Non-exposed Workers Research Articles

N,N-dimethylformamide: evidence of carcinogenicity from national representative cohort study in South Korea.

Objective There is limited epidemiological evidence of carcinogenicity on exposure of N,N-dimethylformamide (DMF). This study aimed to identify the possible association between cancer mortality and DMF exposure. Methods A cohort of 11 953 workers exposed to DMF between 1 January 2000 and 31 December 2004 was studied. A urinary metabolite of DMF, N-methylformamide level (UNMFL), was used for exposure assessment. This cohort was matched with the mortality data of the Korean National Statistical Office and followed up for cancer mortality between 2000 and 2011. Standardized mortality ratios (SMR) of the DMF-exposed workers with reference to Korean men were calculated. Adjusted hazard ratios (HRadj; also controlling for age, other carcinogen exposure including hepatitis B and C) were calculated for the workers categorized in three exposure groups with reference to workers with no exposure. Results The HRadj of overall cancer mortality were significantly increased in workers with 7.5-<15 mg/L [HRadj 2.72, 95% confidence interval (CI) 1.09-6.81] and ≥15 mg/L (HRadj 2.41, 95% CI 1.03-5.66) compared with non-exposed workers. Hepatocellular carcinoma mortality (HRadj 3.73, 95% CI 1.05-13.24) of workers with ≥15 mg/L and lung cancer mortality (HRadj 14.36, 95% CI 1.41-146.86) in workers with 7.5-<15 mg/L were significantly increased. Conclusions Workers with high DMF exposure showed increased mortalities for overall, liver, and lung cancer. Our results suggest that DMF causes cancer, especially hepatocellular carcinoma, which is in agreement with earlier studies on liver cancer in animal experiments.

Genotoxic evaluation and plasma oxidative stress markers in copper smelters

Smelters are at elevated risk of oxidative stress and DNA damage because of metal fumes exposure. This study aimed to evaluate oxidative stress (antioxidant capacity, plasma malondialdehyde (MDA)) and DNA damage in 47 smelters and to compare the results with 33 non-exposed workers. The DNA damage was significantly higher in the exposed compared to the non-exposed group (p < .001), with the largest effect size for tail intensity. There was no significant difference in the MDA and total antioxidant capacity between exposed and non-exposed participants. Exposure to metal fumes could increase the primary DNA damage and accelerate the cellular aging process in smelters.

Arsenic-induced inflammation in workers.

Occupational and environmental exposures to metal and metalloids can result in neurotoxicity and immunotoxicity. Selenium (Se) is essential for the proper functioning of neutrophils, macrophages, natural killer (NK) cells, T-lymphocytes and other immune mechanisms, while zinc (Zn) is a trace element essential for basic cell activities, including cell growth and differentiation. Arsenic (As) may lead to different types of immunosuppressive effects. This study consisted of 62 male workers, who had been exposed to arsenic for different durations and 73 non-exposed male workers (control group) with no history of occupational toxic metal exposure. Whole blood and serum samples were taken from each participant for immunological, toxicological and routine analysis during their annual periodical examination. Arsenic, selenium and zinc levels were determined by the ICP-MS and cytokines, IL-6, IL-10, TNF-α, sE-selectin and VCAM-1, were measured by ELISA. There were statistically significant differences (p < 0.001) between control and As-exposed group in As (1.37 ± 0.42 vs. 4.27 ± 1.54µg/L) and Se levels (106.37 ± 48.04 vs. 74.70 ± 30.45µg/L). The changing levels of As, Zn and Se seems to affect the severity of inflammatory reactions based on IL-6, IL-10 and TNF-α levels (r = 0.755, r = 0.679 and r = 0.617, respectively, for all p < 0.01). Selenium was found to have a suppressive effect on cytokines, as evidenced by Pearson correlations and regression analysis. These findings support the need to closely monitor Se levels in individuals exposed to arsenic and benefits for Se supplementation in the case of arsenic exposure, occupationally or environmentally.

