Preventing Sickness Absence With Career Management Intervention: A Randomized Controlled Field Trial.

This study examined whether a group intervention focusing on building up preparedness for career management can prevent future sickness absence.Register-based data on the number of sickness absence days and sickness absence episodes were examined as outcomes of the intervention among 684 employees in 17 organizations in a randomized controlled trial. Sickness absence data were collected covering a period from 1 year before (baseline) to approximately 2 years after the intervention (follow-up). The data were analyzed using zero-inflated negative binomial models.After controlling for baseline absence, age, gender, and organization, the intervention was effective in decreasing the number of longer sickness absences (lasting longer than > 2 weeks), but no other significant effects were found.These findings point out that it is feasible to use a career management intervention to prevent future sickness absence in work organizations.

Role of overweight and obesity in low back disorders among men: a longitudinal study with a life course approach.

OBJECTIVES: To assess the association between being overweight or obese with low back pain (LBP) and clinically defined low back disorders across the life course. DESIGN: A longitudinal and cross-sectional study. SETTING: A nationwide health survey supplemented with data from records of prior compulsory military service. PARTICIPANTS: Premilitary health records (baseline) were searched for men aged 30-50 years (n=1385) who participated in a national health examination survey (follow-up). METHODS AND OUTCOME MEASURES: Height and weight were measured at baseline and follow-up, and waist circumference at follow-up. Weight at the ages of 20, 30, 40 and 50 years were ascertained, when applicable. Repeated measures of weight were used to calculate age-standardised mean body mass index (BMI) across the life course. The symptom-based outcome measures at follow-up included prevalence of non-specific and radiating LBP during the previous 30 days. The clinically defined outcome measures included chronic low back syndrome and sciatica. RESULTS: Baseline BMI (20 years) predicted radiating LBP in adulthood, with the prevalence ratio (PR) being 1.26 (95% CI 1.08 to 1.46) for one SD (3.0 kg/m(2)) increase in BMI. Life course BMI was associated with radiating LBP (PR=1.23; 95% CI 1.03 to 1.48 per 1 unit increment in Z score, corresponding to 2.9 kg/m(2)). The development of obesity during follow-up increased the risk of radiating LBP (PR=1.91, 95% CI 1.03 to 3.53). Both general and abdominal obesity (defined as waist-to-height ratio) were associated with radiating LBP (OR=1.64, 95% CI 1.02 to 2.65 and 1.44, 95% CI 1.02 to 2.04). No associations were seen for non-specific LBP. CONCLUSIONS: Our findings imply that being overweight or obese in early adulthood as well as during the life course increases the risk of radiating but not non-specific LBP among men. Taking into account the current global obesity epidemic, emphasis should be placed on preventive measures starting at youth and, also, measures for preventing further weight gain during the life course should be implemented.

Effects of cumulative sleep restriction on self-perceptions while multitasking.

This study addressed a rarely studied question of self-perceptions of performance and overall functional state during cumulative sleep restriction and the ensuing recovery period. Twenty healthy male volunteers, aged 19-29 years, were divided into a sleep restriction group (n = 13) and a control group (n = 7). On the first 2 nights, the sleep restriction group had an 8-h sleep opportunity that was restricted to 4 h for the next 5 nights, and then restored to 8 h for the last 2 nights. The control group had an 8-h sleep opportunity each night. Each day participants accomplished 50-min multitask sessions and gave self-ratings in their connection. Similar to our previous findings on multitasking performance, self-perceived task performance, sleepiness and mental fatigue impaired during the sleep restriction and returned to baseline during the recovery phase. Self-perceived mental effort, tension, task difficulty and task pace showed no sensitivity to the sleep restriction. We concluded that sleep-restricted individuals can probably make use of some self-perceptions when assessing their 'fitness for duty'. However, at the individual level these measures seem to be inaccurate in revealing actual performance impairments.

Trends in musculoskeletal disorders and related health care utilization among conscripts in Finland, 1967-2006.

