Work-related neck and upper limb disorders - quantitative exposure-response relationships adjusted for personal characteristics and psychosocial conditions.

BACKGROUND: We have previously reported quantitative exposure-response relationships between physical exposures recorded by technical methods, and complaints and diagnoses in the neck/shoulders, and the elbows/hands, based on group data. In the present study the number of workers was doubled, and information on individual factors, and psychosocial working conditions was used. Relationships between various kinds of exposure and response have been analysed in this larger and more detailed sample. METHODS: The prevalence of complaints (Nordic Questionnaire) and diagnoses (clinical examination) were recorded in a number of occupational groups within which the participants had similar work tasks, 34 groups of female employees (N = 4733 women) and 17 groups of male employees (N = 1107 men). Age and other individual characteristics were recorded, as well as psychosocial work environment factors (job-content questionnaire) for most participants. Postures and velocities (inclinometry) of the head (N = 505) and right upper arm (N = 510), right wrist postures and velocities (electrogoniometry; N = 685), and muscular activity (electromyography; EMG) in the right trapezius muscle (N = 647) and forearm extensors (N = 396) were recorded in representative sub-groups. Exposure-response relationships between physical exposure and musculoskeletal disorders, adjusted for individual factors with Poisson regression were then calculated. The effect of introducing psychosocial conditions into the models was also assessed. RESULTS: Associations were found between head velocity, trapezius activity, upper arm velocity, forearm extensor activity and wrist posture and velocity, and most neck/shoulder and elbow/hand complaints and diagnoses. Adjustment for age, other individual characteristics and psychosocial work conditions had only a limited effect on these associations. For example, the attributable fraction for tension neck syndrome among female workers with the highest quintile of trapezius activity was 58%, for carpal tunnel syndrome versus wrist velocity it was 92% in men in the highest exposure quintile. CONCLUSIONS: Based on the findings, we propose threshold limit values for upper arm and wrist velocity.

Fish consumption and risk of stroke: a second prospective case-control study from northern Sweden.

BACKGROUND: Fish consumption has been concluded to be associated with decreased risk of stroke in several reviews. However, among men, but not women, an increased risk of stroke was previously found at high fish consumption (>3 meals/week) in northern Sweden. This study investigates if previous results on elevated stroke risk with high fish consumption in men in northern Sweden can be confirmed in a larger study with new cases in the same population. METHODS: A prospective nested case-control study was performed within the population-based Northern Sweden Health and Disease Study cohort. Information on fish consumption, other lifestyle and medical data was collected at baseline. Incident stroke cases (1987-2007, n = 735) were identified and 2698 controls matched for gender, age, year of baseline and geographical region. RESULTS: There were no associations between total fish or fatty fish consumption and stroke risk; thus the previous finding of increased risk of stroke with high fish consumption in men could not be repeated. High intake of lean fish (>twice/week compared to < once/month) was associated with increased stroke risk in men [OR 1.80 (95% CI 1.00, 3.21), but not in women [OR 0.50 (95% CI 0.24, 1.10)]. The association was driven by men living alone. CONCLUSIONS: The previous association between high total fish consumption and risk of stroke in men could not be repeated. The increased risk found in men with high intake of lean fish may be due to chance or confounding specific for this group.

Associations between cadmium exposure and circulating levels of sex hormones in postmenopausal women.

Recent epidemiological as well as in vivo and in vitro studies collectively suggest that the metalloestrogen cadmium (Cd) could be a potential risk factor for hormone-related cancers in particularly breast cancer. Assessment of the association between Cd exposure and levels of endogenous sex hormones is of pivotal importance, as increased levels of such have been associated with a higher risk of breast cancer in postmenopausal women. The present study investigated the perceived relationship (multivariable-adjusted linear regression analyses) between Cd exposure [blood Cd (B-Cd) and urinary Cd (U-Cd)], and serum levels of androstenedione, testosterone, estradiol, and sex-hormone binding globulin (SHBG), in 438 postmenopausal Swedish women without hormone replacement therapy (HRT). A significant positive association between B-Cd (median 3.4 nmol/L) and serum testosterone levels, as well as a significant inverse association between B-Cd and serum estradiol levels and with the estradiol/testosterone ratio were encountered. However, U-Cd (median 0.69 nmol/mmol creatinine) was inversely associated with serum estradiol levels only. Our data may suggest that Cd interferes with the levels of testosterone and estradiol in postmenopausal women, which might have implications for breast cancer risk.

