Effects Of Chronic Occupational Exposure Research Articles

Evaluation of the effects of chronic occupational exposure to metallic mercury on the thyroid parenchyma and hormonal function.

Experiments in animals exposed to mercury (Hg) in different chemical states have shown thyroid parenchymal and hormone alterations. However, these experiments did not allow the establishment of dose-response curves or provide an understanding of whether these Hg effects on the thyroid parenchyma occur in humans. To evaluate the association between chronic occupational exposure to metallic Hg and alterations in thyroid hormones and gland parenchyma 14years after the last exposure. A cross-sectional study including 55 males exposed in the past to metallic Hg and 55 non-exposed males, paired by age, was conducted in the Hospital das Clínicas (Brazil) from 2016 to 2017. Serum concentrations of total and free triiodothyronine (TT3 and FT3), free thyroxine (FT4), thyrotropin (TSH), reverse T3 (RT3), selenium and antithyroid antibody titers were obtained. The Hg and iodine concentrations were measured in urine. The thyroid parenchyma was evaluated by B-mode ultrasonography with Doppler. The nodules with aspects suspicious for malignancy were submitted to aspiration puncture with a thin needle, and the cytology assessment was classified by the Bethesda system. The t test or Mann-Whitney test, Chi-square test and Spearman correlation were used to compare the exposed and non-exposed groups and examine the relationships between the variables. Univariate and multivariate logistic regression models were used to trace determinants of the risk of thyroid hormone alteration. Statistical significance was defined by p < 0.05. The urinary Hg average was significantly higher in the exposed group than in the non-exposed group (p < 0.01). The mean TSH serum concentration in the exposed group was higher, with a statistically significant difference between the groups (p = 0.03). Serum concentrations of TSH exceeded the normality limit (4.20µIU/ml) in 13 exposed individuals (27.3%) and 4 non-exposed individuals (7.3%), with a statistically significant association between the hormonal increase and exposure to Hg (p = 0.02). In the logistic regression model, exposure to Hg (yes or no) showed an odds ratio = 4.86 associated with an increase of TSH above the normal limit (p = 0.04). The serum concentrations of RT3 showed a statistically borderline difference between the groups (p = 0.06). There was no statistically significant difference between the mean TT3, FT3 and FT4 serum concentrations in the Hg-exposed group compared to the non-exposed group. The proportions of the echogenicity alterations were higher in the exposed group compared to the non-exposed group (27.3% versus 9.1%; p = 0.03). Papillary carcinomas were documented in three exposed individuals and one non-exposed individual. A follicular carcinoma was recorded in one non-exposed individual. Due to the higher serum TSH concentration and the prevalence of parenchymal alterations in the Hg-exposed group, even after cessation of exposure, it is recommended that the thyroid status of exposed workers be followed for a long period.

Environmental Assessment and Evaluation of Oxidative Stress and Genotoxicity Biomarkers Related to Chronic Occupational Exposure to Benzene.

Environmental and occupational exposure to benzene from fuels is a major cause for concern for national and international authorities, as benzene is a known carcinogen in humans and there is no safe limit for exposure to carcinogens. The objective of this study was to evaluate the genotoxic effects of chronic occupational exposure to benzene among two groups of workers: filling station workers (Group I) and security guards working at vehicles entrances (Group II), both on the same busy highway in Rio de Janeiro, Brazil. Sociodemographic data on the workers were evaluated; the concentration of benzene/toluene (B/T) in atmospheric air and individual trans,trans-muconic acid (ttMA) and S-phenylmercapturic acid (S-PMA) were measured; oxidative stress was analyzed by catalase (CAT), glutathione S-transferase (GST), superoxide dismutase (SOD), thiol groups (THIOL) and malondialdehyde (MDA); genotoxicity was measured by metaphases with chromosomal abnormalities (MCA) and nuclear abnormalities, comet assay using the enzyme formamidopyrimidine DNA glycosylase (C-FPG), and methylation of repetitive element LINE-1, CDKN2B and KLF6 genes. Eighty-six workers participated: 51 from Group I and 35 from Group II. The B/T ratio was similar for both groups, but Group I had greater oscillation of benzene concentrations because of their work activities. No differences in ttMA and S-PMA, and no clinical changes were found between both groups, but linearity was observed between leukocyte count and ttMA; and 15% of workers had leukocyte counts less than 4.5 × 109 cells L−1, demanding close worker’s attention. No differences were observed between the two groups for THIOL, MDA, MCA, or nuclear abnormalities. A multiple linear relationship was obtained for the biomarkers MCA and C-FPG. A significant correlation was found between length of time in current job and the biomarkers C-FPG, MCA, GST, and MDA. Although both populations had chronic exposure to benzene, the filling station workers were exposed to higher concentrations of benzene during their work activities, indicating an increased risk of DNA damage.