OBJECTIVES: The aim was to investigate time trends in musculoskeletal disorders (MSDs) among Finnish conscripts over a period of 40 years. METHODS: A nationally representative health examination survey (the Health 2000 study) was carried out in 2000-2001 among 10,000 adult Finns. All 18- to 50-year-old men were further sampled (n = 2674) and those with completion of the 6 to 12 month compulsory service were included. (n = 2296). Time trends in consultations because of MSDs during service and findings at call-up examinations were analysed. RESULTS: From 1967 to 2006 altogether 4872 MSD-related consultations were done, most commonly because of problems in the ankle or foot, knee, or back. The proportion of conscripts visiting military health care because of MSDs increased 1.6-fold (from 44 to 72%). The average number of MSD-related consultations per conscript tripled. The proportion of conscripts with > or = 6 consultations increased 5-fold and those seeking care for multisite symptoms increased 10-fold. No increase in symptoms or findings before service could be seen at preservice examinations. CONCLUSIONS: Conscripts seek care because of musculoskeletal symptoms considerably more often nowadays than before. More attention should be focused to the prevention of traumatic and overexertion injuries of the lower limbs, although the reasons for increasing careseeking should be further investigated.

Resource-enhancing group intervention against depression at workplace: who benefits? A randomised controlled study with a 7-month follow-up.

OBJECTIVES: The aim of the present study was to investigate whether participation in a structured resource-enhancing group intervention at work would act as primary prevention against depression. The authors analysed whether the intervention resulted in universal, selected or indicated prevention. METHODS: A total of 566 persons participated in a prospective, within-organisation, randomly assigned field experimental study, which consisted of 34 workshops in 17 organisations. The participants filled in a questionnaire, were randomly assigned to either intervention (n=296) or comparison (n=324) groups and returned another questionnaire 7 months later. The intervention, lasting four half-day sessions, was delivered by trainers from occupational health services and human resources. The aim of the structured programme was to enhance participants' career management preparedness by strengthening self-efficacy and inoculation against setbacks. The comparison group received a literature package. The authors measured depressive symptoms using the short version of the Beck Depression Inventory. A high number of depressive symptoms (over 9 points) were used as a proxy for depression. RESULTS: At follow-up, the odds of depression were lower in the intervention group (OR=0.40, 95% CI 0.19 to 0.85) than in the comparison group when adjusted for baseline depressive symptoms, job strain and socio-demographics. In addition, the odds of depression among those with job strain (OR=0.15, 95% CI 0.03-0.81) at baseline were lower after the intervention. The intervention had no statistically significant effect on those with depressive symptoms (over 4 points) at baseline. CONCLUSION: The resource-enhancing group intervention appeared to be successful as universal and selective prevention of potential depression.

Similar DNA methylation pattern in lung tumours from smokers and never-smokers with second-hand tobacco smoke exposure.

Tobacco smoke causes lung cancer in smokers and in never-smokers exposed to second-hand tobacco smoke (SHS). Nonetheless, molecular mechanisms of lung cancer in SHS-exposed never-smokers are still elusive. We studied lung cancers from current smokers (n = 109), former smokers (n = 56) and never-smokers (n = 47) for promoter hypermethylation of five tumour suppressor genes--p16, RARB, RASSF1, MGMT and DAPK1--using methylation-specific polymerase chain reaction. Lung tumours from ever-smokers suggested an increased risk of p16 hypermethylation as compared to never-smokers (P = 0.073), with former smokers having the highest frequency of p16 hypermethylation (P = 0.044 versus current smokers and P = 0.009 versus never-smokers). In the never-smoking group, p16 hypermethylation was seen in lung tumours from SHS-exposed individuals (4/33; 12%) but in none of the non-exposed individuals (0/9). The overall occurrence of hypermethylation (measured both as methylation index and as number of genes affected) was similar in those ever exposed to tobacco smoke (smokers, SHS-exposed never-smokers) and differed from non-exposed never-smokers. In multivariate analysis, p16 hypermethylation was more prevalent in lung tumours from male than female patients (P = 0.018) and in squamous cell carcinomas than in adenocarcinomas (P = 0.025). Occurrence of TP53 mutation in the tumour was associated with hypermethylation of at least one gene (P = 0.027). In all, our data suggest that promoter hypermethylation pattern in SHS-exposed never-smokers resembles that observed in smokers. Association between TP53 mutation, a hallmark of smokers' lung cancer, and methylation of one or more of the lung cancer-related genes studied, provides further evidence for common tobacco smoke-related origin for both types of molecular alterations.

Effects of resource-building group intervention on career management and mental health in work organizations: randomized controlled field trial.