End-stage renal disease and low level exposure to lead, cadmium and mercury; a population-based, prospective nested case-referent study in Sweden.

BACKGROUND: Cadmium (Cd), lead (Pb), and mercury (Hg) cause toxicological renal effects, but the clinical relevance at low-level exposures in general populations is unclear. The objective of this study is to assess the risk of developing end-stage renal disease in relation to Cd, Pb, and Hg exposure. METHODS: A total of 118 cases who later in life developed end-stage renal disease, and 378 matched (sex, age, area, and time of blood sampling) referents were identified among participants in two population-based prospective cohorts (130,000 individuals). Cd, Pb, and Hg concentrations were determined in prospectively collected samples. RESULTS: Erythrocyte lead was associated with an increased risk of developing end-stage renal disease (mean in cases 76 µg/L; odds ratio (OR) 1.54 for an interquartile range increase, 95% confidence interval (CI) 1.18-2.00), while erythrocyte mercury was negatively associated (2.4 µg/L; OR 0.75 for an interquartile range increase, CI 0.56-0.99). For erythrocyte cadmium, the OR of developing end-stage renal disease was 1.15 for an interquartile range increase (CI 0.99-1.34; mean Ery-Cd among cases: 1.3 µg/L). The associations for erythrocyte lead and erythrocyte mercury, but not for erythrocyte cadmium, remained after adjusting for the other two metals, smoking, BMI, diabetes, and hypertension. Gender-specific analyses showed that men carried almost all of the erythrocyte lead and erythrocyte cadmium associated risks. CONCLUSIONS: Erythrocyte lead is associated with end-stage renal disease but further studies are needed to evaluate causality. Gender-specific analyses suggest potential differences in susceptibility or in exposure biomarker reliability.

Mercury in serum predicts low risk of death and myocardial infarction in Gothenburg women.

PURPOSE: Markers of mercury (Hg) exposure have shown both positive and negative associations with cardiovascular disease (CVD). We assessed the association between serum Hg (S-Hg) and risk of cardiovascular disease in a prospective population-based cohort, with attention to the roles of dental health and fish consumption. METHODS: Total mortality, as well as morbidity and mortality from acute myocardial infarction (AMI) and stroke, was followed up for 32 years in 1,391 women (initially age 38-60), in relation to S-Hg at baseline, using Cox regression models. Potential confounders (age, socioeconomic status, serum lipids, alcohol consumption, dental health, smoking, hypertension, waist-hip ratio, and diabetes) and other covariates (e.g., fish consumption) were also considered. RESULTS: Hazard ratios (HR) adjusted only for age showed strong inverse associations between baseline S-Hg and total mortality [highest quartile: hazard ratio (HR) 0.76; 95% confidence interval (CI) 0.59-0.97], incident AMI (HR 0.56; CI 0.34-0.93), and fatal AMI (HR 0.31; CI 0.15-0.66). Adjustment for potential confounding factors, especially dental health, had a strong impact on the risk estimates, and after adjustment, only the reduced risk of fatal AMI remained statistically significant. CONCLUSIONS: There was a strong inverse association between Hg exposure and CVD. Likely, reasons are confounding with good dental health (also correlated with the number of amalgam fillings in these age groups) and/or fish consumption. The results suggest potential effects of dental health and/or fish consumption on CVD that deserve attention in preventive medicine.

A regional comparison of children's blood cadmium, lead, and mercury in rural, urban and industrial areas of six European countries, and China, Ecuador, and Morocco.

