Biomedical subjects

A Smargiassi

Publications and source records attributed to A Smargiassi.

13 recordsLinked to original sources

PubMed2000

Assessment of exposure to manganese in welding operations during the assembly of heavy excavation machinery accessories.

Welder exposure to metals in various industrial sectors is poorly characterized. We had the opportunity to carry out an exploratory study to characterize manganese exposure in welding operations in a recently established Quebec factory that assembled accessories for heavy excavation machinery. Ten workers were sampled for total manganese for at least two consecutive days out of three followed by two consecutive days for respirable manganese (with a size selective sampler with a median cut-off of 4 microns), during a typical week in the summer of 1998. Parts being welded were characterized as large or small. Small parts were those being welded on tables during subassembly. Workers were divided into two groups according to the parts they were welding. Seventy-eight percent of the total manganese exposure levels of welding operations during the assembly of large accessories of heavy excavation machinery exceeded the manganese American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) of 0.20 mg/m3 (GM 0.24 mg/m3, n = 14) while none exceeded the TLV during the assembly of small pieces (GM 0.06 mg/m3, n = 8). Welding operations during the assembly of large heavy excavation machinery accessories may pose a significant health hazard. Considering the importance of task-related variables affecting exposure among workers, further studies are needed to better characterize exposure determinants of welding operations during the assembly of heavy excavation machinery accessories.

Adult↗

PubMed1997

Motor function, olfactory threshold, and hematological indices in manganese-exposed ferroalloy workers.

A cross-sectional study was conducted in 35 male subjects randomly selected from workers of a ferroalloy production plant and exposed to manganese (Mn) oxides; the objective was to detect early signs of neurologic impairment. The subjects' mean age was 39.4 years (SD, 8. 4); the average exposure duration was 14.5 years (range, 5-29 years). A control group of industrial workers not exposed to neurotoxic chemicals and comparable in age and confounding factors was recruited. The intensity of Mn exposure was moderate, as reflected by airborne Mn concentrations in total dust averaging 193 [corrected] micro g/m3. Mn levels in blood (MnB) and urine (MnU) were significantly higher in the Mn-exposed workers than in control workers. A relationship (not found with MnU) was found between MnB and a cumulative exposure index calculated on the basis of air concentration and exposure history for each subject (r = 0.52; r2 = 0.27; P = 0.002). Psychomotor function scores were lower among Mn-exposed subjects. The Aiming score was negatively correlated with MnB in the exposed group. The olfactory threshold did not differ between the two groups, although it was negatively associated with MnU in the exposed group. The white blood cell count results were significantly higher in Mn-exposed subjects than in controls. These findings show that an increase in Mn body burden is associated with an impairment of motor functions, whereas the increased excretion of Mn is related to an increased olfactory perception. Changes in numbers of leukocytes could indicate possible interferences of Mn with the immunological system.

Air Pollutants, Occupational↗

PubMed1997

Peripheral markers of catecholaminergic dysfunction and symptoms of neurotoxicity among styrene-exposed workers.