A resource-building group intervention was developed to enhance career management, mental health, and job retention in work organizations. The in-company training program provided employees with better preparedness to manage their own careers. The program activities were universally implemented using an organization-level, 2-trainer model with trainers from the human resources management and occupational health services. The study was a within-organizations, randomly assigned field experimental study; it investigated the impacts of the intervention on immediate career management preparedness and later mental health and intentions to retire early. A total of 718 eligible individuals returned a questionnaire in 17 organizations and became voluntary participants. The respondents were randomly assigned to either an intervention (N = 369) or a comparison group (N = 349). Those in the intervention group were invited to group intervention workshops, whereas those in the comparison group received printed information about career and health-related issues. The 7-month follow-up results showed that the program significantly decreased depressive symptoms and intentions to retire early and increased mental resources among the group participants compared to the others. The mediation analyses demonstrated that the increase in career management preparedness as a proximal impact of the intervention mediated the longer term mental health effects. Those who benefited most from the intervention as regards their mental health were employees with elevated levels of depression or exhaustion and younger employees, implying additional benefits of a more targeted use of the intervention. The results demonstrated the benefits of the enhancement of individual-level career management and resilience resources as career and health promotion practice in work organizations.

Association of modic changes, Schmorl's nodes, spondylolytic defects, high-intensity zone lesions, disc herniations, and radial tears with low back symptom severity among young Finnish adults.

STUDY DESIGN: A cross-sectional magnetic resonance imaging (MRI) study. OBJECTIVE: We investigated the association among Modic changes, Schmorl's nodes, spondylolytic defects, high-intensity zone lesions, radial tears, herniations, and low back symptom severity. SUMMARY OF BACKGROUND DATA: Disc degeneration is associated with low back pain in early adulthood, but the associations between other MRI findings and low back pain are not well known. METHODS: Questionnaire data and MRI scans (1.5-T) were available for 554 subjects derived from a birth cohort at 21 years of age. Data on low back pain and back-related functional limitations at 18, 19, and 21 years of age were used for clustering of subjects, using latent class analysis. We used logistic regression with adjustment for the degree of disc degeneration to evaluate the associations between specific imaging findings and low back symptom severity. RESULTS: The prevalence of herniations was 20%, Schmorl's nodes 17%, radial tears 9.9%, high-intensity zone lesions 3.2%, spondylolytic defects 5.8%, and Modic changes 0.7%. Latent class analysis produced 5 clusters: "Always Painful" (n = 65) meant painful at all time points and "Recent Onset Pain" (n = 56) meant increasing symptom severity, whereas subjects in the "Moderately Painful" (n = 73), "Minor Pain" (n = 193), and "No Pain" (n = 167) clusters had fewer symptoms. Compared with the "No Pain" cluster, Schmorl's nodes were more likely to occur in the "Always Painful" cluster (P = 0.017) and herniations in the 3 most painful clusters (P < 0.001). Herniations were associated with low back symptom severity (odds ratio, 2.5; 95% confidence interval, 1.4-4.4). Schmorl's nodes and radial tears were associated with symptoms in crude analyses only, whereas high-intensity zone lesions and spondylolytic defects occurred in similar frequencies in all clusters. CONCLUSION: Herniations were most likely in the subjects with recent onset or persistent (3-yr period) low back symptoms, although they were also detected in subjects with no symptoms. The clinical relevance of herniations on MRI remains to be evaluated in the context of symptoms.

Does lumbar disc degeneration on magnetic resonance imaging associate with low back symptom severity in young Finnish adults?

STUDY DESIGN: A cross-sectional magnetic resonance imaging study with questionnaires on low back pain (LBP) and functional limitations. OBJECTIVE: To investigate the association between lumbar intervertebral disc degeneration (DD) and low back symptom severity among young Finnish adults. SUMMARY OF BACKGROUND DATA: Both LBP and lumbar DD are common already in adolescence, but very little is known of their association in young adults. METHODS: Young adults belonging to a birth cohort (n=874) were invited to lumbar magnetic resonance imaging using a 1.5-T scanner. Data on LBP and functional limitations at the ages of 18, 19, and 21 years were used to cluster the subjects with respect to low back symptoms using latent class analysis. The prevalence and 95% confidence intervals of DD at 21 years and the sum score of DD at all lumbar levels were compared between the clusters. The contribution of DD and other imaging findings (herniations, anular tears, Modic changes, spondylolytic defects) to symptom severity was analyzed with logistic regression analysis. RESULTS: Latent class analysis produced five clusters from the 554 subjects, ranging from a cluster where subjects (n=65) had been painful at all time points to an asymptomatic cluster (n=168). DD was more prevalent in the three most symptomatic clusters compared to the two least symptomatic ones. Similar findings were obtained for the DD sum scores. Lumbar DD was related to symptom severity independently of other degenerative findings. Moreover, moderately degenerated discs were more likely than mildly degenerated discs to be associated with the most severe low back symptoms. CONCLUSION: Intervertebral DD was associated with low back symptom severity among young adults, suggesting that the symptoms may have a discogenic origin at this age. However, DD was also found in one-third of asymptomatic subjects.

