The concentration of protoporphyrin IX in workers occupationally exposed to lead

In the study a relationship was undertaken between the concentration of erythrocyte protoporphyrin IX and concentrations of lead and hemoglobin in blood as well as iron serum concentration in men workers exposed to lead. The test group were 54 men, 28-56 years of age, occupationally exposed to lead for a period of 9-33 years. The control were 40 men not exposed to lead, between 25-60 years of age. The test group was divided into 3 subgroups according to exposure duration. As regards the concentrations of protoporphyrin and other parameters examined, the study revealed no significant differences between the subgroups. Those concentrations were also found to be similar in respective control groups. Significantly increased level of protoporphyrin IX concentration was noted in 17 men out of the whole test group. However as compared with other groups results, all the remaining parameters showed no difference. As regards the concentrations of iron in serum and hemoglobin in blood, they fell within the range of physiological values, in all the groups studied.     

Relationship between lead concentration in blood and biological response for porphyrin metabolism in workers occupationally exposed to lead

Summary The biological responses of the heme biosynthesis pathway in male workers moderately exposed to lead are discussed in relation to the concentration of lead in the blood. The level of erythrocyte delta-aminolevulinic acid dehydratase (ALA-D) activity in the group of lead-exposed workers was remarkably reduced while the level of erythrocyte protoporphyrin (Proto) in them was strikingly increased, compared to normal levels. On the other hand, the amounts of hemoglobin (Hb) and urinary delta-aminolevulinic acid (ALA) in the group of lead-exposed workers kept the normal levels.In the workers moderately exposed to lead, the log of erythrocyte Proto level was closely correlated to the blood lead level and the sensitivity of the Proto test was almost equal to that of erythrocyte ALA-D test. It was observed that the erythrocyte Proto was remarkably increased even in lead-exposed workers whose ALA excretion into the urine was in the range of normal level.     

Serum succinyltrialanine p-nitroanilide-hydrolytic activity in workers occupationally exposed to lead

The relationship between blood lead concentration and serum succinyltrialanine p-nitroanilide-hydrolytic (STN) activity was investigated in 74 workers occupationally exposed to lead and in 28 non-exposed workers. Exposure to lead was observed during transfer-printing processes in which paints or paint powders containing 20-50% lead were used. The mean lead concentration was 0.49 mg/m3 (0.12-1.43 mg/m3) in the working environment and 1.42 mg/m3 (0.21-4.34 mg/m3) in workers involved in printing processes. Serum STN activity became lower with increasing concentrations of blood lead (PbB) in non-exposed workers (controls). In lead-exposed workers, the activity decreased with increasing concentrations of PbB of 2.0 mumol/l and more, but increased when less than 1.9 mumol/l. Among lead-exposed workers with high PbB concentrations and/or with hepatic dysfunction, the STN/PbB ratio was distributed above the regression line obtained from the controls. The present investigation suggests that serum STN activity decreases in those highly exposed to lead. Enzymes such as elastase, which hydrolyzes succinyltrialanine p-nitroanilide and additionally is not inhibited by lead, may possibly be induced among lead workers when liver function is impaired.     

Effects of lead on neutrophil functions in occupationally exposed workers

Chemotactic and intracellular killing activity of neutrophils were examined in 25 male lead-exposed workers from storage-battery plants and compared to 25 healthy males with no history of lead exposure. Lead exposure was assessed using blood lead levels measured by atomic absorption spectrophotometry and zinc protoporphyrin levels assayed by hematofluorometry. Chemotaxis was carried out in Boyden chambers using zymosan activated serum as chemotactic stimulus. Intracellular killing activity of neutrophils was measured using nitroblue tetrazolium reduction test, measured of 515 nm in spectrophotometry. In lead-exposed workers a significant decrease in chemotaxis and random migration of neutrophils (p<0.001) was observed compared to controls. Intracellular killing activity of polymorphonuclear leukocytes have also seemed to be slightly but not significantly reduced. These results suggest that human chronic exposure to lead may diminish neutrophil function in man.     