Formaldehyde Exposure, Health Symptoms and Risk Assessment among Hospital Workers in Malaysia

Formaldehyde is a chemical commonly used in hospitals as a tissue preservative; histopathology laboratory personnel are therefore among the workers most heavily exposed to formaldehyde. This study measured the formaldehyde exposure through ambient and personal air sampling, assessed the symptoms of poor health as well as estimating the health risk among hospital workers. We conducted a comparative cross-sectional study of both histopathology laboratory (exposed) and administration (nonexposed) workers in four hospitals in the Klang Valley, Selangor, Malaysia. Ambient and personal exposure to formaldehyde was measured using the OSHA 52 and NIOSH 2541 methods, respectively. The 8-hr time-weighted-average formaldehyde concentration was higher in exposed areas (0.25 ± 0.11 ppm) than nonexposed areas (0.08 ± 0.02 ppm). Histopathology workers were exposed to between 140% and 480% higher concentrations of formaldehyde than administration workers. Personal exposure was highest during grossing tasks (0.797 ± 0.436 ppm). A total of 67% of the exposed workers exhibited the same ten health symptoms related to formaldehyde exposure, and 57% of the nonexposed workers reported similar symptoms at their current workplace. Notably, symptoms of eye irritation, headache, drowsiness, and chest tightness were significantly more prevalent (p < 0.05; chi square and Fisher’s exact tests) among the exposed workers than the nonexposed workers. Among those with symptoms, 37% of the exposed workers, and 16% of the nonexposed workers believed that the symptoms were related to their current working environment. The noncancer effect of formaldehyde from air inhalation poses a potential risk of eye irritation among exposed workers. The cancer risk was not significant in both groups. Formaldehyde levels and symptoms of poor health were significantly higher among the exposed group. Exposure and risk could be minimised by strengthening control measures to improve indoor air quality in the workplace.

Increased DNA Damage, Instability and Cytokinesis Defects in Occupationally Exposed Car Painters.

Car painting is considered an occupational exposure job with high risk for cancer development, due to the association with harmful chemicals and mutagens. This study aimed to profile car painters occupationally exposed and determine its association with DNA damage and genomic instability. We collected a questionnaire and buccal cells of 74 individuals (37 car painters and 37 non-exposed workers) paired by age, alcohol and smoking habits. The number of pyknotic cells, karyolitic cells, karyorrhetic cells, condensed chromatin, binucleated cells, basal cells, differentiated cells (DIFF), micronucleated cells and nuclear buds were evaluated using the Buccal Micronucleus Cytome Assay protocol. A statistically significant increase was observed in all parameters (p<0.05) in the exposed group, but DIFF showed a statistically significant decrease (p<0.001), compared to the control group. In association with the poor work environment and lack of personal and collective protective equipment, occupational exposure of car painters leads to high DNA damage, genomic instability and alterations in cellular kinetics.

257. Workplace Safety: Risks assessment of electromagnetic fields exposure

Purpose The European Directive 2013/35/UE, implemented in Italy by Legislative decree 159 dated 1 August 2016, introduces new exposure limits and it modifies the procedures for evaluating the exposure of workers to electromagnetic fields. Since June 2016, UBT srl, in collaboration with ARPA Umbria, has analyzed the issues recalled by the new Directive. In particular, this study focuses on investigating the instrumentation for performing electromagnetic fields measurements and on drafting of guidelines for standard assessment of electromagnetic fields exposure. Methods The devices here analyzed are magnetotherapies, electrosurgical units, welders, magnetizers, radio frequency dryers and test banks, both in healthcare and in general work environments. The instruments, used for measurements, are broadband probes from different manufacturers and with different characteristics. The data analysis method was chosen based on frequencies and waveform of electromagnetic radiations generated by different kinds of devices; specifically, the weighted peak method has been used. Results The measurements highlight different and complex exposure conditions based on the type of source (i.e. device) and workplace. In the case of magnetotherapy rooms, the worker’s weighted peak index was lower than unit; whereas, in the same rooms, general public limits can be exceeded 4 times also. Regarding welders and electrosurgical units, the exposure conditions were more complex and, before evaluation, a detailed analysis of radiation source was required. Conclusions The exposure assessment showed the necessity to delimit the area and/or to use dedicated warning signs so that non-exposed workers or the general public (for example, people accompanying patients) don’t have access to areas in which exposure limits are higher than the action levels. Finally, professional training is fundamental in preventing risks [1] .

Evaluation of hematological, biochemical parameters and thiol enzyme activity in chrome plating workers.

