Vibration related symptoms and signs in quarry and foundry workers.

PURPOSE: The development of vascular and neurosensory findings were studied in two groups of long-term exposed quarry and foundry workers with different vibration exposures, working conditions and work tasks. METHODS: The study included 10 quarry workers (mean age 43 yrs., mean exposure time 16 yrs.) and 15 foundry workers (35 yrs.; 11 yrs.) at two plants in Sweden. All participants completed a basic questionnaire and passed a medical examination including a number of neurosensory tests, e.g. the determination of vibration (VPT) and temperature (TPT) perception thresholds as well as a musculoskeletal examination of the neck, shoulders, arms and hands. RESULTS: A high prevalence of neurosensory findings (40%) was found among the quarry workers. Both groups, however, showed a low prevalence of vibration white fingers (VWF). Foundry workers showed significantly better sensitivity than quarry workers for all monofilament tests (p ≤ 0.016), TPT warmth in dig 2 (p = 0.048) and 5 dexter (p = 0.008), and in dig 5 sinister (p = 0.005). They also showed a better VPT performance in dig 5 dexter (p = 0.031). CONCLUSIONS: Despite high vibration exposure, the prevalence of VWF was low. The high prevalence of neurosensory findings among the quarry workers may depend on higher A(8) vibration exposure and higher exposure to high-frequency vibrations. An age-effect and exposure to cold could also be contributing factors. The nervous system seems to be more susceptible to high-frequency vibrations than the vascular system. For neurosensory injuries, the current ISO 5349-1 standard is not applicable.

Work-related exposure to organic solvents and the risk for multiple sclerosis-a systematic review.

PURPOSE: Multiple sclerosis (MS) is a chronic progressive neurological disorder. Several environmental factors have been discussed as possible causing agents, e.g. organic solvents, whose impact on the disease is analysed in this review. METHODS: Systematic search strategies were used to identify high-quality studies of workers exposed to organic solvents, published up to September 30, 2019, in databases, such as PubMed, Cochrane library and Scopus. The exposure was in most studies obtained by questionnaires, supplemented with telephone interviews. The diagnosis MS was mainly detemined following a thorough neurological examination. Finally, fourteen case-control studies and two cohort studies met the inclusion criteria and were included in the meta-analysis. Random effects models were used to pool the results of the studies. RESULTS: The odds ratios from the 14 case-control studies included in the meta-analysis ranged from 0.12-4.0. Five case-control studies and one cohort study showed a significant association between the development of multiple sclerosis and exposure to organic solvents. The results from the other nine case-control studies and from one of the two cohort studies did not reach statistical significance. The pooled data from the 14 case-control studies gave an OR of 1.44 (95% CI 1.03-1.99), which shows a moderately increased risk of developing MS after exposure to organic solvents. CONCLUSIONS: The final interpretation of the result is that organic solvents may be slightly associated with an increased risk to develop MS. In addition, other factors, e.g. genetic markers and smoking, may contribute to the development of the disease.

Vibration-induced injuries in workers exposed to transient and high frequency vibrations.

BACKGROUND: The risk of developing vibration white fingers and neurosensory symptoms increases with the duration and intensity of the exposure. The aim of this study was to investigate the risk of developing vibration white fingers (VWF), neurosensory symptoms and musculoskeletal disorders among workers exposed to transient and high frequency vibrations. METHODS: The study included 38 vibration exposed workers from a loader assembly plant in Sweden (30 males and 8 females). All participants answered questionnaires and had a structured interview about work and medical history. A following medical examination included the determination of vibration and temperature perception thresholds and musculoskeletal symptoms in the neck, shoulder, elbow and hands. The individual vibration exposure expressed as A (8)-values and vibration exposure in minutes per day, were obtained from questionnaires answered by the participants. RESULTS: The prevalence of VWF was 30% among the male workers and 50% among the females. The corresponding prevalence of neurosensory symptoms was 70% among the males and 88% among the females. Musculoskeletal findings were common among the male workers. Dominant symptoms/syndromes were tension neck syndrome, biceps tendinitis, carpal tunnel syndrome and ulnar entrapment in hand/wrist. A total of 32 diagnoses were observed among the male workers and four diagnoses among the female workers. Numbness in fingers and age had the strongest impact on perceived work ability. CONCLUSIONS: ISO 5349-1 considerably underestimates the risks of VWF for this group of workers exposed to transient and high frequency vibrations. It is therefore important to develop a risk assessment standard also covering this frequency range.