AIM: A cross-sectional investigation was carried out to assess possible relations between styrene-induced changes in three peripheral markers of catecholaminergic dysfunction and self-reported symptoms of neurotoxicity. SUBJECTS: Male workers (n = 46) aged 14-60 (mean 29.5) years who had been exposed to styrene for an average of 6 (0.2-29) years were recruited in glassfiber reinforced plastics plants. A control group of 30 blue-collar workers aged 22-52 (mean 35) years and with no history of exposure to chemicals was recruited from local industries. Styrene exposure ranged from 5 to 120 ppm (8 h-TWA), the median level being relatively low (25 ppm, 8 h-TWA). Styrene metabolites, mandelic and phenylglycoxylic acids (MAPGA) in the "next morning" urine spot samples ranged from 32.0 to 931.1 mg/g creatinine (median 186.5). METHODS: Platelet monoamine oxidases B (MAO B) and dopamine beta-hydroxylase (DBH) activities were assessed using methods based on HPLC and electrochemical detection. Plasma prolactin (PRL) was measured by a commercially available immunoassay. Questionnaire 16 (Q16) was used to survey self-reported symptoms. RESULTS: Although there was no difference in DBH activity between exposed workers and controls, the most highly exposed workers had significantly lower activity than control subjects. A tendency to lower platelet MAO B activity in exposed than in control subjects was observed. The prevalence of plasma DBH and platelet MAO B values below the lower reference limit was similar in the two groups. PRL values exceeding the upper reference limit were higher (14/46 vs 2/30) among styrene-exposed workers, who also exhibited significantly higher median levels (10.0 vs 5.7 micrograms/l) than control subjects. Although the number of reported symptoms was similar among exposed and control subjects, in the exposed group it was positively associated with urinary MAPGA (Rho = 0.30, P = 0.04). Of the three peripheral markers of catecholaminergic dysfunction, plasma DBH was the only parameter negatively related to both urinary MAPGA (F = 9.56, P = 0.003) and the number of reported symptoms (Rho = 0.23, P = 0.05). CONCLUSIONS: Plasma PRL appears to be a sensitive marker of styrene-induced tubero-infundibular dopaminergic dysfunction in male subjects. DBH in plasma and MAO B in platelets seem to be less suitable markers for biomonitoring effect at the individual level, although DBH was related to the number of reported symptoms and to internal dose. Further studies on a larger and more exposed population are necessary to clarify the significance of these markers for health and their predictive value with regard to both subjective disturbances and concurrently administered performance tests.

Adolescent↗

PubMed1995

Immunological changes among workers occupationally exposed to styrene.

The functional status of the immune system was investigated in a group of 71 workers exposed to styrene and in 65 control subjects, recruited according to the same selection criteria and comparable as to sex, age, and confounding variables. Air and biological monitoring were used to characterize styrene exposure (median of the main urinary metabolites in the "next-morning" spot samples: 106 mg/g creatinine). Phenotypic analysis of peripheral blood lymphocytes (PBL) by automated flow cytometry revealed a reduced proportion of T lymphocyte subsets (CD3+, CD4+ and CD4+45+), with no changes in CD8+, and a higher proportion of B lymphocytes (CD19+) among styrene-exposed workers. The exposed workers showed a higher proportion of activation markers, namely DR and interleukin-2 receptors (CD25). Immunoglobulin subclasses were comparable in the two groups. An increased prevalence of abnormally low values was apparent for CD2+, CD3+, CD4+, CD4+45+ and CD11b subsets among workers exposed to styrene, whereas CD19+, DR+ and CD25+ showed an increased prevalence of abnormally high values. Natural killer-related phenotypes (CD56+, CD56+16+, and CD56+16-) were more expressed among styrene workers, with average increase of 30%. However, the frequency distribution of the lytic activity of natural killer cells against K-562 target cells was shifted towards lower values in the exposed workers as compared to control subjects. Dose-response relationships between indices of internal dose and prevalence of abnormal values were detectable for T lymphocyte subsets, NK phenotypes, and activation markers. These findings suggest that moderate exposure to styrene is associated with an altered distribution of lymphocyte subsets.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Peripheral markers of catecholamine metabolism among workers occupationally exposed to manganese (Mn).

In a preliminary study of 11 men randomly selected in a ferro-alloy plant and of 15 control subjects, platelet monoamine oxidase (MAO) and serum dopamine beta-hydroxylase (DBH) activities were measured. A tendency towards lower MAO-B activity in the exposed workers as compared to control subjects (t = 1.95; P = 0.06) was found whereas DBH activity was similar. In the exposed group, a dose-effect relationship was noted between a manganese (Mn) cumulative exposure index (CEI) and DBH activity (R2 = 0.40, P < 0.05). Since DBH is an expression of catecholamine release, the relative increase in such activity could be envisaged as a compensatory mechanism to a reduced turnover rate as reflected by MAO-B activity. Owing to the limited sample size, these findings should be confirmed by further epidemiological and experimental studies.