The most commonly used solution in chrome plating bath is chromic acid (hexavalent Cr), and a considerable amount of mists is released into the air and consequently produce hazards to workers. Thus, the aim of this study was to evaluate whether the biomarker of exposure to metals, specially Cr levels, presents associations with hematological and biochemical parameters and if they can alter the activity of enzymes that contain thiol groups such as pyruvate kinase, creatine kinase, adenylate kinase, and δ-aminolevulinate dehydratase. Fifty male chrome plating workers were used for exposed group and 50 male non-exposed workers for control group. For that, biological monitoring was performed through quantification of metals on total blood and urine by inductively coupled plasma mass spectrometry (ICP-MS) and enzyme activity was performed by spectrometry in erythrocytes. In addition, chromium levels in water was quantified and ecotoxicology assay was performed with Allium cepa test. The results demonstrated that blood and urinary chromium levels in exposed group were higher than the control group (p < 0.0001). Furthermore, decreased activity of enzymes was found in those that contain thiol groups from exposed group when compared with the control group (p < 0.001). The water analysis did not present a statistical difference between control and exposed groups (p > 0.05), demonstrating that water did not seem to be the source of contamination. In summary, our findings indicated some toxicology effects observed in the exposed group, such as thiol enzyme inhibition, mainly associated with occupational exposure in chrome plating and besides the presence of other metals, and Cr demonstrated to influence the activity of the enzymes analyzed in this research.

Occupational exposure to particulate matters and telomere length.

Little is known about the possible association between occupational exposure to mineral particulate matters and change in leukocyte telomere length (LTL) as a hallmark of aging. The present study studied the relationship between occupational exposures to mineral dust and LTL in the exposed group of workers and compared to non-exposed workers. One hundred and ten male workers (80 exposed and 30 non-exposed) from different units of a ceramic factory were recruited in the study. Personal air samples were collected in the breathing zone of the workers for inhalable and respirable fractions. Relative LTL was measured in blood genomic DNA using the quantitative real-time PCR method and expressed as telomere/single copy gene ratio. Exposure to inhalable and respirable dusts in the exposed group was 22.66 ± 52.38 and 2.54 ± 9.34mg/m3 respectively. Inhalable and respirable exposure values were highly correlated (r2 = 0.43; p < 0.001). Exposure to respirable and inhalable particles in 38.75% and 8.75% of exposed workers was higher than threshold limit value respectively. Mean LTL in the exposed workers (0.64 ± 0.06) was significantly shorter than the non-exposed workers (0.73 ± 0.07) (p < 0.001). Despite the significant difference in exposure intensity according to working units in the exposed group, there was no significant difference in LTL according to the working units (p = 0.60). In the adjusted regression models, but not crude models, marginally significant and positive association was found between both size fractions and LTL. The observed effect size for respirable particles was five times of that found for the inhalable fraction (beta 0.005 and 0.001 respectively). Mineral dust-and not only traffic-related air pollutant exposure-could be regarded as a risk factor in the process of cell aging. Our findings imply that early biological aging, as reflected in telomere shortening, may mediate the effects of occupational air pollution exposure on human health.

A new potential biomarker in early diagnosis of firefighter lung function impairment: dynamic thiol/disulphide homeostasis.

The aim of this study was to investigate the associations between urinary arsenic, oxidative stress, assessed by thiol/disulphide homeostasis, and lung diseases in firefighters. The study conducted among the municipality-based male firefighters (n = 100) who were admitted to occupational diseases clinic for periodic medical examination. The control group consisted of non-exposed male office workers (n = 50). Urinary arsenic levels, thiol/disulphide homeostasis parameters of participants were determined. Also, lung diseases were assessed by chest X-ray and pulmonary function tests. The mean age and work year did not differ in the study and control group. The median urinary arsenic concentration of firefighters was significantly higher than in the control group: 15.65 (2.5-246) μg/L and 3 (0.10-6) μg/L, respectively (p < 0.001). The parameters of pulmonary function tests (PFT) FVC (%), FEV1 (%), FEV1/FVC ratio and FEF 25-75 (%) were all significantly lower in firefighters compared to controls. A significant increase in mean serum disulphide concentration (17.10 ± 8.31 μmol/L vs. 7.48 ± 5.91) (Fig. 1) and disulphide/native thiol % ratio: 3.63 (0.53-11.43) vs. 1.51 (0.03-7.65) (p < 0.001) were found between exposed group and controls. The Spearman's correlation analysis revealed a positive correlation between urinary arsenic and disulphide (r = 0.422, p < 0.001), disulphide/native thiol % ratio (r = 0.409, p < 0.001). Nevertheless, urinary arsenic correlated negatively with all PFT parameters including FVC (%), FEV1 (%), FEV1/FVC and FEF 25-75 (%) (p < 0.001). We showed the arsenic-induced oxidative stress in firefighters with impairments of several lung functions determined by thiol/disulphide homeostasis using a novel method.