Correction to: Vibration induced injuries in hands in long-term vibration exposed workers.

[This corrects the article DOI: 10.1186/s12995-019-0242-0.].

Style: J of occupational medicine and toxicology vibration induced injuries in hands in long-term vibration exposed workers.

INTRODUCTION: Long-term vibration exposure may cause neurophysiological disturbances such as numbness and tingling, reduced grip strength and difficulties in handling small objects. The dominant hand will usually have a higher vibration exposure than the non-dominant hand, which may cause more severe neurological symptoms and signs in the dominant hand. METHODS: The study is based on 47 (36 males and 11 females) vibration exposed workers, all former patients from the department of Occupational and Environmental medicine, Gothenburg university. The comparison group consisted of 18 randomly selected subjects from the general population of Gothenburg. All participants completed several questionnaires and had a standardized medical examination. Thereafter, neurophysiological tests such as the determination of vibration and thermal perception thresholds were performed, as well as muscle strength tests in hands and fingers. RESULTS: The temperature perception thresholds (TPTs) and the vibration perception thresholds (VPTs) did not differ significantly between the dominant and non-dominant hand in vibration exposed workers. The referents showed a significantly better performance (p ≤ 0.02 and p ≤ 0.034, respectively) than the workers for both TPTs and VPTs, indicating a negative effect on the Aß, as well as on the Aδ and C-fibers among the exposed workers.The Purdue Pegboard test showed a significantly better performance in the dominant vs non-dominant hand in both workers (p = 0.001) and referents (p = 0.033). The referents showed a better performance than the workers in both hands (p < 0.001). The Baseline handgrip, the Pinch grip and 3-Chuck grip tests did not differ significantly between the dominant and non-dominant hand in neither workers nor referents. CONCLUSIONS: In this study, minor differences between the dominant and non-dominant hand were noted for the Purdue Pegboard test in both workers and referents. Despite a probably higher vibration exposure in the dominant hand (mostly the right hand), however, quite similar test results were noted for VPTs, TPTs, Baseline handgrip, Pinch grip and 3-Chuck grip when comparing the dominant and non-dominant hand in the vibration exposed workers. In case of lack of time and financial obstacles, neurological tests in solely the dominant hand, will probably satisfactory reflect the conditions in the non-dominant hand.

Long-term effect of hand-arm vibration on thermotactile perception thresholds.

BACKGROUND: Occupational exposure to hand-transmitted vibration (HTV) is known to cause neurological symptoms such as numbness, reduced manual dexterity, grip strength and sensory perception. The purpose of this longitudinal study was to compare thermotactile perception thresholds for cold (TPTC) and warmth (TPTW) among vibration exposed manual workers and unexposed white collar workers during a follow-up period of 16 years to elucidate if long-term vibration exposure is related to a change in TPT over time. METHODS: The study group consisted of male workers at a production workshop at which some of them were exposed to HTV. They were investigated in 1992 and followed-up in 2008. All participants were physically examined and performed TPT bilaterally at the middle and distal phalanges of the second finger. Two different vibration exposure dosages were calculated for each individual, i.e. the individual cumulative lifetime dose (mh/s2) or a lifetime 8-h equivalent daily exposure (m/s2). RESULTS: A significant mean threshold difference was found for all subjects of about 4-5 °C and 1-2 °C in TPTW and TPTC, respectively, between follow-up and baseline. No significant mean difference in TPTC between vibration exposed and non-exposed workers at each occasion could be stated to exist. For TPTW a small but significant difference was found for the right index finger only. Age was strongly related to thermotactile perception threshold. The 8-h equivalent exposure level (A (8)) dropped from about 1.3 m/s2 in 1992 to about 0.7 m/s2 in 2008. CONCLUSIONS: A lifetime 8-h equivalent daily exposure to hand-transmitted vibration less than 1.3 m/s2 does not have a significant effect on thermotactile perception. Age, however, has a significant impact on the change of temperature perception thresholds why this covariate has to be considered when using TPT as a tool for health screening.