Effect of lead on the levels of some immunoregulatory cytokines in occupationally exposed workers

Lead (Pb) may affect humoral and cellular immunity, acting on lymphocytes as well as on granulocytes and monocytes. Cytokines and nitric oxide (NO) play a central role in the immune balance. In this study, plasma levels of nitrites and nitrates (NOx), IL2, IL4, IL6, IL10, TNF-alpha and INF-gamma, were measured in healthy workers with very low (Pb-B=3.2-18.0 microg/dL) and low (Pb-B=9.1-46.0 microg/dL) Pb-exposure compared to non-exposed workers. Low Pb-exposed workers (Pb-B=9.1 -46.0 microg/ dL) were found to have significantly higher plasma IL-10 levels, and tendentially higher plasma TNF-alpha levels compared to non-exposed workers. This is the first report of a significant increase of plasma IL-10 levels in Pb-exposed workers. Plasma IL-10 increase was influenced by blood Pb levels even after correction for main confounding factors. No difference was found in plasma NOx levels between Pb-exposed and non-exposed workers, which is in agreement with previous findings exclusively regarding groups in the general population. Low Pb-exposure can induce an increase of pro-inflammatory cytokines, such as TNF-alpha, with a consequent increase of other cytokines, such as IL-10, considered a T cell cross-regulatory factor, suggesting possible interference of Pb in the system of immunophlogosis.     

Impaired endothelial function assessed by flow-mediated vasodilatation in workers occupationally exposed to lead

The aim of the study was to examine endothelial function in workers occupationally exposed to lead by means of FMD (flow-mediated dilatation). 44 men professionally exposed to lead, smelters and refiners, employees working at copper smelter and control group of 41 healthy men were enrolled into the study. Within the group of men occupationally exposed to lead the absolute increase in diameter after ischaemia (BAD, brachial artery diameter) and flow-mediated dilation were statistically less significant when compared to those of the control group. There was a negative linear correlation between FMD and lead concentration in copper smelters (r=-0.64). Multivariate backward step-wise regression analysis showed that blood lead concentration in copper smelters independently influenced the impairment of endothelial function expressed as decreased FMD value. In conclusion, results of our study suggest that endothelial function assessed by flow-mediated dilatation was impaired in workers occupationally exposed to lead.     

Gene expression and activity of antioxidant enzymes in the blood cells of workers who were occupationally exposed to lead

In this study, we sought to understand the influence of occupational lead-exposure on the gene expression (Sod1) and activity (SOD) of superoxide dismutase, catalase and glutathione peroxidase (GPx, Gpx1) in leukocytes and erythrocytes. The study group consisted of 45 healthy male employees of a lead-zinc works and was divided into two subgroups: those with low exposure to lead (LE) and those with high exposure to lead (HE). In addition, 17 healthy male administrative workers participated in the study as the control group. The gene expression levels of both Sod1 and Gpx1 were significantly increased in the LE group as compared to the control group. By contrast, we noted only an insignificant tendency for increased gene expression of both Sod1 and Gpx1 in the HE group. The expression and activity of catalase were unchanged. Nevertheless, SOD and GPx activities in erythrocytes was significantly elevated in both examined subgroups, whereas SOD activity in leukocytes was raised only in the LE group. The results of this study led us to conclude that lead has a significant influence not only on the activities of antioxidant enzymes but also on the dose-dependent expression in their genes.     