Selective D2 receptor PET in manganese-exposed workers.

To investigate the associations between manganese (Mn) exposure, D2 dopamine receptors (D2Rs), and parkinsonism using [11C](N-methyl)benperidol (NMB) PET. We used NMB PET to evaluate 50 workers with a range of Mn exposure: 22 Mn-exposed welders, 15 Mn-exposed workers, and 13 nonexposed workers. Cumulative Mn exposure was estimated from work histories, and movement disorder specialists examined all workers. We calculated NMB D2R nondisplaceable binding potential (BPND) for the striatum, globus pallidus, thalamus, and substantia nigra (SN). Multivariate analysis of covariance with post hoc descriptive discriminate analysis identified regional differences by exposure group. We used linear regression to examine the association among Mn exposure, Unified Parkinson's Disease Rating Scale motor subsection 3 (UPDRS3) score, and regional D2R BPND. D2R BPND in the SN had the greatest discriminant power among exposure groups (p < 0.01). Age-adjusted SN D2R BPND was 0.073 (95% confidence interval [CI] 0.022-0.124) greater in Mn-exposed welders and 0.068 (95% CI 0.013-0.124) greater in Mn-exposed workers compared to nonexposed workers. After adjustment for age, SN D2R BPND was 0.0021 (95% CI 0.0005-0.0042) higher for each year of Mn exposure. Each 0.10 increase in SN D2R BPND was associated with a 2.65 (95% CI 0.56-4.75) increase in UPDRS3 score. Nigral D2R BPND increased with Mn exposure and clinical parkinsonism, indicating dose-dependent dopaminergic dysfunction of the SN in Mn neurotoxicity.

Effects of Occupational Metal Exposure on the Auditory System

Effects of Occupational Metal Exposure on the Auditory System

Cytotoxic and Genotoxic Effects of Pesticide Exposure in Male Coffee Farmworkers of the Jarabacoa Region, Dominican Republic.

Intensive agrochemical use in coffee production in the Global South has been documented. The aim of this study was to investigate cytotoxic and genotoxic effects of pesticide exposure in male farmworkers in the Dominican Republic comparing conventional farming using pesticides to organic farming. Furthermore, feasibility of the buccal micronucleus cytome assay (BMCA) for field studies under difficult local conditions was tested. In a cross-sectional field study, pesticide exposed (sprayers) and non-exposed male workers on coffee plantations were interviewed about exposure history, and pesticide application practices. Buccal cells were sampled, and BMCA was applied to assess potential effects on cell integrity. In total, 38 pesticide-exposed and 33 non-exposed workers participated. Eighty-four and 87%, respectively, of the pesticide-exposed respondents did not use masks or gloves at all. All biomarkers from the BMCA were significantly more frequent among exposed workers—odds ratio for micronucleated cells: 3.1 (95% confidence interval: 1.3–7.4) or karyolysis: 1.3 (1.1–1.5). Buccal cells as sensitive markers of toxic oral or respiratory exposures proved feasible for challenging field studies. Our findings indicate that the impact of pesticide use is not restricted to acute effects on health and wellbeing, but also points to long-term health risks. Therefore, occupational safety measures including training and protective clothing are needed, as well as encouragement towards minimal application of pesticides and more widespread use of organic farming.

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

BackgroundOccupational 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.MethodsThe 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).ResultsA 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.ConclusionsA 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.

Nasal cytology as a screening tool in formaldehyde-exposed workers.