Test-retest reliability of neurophysiological tests of hand-arm vibration syndrome in vibration exposed workers and unexposed referents.

BACKGROUND: Exposure to hand-held vibrating tools may cause the hand-arm vibration syndrome (HAVS). The aim was to study the test-retest reliability of hand and muscle strength tests, and tests for the determination of thermal and vibration perception thresholds, which are used when investigating signs of neuropathy in vibration exposed workers. METHODS: In this study, 47 vibration exposed workers who had been investigated at the department of Occupational and Environmental Medicine in Gothenburg were compared with a randomized sample of 18 unexposed subjects from the general population of the city of Gothenburg. All participants passed a structured interview, answered several questionnaires and had a physical examination including hand and finger muscle strength tests, determination of vibrotactile (VPT) and thermal perception thresholds (TPT). Two weeks later, 23 workers and referents, selected in a randomized manner, were called back for the same test-procedures for the evaluation of test-retest reliability. RESULTS: The test-retest reliability after a two week interval expressed as limits of agreement (LOA; Bland-Altman), intra-class correlation coefficients (ICC) and Pearson correlation coefficients was excellent for tests with the Baseline hand grip, Pinch-grip and 3-Chuck grip among the exposed workers and referents (N = 23: percentage of differences within LOA 91 - 100%; ICC-values ≥0.93; Pearson r ≥0.93). The test-retest reliability was also excellent (percentage of differences within LOA 96-100 %) for the determination of vibration perception thresholds in digits 2 and 5 bilaterally as well as for temperature perception thresholds in digits 2 and 5, bilaterally (percentage of differences within LOA 91 - 96%). For ICC and Pearson r the results for vibration perception thresholds were good for digit 2, left hand and for digit 5, bilaterally (ICC ≥ 0.84; r ≥0.85), and lower (ICC = 0.59; r = 0.59) for digit 2, right hand. For the latter two indices the test-retest reliability for the determination of temperature thresholds was lower and showed more varying results. CONCLUSION: The strong test-retest reliability for hand and muscle strength tests as well as for the determination of VPTs makes these procedures useful for diagnostic purposes and follow-up studies in vibration exposed workers.

A prospective cohort study investigating an exposure-response relationship among vibration-exposed male workers with numbness of the hands.

OBJECTIVE: The aim of this study was to investigate the exposure-response relationship of hand-arm vibration exposure to neurological symptoms (numbness) of the hand in a cohort of vibration-exposed workers. METHODS: The baseline cohort comprised 241 office and manual workers with and without exposure to hand-arm vibration. Numbness (the symptom or event) in the hand was assessed for all subjects at baseline and follow-ups after 5, 10, and 16 years. The workers were stratified into quartiles with no exposure in the first quartile and increasing intensity of exposure in quartiles 2-4 (groups 1-3). Data analysis was performed using survival analysis (time to event). Information on cumulative exposure and years of exposure to event was collected via questionnaires. Measurements were performed in accordance with the International Organization for Standardization (ISO) 5349-1. RESULTS: The hazard ratio (HR) of risk of event (numbness) differed statistically significantly between the non-exposed group (group 0) and the two higher exposure groups (groups 2 and 3). There was also a significant ratio difference between the lowest exposure group (group 1) and the two higher groups. The ratio for group 1 was 1.77 [95% confidence interval (95% CI) 0.96-3.26] compared with 3.78 (95% CI 2.15-6.62) and 5.31 (95% CI 3.06-9.20) for groups 2 and 3, respectively. CONCLUSION: The results suggest a dose-response relationship between vibration exposure and numbness of the hands. This underlines the importance of keeping vibration levels low to prevent neurological injury to the hands.

