups in men. Increased triglycerides (>1.7 mmol/l) were more common among two age groups of shift working women but not among men. Low concentrations of high density lipoprotein (HDL) cholesterol (men<0.9 and women<1.0 mmol/l) were present in the youngest age group of shift workers in both men and women. Impaired glucose tolerance was more often found among 60 year old women shift workers. Obesity and high triglycerides persisted as risk factors in shift working men and women after adjusting for age and socioeconomic factors, with an OR of 1.4 for obesity and 1.1 for high triglyceride concentrations. The relative risks for women working shifts versus days with one, two, and three metabolic variables were 1.06, 1.20, and 1.71, respectively. The corresponding relative risks for men were 0.99, 1.30, and 1.63, respectively.

CONCLUSIONS In this study, obesity, high triglycerides, and low concentrations of HDL cholesterol seem to cluster together more often in shift workers than in day workers, which might indicate an association between shift work and the metabolic syndrome.

The objective was to study the postprandial responses of glucose, insulin and triglycerides to meal intake at different clock times during night work. Eleven night shift working nurses participated. Identical test meals were ingested at 19:30, 23:30 and 03:30, and contained 440 kcal/1,860 kJ of energy (33 E% fat, 51 E% carbohydrate, 16 E% protein). The food intake was standardized three days before the first test meal. Blood samples were drawn just before the test meals were ingested and thereafter at 30, 60, 90, 120, 180 and 240 minutes. The postprandial responses were estimated as the total area under the curve (AUC) and significance testing was done using repeated measures ANOVA. The highest insulin level was found after meal intake at 23:30, and the lowest after meal intake 03:30. The glucose response showed the same pattern. The insulin response to food intake in night working nurses is more pronounced in the night compared with morning and evening. The results would have implications for metabolic and cardiovascular disorders in night workers.

OBJECTIVES: Occupational assessments of chemical exposure are often inadequate because of difficulties in obtaining sufficient numbers of measurements by trained professionals (experts). The objective of this study was to determine whether workers can provide unbiased data via self-assessments of exposure facilitated by the use of simple passive monitors for personal sampling.

METHODS: Untrained workers obtained personal measurements of their exposures to gaseous contaminants (terpenes in sawmills and styrene in reinforced plastics factories) with passive monitors and written instructions. To study the validity of the self-assessments, an occupational hygienist performed exposure measurements on the same occupational groups after the workers had obtained two or more measurements independently. The potential bias of the self-assessments was evaluated by comparing the self-assessments with the expert assessments in mixed-effects statistical models.

RESULTS: A total of 153 terpene (97 self and 56 expert) and 216 styrene (159 self and 57 expert) measurements were obtained from four sawmills and six reinforced plastics factories, respectively. No significant differences in the geometric mean exposures were observed between the self-assessments and the expert assessments in 3 of 4 sawmills and 5 of 6 reinforced plastics factories (P > 0.10). The potential bias of the self-assessments of exposure ranged from less than 0.1% to 102% and was less than 17% in 9 of the 10 groups investigated.

CONCLUSIONS: The results indicate that untrained, unsupervised workers are able to collect consistently unbiased exposure data by employing currently available passive monitors.

In Sweden, all children must have access to education of equal value and the curriculum points out the importance of a good environment for development and learning. Modern working methods differ a lot from the traditional. Teaching nowadays is focused on problem-solving. Students are more interactive, working in groups and projects. The teacher has become a supervisor, guiding not lecturing.

Hearing loss, vegetative responses, biochemical effects, speech interference, behavioural effects and subjective reactions are all part of the problem of noise exposure. There is no unequivocal method of assessing noise and its effects. The most common method of noise assessment and appraisal of negative noise reactions is based on measurement of acoustic characteristics. Recommendations made and targets set by authorities are often stated in terms of equivalent Aweighted sound level L (A)eq.

The purposes of this thesis have been to increase knowledge of noise exposure in classrooms and the subjective response among pupils and also to identify factors of special importance when assessing negative noise effects in the classroom. The work consists of five separate articles considering different aspects of sound exposure and its adverse effects on pupils in school: three field studies, one article on development of a mood-rating instrument and one laboratory study. Analyses of exposure were based on equivalent sound levels and subjective responses were evaluated using ratings on a visual analogue scale and forced choice questions.