Assessment of association between low back pain and paraspinal muscle atrophy using opposed-phase magnetic resonance imaging: a population-based study among young adults.

STUDY DESIGN: A cross-sectional imaging study of young adults. OBJECTIVE: To evaluate whether severity of low back symptoms predicts atrophy in the paraspinal muscles of young adults. SUMMARY OF BACKGROUND DATA: Although an increased fat content of the lumbar muscles has been observed among adults with chronic LBP, there is limited knowledge of this association in younger populations. METHODS: The population-based study sample consisted of 554 subjects (321 females and 233 males) from the 1986 Northern Finland Birth Cohort. Latent Class Analysis (LCA) was used to cluster the subjects according to the low back symptoms and functional limitations at 18, 19, and 21 years. The mean age of the subjects at the time of the MRI (magnetic resonance imaging) was 21 years (range, 20-23). Muscle atrophy was evaluated by assessing the fat content of the paraspinal muscles using Opposed-Phase MRI. The cross-sectional areas (CSAs) of the erector spinae and multifidus muscles were also measured. RESULTS: LCA analysis produced five clusters differing in symptoms, ranging from a cluster (n = 65) in which subjects had high likelihood of symptoms and functional limitations at all time points, to a cluster (n = 165) with no pain ever. The fat content of the multifidus muscles was significantly higher among women than men (14.0% vs. 5.3%, P < 0.001), but it was not significantly associated with symptom severity. The CSA of both erector spinae and multifidus muscles were significantly larger among men than women (P < 0.001 in all of the muscles), but were not associated with pain severity. CONCLUSION: Low back symptoms and functional limitations over a 3-year period were not associated with increased fat content or a reduction in the cross-sectional area of lumbar paraspinal muscles among young adults.

Sleep restriction for the duration of a work week impairs multitasking performance.

It is important to develop shift schedules that minimise the chance for sleep-related human error in safety-critical domains. Experimental data on the effects of sleep restriction (SR) play a key role in this development work. In order to provide such data, we conducted an experiment in which cognitively demanding and long-duration task performance, simulating task performance at work, was measured under SR and following recovery. Twenty healthy male volunteers, aged 19-29 years, participated in the study. Thirteen of them had first two baseline days (8-h sleep opportunity per day), then five SR days (4-h sleep) and finally two recovery days (8-h sleep). Seven controls were allowed to sleep for 8 h each night. On each experimental day, multitask performance was tested in 50-min sessions, physiological sleepiness was evaluated during multitask performance using electroencephalogram (EEG)/electrooculogram (EOG) recordings, and psychomotor vigilance task performance and Karolinska Sleepiness Scale were recorded. Sleep-wake rhythm was monitored throughout the experiment. The multitask performance progressively deteriorated as a result of prolongation of the SR and the time spent on the task. The effect was significant at group level, but individual differences were large: performance was not markedly deteriorated in all participants. Similar changes were observed also in EEG/EOG-defined sleepiness. The recovery process of performance and sleepiness from the SR continued over the two recovery sleep opportunities. In all, our findings emphasise the importance of shift systems that do not restrict sleep for several consecutive days.

Effect of a participatory ergonomics intervention on psychosocial factors at work in a randomised controlled trial.