Noise disturbances in daycare centers before and after acoustical treatment.

The authors' aim was to study noise-related problems in personnel at Swedish daycare centers. The authors' study comprised staff (N = 81) who completed a questionnaire (noise, illumination, indoor climate, hearing problems) at five daycare centers with noise problems. After basic and activity sound measurements, absorbers were attached to the ceilings and to two adjacent walls in the playing and dining rooms. Thereafter, basic and activity sound measures were repeated and the questionnaire was also repeated six months later. The acoustical treatment reduced the sound pressure levels by 2 to 6 dB in the playing rooms and by 0 to 3 dB in the dining rooms. The reverberation time was reduced by 20% to 50%. After the treatment the perceived noise disturbance level decreased slightly but not significantly and the proportion of the staff who often or very often planned the daily activities to reduce the noise level had decreased from about 39% to 25%. Similarly, the percentage that often or very often had a need for silence after work had decreased from 42% to 37%.

Quantitative neurosensory findings, symptoms and signs in young vibration exposed workers.

BACKGROUND: Long-term exposure to hand-held vibrating tools may cause the hand arm vibration syndrome (HAVS) including vibration induced white fingers and sensorineural symptoms. The aim was to study early neurosensory effects by quantitative vibrotactile and monofilament tests in young workers with hand-held vibration exposure. METHODS: This cross-sectional study consisted of 142 young, male machine shop and construction workers with hand-held exposure to vibrating tools. They were compared with 41 non-vibration exposed subjects of the same age-group. All participants passed a structured interview, answered several questionnaires and had a physical examination including the determination of vibrotactile perception thresholds (VPTs) at two frequencies (31.5 and 125 Hz) and Semmes Weinstein's Monofilament test. RESULTS: In the vibration exposed group 8% of the workers reported episodes of tingling sensations and 10% numbness in their fingers. Approximately 5-10% of the exposed population displayed abnormal results on monofilament tests. The vibrotactile testing showed significantly increased VPTs for 125 Hz in dig II bilaterally (right hand, p = 0.01; left hand, p = 0.024) in the vibration exposed group.A multiple regression analysis (VPT - dependent variable; age, height, examiner and five different vibration dose calculations - predictor variables) in dig II bilaterally showed rather low R2-values. None of the explanatory variables including five separately calculated vibration doses were included in the models, neither for the total vibration exposed group, nor for the highest exposed quartile.A logistic multiple regression analysis (result of monofilament testing - dependent variable; age, height, examiner and five vibration dose calculations - predictor variables) of the results of monofilament testing in dig II bilaterally gave a similar outcome. None of the independent variables including five calculated vibration doses were included in the models neither for the total exposed group nor for the highest exposed quartile. CONCLUSION: In spite of the fairly short vibration exposure, a tendency to raised VPTs as well as pathologic monofilament test results was observed. Thus, early neurophysiologic symptoms and signs of vibration exposure may appear after short-term exposure also in young workers.

Physical capacity and psychological mood in association with self-reported work ability in vibration-exposed patients with hand symptoms.

BACKGROUND: The aim of this study was to investigate whether self-reports of work ability correlated to the results of quantitative tests measuring physical capacity and a questionnaire assessing psychological mood in vibration-exposed patients with hand symptoms. METHODS: The participants comprised 47 patients (36 men and eleven women) with exposure to hand vibration and vascular and/or neurological symptoms in the hands. They performed several quantitative tests (manual dexterity, hand grip strength, finger strength) and completed the Work Ability Index (WAI) and Hospital Anxiety and Depression Scale (HADS) questionnaires. RESULTS: Correlation analysis revealed statistically significant associations between the WAI results, the HADS indices, hand grip and finger strength, and manual dexterity measured using the Purdue Pegboard®. Multiple regression analysis revealed age and HADS indices as the strongest predictors of work ability. CONCLUSIONS: The patient's age and psychological mood may be stronger predictors of work ability compared with results from tests measuring physical capacity of the hands in vibration-exposed patients with hand symptoms. When using the WAI as an instrument for assessing work ability in these patients, health care providers need to be more aware of the impact of the psychological mood.