The results point to speech and structure-borne sounds as the most annoying sound sources to the pupils. Annoyance will increase with variability of the exposure. This is typical of the character of structure-borne sounds such as footsteps, scraping of chairs and tables and slamming of doors, as well as of speech.

The background sound level exposure levels in the classrooms ranged between 33 and 42 dB (A)eq. The background sound in about 2/3 of the classrooms investigated was considered to be LFN. Pupils exposed to high LFN levels were not more annoyed than pupils exposed to low LFN levels.

The activity sound level ranged between 47 and 69 dB(A)eq. These are levels that must be considered high for a work environment such as the school, which has at all times to be conducive to steady concentration, communication and learning. The risk of hearing damage during this exposure must be concidered as low. The thesis also describes the development of a mood-rating instrument to identify effects of noise and other aspects of the classroom environment. The questionnaire is easy to administer, takes little time to complete and is therefore well suited to studies in field settings.

The ratings of annoyance in the classroom correspond to the verbal definition “Somewhat annoying - Rather annoying”. Data from the field studies does not support the idea that the negative responce will increase with higher sound levels. In the laboratory setting, a relationship between increasing sound level and increase in rated annoyance was displayed.

 The principle of this field study is an investigation of recorded sound levels in 24 classrooms and relations between sound level measures and aspects of children's rated annoyance, task orientation, and inattentiveness. The background sound-exposure levels were distributed within the interval of 33-42 dB(A)eq and the activity sound level exposure ranged between 47-68 dB(A)eq. The recorded levels must be considered as high for work environments where steady concentration and undisturbed communication is essential. Results do not support the hypothesis that lower background-sound level and fewer students per class would improve the sound environment by generating a lower activity noise or the hypothesis that higher sound levels should increase annoyance and inattentiveness as well as deteriorate task orientation ratings.

The aim of this study is to investigate how students rate the annoyance and effects of noise in their working environment. 216 students, between the ages 13-15 years, and 12 teachers took part in this study. Sound level measurements were made for 20 minutes in the middle of a lesson for each class. On the measurement occasion the students were seated in a class room working on mathematics. Immediately after the sound level measurement, the students and the teachers filled in a questionnaire. The correlation between sound level and perceived annoyance and rated effect of noise on the students´ schoolwork was poor. The correlation between the annoyance and rated effect of noise on the students´ schoolwork was significant. Equivalent sound levels during mathematics lessons were 58-69 dB(A). Even though the sound levels were relatively high the students claimed that they were just moderately annoyed. More than 1/3 of the students claimed that the existing sound environment obstructed their work. No difference was found between boys and girls in rated annoyance and rated effect on their work. The younger students were more annoyed than the older ones. The participants claimed that chatter in the class room and scraping sounds from tables and chairs were the most annoying sound sources. The teachers shared this opinion. The concurrency between the students´ rating of their annoyance and the teachers´ rating of the students annoyance was remarkably low.

The most common method for noise assessment is the A-weighted sound pressure level. The question has been raised as to whether the frequency weighting with an A-filter gives a correct result when assessing the annoyance response to noise containing strong low frequency noise (LFN) components. One method suggested to identify LFN is the dB(C) – dB(A) difference. The aims of this study are to investigate if background noise in Swedish elementary schools is to be considered as LFN, further to test the hypothesis that students exposed to audible LFN at high levels are more annoyed than students exposed to LFN at lower levels. The results indicate that the noise in 16 out of 22 classrooms should be considered as LFN. The analysis did not show any difference in rated annoyance between students exposed to high LFN levels and students exposed to low LFN levels.

The aim of this study was to develop a mood-rating instrument primarily aimed at identifying effects of noise and other aspects of the classroom environment, that probably are of importance, for the children's scholastic performance. None of the existing mood questionnaires was found to be directly applicable to the target group, viz., children in upper compulsory school in Sweden. An adjective checklist containing 45 mood-describing adjectives was constructed and answered by a group of 280 students. Thirteen of the items had a non-response rate above 10 per cent and were excluded. The remaining 32 items were subjected to factor analyses, and another group of 443 students were used to cross-validate the obtained factor structure.