OBJECTIVES: The authors aimed to evaluate whether blood cadmium (B-Cd), lead (B-Pb) and mercury (B-Hg) in children differ regionally in 9 countries, and to identify factors correlating with exposure. MATERIAL AND METHODS: The authors performed a cross-sectional study of children aged 7-14 years, living in 2007-2008 in urban, rural, or potentially polluted ("hot spot") areas (ca. 50 children from each area, in total 1363 children) in 6 European and 3 non-European countries. The authors analyzed Cd, Pb, and total Hg in blood and collected information on potential determinants of exposure through questionnaires. Regional differences in exposure levels were assessed within each country. RESULTS: Children living near industrial "hot-spots" had B-Cd 1.6 (95% CI: 1.4-1.9) times higher in the Czech Republic and 2.1 (95% CI:1.6-2.8) times higher in Poland, as compared to urban children in the same countries (geometric means [GM]: 0.13 µg/l and 0.15 µg/l, respectively). Correspondingly, B-Pb in the "hot spot" areas was 1.8 (95% CI: 1.6-2.1) times higher than in urban areas in Slovakia and 2.3 (95% CI: 1.9-2.7) times higher in Poland (urban GM: 19.4 µg/l and 16.3 µg/l, respectively). In China and Morocco, rural children had significantly lower B-Pb than urban ones (urban GM: 64 µg/l and 71 µg/l, respectively), suggesting urban exposure from leaded petrol, water pipes and/or coal-burning. Hg "hot spot" areas in China had B-Hg 3.1 (95% CI: 2.7-3.5) times higher, and Ecuador 1.5 (95% CI: 1.2-1.9) times higher, as compared to urban areas (urban GM: 2.45 µg/l and 3.23 µg/l, respectively). Besides industrial exposure, traffic correlated with B-Cd; male sex, environmental tobacco smoke, and offal consumption with B-Pb; and fish consumption and amalgam fillings with B-Hg. However, these correlations could only marginally explain regional differences. CONCLUSIONS: These mainly European results indicate that some children experience about doubled exposures to toxic elements just because of where they live. These exposures are unsafe, identifiable, and preventable and therefore call for preventive actions. Int J Occup Med Environ Health. 2023;36(3):349-64.

Retinol may counteract the negative effect of cadmium on bone.

Cadmium and high vitamin A intake are both proposed risk factors for low bone mineral density (BMD), but potential interactions have not been studied. Within the Women's Health in the Lund Area, a population-based study in southern Sweden, we measured retinol in serum among 606 women aged 54-64 y. Data on BMD were measured by DXA at the distal forearm. Parathyroid hormone (PTH), bone alkaline phosphatase (bALP), and osteocalcin in serum and deoxypyridinoline (DPD) and cadmium in urine were available. Associations were evaluated using multivariable-adjusted linear regression analysis. Serum retinol concentrations (median, 1.9; range, 0.97-4.3 µmol/L) were inversely associated with the bone formation markers bALP and osteocalcin (P ≤ 0.04) and with PTH (P = 0.07) and tended to be positively associated with BMD (P = 0.08) but not with the bone resorption marker DPD, indicating different effects on bone compared to urinary cadmium (median, 0.66; range, 0.12-3.6 nmol/mmol creatinine). Women with serum retinol less than the median and cadmium greater than the median had lower BMD than those with retinol greater than the median and cadmium less than the median (P = 0.016 among all women and P = 0.010 among never-smokers). Our findings suggest that adequate vitamin A status may counteract the adverse association between cadmium and BMD.

Evaluation of the impact of genetic polymorphisms in glutathione-related genes on the association between methylmercury or n-3 polyunsaturated long chain fatty acids and risk of myocardial infarction: a case-control study.