Exposure and toxic effects of elemental mercury in gold-mining activities in Ecuador.

Traditional gold mining, using metallic mercury (Hg(0)) to form gold amalgam, followed by burning to remove the Hg(0), is widely used in South America, Africa and Asia. The gold is sold to merchants who burn it again to eliminate remaining Hg(0). In Ecuador, 200 gold miners, 37 gold merchants and 72 referents were studied. The median Hg concentrations in urine (U-Hg) were 3.3 (range 0.23-170), 37 (3.2-420), and 1.6 (0.2-13)µg/g creatinine, respectively, and in whole blood (B-Hg) were 5.2, 30, and 5.0 µg/L, respectively. Biomarker concentrations among merchants were statistically significantly higher than among miners and referents; also the miners differed from the referents. Burning of gold amalgam among miners was intermittent; U-Hg decreased in the burning-free period. In computerized neuromotor examinations, B-Hg and U-Hg concentrations were associated with increases in the centre frequency of the tremor, as well as in reaction time and postural stability.Retention of Hg (B-Hg), and the elimination rate (U-Hg) appears to be modified by polymorphism in a gene of an enzyme in the glutathione synthesis (GCLM), but there were no significant genetic modifications for the associations between exposure and neurotoxicity.Thus, the gold merchants have a much higher exposure and risk than the miners, in whom the exposure varies over time. The metabolism of Hg is modified by genetic traits. The present exposure to Hg had limited neurotoxic effects.

Cerebrospinal fluid/plasma quotients of essential and non-essential metals in patients with Alzheimer's disease.

In this study, the quotients (Q) between metal concentrations in cerebrospinal fluid (CSF) and plasma were studied in subjects with Alzheimer's disease (AD) and referents to investigate if the leakage through the blood-CSF barrier (BCB) increased with increased duration and severity of the disease. Concentrations of 18 metals (Mg, Ca, Mn, Fe, Co, Ni, Cu, Zn, Se, Rb, Sr, Mo, Cd, Sn, Sb, Cs, Hg, and Pb) were determined by ICP-MS in plasma and cerebrospinal fluid in 264 patients with AD, and in 54 healthy referents. The quotients Q (Mn), Q (Rb), Q (Sb), Q (Pb) and Q (Hg) were significantly lower (p ≤ 0.003) and Q (Co) significantly higher (p ≤ 0.001) in subjects with AD as compared with the controls. Subjects in a subgroup with more severe AD, showed the same pattern. The metal leakage into CSF did not increase with increased duration and/or severity of the disease. The permeability of BCB varied considerably between the studied metals with low median quotients (Q ≤ 0.02) for Cd, Cu, Sb, Se and Zn and higher median quotients for Ca (Q ~ 0.5) and Mg (Q ~ 1.3), probably partly depending on differences in size and lipophilicity of metal-carrier complexes and specific carrier mechanisms.

Metal concentrations in blood and hair in pregnant females in southern Sweden.

The study described here was comprised of 100 pregnant females from two prenatal care units at the cities of Hassleholm and Simrishamn in southern Sweden. It included a questionnaire as well as whole blood (total mercury, cadmium, and lead) and hair (total mercury) sampling (collection period 2002-2003). The median values of total mercury (B-Hg 0.70 microg/L; range 0.27-2.1 microg/L), cadmium (0.30 microg/L, 0.05-4.8 microg/L) and lead (11.0 microg/L, 4.2-79 microg/L) in whole blood were low in the total material, as were the hair mercury concentrations (Hair-Hg 0.22 microg/g, 0.04-0.83 microg/g). In a multiple linear regression model, B-Hg was related to the number of fish meals per week and to the number of occlusal amalgam fillings (multiple r = 0.51; p < .001). The levels of mercury, cadmium, and lead in whole blood were lower than suggested biological reference intervals, and did not indicate risks for adverse health effects.