The analyses showed that the adjective checklist reflected two slightly negatively correlated latent factors. One factor described task orientation, the other inattentiveness. A questionnaire was constructed containing 12 items covering the content of these two factors.

This instrument reflects important aspects of the classroom climate. It is easy to administer, quickly completed, and should be useful in studies of the classroom environment.

Musculoskeletal disorders are common among professional driver groups. Ergonomic risk factors at work are often suggested as causative, aggravating or preserving. The general aim with this thesis is to investigate the association between musculoskeletal disorders and physical exposure with special with special focus on whole-body vibration (WBV), among professional drivers of all-terrain vehicles (ATVs). Drivers of ATVs are expsosed to high magnitudes of WBV and shock. This thesis included drivers of forest machines, snowgroomers and snowmobiles. A cross-sectional study revealed that ATV drivers had an increased risk of musculoskeletal symptoms in the neck-shoulder and thoracic regions, even after adjusting for age, smoking habits and psychosocial stress. Prevalence rates were in the range of 1.5-2.9 (CI:1.2-5.2) compared to an age-matched group from the general population. No group of ATV drivers had a significantly increased risk of low back pain. Trend analysis showed no association between symptoms and exposure time. A clinical investigation of a subgroup found that it was for ATV drivers with neck pain to have assymetrical and focal neuropathies, pure or in mix with a nociceptive disorder, in the neck and upper extremities (47-79%), which was in contrast to referents with neck pain who had more nociceptive disorders (27% prevalence of neuropathy). Two studies measured characteristics of seated WBV exposure in forest machines (forwarders), snowgroomers and snowmobiles. The magnitudes of WBV in ATVs, measured and analyzed according to ISO 2631-1, were between 0.5-3.5 m/s² (frequency weighted vector sum), which was considered high compared to limits suggested by the international standard ISO 2631-1 and the physical agent directive from the Euoropean Union (0.5 m/s², rms). Drivers of ATVs were exposed to horizontally directed WBV and shocks. Non-neutral neck postures are ergonomic risk factors that occured infrequently and with short duration. The magnitude of seated WBV in forwarder vehicles varied substantiálly depending on model, terrain condition and driver. This may result in different conclusions regarding health risk assessments. The main conclusion from this thesis is that musculoskeletal symptoms and disorders in the neck and upper extremities, among drivers of ATVs, may be a result of long-time exposure to shock-type and horisozontally oriented seated WBV.

Exposure to whole-body vibration (WBV) may cause health problems, e.g. lumbago. The risk will depend on intensity and duration. Exposure to WBV in vehicles varies due to several factors as the vehicle type, the terrain condition, the driver, the speed etc. To estimate the health risk, the measurement strategy has to consider this variation. Furthermore, to understand the importance of different preventive strategies, the cause of the variation has to be known. The objective of this study was to describe variation in exposure to seated WBV during occupational operation of forwarder vehicles and to investigate sources for variation. WBV was measured in 10 various terrain types for seven forwarders operated by 11 drivers. For each driver there were between four and 35 measurements. The measurement periods varied between 0.2 and 34 min. The vibration total value (a_v) and total vibration dose value (VDV_t) were determined. Results showed that WBV exposure varied considerably and that this variation could result in different conclusions regarding health risk assessments. The highest magnitudes were achieved during travelling activities. During travelling empty, variations in a_v were significantly dependent upon forwarder model and terrain type. No significant predictor for variation in VDV_t was however found for travelling empty. During travelling loaded the forwarder model and operator were the most important predictors for variation in a_v. Variation in VDV_t was also dependent on the forwarder model during travelling loaded.