Cardiorespiratory response to exercise of nonsmokers occupationally exposed to second hand smoke (SHS).

INTRODUCTIONOccupational exposure to Second Hand Smoke (SHS) continues to be an issue, even in countries with strong tobacco control legislation. The current study assessed the effect of chronic occupational exposure to SHS on cardiorespiratory exercise response among healthy adult non-smokers.METHODS60 healthy non-smokers; 38 men, 22 women, aged 18-58 years with body mass index (BMI)<30 were separated into exposed to occupational SHS (exposed, n=30) and those non-exposed (controls, n=30) to occupational SHS in the hospitality sector. All individuals underwent baseline spirometry and ergospirometry testing. Non-smoking status was confirmed with exhaled CO, SHS exposure with urine cotinine measurement and indoor environmental pollution with PM2.5 concentration. Statistical differences among groups were determined with an independent t-test and p-value set to <0.05.RESULTSThe exposed group had an average range of 6.9% to 14% lower exercise performance against their % predicted compared to controls. Significant mean differences ±standard deviation found between groups for ergospirometry were: oxygen uptake (VO2, mL/minute) 11.8 ±3.9 (p=0.004) and 11.7 ±4.8 (p=0.019); carbon dioxide output (VCO2) 14.0 ±3.7 (p<0.001) and 13.4 ±5.0 (p=0.009); metabolic equivalents (METS) 11.9 ±3.9 (p=0.003) and 11.7 ±4.9 (p=0.018) and for oxygen pulse (VO2/HR) 16.6 ±7.551 (p=0.032) and 11.9 ±4.554 (p=0.011) at points of maximum oxygen uptake (VO2max) and recovery (RC) against % predicted values, respectively.CONCLUSIONChronic occupational SHS exposure among non-smokers deteriorates CR exercise performance. Its impact on chronic disease development should be further explored. These results add to the evidence of the importance of enforcing clean indoor air legislations..

Chronic exposure to organophosphate (OP) pesticides and neuropsychological functioning in farm workers: a review.

Previous studies have demonstrated that acute poisoning from exposure to organophosphate (OP) pesticides in agricultural workers causes adverse health effects. However, neuropsychological and cognitive effects of chronic occupational exposure to OP pesticides remain controversial. To identify, evaluate, and systematize existing evidence regarding chronic exposure to OP pesticides and neuropsychological effects in farmworkers. Using the PubMed search engine, a systematic review process was implemented and replicated according to the PRISMA statement. Eligibility criteria included workers over 18years of age exposed to OP pesticides as well as assessment of neuropsychological and cognitive functioning. Search terms were in English and Spanish languages and included organophosphate and workers. Of the search results, 33 of 1,256 articles meet eligibility criteria. Twenty-four studies found an association between chronic occupational exposure to OP pesticides and low neuropsychological performance in workers. We classified nine of the studies to have study design limitations. Studies indicated occupational exposure to OP pesticides is linked to difficulties in executive functions, psychomotor speed, verbal, memory, attention, processing speed, visual-spatial functioning, and coordination. Nine studies find no relationship between OP pesticides exposure and neuropsychological performance. Overall, evidence suggests an association between chronic occupational exposure to OP pesticides and neuropsychological effects. However, there is no consensus about the specific cognitive skills affected.

Occupational mercury exposure in association with prevalence of multiple sclerosis and tremor among US dentists

BackgroundThe effects of chronic occupational exposure to elemental mercury (Hg0) are largely unknown. The objective was to evaluate the association of occupational Hg0 exposure with multiple sclerosis (MS) and tremor. MethodsThe study included 13,906 dentists who attended the American Dental Association’s annual meeting over 24 years (1986-2007 and 2011-2012). Participants reported MS and tremor and provided urine specimens for Hg0 analysis. The authors estimated mean Hg0 exposures over time and used logistic regression to estimate the associations of 3 Hg0 exposure measures with MS or tremor. ResultsAmong participants, 0.18% reported MS and 1.24% reported tremor. Hg0 exposure was not associated with MS (odds ratio [OR] per 191 micrograms per liter in cumulative Hg0 exposure, 0.85; 95% confidence interval [CI], 0.39-1.85). Increased prevalent risk of tremor was found with exposure to both urinary Hg0 exposure (OR, 1.10 [95% CI, 1.00-1.22]) and cumulative Hg0 exposure among younger dentists (< 51 years; OR, 1.13 [95% CI, 1.05-1.22]). ConclusionsOccupational Hg0 exposure in US dentists decreased over time and now is approaching that of the general population. Our results suggest a positive association between Hg0 exposure and tremor. Practical ImplicationsStudies with more sophisticated outcome and exposure measures, and including more retired dentists, would provide critical information toward understanding the relation of Hg0 exposures to MS and tremor risk.