OBJECTIVES: To study the effect of a participatory ergonomics intervention on psychosocial factors among kitchen workers. DESIGN: A cluster randomised controlled trial. SETTING: Four cities in Finland, 2002-2005. PARTICIPANTS: 504 workers in 119 municipal kitchens. INTERVENTION: Kitchens were randomised to intervention (n=59) and control (n=60) groups. The intervention lasted 11-14 months and was based on the workers' active participation in work analysis, planning and implementing the ergonomic changes aimed at decreasing the physical and mental workload. MAIN OUTCOME MEASURES: Mental stress, mental strenuousness of work, hurry, job satisfaction, job control, skill discretion, co-worker relationships and supervisor support. Data were collected by questionnaire at baseline, at the end of the intervention, and at a 12-month follow-up (PI(12)). RESULTS: At the end of the intervention, the OR of job dissatisfaction for the intervention group as compared with the control group was 3.0 (95% CI 1.1 to 8.5), of mental stress 2.3 (1.2 to 4.7) and of poor co-worker relationships 2.3 (1.0 to 5.2). At the PI(12), the OR of job dissatisfaction was 3.0 (1.2 to 7.8). Analysis of the independent and joint effects of the intervention and unconnected organisational reforms showed that adverse changes were accentuated among those with exposure to both. CONCLUSIONS: No favourable effects on psychosocial factors at work were found. The adverse changes were due to a joint effect of the intervention and the unconnected organisational reforms. The findings do not support the usefulness of this kind of intervention in changing unsatisfactory psychosocial working conditions.

Dairy products and metabolic effects in overweight men and women: results from a 6-mo intervention study.

BACKGROUND: Some epidemiologic studies have suggested inverse relations between intake of dairy products and components of the metabolic syndrome. OBJECTIVE: The objective was to investigate the effects of an increased intake of dairy products in persons with a habitually low intake on body composition and factors related to the metabolic syndrome. DESIGN: Middle-aged overweight subjects (n = 121) with traits of the metabolic syndrome were recruited in Finland, Norway, and Sweden and randomly assigned into milk or control groups. The milk group was instructed to consume 3-5 portions of dairy products daily. The control group maintained their habitual diet. Clinical investigations were conducted on admission and after 6 mo. RESULTS: There were no significant differences between changes in body weight or body composition, blood pressure, markers of inflammation, endothelial function, adiponectin, or oxidative stress in the milk and the control groups. There was a modest unfavorable increase in serum cholesterol concentrations in the milk group (P = 0.043). Among participants with a low calcium intake at baseline (<700 mg/d), there was a significant treatment effect for waist circumference (P = 0.003) and sagittal abdominal diameter (P = 0.034). When the sexes were analyzed separately, leptin increased (P = 0.045) and vascular cell adhesion molecule-1 decreased (P = 0.001) in women in the milk group. CONCLUSIONS: This study gives no clear support to the hypothesis that a moderately increased intake of dairy products beneficially affects aspects of the metabolic syndrome. The apparently positive effects on waist circumference and sagittal abdominal diameter in subjects with a low calcium intake suggest a possible threshold in relation to effects on body composition.

Musculoskeletal pain combinations in adolescents.

STUDY DESIGN: A 2-year follow-up in a birth cohort of adolescents aged 15 to 19 years. OBJECTIVE: To evaluate the prevalence of neck, shoulder, low back, peripheral (limb) pain, and combinations of pain at these anatomic locations. SUMMARY OF BACKGROUND DATA: Few previous studies have evaluated combinations of musculoskeletal pain among adolescents. METHODS: Prevalence of neck, shoulder, low back, and peripheral pain (elbow, wrist, knee, and ankle-foot pain) during the previous 6 months were obtained by questionnaire in a follow-up study of the Northern Finland Birth Cohort 1986 at 16 and 18 years of age (n = 1773). Latent class analysis was used in clustering of pain combinations at both time points. RESULTS: No pain at all in the past 6 months at 16 and 18 years was reported by 17% and 8% of girls, and 33% and 24% of boys, respectively. Only 1 pain location (neck, shoulder, low back, or peripheral pain) was reported by 21% of girls and 25% of boys at 16, and 11% of girls and 20% of boys at 18 years, while all 4 pain locations were reported by 15% of girls and 9% of boys at 16, and 27% and 15%, respectively, at 18 years. Latent class analysis resulted in 2 to 3 pain clusters in both genders at both time points. Probability of pain increased during the 2-year follow-up, with subjects more likely to belong to a cluster with a higher likelihood of pain. CONCLUSION: As very few adolescents did not report any pain, the relevance of self-reported pain is questionable without assessment of pain-related disability. The clinical relevance of these pain combinations must be evaluated in further studies.

Musculoskeletal pains in relation to different sport and exercise activities in youth.