BACKGROUND: The n-3 polyunsaturated fatty acids eicosapentaenoic acid and docosahexaenoic acid, which are present in fish, are protective against myocardial infarction. However, fish also contains methylmercury, which influences the risk of myocardial infarction, possibly by generating oxidative stress. Methylmercury is metabolized by conjugation to glutathione, which facilitates elimination. Glutathione is also an antioxidant. Individuals with certain polymorphisms in glutathione-related genes may tolerate higher exposures to methylmercury, due to faster metabolism and elimination and/or better glutathione-associated antioxidative capacity. They would thus benefit more from the protective agents in fish, such as eicosapentaenoic+docosahexaenoic acid and selenium. The objective for this study was to elucidate whether genetic polymorphisms in glutathione-related genes modify the association between eicosapentaenoic+docosahexaenoic acid or methylmercury and risk of first ever myocardial infarction. METHODS: Polymorphisms in glutathione-synthesizing (glutamyl-cysteine ligase catalytic subunit, GCLC and glutamyl-cysteine ligase modifier subunit, GCLM) or glutathione-conjugating (glutathione S-transferase P, GSTP1) genes were genotyped in 1027 individuals from northern Sweden (458 cases of first-ever myocardial infarction and 569 matched controls). The impact of these polymorphisms on the association between erythrocyte-mercury (proxy for methylmercury) and risk of myocardial infarction, as well as between plasma eicosapentaenoic+docosahexaenoic acid and risk of myocardial infarction, was evaluated by conditional logistic regression. The effect of erythrocyte-selenium on risk of myocardial infarction was also taken into consideration. RESULTS: There were no strong genetic modifying effects on the association between plasma eicosapentaenoic+docosahexaenoic acid or erythrocyte-mercury and risk of myocardial infarction risk. When eicosapentaenoic+docosahexaenoic acid or erythrocyte-mercury were divided into tertiles, individuals with GCLM-588 TT genotype displayed a lower risk relative to the CC genotype in all but one tertile; in most tertiles the odds ratio was around 0.5 for TT. However, there were few TT carriers and the results were not statistically significant. The results were similar when taking plasma eicosapentaenoic+docosahexaenoic acid, erythrocyte-selenium and erythrocyte-mercury into account simultaneously. CONCLUSIONS: No statistically significant genetic modifying effects were seen for the association between plasma eicosapentaenoic+docosahexaenoic acid or erythrocyte-mercury and risk of myocardial infarction. Still, our results indicate that the relatively rare GCLM-588 TT genotype may have an impact, but a larger study is necessary for confirmation.

Geographical patterns in blood lead in relation to industrial emissions and traffic in Swedish children, 1978-2007.

BACKGROUND: Blood lead concentrations (B-Pb) were measured in 3 879 Swedish school children during the period 1978-2007. The objective was to study the effect of the proximity to lead sources based on the children's home and school location. METHODS: The children's home address and school location were geocoded and their proximity to a lead smelter and major roads was calculated using geographical information system (GIS) software. All the statistical analyses were carried out using means of generalized log-linear modelling, with natural-logarithm-transformed B-Pb, adjusted for sex, school year, lead-exposing hobby, country of birth and, in the periods 1988-1994 and 1995-2007, parents' smoking habits. RESULTS: The GIS analysis revealed that although the emission from the smelter and children's B-Pb levels had decreased considerably since 1978, proximity to the lead smelter continued to affect levels of B-Pb, even in recent years (geometric mean: near smelter: 22.90 microg/l; far from smelter 19.75 microg/l; p = 0.001). The analysis also revealed that proximity to major roads noticeably affected the children's B-Pb levels during the period 1978-1987 (geometric mean near major roads: 44.26 microg/l; far from roads: 38.32 microg/l; p = 0.056), due to the considerable amount of lead in petrol. This effect was, however, not visible after 1987 due to prohibition of lead in petrol. CONCLUSION: The results show that proximity to the lead smelter still has an impact on the children's B-Pb levels. This is alarming since it could imply that living or working in the vicinity of a former lead source could pose a threat years after reduction of the emission. The analysis also revealed that urban children exposed to lead from traffic were only affected during the early period, when there were considerable amounts of lead in petrol, and that the prohibition of lead in petrol in later years led to reduced levels of lead in the blood of urban children.

Risk of musculoskeletal disorders among females and males in repetitive/constrained work.