Adult↗

PubMed1994

Nervous system dysfunction among workers with long-term exposure to manganese.

Neurological disorders, bearing many similarities to Parkinson's disease, have been associated with environmental and occupational exposure to manganese (Mn). To document early nervous system dysfunction associated with long-term exposure to Mn, a battery of neurofunctional tests was administered to workers employed in Mn alloy production. Study participation was 95% (n = 115). A matched pair design was used; actively working men, with no history of workplace exposure to neurotoxins, were recruited from the region as referents. Matching was done on the variables: age (+/- 3 years), educational level (+/- 2 years), smoking status, and number of children. Stationary environmental sampling indicated that Mn levels varied widely (geometric means: Mn dust, 0.89 mg/m3; respirable Mn, 0.04 mg/m3). The alloy workers had significantly higher levels of whole blood Mn (geometric mean: 1.03 microgram/100 ml vs 0.68 microgram/100 ml); no differences were observed for urinary Mn. Univariate analysis (paired t test, Signed Rank and McNemar) and multivariate analysis of variance (Hotelling-Lawley statistic) revealed that the pairs differed on symptom reporting, emotional state, motor functions, cognitive flexibility, and olfactory perception threshold; verbal fluency, basic mathematics, reading capability, and attentional capacity were similar. These findings are consistent with current knowledge on brain Mn activity and suggest that manifestations of early manganism can be observed in well designed population studies, using sensitive testing methods.

Adult↗

PubMed1994

Multiple interferences on catecholamine metabolism by tetrahydroisoquinolines (TIQs).

TIQs are thought to be formed by condensation between dopamine and certain metabolites of ethanol, organic solvents and anesthetic gases. Described here are experiments aimed at evaluating TIQs interference with catecholamine synthesis. Rat adrenal pheochromocytoma (PC12) cell lysates were exposed to benzyl-TIQ and phenyl-TIQ. The activities of tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH) were measured by HPLC-based methods following exposure to variable concentrations of TIQs. The effects of TIQs on DBH activity were also assessed in human serum. Dixon plot analyses revealed that TIQs act on TH as competitive inhibitors with different affinity. Ki for benzyl- and phenyl-TIQ were 5 and 3 microM respectively. DBH activity in serum exposed to benzyl- and phenyl-TIQ ranging from 0.2 to 20 microM rose respectively by 12.5% to 58% for benzyl- and by 7.8% to 26% for phenyl-TIQ. Such TIQs interferences with catecholamine metabolism seem to account for dopamine (DA) depletion observed in parallel in vitro experiments on PC12 cells. The dose-dependent inhibition of TH and the increased activity of DBH together with the relatively low effective doses of TIQs suggest this mechanism as a possible explanation of the selective toxicity of styrene and other solvents to dopaminergic systems observed in rabbits following experimental exposure and suspected to occur in occupationally-exposed workers.

Animals↗

PubMedDate not supplied

Blood manganese content at birth and cord serum prolactin levels.

Manganese (Mn) is both an essential element and, at a high dose, a potent neurotoxin that can interact with dopaminergic neurotransmission. Plasma prolactin (PRL), an indirect indicator of dopaminergic functioning, has been shown to vary with Mn exposure in adults, but little is known about this relation in the developing brain. The objective of this study was to examine the relations between maternal and cord Mn blood concentrations at birth and PRL cord blood levels. Blood Mn levels were determined in 87 pregnant women at delivery, and PRL was measured in the cord blood plasma. Mn cord blood concentration (mean 34.4 microg/l, range 16.7-89.4) was significantly and positively related to cord PRL levels. These findings suggest that Mn accumulation in utero could contribute to PRL level variation in neonates, which, in turn, may influence important developmental parameters.