PURPOSE: We examined the associations between participation in different sports and exercise activities and neck, shoulder, and low back pains in adolescents. METHODS: This population-based study included the members of the Northern Finland Birth Cohort 1986, who, at the age of 15 to 16 yr, completed a questionnaire including items about their musculoskeletal pains and participation in various sport and exercise activities (N = 6945). Logistic regression analysis was used to evaluate how musculoskeletal pains are associated a) with participation in a certain type of sport or exercise activity and b) with the clusters formed by latent class analysis (LCA) according to the adolescents' profiles of participation in different sport and exercise activities. RESULTS: Participation in certain sports showed some direct and inverse associations with musculoskeletal pains when adjusted for participation in other sports and for the amount of physical activity. However, after grouping the individuals into clusters by their participation in different sports, these associations vanished. Only the cluster characterized by boys' active participation in several sports (i.e., ice hockey, cycling, ice-skating, soccer, floorball, rinkball/bandy, swimming, roller-skating/skateboarding, Finnish baseball) had lower prevalence of neck pain compared with the physically inactive group. CONCLUSIONS: Physically active adolescents usually engage in several different sport and exercise activities, which make associations between single sports and musculoskeletal pains inconsequential in the general population of adolescents. Participation in several sports seemed to protect from harmful effects of a single risk sport. However, this finding cannot be generalized to adolescent elite athletes who are often involved in intense training for a single sport.

Promoter hypermethylation in tumour suppressor genes shows association with stage, grade and invasiveness of bladder cancer.

AIMS: Superficial bladder cancer is a highly recurrent disease, with progression to muscle invasiveness occurring in 15-30% of cases. Promoter hypermethylation in a panel of tumour suppressor genes involved in cell cycle control, apoptosis and DNA repair was analyzed in superficial bladder tumours in order to evaluate the suitability of epigenetic biomarkers for an earlier prediction of the aggressive course of the disease. METHOD: Promoter hypermethylation in p16, RARbeta, RASSF1A, DAPK, and MGMT genes was analyzed in 58 cases with superficial bladder cancer and 2 cases with benign urological disease using methylation-specific PCR. RESULTS: Promoter hypermethylation was frequently detected in RARbeta, RASSF1A and DAPK genes, and 62% of bladder tumours exhibited hypermethylation in at least one gene. The overall frequency of hypermethylation and the number of genes involved increased with tumour stage, grade and muscle invasiveness. Aberrant methylation of RASSF1A and RARbetawas predominant (p < 0.05) in muscle-invasive tumours and high-grade tumours, respectively. Cases with concurrent hypermethylation in DAPK, p16 and RARbeta genes were moresusceptible to relapse. CONCLUSION: The results suggest analysis of promoter hypermethylation as a valuable biomarker for prognosis of the aggressive course of disease in bladder cancer.

Isometric trunk muscle strength and body sway in relation to low back pain in young adults.

STUDY DESIGN: A cross-sectional study on young adults. OBJECTIVE: To evaluate the relationships between low back pain (LBP), maximal isometric trunk muscle strength, and body sway among young adults. SUMMARY OF BACKGROUND DATA: The results of previous studies evaluating the association between trunk muscle strength and LBP are conflicting and heterogeneous. Furthermore, there are only few studies on the association between body sway and LBP. METHODS: The subjects (n = 874) belonged to a subcohort of the Northern Finland Birth Cohort 1986 (mean age 19 years). Trunk muscle strength and body sway were measured from all subjects. LBP symptoms were inquired with a questionnaire, which was completed concurrently with the examinations. Latent Class Analysis (LCA) was used to cluster the subjects according to their LBP symptoms. RESULTS: LCA analysis produced 6 clusters differing with respect to LBP symptoms. There were no statistically significant differences between the clusters in trunk muscle strength or body sway. CONCLUSION: LBP does not seem to be associated with maximal isometric trunk muscle strength or body sway in young adults.

Behavior of aluminum in aluminum welders and manufacturers of aluminum sulfate--impact on biological monitoring.