Expression of blood serum proteins and lymphocyte differentiation clusters after chronic occupational exposure to ionizing radiation.

This study aimed to assess effects of chronic occupational exposure on immune status in Mayak workers chronically exposed to ionizing radiation (IR). The study cohort consists of 77 workers occupationally exposed to external gamma-rays at total dose from 0.5 to 3.0 Gy (14 individuals) and workers with combined exposure (external gamma-rays at total dose range 0.7-5.1 Gy and internal alpha-radiation from incorporated plutonium with a body burden of 0.3-16.4 kBq). The control group consists of 43 age- and sex-matched individuals who never were exposed to IR, never involved in any cleanup operations following radiation accidents and never resided at contaminated areas. Enzyme-linked immunoassay and flow cytometry were used to determine the relative concentration of lymphocytes and proteins. The concentrations of T-lymphocytes, interleukin-8 and immunoglobulins G were decreased in external gamma-exposed workers relative to control. Relative concentrations of NKT-lymphocytes, concentrations of transforming growth factor-β, interferon gamma, immunoglobulins A, immunoglobulins M and matrix proteinase-9 were higher in this group as compared with control. Relative concentrations of T-lymphocytes and concentration of interleukin-8 were decreased, while both the relative and absolute concentration of natural killers, concentration of immunoglobulins A and M and matrix proteinase-9 were increased in workers with combined exposure as compared to control. An inverse linear relation was revealed between absolute concentration of T-lymphocytes, relative and absolute concentration of T-helpers cells, concentration of interferon gamma and total absorbed dose from external gamma-rays in exposed workers. For workers with incorporated plutonium, there was an inverse linear relation of absolute concentration of T-helpers as well as direct linear relation of relative concentration of NKT-lymphocytes to total absorbed red bone marrow dose from internal alpha-radiation. In all, chronic occupational IR exposure of workers induced a depletion of immune cells in peripheral blood of the individuals involved.

Evaluation of prevalence of acquired color vision impairment in detergent factory workers

Background and Aim: Color vision is an important function of the visual system. Therefore, this study was aimed to evaluate the effect of chronic occupational exposure to detergents on color vision ability in different group. Materials and Methods: This descriptive study was conducted in a detergent producer factory on all (300) workers who were in detergents production hall. After considering exclusion criteria, 279 persons were qualified to participate in the study. General visual exam and color vision test was performed for participants. Their color vision was evaluated by Ishihara and Farnsworth D-15. Results: 12.9% of participants showed color vision disorder , the prevalence of which was mostly related to powder groups. Conclusion: Chronic occupational exposure to excess amount of detergents can cause acquired color vision disorder. Key words: Color vision, Occupational exposure, Detergents workers

Occupational Exposure to Formaldehyde: Genotoxic Risk Evaluation By Comet Assay And Micronucleus Test Using Human Peripheral Lymphocytes

Formaldehyde (FA) is a world high-production compound with numerous applications ranging from production of resins to medicines. Due to its sensitizing properties, irritating effects and potential cancer hazard FA is of great environmental health concern. Numerous studies in humans and experimental animals demonstrated that inhaled FA produced toxicity, genotoxicity, and cancer at distal sites. IARC, based on sufficient data, reclassified FA as a human carcinogen. The highest level of human exposure to this aldehyde occurs in occupational settings, namely, in pathology and anatomy laboratories, where FA is commonly used as a fixative and tissue preservative. Several studies consistently showed that the levels of airborne FA in anatomy laboratories exceeded recommended exposure criteria. In order to assess the genotoxic effects of chronic occupational exposure to FA, a group of pathology/anatomy workers was assessed using a micronucleus (MN) test and comet assay. The level of exposure to FA was also determined and the time-weighted average (TWA) of exposure was calculated for each subject. The TWA mean value for FA exposed workers was 0.43 ± 0.06 ppm, exceeding national and international recommended limit levels of 0.3 ppm. Both MN frequency and comet assay parameters were significantly higher in exposed subjects. Data obtained confirm a correlation between genetic damage and occupational exposure to FA. These data, along with recent implications of human carcinogenicity, point out the need for close monitoring of occupational exposure to FA. Implementation of security and hygiene measures as well as good practices campaigns may be crucial to decrease risk.