This paper combines epidemiological data on musculoskeletal morbidity in 40 female and 15 male occupational groups (questionnaire data 3720 females, 1241 males, physical examination data 1762 females, 915 males) in order to calculate risk for neck and upper limb disorders in repetitive/constrained vs. varied/mobile work and further to compare prevalence among office, industrial and non-office/non-industrial settings, as well as among jobs within these. Further, the paper aims to compare the risk of musculoskeletal disorders from repetitive/constrained work between females and males. Prevalence ratios (PR) for repetitive/constrained vs. varied/mobile work were in neck/shoulders: 12-month complaints females 1.2, males 1.1, diagnoses at the physical examination 2.3 and 2.3. In elbows/hands PRs for complaints were 1.7 and 1.6, for diagnoses 3.0 and 3.4. Tension neck syndrome, cervicalgia, shoulder tendonitis, acromioclavicular syndrome, medial epicondylitis and carpal tunnel syndrome showed PRs > 2. In neck/shoulders PRs were similar across office, industrial and non-office/non-industrial settings, in elbows/hands, especially among males, somewhat higher in industrial work. There was a heterogeneity within the different settings (estimated by bootstrapping), indicating higher PRs for some groups. As in most studies, musculoskeletal disorders were more prevalent among females than among males. Interestingly, though, the PRs for repetitive/constrained work vs. varied/mobile were for most measures approximately the same for both genders. In conclusion, repetitive/constrained work showed elevated risks when compared to varied/mobile work in all settings. Females and males showed similar risk elevations. This article enables comparison of risk of musculoskeletal disorders among many different occupations in industrial, office and other settings, when using standardised case definitions. It confirms that repetitive/constrained work is harmful not only in industrial but also in office and non-office/non-industrial settings. The reported data can be used for comparison with future studies.

Genetic variation in glutathione-related genes and body burden of methylmercury.

BACKGROUND: Exposure to toxic methylmercury (MeHg) through fish consumption is a large problem worldwide, and it has led to governmental recommendations of reduced fish consumption and blacklisting of mercury-contaminated fish. The elimination kinetics of MeHg varies greatly among individuals. Knowledge about the reasons for such variation is of importance for improving the risk assessment for MeHg. One possible explanation is hereditary differences in MeHg metabolism. MeHg is eliminated from the body as a glutathione (GSH) conjugate. OBJECTIVES: We conducted this study to assess the influence of polymorphisms in GSH-synthesizing [glutamyl-cysteine ligase modifier subunit (GCLM-588) and glutamyl-cysteine ligase catalytic subunit (GCLC-129)] or GSH-conjugating [glutathione S-transferase pi 1 (GSTP1-105 and GSTP1-114)] genes on MeHg retention. METHODS: Based on information obtained from questionnaires, 292 subjects from northern Sweden had a high consumption of fish (lean/fat fish two to three times per week or more). We measured total Hg in erythrocytes (Ery-Hg) and long-chain n-3 polyunsaturated fatty acids in plasma (P-PUFA; an exposure marker for fish intake). RESULTS: The GSTP1 genotype modified Ery-Hg; effects were seen for GSTP1-105 and -114 separately, and combining them resulted in stronger effects. We found evidence of effect modification: individuals with zero or one variant allele demonstrated a steeper regression slope for Ery-Hg (p=0.038) compared with individuals with two or more variant alleles. The GCLM-588 genotype also influenced Ery-Hg (p=0.035): Individuals with the GCLM-588 TT genotype demonstrated the highest Ery-Hg, but we saw no evidence of effect modification with increasing P-PUFA. CONCLUSIONS: These results suggest a role of GSH-related polymorphisms in MeHg metabolism.

Phthalate diesters and their metabolites in human breast milk, blood or serum, and urine as biomarkers of exposure in vulnerable populations.

BACKGROUND: Phthalates may pose a risk for perinatal developmental effects. An important question relates to the choice of suitable biological matrices for assessing exposure during this period. OBJECTIVES: This study was designed to measure the concentrations of phthalate diesters or their metabolites in breast milk, blood or serum, and urine and to evaluate their suitability for assessing perinatal exposure to phthalates. METHODS: In 2001, 2-3 weeks after delivery, 42 Swedish primipara provided breast milk, blood, and urine samples at home. Special care was taken to minimize contamination with phthalates (e.g., use of a special breast milk pump, heat treatment of glassware and needles, addition of phosphoric acid). RESULTS: Phthalate diesters and metabolites in milk and blood or serum, if detected, were present at concentrations close to the limit of detection. By contrast, most phthalate metabolites were detectable in urine at concentrations comparable to those from the general population in the United States and in Germany. No correlations existed between urine concentrations and those found in milk or blood/serum for single phthalate metabolites. Our data are at odds with a previous study documenting frequent detection and comparatively high concentrations of phthalate metabolites in Finnish and Danish mothers' milk. CONCLUSIONS: Concentrations of phthalate metabolites in urine are more informative than those in milk or serum. Furthermore, collection of milk or blood may be associated with discomfort and potential technical problems such as contamination (unless oxidative metabolites are measured). Although urine is a suitable matrix for health-related phthalate monitoring, urinary concentrations in nursing mothers cannot be used to estimate exposure to phthalates through milk ingestion by breast-fed infants.