Neuropsychological effect of lead in occupationally exposed workers: a critical review

In their discussion of field testing of health effects of environmental and industrial toxins, Gullion and Eckerman make the following observations which can be applied to the current literature survey: "The general inattention to methodological consistency makes it difficult to integrate the research to date into a clear picture of what is known and not known about the effects of toxic substances on human behavior. In view of the variation in methods of subject selection, measurement, and statistical analysis, the completion of a series of studies of a particular toxic substance does not assure that there has been a concurrent accumulation of reliable knowledge about the effects of that substance. Apparent replications or failures to replicate a significant relationship must be evaluated carefully, since different studies may have measured different things in different populations." Therefore, the issue of psychological and neuropsychological effects of low-level lead exposure in adults remains to be resolved in the studies reviewed. The methodologies were so varied and the cultures in which the studies were conducted so diverse that it is impossible to generalize across findings. For example, studies were conducted in the U.S., Denmark, Sweden, Finland, and Australia. Although, in some instances, equivalent versions of neuropsychological and psychological tests were used, this was generally not the case. Nevertheless, a few general statements can be made. Studies that have been carried out in recent years are beginning to pay attention to more methodology and therefore do a much better job of controlling for possible confounding variables. Also, their statistical methods are more sophisticated and reporting techniques are superior to the earlier investigations in this area. The issue of whether current blood lead levels or cumulative levels are preferable is still unresolved with regard to the relationship of neuropsychological impairment. In the area of psychosocial functioning, there appears to be at least some evidence to support the observation that increased irritability and fatigue may lead to the interpersonal problems noted in various studies. However, this observation may be related to other factors which have not been controlled for, such as the workers' attitudes toward their job, level of motivation, and overall level of mental health. With regard to neuropsychological functions, there is some suggestive preliminary evidence for subtle changes in the ability to process information quickly.(ABSTRACT TRUNCATED AT 400 WORDS)     

Effects of lead on polymorphonuclear leukocyte (PMN) functions in occupationally exposed workers

Previous in vitro experiments have shown that lead can inhibit PMN chemotaxis, phagocytosis and super-oxide formation. Moreover, we have observed an inhibition of PMN chemotaxis in workers occupationally exposed to lead with a mean blood lead concentration of 3.06 (mol/l. The present study was carried out to evaluate locomotion and luminol assisted chemiluminescence (CL) of polymorphonuclear leukocytes (PMN) harvested from ten lead occupationally exposed workers with blood lead concentrations of 1.59 mol/l (SD 0.27 mol/l). Since lipids affect PMN activity and lipid composition is modified in erythrocytes of lead workers, PMN lipids were also studied. Ten healthy male subjects of the same age were taken as controls. Chemotaxis, i.e. locomotion stimulated through a specific membrane receptor, was impaired in the PMN of lead workers, but random migration, i. e. unstimulated cell locomotion, and respiratory burst were both unmodified. Cholesterol and phospholipids were not changed, but the percentage of arachidonic acid was significantly increased. The release of LTB4, generated by the oxidative metabolism of arachidonic acid, was increased. CL, which detects reactive oxygen species (ROS), was unmodified, but this lack of change could be the result of an increase in ROS, due to the augmentated percentage of arachidonic acid, and of a decrease in ROS, due to a direct inhibitory effect of lead on ROS generation. On the basis of the results from these ex vivo experiments, the conclusion that chemotaxis is the PMN function primarily affected by lead was confirmed. PMN are considered to be one of the first cellular targets for the action of lead; low exposure to lead modifies their activity and mainly modifies chemotaxis and LTB4 production.     

Immunological monitoring in workers occupationally exposed to asbestos

Occupational exposure to asbestos is strongly associated with pulmonary diseases, cancer and immunotoxic effects. Both systemic and local immunity may play an important role in the pathogenesis of these events. Immune cells appear to be influenced by asbestos exposure, either through direct effects or as a result of the host's protective response to exposure. In this study several immune system parameters were assessed in workers (n = 61) with at least 5 years' exposure to asbestos at an industrial plant. Workers exposed to asbestos fibres had significantly increased levels of immunoglobulin E and concentrations of interleukin-6 and -8 in comparison with two sets of controls (in-plant and town control groups). The levels of soluble adhesion molecule ICAM-1 were higher in the exposed group compared to the town control group. Significantly increased levels of IgA were found in asbestos-exposed group in comparison to the town control. Evaluation of the expression of adhesion molecules on lymphocytes, monocytes and granulocytes by flow cytometry showed significant increases in the class of selectins CD62L on monocytes and granulocytes. Moreover, significantly increased expression of markers CD69 and CD66b on eosinophils was found among workers exposed to asbestos. In conclusion, exposure to asbestos fibres was found to have several effects on immune system. Alterations of these immune parameters may indicate hypersensitivity (increased levels of IgE, increased expression of activation markers CD66b and CD69 on eosinophils) and an elevated inflammatory status (increased levels of interleukins--IL-6, IL-8) in exposed workers.     