OBJECTIVES: The suitability of determining aluminum in serum or urine as a form of biological monitoring was critically assessed. METHODS: Airborne and internal aluminum exposure was assessed for 12 aluminum welders in a shipyard and 5 manufacturers of aluminum sulfate. Particles were characterized with X-ray diffraction and scanning electron microscopy. Aluminum in air and biological samples was analyzed using electrothermal atomic absorption spectrometry. Basic toxicokinetic features were inferred from the data. RESULTS: The mean 8-hour time-weighted average concentration of aluminum was 1.1 (range 0.008-6.1) mg/m(3) for the shipyard and 0.13 (range 0.02-0.5) mg/m(3) for the aluminum sulfate plant. Welding fume contained aluminum oxide particles <0.1 microm in diameter and their agglomerates, whereas bauxite and aluminum sulfate particles ranged from 1 to 10 microm in diameter. The shipyard welders' mean postshift serum and urinary concentrations of aluminum (S-Al and U-Al, respectively) were 0.22 and 3.4 micromol/l, respectively, and the aluminum sulfate workers' corresponding values were 0.13 and 0.58 micromol/l. Between two shifts, the welders' S-Al concentration decreased by about 50% (P<0.01), but their U-Al concentration did not change (P=0.64). No corresponding temporal changes occurred among the aluminum sulfate workers. After aluminum welding at the shipyard had ceased, the median S-Al concentration decreased by about 50% (P=0.007) within a year, but there was no change (P=0.75) in the corresponding U-Al concentration. CONCLUSIONS: About 1% of aluminum in welding fume appears to be rapidly absorbed from the lungs, whereas an undetermined fraction is retained and forms a lung burden. A higher fractional absorption of aluminum seems possible for aluminum sulfate workers without evidence of a lung burden. After rapid absorption, aluminum is slowly mobilized from the lung burden and dominates the S-Al and U-Al concentrations of aluminum welders. For kinetic reasons, S-Al or U-Al concentrations cannot be used to estimate the accumulation of aluminum in the target organs of toxicity. However, using U-Al analysis to monitor aluminum welders' lung burden seems practical.

Occupational and genetic risk factors associated with intervertebral disc disease.

STUDY DESIGN: Cross-sectional epidemiologic study. OBJECTIVE: To evaluate the interaction between known genetic risk factors and whole-body vibration for symptomatic intervertebral disc disease (IDD) in an occupational sample. SUMMARY OF BACKGROUND DATA: Risk factors of IDD include, among others, whole-body vibration and heredity. In this study, the importance of a set of known genetic risk factors and whole-body vibration was evaluated in an occupational sample of train engineers and sedentary controls. METHODS: Eleven variations in 8 genes (COL9A2, COL9A3, COL11A2, IL1A, IL1B, IL6, MMP-3, and VDR) were genotyped in 150 male train engineers with an average of 21-year exposure to whole-body vibration and 61 male paper mill workers with no exposure to vibration. Subjects were classified into IDD-phenotype and asymptomatic groups, based on the latent class analysis. RESULTS: The number of individuals belonging to the IDD-phenotype was significantly higher among train engineers (42% of train engineers vs. 17.5% of sedentary workers; P = 0.005). IL1A -889T allele represented a significant risk factor for the IDD-phenotype both in the single marker allelic association test (P = 0.043) and in the logistic regression analysis (P = 0.01). None of the other allele markers was significantly associated with symptoms when analyzed independently. However, for all the SNP markers considered, whole-body vibration represents a nominally significant risk factor. CONCLUSION: The results suggest that whole-body vibration is a risk factor for symptomatic IDD. Moreover, whole-body vibration had an additive effect with genetic risk factors increasing the likelihood of belonging to the IDD-phenotype group. Of the independent genetic markers, IL1A -889T allele had strongest association with IDD-phenotype.

Inhalation exposure to 1,3-butadiene and styrene in styrene-butadiene copolymer production.

This study assessed personal exposure to 1,3-butadiene (BD) and styrene in three plants manufacturing styrene-butadiene (SB) copolymers. Air samples were collected from the breathing zone of 28 workers over 4 months in three SB plants using diffusive samplers. The total number of samples was 885 with the number of samples per participant varying from 19 to 39. Samples were collected by use of 3M 3500 passive monitors and analyzed with a gas chromatograph (GC). Sampling proved to be simple and inexpensive and laboratory analysis of BD could detect 0.01 and 0.007 part per millions (ppm) of styrene in the 8h samples. In the case of BD, 624 samples were below the limit of quantification (LOQ), 240 samples were between the LOQ and 1 ppm, and 21 samples exceeded the threshold limit value (TLV). In the case of styrene 336 samples were below the LOQ, 548 samples were between the LOQ and 20 ppm. The TLV was exceeded once. The data gives a comprehensive picture of personal exposure of workers in modern SB latex manufacturing plants. The study illustrates also how the new TLV of BD is being implemented.