Workers in pathology and anatomy laboratories may be exposed to formaldehyde. An evaluation of the early effects of this substance is, therefore, paramount. This preliminary study was conducted to evaluate if nasal cytology could be used as a tool to detect changes in nasal mucosa in workers exposed to formaldehyde. To assess whether nasal cytology was able to reveal any alteration of nasal mucosa in workers exposed to formaldehyde compared to unexposed subjects, and to ascertain whether a specific pattern of alterations correlated with years of exposure in order to evaluate long-term occupational exposure effects. The study included a group of workers exposed to formaldehyde and a group of non-exposed workers. All subjects underwent clinical examination, followed by nasal cytology. Pathological indices from each rhinocytograms were compared between the two groups. Nasal cytology revealed a chronic inflammatory non-allergic condition in the exposed group. Qualitative analysis of data distribution of neutrophils and mucous-secreting/ciliated cells ratio showed data clustering with a cut-off set at 15 years of exposure. The mean formaldehyde concentrations ranged from <0.04 to 0.15 parts per million (ppm). The maximum levels of formaldehyde concentrations ranged from 0.2 to 0.67 ppm. Our data indicate that nasal cytology may be a promising tool for the health surveillance of workers exposed to formaldehyde and may also represent a useful research tool for the study of the health effects of other chemicals irritants for the upper airways.

Hematologic Evaluation of Painting Hall Workers in an Automobile Manufacturing Company

Background: Exposure to benzene causes several adverse effects, including decreased number of erythrocytes, leucocytes, and red blood cells, and results in aplastic anemia. The aim of this study was to investigate hematological changes due to benzene exposure in painting workers. Methods: This study was conducted on benzene-exposed and nonexposed workers in Tehran, Iran. The study sample included 40 painters exposed to different levels of benzene and 40 unexposed controls in an automobile manufacturing company. Sampling was carried out with an active pump sampler, using the NIOSH method 1501. Varian C-3800 gas chromatography-flame ionization detector (GC-FID) was used for the analysis of 40 benzene samples. Blood samples from 80 workers were collected from both the case and control groups. Hematological indices were analyzed for red blood cell, white blood cell, hematocrit, hemoglobin, platelet, and white cell differential count. Results: The average amount of benzene in painting workers was 0.775 ± 0.12 ppm. Benzene was not detected in the breathing zone of the control group. Long-term occupational exposure to benzene was lower than 1 ppm. Some blood indices, including the mean corpuscular hemoglobin concentration (MCHC) and eosinophil count, showed significant differences in comparison with the control group (P 0.05). Moreover, the platelet count was normal in workers with exposure to benzene. Conclusions: The painters showed evidence of relative exposure to benzene at a concentration below 1 ppm, causing changes in blood cells. The results of this study demonstrated that eosinophils are more sensitive than lymphocytes or neutrophils.

Reticulocytosis in screen-printing workers exposed to 2-butoxyethanol and 2-ethoxyethanol

BackgroundStudies on the hematologic toxicity of ethylene glycol ethers in humans are limited. Therefore, the aim of this study was to examine the association between exposure to solvents (containing 2-butoxyethanol and 2-ethoxyethanol) and hematological effects.MethodsThirty-four screen-printing workers who were exposed to 2-butoxyethanol and 2-ethoxyethanol and 37 non-exposed clerical workers were selected using data from the health care facilities that provided regular health screening services. Student’s t-tests and Pearson’s chi-square tests were used to compare differences in hematological parameters between the exposed and the control groups. A multivariate analysis was performed using the multiple logistic regression models to adjust for other variables.ResultsThe chi-square test showed the reticulocyte percentages and corrected reticulocyte counts to be significantly higher in the exposed group. The t-tests showed a significant increase in white blood cell counts, reticulocyte percentages, and corrected reticulocyte count (i.e., reticulocyte index) in the exposed group, with p-values of 0.002, 0.004, and 0.002, respectively. Multivariate analysis showed the odds ratio for the corrected reticulocyte counts to be 16.30 for the exposed group, when compared with that of the control group.ConclusionsExposure to 2-butoxyethanol and 2-ethoxyethanol was significantly associated with reticulocytosis, necessitating the implementation of preventive measures for workers prone to occupational exposure to ethylene glycol ethers.