Adolescent↗

PubMedDate not supplied

Selective vulnerability of dopaminergic systems to industrial chemicals: risk assessment of related neuroendocrine changes.

Increased serum prolactin (PRL) is a common finding among subjects exposed to styrene, perchloroethylene, lead (Pb), and manganese (Mn) at levels below the current threshold limit values. On a group basis, abnormally high basal PRL shows a dose-related distribution among workers exposed to styrene, Pb, and Mn. On the basis of dose-response relationships, the benchmark doses (BMD) for styrene metabolites in urine, lead in blood (Pb-B), and Mn in urine (Mn-U), are 4 mg/g creatinine, 112 micrograms/L, and 0.3 microgram/L, respectively. Noteworthy, the BMD for Mn-U and Pb-B is well below the upper reference limit. A shift in the distribution but not in the prevalence of abnormally high values of serum PRL was observed among perchloroethylene-exposed dry cleaners, which makes interpretation in terms of risk difficult. The measurement of PRL thus provides opportunities for early identification of excess exposure to neurotoxic chemicals affecting dopaminergic control of pituitary secretion. For styrene, Pb, and Mn the BMD provides an objective and statistically determined threshold, which seems to be in good agreement with the estimated no-observed-adverse-effect-level (NOAEL). The NOAEL, however, is based on traditional approaches that require the application of uncertainty factors, e.g., a default factor of 10 when extrapolating the NOAEL from the lowest-observed-adverse-effect-level (LOAEL). Due to its sensitivity to a number of potential confounders, caution must be exercised when using PRL as a screening test at the individual level. Also, age and sex dependent variations in susceptibility may hamper extrapolations from the occupational settings to the general population.

Biomarkers↗

PubMedDate not supplied

Peripheral biomarkers and exposure to manganese.

Biochemical mechanisms underlying manganese (Mn) toxicity include dopamine (DA) auto-oxidation and free radical generation with subsequent neuronal damage. A neuroendocrine approach based on the measurement of serum prolactin (PRL) has been proposed to assess the tonic inhibition of pituitary lactotrope cells by the tubero-infundibular DA system. Low level exposure to Mn oxides in industrial settings is associated with a shift in the distribution of serum PRL towards higher levels as compared to matched controls. The follow-up of a small cohort of workers from a ferro-manganese plant showed that the increased prevalence of abnormally high PRL values is stable over time. Although the mechanistic basis for their application is less straightforward, other biochemical markers such as dopamine beta hydroxylase and monoamine oxidase Type B, have also been assessed. Contrary to PRL levels, these markers cannot be recommended to monitor early biochemical effects of manganese exposure at the workplace. Early biochemical events can be modified by genetically determined individual differences. Owing to the possible role of a reduced capacity of glutathione conjugation as a risk factor increasing the susceptibility to the action of free radicals generated in the presence of Mn, the class mu glutathione S transferase (GSTM1) genotype has also been assessed in workers occupationally exposed. However, the GSTM1 null genotype does not appear to play an important role in the susceptibility to biochemical effects of Mn. A logistic model of the dose-response relationship based on urinary Mn as marker of exposure indicates that the benchmark dose corresponds to Mn levels as low as 0.4 microgram/l. This would imply that environmental exposure to Mn may contribute to abnormally high serum PRL in the general population.

Biomarkers↗

PubMedDate not supplied

Pilot study of peripheral markers of catecholaminergic systems among workers occupationally exposed to toluene.