Cerebrospinal fluid total tau is associated with shorter survival in dementia with Lewy bodies.

A pathology typical of dementia with Lewy bodies (DLB) has been demonstrated to increase mortality to a greater extent than the pathology of Alzheimer's disease (AD). However, mortality in DLB has also been shown to increase with concomitant AD pathology. Furthermore, in a recent publication, we showed that there is a robust and specific increase in CSF calcium and magnesium in DLB patients compared to both AD patients and controls. Thus, in order to explore the influence of CSF AD markers and trace element concentrations on mortality in DLB, we undertook a longitudinal prospective study of 47 clinically diagnosed DLB patients and 157 AD patients as well as 49 healthy volunteers. Both AD and DLB patients showed an increased mortality compared to the healthy controls (relative risk: 10 and 8, respectively; p < 0.001). Increased levels of CSF total tau were associated with increased mortality among the DLB patients (p < 0.05), but not among the AD patients or controls. Gender, age, MMSE score, Abeta42 concentration and phosphorylated tau, and CSF trace element concentrations did not influence survival in the obtained models.

Concentrations of metals, beta-amyloid and tau-markers in cerebrospinal fluid in patients with Alzheimer's disease.

BACKGROUND/AIMS: In this study, metal concentrations were related to the levels of well-known Alzheimer markers in cerebrospinal fluid (CSF), such as amyloid-beta (Abeta), total tau (T-tau) and phosphorylated-tau (P-tau). METHODS: Concentrations of 19 metals (Mg, Ca, V, Mn, Fe, Co, Ni, Cu, Zn, Se, Rb, Sr, Mo, Cd, Sn, Sb, Cs, Hg and Pb by inductively coupled plasma-mass spectrometry) and the levels of Abeta, T-tau and P-tau in CSF were determined (xMAP technology) in 264 patients with Alzheimer's disease (AD), and in 54 healthy referents. RESULTS: The AD subjects showed positive correlations between CSF-T-tau and CSF-P-tau versus CSF-Mn (r(s) = 0.22, p = 0.004; r(s) = 0.18, p = 0.021). CSF-T-tau, however, showed a negative correlation with CSF-Cs (r(s) = -0.17; p = 0.027). In subjects with severe AD, CSF-Abeta showed a strong positive correlation with CSF-Cs (r(s) = 0.49; p = 0.026), while CSF-T-tau showed a strong negative correlation with CSF-Cs (r(s) = -0.49; p = 0.026). Also, CSF P-tau was negatively associated with CSF-Cs (r(s) = -0.41; p = 0.06). CONCLUSION: The different relationships between the CSF-levels of Abeta and tau-markers versus the levels of CSF-Mn and CSF-Cs may be due to different binding affinity between these metals and metal binding proteins in the CSF and the surrounding brain.

CSF Mg and Ca as diagnostic markers for dementia with Lewy bodies.