STUDY OF SOME HEALTH EFFECTS IN WORKERS EXPOSED TO CHLOROFORM

Chloroform (also known as trichloromethane or methyltrichloride), is a colorless liquid with a pleasant, non-irritating odor. Most of chloroform found in the environment comes from industry; it is also found in waste water from sewage treatment plants and drinking water to which chlorine is added. Chloroform is used in pesticide formulation, in drugs and chemical industry and as a laboratory reagent. Chloroform toxicity can be attributed to the presence of both the parent compound and the formation of reactive metabolite (phosgene). Chloroform has obvious hepatic - nephrotoxicity and is a suspected human carcinogen. The genotoxic potential of chloroform has been investigated in anumber of studies both in vitro and in vivo.Also, the mechanism of action of chloroform had been investigated, several modes of actions were studied, of which cytotoxicity and cell replication, induction of gene mutation and DNA damage, lipid peroxidation and antioxidants depletion are the most common effects.Objectives: (1) To study and evaluate some of the health effects of chronic occupational exposure to chloroform when used as a main laboratory reagent, with special emphasis on hepatorenal, and cytogenetic effects. (2) Also, assessment of possible effect of chloroform in causing oxidative stress and lipid peroxidation. Methods: This study was carried out in the laboratory of Analgesic and Narcotic Drugs Department in the National Organization for Drug Control and Research. The study population was composed of 52 subjects; 30 workers were exposed to chloroform (by inhalation and skin contact) and 22 matched unexposed females were included as control.Every individual in the study was subjected to clinical examination and special questionnaire, investigation of liver and kidney functions (ALT, AST, ALK phosphatase,bilirubin, serum creatinine and blood urea). Serum malondialdehyde (MDA)was measured for assessment of lipid peroxidation, and chromosomal simple analysisstudy was done.Results: As regards the significant clinical manifestations, sensory disturbances,skin manifestations (redness, itching and allergic dermatitis), and cardio-vascularmanifestations (arrhythmia and syncope) were elicited in 50% of the exposed workers,and musculoskeletal manifestation were also found in the exposed group with statistically significant difference when compared to control.Liver and kidney function parameters did not show statistically significant difference between the two groups, while serum MDA was statistically significantly higher in the exposed group (P<0.05). Chromosomal aberrations were significantly higher in the exposed subjects. However, orrelations duration of work with MDA level, and with chromosomal aberrations, and MDA level with chromosomal aberrations were non-significant, Conclusion: Occupational exposure to chloroform as a main laboratory reagent, was associated with significant increase in lipid peroxidation indicated by increased level of a lipid peroxidation product, serum MDA, and was associated with increased chromosomal aberrations that did not correlate with the level of serum MDA or with duration of exposure. Hepatorenal function parameters were within normal, skin manifestation arrhythmia, and sensory manifestations are the most significant clinical effects.

Olfactory toxicity: long-term effects of occupational exposures

To present and discuss the results of research on olfactory function impairments related to chronic occupational exposure to industrial chemicals. This review is mainly focused on the results of epidemiological studies on olfactory function, evaluated using quantitative testing methods, in workers chronically exposed to airborne industrial chemicals. Papers published in peer-reviewed scientific journals were mainly considered. The prevalence of olfactory impairments related to occupational exposure to chemicals is unknown: frequencies ranging 0.5-5% of all olfactory dysfunctions have been proposed, considering both exposure to chemicals and the use of pharmaceutical drugs, but the real relevance of this problem is possibly overlooked, especially considering that occupational exposure may account for a significant part of "idiopathic" smell disorders, i.e., the 10-25% of all olfactory problems within the general population. An adverse effect has been reported in workers chronically exposed to some metals as cadmium, chromium, manganese, arsenic, mercury, and organic lead, and to other chemicals as acrylates, styrene, and solvent mixtures. The results of relevant studies are discussed. A problem in the evaluation of data is that different methods have been applied in different studies, affecting the comparability of results. To date, knowledge of the effect of chronic occupational exposure to industrial chemicals on olfactory function is largely incomplete, but supports the hypothesis that olfactory neuroepithelium is susceptible to environmental exposures to chemicals. Occupational-related olfactory impairment is usually sub-clinical, and can be only detected using adequate quantitative olfactory function testing procedures. Available data show the need for further good quality research in this field.