Yearly measurements of blood lead in Swedish children since 1978: the declining trend continues in the petrol-lead-free period 1995-2007.

BACKGROUND: We have measured blood lead concentrations (B-Pb) in Swedish children, yearly since 1978. As reported previously, a substantial decrease of B-Pb was found for the period 1978-1994 (2440 children measured), as an effect of gradual reduction of lead in petrol. In another report focusing on the petrol-lead-free period 1995-2001, we noted that B-Pb seemed to stabilize at an average level close to 20 microg/L. OBJECTIVE: We here analyze data from the extended petrol-lead-free period 1995-2007. METHODS: B-Pb was measured in 1268 children, aged 7-11 years, from the municipalities of Landskrona and Trelleborg in southern Sweden, yielding 1407 measurements on B-Pb (since 139 children were measured in two different calendar years). RESULTS: We observed statistically significant decreases of the average concentrations during the recent years. The average B-Pb reduction rate was close to 5%/yr in the petrol-lead-free period 1995-2007; a similar reduction rate was estimated for the period with gradual reduction of lead in petrol, 1978-1994. The most recent geometric mean of B-Pb was 13.1 (range, 6.9-29.1)microg/L in Trelleborg (sample year 2005) and 13.2 (5.7-58.5)microg/L in Landskrona (2007). A declining B-Pb time trend was observed during the recent years among children who lived in near smelter, urban, and rural residential areas, respectively. B-Pb was influenced by the variables sex (boys had higher B-Pb), parents' smoking habits (children with one or both parents smoking had higher B-Pb), and potentially lead-exposing hobbies (for example, shooting air guns). CONCLUSION: Children's B-Pb levels can continue to decline markedly more than a decade after lead in petrol has been phased out in a country.

Biomonitoring of lead exposure-alternatives to blood.

Lead ( Pb) is one of the most important models for biomonitoring of exposure, with the blood Pb concentration as a predominant choice in practice and in epidemiology. In this article the alternatives for biomarkers to blood are reviewed. This overview focuses on a number of different qualities that are of importance in the evaluation of a biomarker's usefulness and performance. The qualities scrutinized included: (1) analytical accuracy and precision; (2) cost; (3) practical issues; (4) what is reflected by the biomarker; (5) relationship to exposure; and (6) relationship to effects. Data indicate that the best biomarker in some circumstances may be blood, but bone or teeth (for past exposures), feces (for current gastrointestinal exposure), or urine (for organic Pb) are sometimes more useful. A striking feature is that no generally accepted biomarker of bioavailable Pb exists, though plasma, bone, teeth, urine, and hair have all been discussed. For one of the most used applications of blood Pb, monitoring of lead workers' exposure, blood has important shortcomings in that it shows a poor response to changes in exposure at high levels. The alternative of plasma has not been sufficiently evaluated to be considered an alternative in occupational health services, although previous analytical problems are basically overcome. Possibly, urine deserves also more attention. Almost all biomarkers lack systematic data on variation within and between individuals.

Follow-up study of musculoskeletal disorders 20 months after the introduction of a mouse-based computer system.