The aim of this cross-sectional study was to characterize the risk of experiencing musculoskeletal symptoms in the region of the neck, shoulders and upper and lower back for professional drivers of various categories of all-terrain vehicles and to assess the association between symptoms and duration of exposure to whole-body vibration (WBV) and shock from driving all-terrain vehicles. The study group consisted of 215 drivers of forest machines, 137 drivers of snowmobiles and 79 drivers of snowgroomers and a control group of 167 men randomly selected from the general population. The subjects were all from one of the four most northern counties in Sweden and they were all men. Musculoskeletal symptoms were assessed by use of a standardized questionnaire. In addition, the questionnaire held items about the driving time with all-terrain vehicles and a subjective estimation of exposure to unpleasant movements (shock, jolt, irregular sway). The job strain was measured according to Karasek's demands/control model. The prevalence ratios were adjusted for age, smoking and job strain. Among drivers, significantly increased prevalence ratios within the range of 1∂5–2·9 were revealed for symptoms from the neck–shoulder and thoracic regions during the previous year. None of the driver categories had a statistically significantly increased risk of low back pain. Forest vehicles were those most reported to cause unpleasant movements. In conclusion, drivers of all-terrain vehicles exhibit an increased risk of symptoms of musculoskeletal disorders in the neck–shoulder and thoracic regions. The increased risk is suggested to be related to physical factors such as exposure to whole-body vibration (WBV) and shock, static overload or extreme body postures. However, since symptoms of low back pain were not significantly increased, it appears that factors other than WBV would explain the occurrence of symptoms in the group of all-terrain drivers.

BACKGROUND: The purpose of this study was to investigate whether professional drivers of all-terrain vehicles (ATVs) with neck pain have a different array of neuromusculoskeletal disorders in the neck and upper extremities than a referent group with neck pain from the general population. It is hypothesized that exposure to shock-type vibration and unfavorable working postures in ATVs have the capacity to cause peripheral nervous lesions. METHODS: This study was based on a case series analyzed according to a case-case comparison design. The study population consisted of 60 male subjects, including professional drivers of forest machines (n = 15), snowmobiles (n = 15), snowgroomers (n = 15) and referents from the general population (n = 15) all of whom had reported neck pain in a questionnaire and underwent an extensive physical examination of the neck and upper extremities. Based on symptom history, symptoms and signs, and in some cases chemical, electroneurographical and radiological findings, subjects were classified as having a nociceptive or neuropathic disorder or a mix of these types. RESULTS: The occurrence of asymmetrical and focal neuropathies (peripheral nervous lesion), pure or in a mix with a nociceptive disorder was common among cases in the ATV driver groups (47%-79%). This contrasted with the referents that were less often classified as having asymmetrical and focal neuropathy (27%), but instead had more nociceptive disorders. The difference was most pronounced among drivers of snowgroomers, while drivers of forest machines were more frequently classified as having a nociceptive disorder originating in the muscles. CONCLUSION: This study found a high prevalence of assymetrical and focal neuropathies among drivers with pain in the neck, operating various ATVs. It seems as if exposure to shock-type whole-body vibration (WBV) and appurtenant unfavorable postures in ATVs may be associated to peripheral nervous lesions.

OBJECTIVES: The purpose of this study was to characterize whole-body vibration (WBV) exposure from various all-terrain vehicles (ATVs) like snowgroomers, snowmobiles and forwarders, and to investigate how frequently the drivers' cervical spine is positioned in a non-neutral rotational position during operation. METHODS: Field measurements of WBV were measured according to the international standard ISO 2631-1 in 19 ATVs. Simultaneous recordings of frequency and duration of rotational neck movements exceeding 15 degrees were achieved through an observational method, PEOflex. RESULTS: The sum of the vectors of frequency-weighted r.m.s. acceleration varied between 0.5 and 3.5 m s(-2), which meant that for most vehicles they exceeded the action value stated by the European Union (0.5 m s(r.m.s.)(-2)). In general, snowmobiles achieved the highest vibration total value. The dominant vibration direction for the snowmobile was the x-axis but the z-axis also had relatively high vibration dose values and maximal transient vibration values. The z-axis was the dominant vibration direction for the snowgroomer and the y-axis for the forwarder. Frequency and duration of non-neutral rotational neck postures were relatively low for all driver categories. CONCLUSIONS: Vibration magnitudes in ATVs are considerably high than the EU's action value and the health guidance caution zones in ISO 2631-1. The dominant vibration direction varies depending on the machine type. Duration and frequency of non-neutral rotational positions do not seem to constitute single ergonomic risk factors for musculoskeletal symptoms in the neck among professional drivers of ATVs. However, synergistic effects with other factors are conceivable.