Effects of chronic occupational exposure to anaesthetic gases on the rate of neutrophil apoptosis among anaesthetists

Effects of chronic occupational exposure to anaesthetic gases on the rate of neutrophil apoptosis among anaesthetists

Effect of process parameters upon the dopamine and lipid peroxidation activity of selected MIG welding fumes as a marker of potential neurotoxicity

There is growing concern over the neurotoxic effects of chronic occupational exposure to metal fume produced by welding. Elevated iron and manganese levels in the brain have been linked to an increase in lipid peroxidation, dopamine depletion and predisposition to the development of a Parkinson's type condition in advanced cases. Chemical and toxicological analysis of selected welding fumes, generated by model processes, were used in order to evaluate their potential to release solutes that promote oxidation of dopamine and peroxidation of brain lipids in cell free assays. This study compared the effect of shield gas, electrode type and voltage/currect upon the dopamine and brain lipid peroxidation potential of selected welding fume, obtained from metal inert gas (MIG) welding systems. Overall, fume extracts were found to enhance dopamine oxidation and inhibit lipid peroxidation. Significant differences were also found in the oxidising potential of fume generated under differing process conditions; it may therefore be possible to determine the potential neurotoxicity of fumes using this system.

Effect of process parameters upon the dopamine and lipid peroxidation activity of selected MIG welding fumes as a marker of potential neurotoxicity

There is growing concern over the neurotoxic effects of chronic occupational exposure to metal fume produced by welding. Elevated iron and manganese levels in the brain have been linked to an increase in lipid peroxidation, dopamine depletion and predisposition to the development of a Parkinson's type condition in advanced cases. Chemical and toxicological analysis of selected welding fumes, generated by model processes, were used in order to evaluate their potential to release solutes that promote oxidation of dopamine and peroxidation of brain lipids in cell free assays. This study compared the effect of shield gas, electrode type and voltage/currect upon the dopamine and brain lipid peroxidation potential of selected welding fume, obtained from metal inert gas (MIG) welding systems. Overall, fume extracts were found to enhance dopamine oxidation and inhibit lipid peroxidation. Significant differences were also found in the oxidising potential of fume generated under differing process conditions; it may therefore be possible to determine the potential neurotoxicity of fumes using this system.

Neurobehavioral Effects of Chronic Occupational Exposure to Organic Solvents Among Japanese Industrial Painters

To investigate the relationship between chronic exposure to organic solvents and changes in central nervous system function, industrial painters were compared with an age- and education-matched referent group of nonexposed workers. Eighty-one male painters completed a symptom questionnaire. Twenty painters underwent both questionnaire and neuropsychological examinations. From the results of pairwise comparisons of the symptoms, dry and scaly skin, being easily depressed without reason, coldness of hands and legs, being easily irritated without reason, loss of appetite, dizziness, and unsteadiness occurred statistically significantly more often among the exposed subjects than among the referents. Performances on the Digit symbol test and vocabulary test scores (synonyms) in exposed subjects were significantly lower than those of controls. In multiple regression models, controlling for age, education, and alcohol intake, a significant relation was found between the duration of the solvent exposure and poor performance in both the Block design and Digit span tests. The relation between toluene exposure and poor performance in both the Santa Ana coordination test and the Benton visual retension test was also significant. The results suggest that a symptom inquiry and some behavioral tests are helpful for detecting the possible effects of exposure to low levels of organic solvents. However, no consistent pattern was observed in regard to the effects of organic solvent exposure on neurobehavioral function, which is coincident with the type I toxic central nervous system disorder as classified by the World Health Organization.

Effects of chronic occupational exposure to measured concentrations of benzene.

All ten employees have a history of exposure to benzene which exceeded a 25 ppm, eight-hour TWA for several years. For five of these employees this exposure level started over 20 years ago. One employee's high exposure level started over 35 years ago. All ten employees had their initial high exposure to benzene more than 16 years ago. At one period (late 1963 and early 1964) all ten employees had alterations in their peripheral blood studies, evidenced by an increase in MCV. Some of the employees had slight reduction of hemoglobin levels. No other significant blood or bone marrow abnormalities were evident. A mortality study, for the years 1940 to 1973, of 594 employees chronically exposed to benzene at the Midland, Mich., Dow location has recently been accepted for publication. This study was followed by a morbidity study of 282 employees, which were a subset of the employees in the mortality study. The morbidity study was based on health data obtained between 1967 and 1974. The ten employees described in this article were included in both the mortality study population of 594 employees and the morbidity study of the 282 employees.