OBJECTIVES: This study attempted to determine whether musculoskeletal health is influenced by mouse-intensive computer work. METHODS: The neck-upper limbs of 148 air-traffic controllers (71 women, 77 men) with demanding computer work were examined before (baseline) and a median of 20 months after (follow-up) a change from varied computer work to a mouse-based system, causing a significant change in the physical exposure of the workers (eg, lower variation of work postures and less rest in the forearm extensor muscles, as assessed by technical measurements). Complaints (according to a Nordic questionnaire), diagnoses (standardized physical examination), and psychosocial work environment (Copenhagen Psychosocial Questionnaire) were recorded. RESULTS: The air traffic controllers had consistently higher prevalences of disorders in the elbows-hands in the follow-up than at the baseline (complaints 30% versus 18%, P=0.03; diagnoses 10% versus 3.4%, P=0.02). The predominance of right-arm disorders was more pronounced in the follow-up than at the baseline. For the neck-shoulders-upper back, there was no consistent difference between the baseline and follow-up values; disorders increased significantly among the "young" controllers (< or =37 years), but not among the "older" ones. Perceived decision latitude decreased, while social support increased, but these changes did not explain the disorders that appeared in the elbows-hands. CONCLUSIONS: Intensive mouse-based computer work, with constrained posture and little rest in the forearm muscles, was associated with an increased risk of disorders in the elbows-hands. This finding should be considered for similar technological developments in other settings.

Gender differences in workers with identical repetitive industrial tasks: exposure and musculoskeletal disorders.

OBJECTIVES: For unknown reasons, females run a higher risk than males of work-related musculoskeletal disorders. The aim of this study was to evaluate whether male and female workers, with identical repetitive work tasks, differ concerning risk of disorders, physical or psychosocial exposures. METHODS: Employees in two industries were studied; one rubber manufacturing and one mechanical assembly plant. These industries were selected since in both, large groups of males and females worked side by side performing identical repetitive work tasks. Physical exposure was measured by technical equipment. Postures and movements were registered by inclinometry for the head and upper arms, and by electrogoniometry for the wrists. Muscular activity (muscular rest and %max) was registered by surface electromyography for m. trapezius and the forearm extensors (18 males and 19 females). Psychosocial work environment was evaluated by the demand-control-support model (85 males and 138 females). Musculoskeletal disorders were assessed (105 males and 172 females), by interview (last 7-days complaints), and by physical examination (diagnoses). RESULTS: Concerning physical exposure, females showed higher muscular activity related to maximal voluntary contractions [(%MVE); m. trapezius: females 18 (SD 9.2), males 12 (SD 4.3); forearm extensors: females 39 (SD 11), males 27 (SD 10), right side, 90th percentile]. Working postures and movements were similar between genders. Also, concerning psychosocial work environment, no significant gender differences were found. Females had higher prevalences of disorders [complaints: age-adjusted prevalence odds ratio (POR) 2.3 (95% CI 1.3-3.8) for neck/shoulders, 2.4 (1.4-4.0) for elbows/hands; diagnoses: neck/shoulder 1.9 (1.1-3.6), elbows/hands 4.1 (1.2-9.3)]. In 225 workers, PORs were adjusted for household work, personal recovery and exercise, which only slightly affected the risk estimates. CONCLUSION: In identical work tasks, females showed substantially higher muscular activity in relation to capacity, and higher prevalence of musculoskeletal disorders of the neck and upper extremity, than did males.

Neck postures in air traffic controllers with and without neck/shoulder disorders.

UNLABELLED: Prolonged computer work with an extended neck is commonly believed to be associated with an increased risk of neck-shoulder disorders. The aim of this study was to compare neck postures during computer work between female cases with neck-shoulder disorders, and healthy referents. Based on physical examinations, 13 cases and 11 referents were selected among 70 female air traffic controllers with the same computer-based work tasks and identical workstations. Postures and movements were measured by inclinometers, placed on the forehead and upper back (C7/Th1) during authentic air traffic control. A recently developed method was applied to assess flexion/extension in the neck, calculated as the difference between head and upper back flexion/extension. RESULTS: cases and referents did not differ significantly in neck posture (median neck flexion/extension: -10 degrees vs. -9 degrees ; p=0.9). Hence, the belief that neck extension posture is associated with neck-shoulder disorders in computer work is not supported by the present data.

Platinum, palladium, rhodium, molybdenum and strontium in blood of urban women in nine countries.