Accumulating evidence implicates a role for altered metal homeostasis in the pathogenesis of neurodegenerative disorders such as Alzheimer's disease (AD). However, few investigations have addressed this issue in dementia with Lewy bodies (DLB). The aim of the present study was to investigate metal concentrations in cerebrospinal fluid (CSF) and plasma from patients with DLB and other neurodegenerative disorders. To that end, CSF and plasma samples were collected from 29 patients with DLB, 174 patients with AD, 90 patients with AD with minor vascular components, and 51 healthy volunteers. Total concentrations of Mg, Ca, Mn, Fe, Cu, Zn, Rb, Sr, and Cs were determined using mass spectrometry. Patients with DLB had elevated Ca and Mg levels in CSF and Mg levels in plasma as compared to all other groups (p<0.001). Furthermore, a combination of CSF-Mg and CSF-Ca could distinguish DLB from AD with a sensitivity of 93% and a specificity of 85%. Cu levels in both CSF and plasma tended to be higher in DLB compared to the other groups, but these trends failed to reach significance after correction for multiple comparisons. Mn, Fe, Zn, Rb, and Sr concentration in CSF or plasma were similar in all groups. The observed elevations of CSF-Mg, CSF-Ca and CSF-Cu may contribute to or be associated with the neurodegenerative process in DLB. Furthermore, determination of CSF-Mg and CSF-Ca concentration may be a valuable tool in distinguishing DLB from AD.

Metal concentrations in plasma and cerebrospinal fluid in patients with Alzheimer's disease.

BACKGROUND/AIMS: The homeostasis of essential metals such as copper, iron, selenium and zinc may be altered in the brain of subjects with Alzheimer's disease (AD). METHODS: Concentrations of metals (magnesium, calcium, vanadium, manganese, iron, cobalt, nickel, copper, zinc, selenium, rubidium, strontium, molybdenum, cadmium, tin, antimony, cesium, mercury and lead) were determined in plasma and cerebrospinal fluid (CSF) by inductively coupled plasma mass spectrometry in 173 patients with AD and in 87 patients with the combination of AD and minor vascular components (AD + vasc). Comparison was made with 54 healthy controls. RESULTS: The plasma concentrations of manganese and total mercury were significantly higher in subjects with AD (p < 0.001) and AD + vasc (p

Lung cancer development in primary smelter workers: a nested case-referent study.

OBJECTIVE: The objective of this study was to study the impact of work-related exposure to mainly arsenic and lead versus smoking in primary smelter workers developing lung cancer. METHODS: In a cohort of 3979 primary smelter workers, 46 subjects had contracted respiratory malignancies. They were compared with 141 age-matched male referents by conditional logistic regression analysis. RESULTS: Cases showed a significantly higher smoking rate as compared with referents: odds ratio (OR) = 4.0; 95% confidence interval (CI) = 1.6-10.1; P = 0.003. When restricted to smokers (33 cases, 63 referents), the cumulative air arsenic exposure index, but not the lead exposure indices, was significantly higher among the cases: OR = 1.07; 95% CI = 1.02-1.11; P = 0.005. CONCLUSIONS: Cumulative arsenic exposure and smoking were identified as risk factors for the development of lung cancer; lead exposure, however, was not.

Plasma-lead concentration: investigations into its usefulness for biological monitoring of occupational lead exposure.

BACKGROUND: The lead concentration in plasma is correlated to that in whole blood with a two to fourfold variation. It has never been investigated if this variation is inter-individual. METHODS: Lead and hemoglobin were determined in blood and plasma from 13 lead workers with a history of relatively high blood-lead concentrations, sampled three times during 1 day. The variation in the distribution of lead between cells and plasma was studied, but not the variation in the lead concentrations as such. RESULTS: Blood hemoglobin decreased with rising plasma lead (0.9-3.0 microg/L). Regarding the distribution of lead, no effect of current exposure during the day or of recent meals appeared. As much as 84% of the overall variance of the distribution of lead between cells and plasma could be attributed to individual factors. After adjustment for erythrocyte volume fraction this decreased to 67%. Plasma samples with elevated hemoglobin concentrations (due to in vitro hemolysis) had somewhat elevated lead concentrations. CONCLUSIONS: Plasma lead is not significantly altered by variation in a single day's exposure and, therefore, the choice of time of the day is not critical for sampling. However, plasma lead is negatively correlated to blood hemoglobin and mild hemolysis (not visible by the eye) in a sample may increase plasma lead with up to 30%. Finally, plasma provides lead exposure information that differs from whole blood, but it is not clear which one of these is the biomarker with the closest relation to exposure and/or effects.