Assessment of cardiovascular risk in workers occupationally exposed to lead without clinical presentation of cardiac involvement

PURPOSE: The objective of this study was to assess, with aid of SCORE system, of 10-year risk of fatal cardiovascular incidents among workers occupationally exposed to lead, without circulatory system disorders. METHODS: The studies included 83 men (mean age: 55.14±4.62 years): the 1st group consisted of persons occupationally exposed to lead (group I, n=40), and 2nd group - persons not exposed to lead (group II, n=43). 10-Year risk of fatal cardiovascular incidents was assessed with application of SCORE risk chart designed for Polish population. RESULTS: In the first group, mean values of SCORE calculated on the basis of the chart including total cholesterol concentration in serum were significantly higher. Also, there were significantly higher: mean values of SCORE calculated on the basis of the chart including total cholesterol to HDL cholesterol ratio, mean values of relative SCORE, percentage of individuals with risk estimated as increased, percentage of individuals with risk estimated as significantly increased. Simultaneously, the significantly lower percentage of individuals with risk estimated as small or moderate was found in the occupationally exposed subjects. CONCLUSIONS: Persons occupationally exposed to lead compounds are burdened with significantly higher 10-year risk of fatal cardiovascular incident than individuals from the same population not exposed to lead.     

蓄电池生产企业铅作业工人骨密度水平调查研究

目的探讨铅蓄电池生产工人职业性铅接触与骨密度的相关性。方法选取某铅蓄电池厂铅作业工人229人作为研究对象,骨密度采用美国Achilles Express型超声骨密度仪进行左脚或右脚跟骨的测定,检测其生产环境铅浓度和工人血铅水平。结果男性工人的血铅[（1．91±0．89）μmol／LVS．（1．39±0．75）μmol／L]、骨质流失（25．28％vs．5．88％）及骨质疏松（8．42％vs．1．96％）发生率显著高于女性（P〈0．01）,其T值也显著低于女性（P〈0．01）,各性别组不同年龄、工龄及血铅水平间差异无显著性（P〉0．05）.结论性别因素可能与铅影响骨密度有关,较短工龄较高的铅接触水平未对人体骨密度有影响。     

DNA damage in workers occupationally exposed to pesticide mixtures

Pesticides are used in agriculture to protect crops but represent at the same time a potential risk to farmers and environment. The aim of this work is the evaluation of 54 subjects occupationally exposed to pesticides and 30 subjects as a control group using the quantification of DNA damage level by means of the alkaline Comet assay and the evaluation of repair processes. Damage index Comet assay (DICA) and damage index repair assay (DIRA) were studied in 27 pesticide applicator workers, 27 non-pesticide applicators and controls. Our results show that both exposed groups revealed significant increase in DICA when compared with controls (P < 0.0001), as well as in DIRA (P < 0.0001). However, the spraying group exhibited a marginally significant difference in DICA (P = 0.05) when years of exposure are considered and a significant difference (P < 0.05) when the personal protective equipment used by individuals was taken as a comparison factor. The influence of confounding factors on the genotoxic effects of occupational exposure to pesticides was investigated and no significant differences were observed considering age, gender, smoking and alcohol consumption in relation to DICA and DIRA. Since DNA damage is an important step in events leading from carcinogen exposure to cancer disease, our study highlights the potential health risk associated with agrochemical exposure in developing countries with vast cultivated areas, such as Argentina.     