A formic acid biosensor for air monitoring has been evaluated using chemometric methods. Using experimental design eleven factors that could influence the performance of the biosensor were examined. The response matrices consisted of six parameters (steady state currents at three different formic acid concentrations and response rates during changes in formic acid concentrations) describing the performance of the biosensor. The data were evaluated using a combination of principal component analysis (PCA) and multiple linear regression (MLR). To confirm the conclusions from the PCA-MLR partial least squares (PLS) was also used. The most important factor for the biosensor performance was found to be the enzyme concentration. Using the information from the chemometric analyses the optimum operation conditions for the biosensor were determined. The steady state currents were increased by 18–30% and the initial two response rates increased by 47–89% compared with a biosensor that had not been optimised.

The possibility of developing a simple, inexpensive and specific personal passive “real-time” air sampler incorporating a biosensor for formic acid was investigated. The sensor is based on the enzymatic reaction between formic acid and formate dehydrogenase (FDH) with nicotinamide adenine dinucleotide (NAD⁺) as a co-factor and Meldola's blue as mediator. An effective way to immobilise the enzyme, co-factor and Meldola's blue on screen-printed, disposable, electrodes was found to be in a mixture of glycerol and phosphate buffer covered with a gas-permeable membrane. Steady-state current was reached after 4–15 min and the limit of detection was calculated to be below 1 mg/m³. However, the response decreased by 50% after storage at −15°C for 1 day.

Inorganic lead is certainly the most extensively studied of all toxic agents. Occupational exposure occurs in a wide variety of settings. There is also widespread exposure in the general environment. However, after the ban of lead addition to petrol, the exposure has decreased dramatically in several parts of the world. Exposure and risk are usually assessed by biological monitoring, mainly by blood-lead concentration (B-Pb). However, B-Pb has limitations, because there is saturation at high exposure. Lead accumulates in teeth and in the skeleton, where it may be determined by in vivo methods, which reflect long-term uptake. Toxic effects may occur in the central and peripheral nervous systems, blood (including inhibition of heme synthesis, which also affects other cells), kidney, and cardiovascular, endocrine and immune systems, gastrointestinal tract, and male reproduction (sperm quality). Lead causes increase of blood pressure; slight effects may occur in adults with a mean B-Pb of 0.4 mu mol/L. Furthermore, lead passes the placenta and may cause effects on the nervous system of the fetus. Lead in the skeleton is mobilized during pregnancy and lactation and is transferred to both the fetus and the lactating infant. Slight (but adverse) effects on the mental development of infants and children have repeatedly been reported at a mean B-Pb of 0.5 mu mol/L, or even less, in the pregnant woman or the child. Lead is carcinogenic in animal experiments, but there is only limited evidence for carcinogenicity in humans. The most important organolead compounds are tetraethyl and tetramethyl lead, which have been used in enormous quantities in leaded petrol. They are easily absorbed through inhalation and through the skin and may cause acute encephalopathia.

Diffusive samplers for monitoring of air quality are user-friendly devices that can normally be operated by the user himself. Hence these samplers are suitable for self-assessment. Practical and work organisational aspects of self-assessment of chemical exposure were studied in different occupational settings. It was found that the diffusive sampler used in these studies, the Perkin-Elmer tube in combination with thermal desorption, worked well for the purpose and could be correctly handled by the individuals using it. The results from self-assessments agreed well with expert measurements carried out by an occupational hygienist. However, in order to obtain a sustainable system of self-assessment strong organizational support is needed.

Objective: The study examined the multivariate relationship between mental fatigue and different work-related (work load, work hours) and background/life style factors, as well as disturbed sleep.

Methods: A total of 5720 healthy employed men and women living in the greater Stockholm area participated in a questionnaire study on cardiovascular risk factors. The data were analysed using a multiple logistic regression analysis with self-rated fatigue as the dependent variable.

Results: Fatigue was predicted by disturbed sleep (4.31; 3.50-5.45, high immersion in work (4.17; 2.93-5.94), high work demands (2.39; 1.54-3.69), social support, being a female, being a supervisor and high age. Shift work, work hours (including overtime) and influence at work did not become significant predictors. With control for work demands a high number of work hours was associated with lower fatigue.

Conclusion: Disturbed sleep is an important predictor of fatigue, apparently stronger than previously well-established predictors such as work load, female gender, lack of exercise, etc. (C) 2004 Elsevier Inc. All rights reserved.