In a pilot study, serum dopamine beta-hydroxylase (DBH), platelets monoamine oxidase type B (MAO B) activities and basal plasma prolactin (PRL) were measured, among 10 workers occupationally exposed to toluene and 10 control subjects, preceding and immediately following vacation. Six exposed subjects were employed in an adhesive tape making industry and 4 in a paint making industry. Their median basal levels of urinary hippuric acid were 0.44 mmole/mmole creatinine (cr) (range 0.23-1.97) and 0.18 mmole/mmole cr (range 0.15-0.19) respectively, the second to last morning of the work week, preceding vacation. The level of basal urinary hippuric acid among the control group was 0.26 mmole/mmole cr (range 0.03-0.38). The workers from the adhesive tape plant reported a significantly higher number of symptoms experienced frequently (Kruskal, Wallis, p < 0.05). On a group basis, serum DBH was lowest among the workers from the adhesive tape plant, who had the highest levels of basal urinary hippuric acid. In addition, a negative relation was observed between hippuric acid and serum DBH, preceding and following vacation (Rho = -0.46, p = 0.05; Rho = -0.51, p = 0.03). The observed changes in serum DBH activity are consistent with its decrease in human, following long-term exposure to styrene, another aromatic hydrocarbon. The findings of this pilot study, on a limited number of individuals suggest that DBH may be a sensitive peripheral bioindicator. Further studies of larger groups should be done to confirm the decrease in serum DBH activity with toluene exposure and explore whether this alteration is related to the neurotoxic impairments associated with exposure.

Adult↗

PubMedDate not supplied

Predictive validity of the Q16 questionnaire: a comparison between reported symptoms and neurobehavioral tests.

The correspondence between the answers to the Q16 questions regarding memory and attention-concentration and relevant neurobehavioral performance test scores has been evaluated. The sensitivity, specificity and diagnostic validity of Q16 have been assessed, taking the relevant neurobehavioral test score as a reference diagnostic criterion, the lower quartile of performance being considered as a poor response. The group under study consisted of 74 volunteers (24 females), aged 40 years on average (SD:7.5) and recruited among styrene-exposed workers and healthy controls. The test battery included the logical memory (short- and long-term) and the verbal learning (short- and long-term) tests of the Wechsler Adult Intelligence Scale (WAIS). The answers to the Q16 questions were poorly related to the performance: self-perceived forgetfulness showed a limited agreement with the long-term logical memory test (r=-0.23, p<0.05). The number of false negatives (no symptom but low test scores) was generally high, giving rise to a very low sensitivity of the questionnaire, despite a relatively high specificity. Accordingly, the positive diagnostic validity was low (<30%), whereas the negative diagnostic validity was high (>80%). Different methods used to investigate subtle neurological changes give rise to inconsistencies between self-perceived disturbances and objective measurements of relevant functions. Owing to its low sensitivity and positive diagnostic value, the Q16 cannot be recommended as a screening tool among workers occupationally exposed to neurotoxic chemicals.

Adult↗

PubMedDate not supplied

A case-control study of occupational and environmental risk factors for Parkinson's disease in the Emilia-Romagna region of Italy.

A questionnaire-based case-control study was carried out on 86 patients with neurologist-confirmed idiopathic Parkinson's disease (PD) and 86 controls similar in sex and age. The control group was recruited in outpatient specialist centers of the same University Hospital (glaucoma, psoriasis vulgaris, essential arterial hypertension and renal diseases). Exposure was defined as occupational or residential contact with a given factor for at least 10 consecutive years prior to the onset of PD. Smoking habits were defined by exclusion of those subjects who never smoked. The following risk factors were identified: cranial trauma (OR: 2.88; 95% CI: 0.98-8.49), well water use (OR: 2.78; 95% CI: 1.46-5.28) and occupational exposure to industrial chemicals (OR: 2.13; 95% CI: 1.16-3.91). Among industrial chemicals, only organic solvents were identified as significant risk factors for PD (O.R. : 2.78, 95% C.I. : 1.23-6.26). Whereas no exposure to neurotoxic metals occurred among controls, making the assessment of the O.R. impossible, exposure pesticides and herbicides was similar in the two groups (O.R. : 1.15; 95% C. : 0.56-2-36). Smoking habits was negatively associated with PD (OR: 0.41; 95% CI: 0.22-0.75), confirming the "protective" role of tobacco smoking suggested by many studies. As a whole, these results support the role of environmental factors in the etiology of PD.

Aged↗