Anesthetic gases and occupationally exposed workers

The aim of this study is to estimate whether the occupational exposure to low dose anesthetic gases could cause alterations of blood parameters in health care workers. 119 exposed subjects and 184 not exposed controls were included in the study. Each worker underwent the complete blood count test (CBC), proteinaemia, leukocyte count, serum lipids, liver and kidney blood markers.The liver blood markers show statistically significant differences in health care workers compared with controls (p < 0.05), a statistically significant decrease in neutrophils and an increase of lymphocytes in health care workers compared with controls (p < 0.05). The prevalence of values outside the range for GPT, GGT, total bilirubin, lymphocytes and neutrophils was statistically significant in health care workers compared with controls (p < 0.05). The results suggest that occupational exposure to low dose anesthetic gases could influence some haematochemical hepatic and hematopoietic parameters in exposed health care workers.     

Assessment of immunotoxicity parameters in individuals occupationally exposed to lead

Although adverse health effects produced by lead (Pb) have long been recognized, studies regarding the immunotoxic effects of occupational exposure report conflicting results. In a previous study, alterations in some immunological parameters were noted in 70 Pb-exposed workers. In view of these results, it was of interest to extend this study comprising a larger population and increasing the number of immunological endpoints assessed. Accordingly, in this study the immunotoxic effects of occupational exposure to Pb were assessed by analyzing (1) percentages of lymphocyte subsets (CD3?, CD4?, CD8?, CD19?, and CD56?/16?); (2) concentration of plasma cytokines, namely, interleukin (IL) 2, IL4, IL6, IL10, tumor necrosis factor (TNF) α, and interferon (IFN) γ; and (3) plasma concentrations of neopterin, tryptophan (Trp), and kynurenine (Kyn). In addition, the possible influence of genetic polymorphisms in the vitamin D receptor (VDR) and δ-aminolevulinic acid dehydratase (ALAD) genes on immunotoxicity parameters was studied. Exposed workers showed significant decreases in %CD3?, %CD4?/%CD8? ratio, IL4, TNFα, IFNγ, and Kyn to Trp ratio (Kyn/Trp), and significant increases in %CD8?, IL10, and Trp levels. All these parameters, except Trp, were significantly correlated with exposure biomarkers. No significant influence of genetic polymorphisms was observed. Significant correlation between Kyn/Trp and neopterin concentrations suggests an involvement of indoleamine 2,3-dioxygenase in the Trp metabolic alterations, which may contribute to some of the immune alterations observed. Results obtained suggest that occupational exposure to PB may influence the immune system by impairing several mechanisms, which might ultimately produce deregulation of the immune response and diminish immunosurveillance in exposed individuals.     

Effect of lead exposure on the immune response of some occupationally exposed individuals

Lead is a ubiquitous pollutant in the industrial environment, which poses serious threats to human health. In the past 20 years increasing attention has been paid to the effects of lead exposure on health. This toxic metal alters the immune response of animals as well as humans. To study the immunological effects of occupational exposure to lead, we examined lymphocyte proliferation, natural killer (NK) cell cytotoxicity and interferon-gamma production with peripheral blood mononuclear cells (PBMCs) of individuals occupationally exposed to lead. We selected three different groups of individuals exposed to lead: three-wheeler drivers (30), battery workers (34) and silver jewelery makers (20); and unexposed healthy volunteers (30) as control for comparison. Our results indicate that though lymphocyte proliferation to phytohaemagglutinin (PHA) is inhibited in lead exposed individuals as compared with unexposed volunteers, there is no correlation between inhibition of lymphocyte proliferation and blood lead level. NK cell cytotoxicity remains unaffected in individuals exposed to lead as compared with controls. On the other hand, we observed that interferon-gamma (IFN-gamma) was significantly elevated in T cell mitogen, PHA, stimulated PBMCs culture supernatant of lead exposed individuals. We found significant positive correlation between blood lead levels and IFN-gamma produced in culture supernatant on stimulation with PHA. In brief, this study demonstrates that lead can affect the immune response of the occupationally exposed individuals such as three-wheeler drivers, battery reconditioning workers and silver jewelery makers.     