BACKGROUND: There is little reliable information on human exposure to the metals platinum (Pt), palladium (Pd) and rhodium (Rh), despite their use in enormous quantities in catalytic converters for automobile exhaust systems. OBJECTIVES: To evaluate blood concentrations of Pt (B-Pt), Pd (B-Pd) and Rh (B-Rh) in women from six European and three non-European countries, and to identify potentially influential factors. In addition, molybdenum (Mo) and strontium (Sr) were analysed. METHODS: Blood from 248 women aged 47-61 was analysed by high resolution inductively coupled plasma mass spectrometry under strict quality control. RESULTS: The medians were: B-Pt 0.8 (range <0.6-5.2), B-Pd <5 (<5-9.3), B-Rh <0.4 (<0.4-3.6)ng/L and B-Mo 2.0 (0.2-16) and B-Sr 16.6 (3.5-49) µg/L. Two women with highly elevated B-Pt (242 and 60ng/L), previously cancer treated with cis-platinum, were not included in the data analysis. All elements varied geographically (2-3 times) (B-Pd P=0.05; all other elements P<0.001); variations within each area were generally 5-10 times. Traffic was not associated with increased concentrations. CONCLUSIONS: General population blood concentrations of Pt, Pd and Rh are within or below the single digit ng/L range, much lower than in most previous reports. This is probably due to improved analytical performance, allowing for more reliable information at ultra-trace levels. In general, Mo and Sr agreed with previously reported concentrations. All elements showed geographical and inter-individual variations, but no convincing relationships with self-reported traffic intensity were found. Pt from the antineoplastic drug cis-platinum is retained in the body for years.

Impact of iron status on cadmium uptake in suckling piglets.

Low iron status is known to increase the uptake of dietary cadmium in both adolescents and adults and there are indications that cadmium is absorbed from the intestine by the two major iron transporters divalent metal transporter 1 (DMT1) and ferroportin 1 (FPN1). In addition, it has been suggested that duodenal metallothionein (MT) may limit the transport of cadmium across the intestinal epithelium. The present investigation was undertaken to examine whether iron status influences cadmium absorption in newborns by applying a model of suckling piglets and the possible roles of duodenal DMT1, FPN1 and MT. An oral cadmium dose (20 microg/kg body weight) was given daily for 6 consecutive days on postnatal days (PNDs) 10-15 to iron-deficient or iron-supplemented piglets. The cadmium dose was chosen to keep the cadmium level at a realistically low but still detectable level, and without inducing any adverse health effects in the piglets. As indicators of cadmium uptake, cadmium levels in blood and kidneys were measured on PND 16 by inductively coupled plasma-mass spectrometry (ICP-MS). Cadmium levels in blood were statistically significantly correlated with cadmium levels in kidneys. The cadmium uptake was not higher in iron-deficient suckling piglets; rather, we detected a higher cadmium uptake in the iron-supplemented ones. The expression and localisation of DMT1, FPN1 and MT were not affected by iron status and could therefore not explain the findings. Our results suggest that there are developmental differences in the handling of both iron and cadmium in newborns as compared to adults.

Cadmium-induced effects on bone in a population-based study of women.

High cadmium exposure is known to cause bone damage, but the association between low-level cadmium exposure and osteoporosis remains to be clarified. Using a population-based women's health survey in southern Sweden [Women's Health in the Lund Area (WHILA) ] with no known historical cadmium contamination, we investigated cadmium-related effects on bone in 820 women (53-64 years of age) . We measured cadmium in blood and urine and lead in blood, an array of markers of bone metabolism, and forearm bone mineral density (BMD) . Associations were evaluated in multiple linear regression analysis including information on the possible confounders or effect modifiers: weight, menopausal status, use of hormone replacement therapy, age at menarche, alcohol consumption, smoking history, and physical activity. Median urinary cadmium was 0.52 microg/L adjusted to density (0.67 microg/g creatinine) . After multivariate adjustment, BMD, parathyroid hormone, and urinary deoxypyridinoline (U-DPD) were adversely associated with concentrations of urinary cadmium (p < 0.05) in all subjects. These associations persisted in the group of never-smokers, which had the lowest cadmium exposure (mainly dietary) . For U-DPD, there was a significant interaction between cadmium and menopause (p = 0.022) . Our results suggest negative effects of low-level cadmium exposure on bone, possibly exerted via increased bone resorption, which seemed to be intensified after menopause. Based on the prevalence of osteoporosis and the low level of exposure, the observed effects, although slight, should be considered as early signals of potentially more adverse health effects. Key words: biochemical bone markers, bone mineral density, cadmium, lead, osteoporosis, women.