Assessment of Arsenic poisoning among printing textile workers in Baghdad.

Background: Workers of textile industry are mainly exposed to a variety of toxic dyes, bleaching agents, salts, acids, alkalis and heavy metals like arsenic through evaporation and inhale by workers or direct skin contact during the textile mordant process and possibly health effect through the printing processObjectives : to assess the health effects of mild to moderate long term exposure to Arsenic trioxide on textile printing workers and to evaluate and compare the clinical utility of blood and urine arsenic for predicting arsenic poisoning.Methods: In this historic cohort study, measurement of serum and urine levels of arsenic of 65exposed workers and 63non exposed workers was carried out during march 2014 through march 2015 All of the studies cases were worked in a cotton textile factories and considered as target population for detection of any possible industrial chronic arsenic exposure associated sign and symptoms . The non-exposed workers were randomly selected from office personnel of the same factories. Clinical examination, signs and symptoms and a questionnaire method used for analysis in both groups.Results: both groups have a similar age structure. Statistical difference was present between the serum arsenic and arsenic in urine mean values for both the exposed and non-exposed groups. The prevalence ratio for the exposure was higher than one for arsenic in urine. The best cut-off values of arsenic in urine to diagnosis arsenic poisoning based on Receiver operating characteristic curve analysis( ROC) was &gt;90 μg/L and the areas under the curve equal to 0.98 was determined for the prediction early chronic arsenic poisoning.Conclusion: measurement of arsenic in urine in early stage was useful to detect mild to moderate health effects based on Receiver operating characteristic curve analysis (ROC) among textile printing workers exposed to arsenic.

Primary DNA Damage in Dry Cleaners with Perchlorethylene Exposure.

Background:Perchloroethylene is a halogenated solvent widely used in dry cleaning. International agency of research on cancer classified this chemical as a probable human carcinogen.Objective:To evaluate the extent of primary DNA damage in dry cleaner workers who were exposed to perchloroethylene as compared to non-exposed subjects. The effect of exposure modifying factors such as use of personal protective equipment, perceived risk, and reported safe behaviors on observed DNA damage were also studied. Methods:59 exposed and non-exposed workers were selected from Yazd, Iran. All the 33 exposed workers had work history at least 3 months in the dry cleaning shops. Peripheral blood sampling was performed. Microscope examination was performed under fluorescent microscope (400×). Open comet software was used for image analysis. All biological analysis was performed in one laboratory. Results:Primary DNA damage to leukocytes in dry cleaners was relatively high. The median tail length, %DNA in tail, and tail moment in exposed group were significantly higher than those in non-exposed group. There was no significant difference between smokers and nonsmokers in terms of tail length, tail moment, and %DNA in tail. There was no significant correlation between duration of employment in dry cleaning and observed DNA damage in terms of tail length, tail moment and %DNA in tail. Stratified analysis based on exposed and nonexposed category showed no significant relationship between age and observed DNA damage. Conclusion: Occupationally exposure to perchloroethylene can cause early DNA damage in dry cleaners.

Occupational styrene exposure and acquired dyschromatopsia: A systematic review and meta-analysis.

Styrene is a chemical used in the manufacture of plastic-based products worldwide. We systematically reviewed eligible studies of occupational styrene-induced dyschromatopsia, qualitatively synthesizing their findings and estimating the exposure effect through meta-analysis. PubMed, EMBASE, and Web of Science databases were queried for eligible studies. Using a random effects model, we compared measures of dyschromatopsia between exposed and non-exposed workers to calculate the standardized mean difference (Hedges'g). We also assessed between-study heterogeneity and publication bias. Styrene-exposed subjects demonstrated poorer color vision than did the non-exposed (Hedges' g = 0.56; 95%CI: 0.37, 0.76; P < 0.0001). A non-significant Cochran's Q test result (Q = 23.2; P = 0.171) and an I2 of 32.2% (0.0%, 69.9%) indicated low-to-moderate between-study heterogeneity. Funnel plot and trim-and-fill analyses suggested publication bias. This review confirms the hypothesis of occupational styrene-induced dyschromatopsia, suggesting a modest effect size with mild heterogeneity between studies.

Interventions to prevent occupational noise-induced hearing loss.

Interventions to prevent occupational noise-induced hearing loss.