Formaldehyde risk assessment for occupationally exposed workers

Formaldehyde has been shown to be carcinogenic in animals and should be considered potentially carcinogenic in humans. The mechanism of action is unknown but formaldehyde is weakly genotoxic and also may act as a late stage carcinogen or promoter. An estimated 1.3 million workers are potentially exposed to formaldehyde through their occupation. Of those exposed workers, about 3.5% were found to be exposed to formaldehyde air concentrations greater than the 3 ppm set by OSHA as a permissible exposure level. Fewer than 12% were exposed to concentrations greater than 1 ppm, but over 88% were exposed to concentrations of 0.5 ppm or more. A quantitative risk assessment, using the multistage low-dose extrapolation model, found the (maximum likelihood) estimate of lifetime risk for excess cancers to be 620 per 100,000 at the OSHA permissible exposure level. The estimated risk is 23 per 100,000 at 1 ppm and 2.8 per 100,000 at 0.5 ppm. Reduction of the OSHA permissible exposure level to 1 ppm would significantly decrease risk with minor economic disruption for most industries involved. However, reduction of risk to levels which have been generally regarded by other regulatory agencies as acceptable, i.e., 10(-5) to 10(-6), would require increased control by all the industries reviewed.     

Hemoglobin adducts of epoxybutene in workers occupationally exposed to 1,3-butadiene

1,3-Butadiene (BD) is an important chemical widely used in the synthetic rubber industry. Hemoglobin adducts of two of its reactive metabolites have been already investigated as possible parameters for exposure assessment. In this study hemoglobin adducts of epoxybutene (EB) were analyzed in blood samples from 17 workers in a BD monomer production unit and 19 controls in a heat production unit of a petrochemical plant near Prague, Czech Republic. BD exposure was determined by personal air sampling. The median level of exposure was 440 microg/m3 (range < 11-17 mg/m3) for the exposed workers and < 6 microg/m3 (< 5-150 microg/m3) for the controls. The adduct N-(2-hydroxy-3-butenyl)valine (HBVal) formed by the reaction of the N-terminal valine of globin with carbon-1 of EB was measured. The N-alkylated amino acid was analyzed by gas chromatography/mass spectrometry (GC/MS) after degradation by the modified Edman procedure. Using published methods problems arose with high background levels, especially in the negative ion chemical ionization (NCI) mode. In the present study a limit of detection of 0.2 pmol/g globin was achieved by using 400 mg globin, a variation in extraction solvents, an additional purification step and a widely extended GC temperature program. The median hemoglobin adduct level of the Czech BD monomer production workers (0.7 pmol/g globin; n = 17) was significantly higher than that of the controls (0.2 pmol/g globin; n = 19; P<0.05). Smoking controls showed higher hemoglobin adduct levels than nonsmoking controls (P<0.1) and significantly higher BD exposure levels (P<0.01).     

Alterations of serum hormone levels in male workers occupationally exposed to cadmium

In order to investigate the influence of occupational exposure to cadmium (Cd) on the levels of serum hormone, a cross-sectional study was undertaken in male workers. Creatinine-adjusted urinary cadmium (UCd) was used as the indicator of cadmium body burden in workers. The levels of serum testosterone (T), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) were determined by radioimmunoassay and enzyme immunoassay, respectively. The results showed that with cadmium exposure, the levels of serum testosterone and LH were significantly increased after controlling for confounding factors such as age, smoking habits, and alcohol consumption. However, no significant cadmium-associated changes in the levels of serum FSH were found. At the same time, a significant negative correlation of serum testosterone levels with age was detected. In contrast, the levels of serum FSH and LH were significantly elevated with increasing age. When taking the marital status into consideration, only significantly elevated FSH levels were noted in married workers after controlling for confounding factors. These results indicate that occupational cadmium exposure and other factors such as age and marital status may independently contribute to alterations in the levels of serum sex hormones in males.