Progress in research of relationship between metal or metalloid and persistent organic pollutants exposures and cardiovascular disease / 中华流行病学杂志

Cardiovascular disease (CVD) is the leading cause of mortality and healthy life expectancy loss, ranking first in causing the global burden of disease. In addition to the traditional CVD risk factors, such as hypertension and diabetes, environmental chemical pollutants may also play a role in the development of CVD. This paper summarizes the evidence regarding the relation of exposures to metal or metalloid and persistent organic pollutants with risk for CVD and introduces the research progress in the relation between the exposures to two environmental chemical pollutants and CVD risk. The study aims to provide scientific evidence for the effective prevention of CVD through the management of chemical pollutants in environment.

Progress in research of deaths and disease burden of major chronic diseases caused by indoor and outdoor air pollution in China / 中华流行病学杂志

Health damage including chronic disease caused by air pollution have attracted increasing attention. With the acceleration of industrialization and urbanization, the emission of air pollutants has increased, and its association with chronic diseases has become a research trending topic. Cardiovascular disease, cancer, diabetes, and chronic respiratory disease are the major chronic diseases, causing about 86.6% of the total deaths in China. The prevention and control of chronic diseases, especially the etiologic prevention, is a major public health issue related to national health. This article summarizes the recent progress in research of association of indoor and outdoor air pollution with all-cause mortality, the deaths and disease burden of four major chronic diseases, i.e. cardiovascular disease, cancer, diabetes, and chronic respiratory disease, and puts forward suggestions for the reduction of the burden caused by chronic diseases due to air pollution to provide a theoretical foundation to revise air quality standards in China.

Association between occupational noise exposure and the risk of cardiovascular diseases / 中华劳动卫生职业病杂志

Objective: To explore the association between occupational noise exposure and cardiovascular disease (CVD) risk in a large Chinese population. Methods: In December 2019, the study included 21412 retired participants from the Dongfeng-Tongji Cohort Study at baseline from September 2008 to June 2010, occupational noise exposure was evaluated through workplace noise level and/or the job titles. In a subsample of 8931 subjects, bilateral hearing loss was defined as a pure-tone mean of 25 dB or higher at 0.5, 1 , 2, and 4 kHz in both ears. Logistic regression models were used to explore the association of occupational noise exposure, bilateral hearing loss with 10-year CVD risk. Results: Compared with participants without occupational noise exposure, the 10-year CVD risk was significantly higher for noise exposure duration ≥20 years (OR=1.20, 95%CI:1.01-1.41 , P=0.001) after adjusting for potential confounders. In the sex-specific analysis, the association was only statistically significant in males (OR=2.34, 95%CI: 1.18-4.66, P<0.001) , but not in females (OR=1.15, 95%CI:0.97-1.37, P=0.153). In the subsample analyses, bilateral hearing loss, which was an indicator for exposure to loud noise, was also associated with a higher risk of 10-year CVD (OR= 1.17, 95% CI:1.05-1.44, P <0.001) , especially for participants who were males (OR =1.24, 95% CI:1.07-2.30, P<0.001) , aged equal and over 60 years old (OR=2.30, 95%CI: 1.84-2.88, P<0.001) , and exposed to occupational noise (OR=1.66, 95%CI: 1.02-2.70, P=0.001). Conclusion: Occupational noise exposure may be a risk factor for CVD.

Prior development of occupational health for healthy China / 中华疾病控制杂志

Since the founding of the People’s Republic of China in the past 70 years, occupational health in China has gradually established its distinctive occupational health regulations, personnel training system, scientific research and work models, and has achieved considerable development and progress. This paper reviews the establishment and development of occupational health, affirms the achievements, presents the current problems and looks to the future. Prior development of occupational health will make greater contributions to the implementation of a healthy China strategy and coordinated economic and social development.

Protective effect of Dendrobium candidum on isoproterenol induced cardiac hypertrophy in rats / 中国中药杂志

To study the effect and mechanism of Dendrobium candidum on isoproterenol-induced myocardial hypertrophy in rats, 60 healthy SD rats(30 males and 30 females) were randomly divided into 5 groups(12 in each group): normal group, model group, three D. candidum preventive administration groups(0.09, 0.18, 1.1 g·kg⁻¹). Except for the normal group, rats of other groups were injected back subcutaneously with ISO(5 mg·kg⁻¹) for 10 consecutive days. At the same time, preventive administration groups began to give different doses of the sample for 30 days and model group began to give normal saline. Left ventricular systolic pressure(LVSP) was measured in each group by common carotid artery cannulation, and the left ventricle(LW)/tibia length, heart weight index(HWI) and myocardial hydroxyproline(Hydro) content were calculated. Myocardial tissue HE staining and Masson staining were used to observe the myocardial structure and the degree of myocardial fibrosis respectively. Atrial natriuretic peptide(ANP), brain natriuretic peptide(BNP), and cardiac troponin I(cTN-I) concentration were measured by enzyme-linked immunosorbent assay(ELISA). The results showed that as compared with the normal group, the levels of ANP, BNP and cTN-I in plasma were significantly increased in ISO-induced hypertrophic rats; as compared with the model group, D. candidumcan inhibit ISO-induced ventricular pressure and ventricular hypertrophy, reduce myocardial collagen synthesis, improve myocardial fibrosis and ventricular remodeling, and significantly down-regulate ANP, BNP and cTN-I levels in plasma. This study shows that D. candidum has a protective effect on isoproterenol-induced cardiac hypertrophy.

Neural structural imaging in the assessment of cognitive impairment / 医学研究生学报

As our country steps into the aging society gradually, the number of cognitive impairments and the prevalence rate are increasing yearly. The family and society bear a heavy burden. It is more important to explore the more direct and Objective morphological changes of cognitive impairment through neural structural imaging , which is better for early diagnosis, intervention and delay or even prevent its progress. Here we present a review of this topic focusing on neural structural imaging in the assessment of cognitive impairment.

Effects of Plasma Lipids and Statins on Cognitive Function / 中华医学杂志(英文版)

<p><b>Objective:</b>Dementia is the fourth most common cause of death in developed countries. The relationship between plasma lipids and cognitive function is complex and controversial. Due to the increasing life expectancy of the population, there is an urgent need to control vascular risk factors and to identify therapies to prevent and treat both cognitive impairment and dementia. Here, we reviewed the effects of plasma lipids and statins on cognitive function.</p><p><b>Data Sources:</b>We searched the PubMed database for research articles published through November 2017 with key words including "plasma lipids," "hyperlipidemia," "hypercholesterolemia," "statins," and "cognition function."</p><p><b>Study Selection:</b>Articles were retrieved and reviewed to analyze the effects of plasma lipids and statins on cognitive function and the mechanisms underlying these effects.</p><p><b>Results:</b>Many studies have examined the relationship between plasma lipids and cognitive function, but no definitive conclusions can be drawn. The mechanisms involved may include blood-brain barrier injury, the influence on small blood vessels in the brain, the influence on amyloid deposition, and a neuroprotective effect. To date, most studies of statins and cognition have been observational, with few randomized controlled trials. Therefore, firm conclusions regarding whether mid- or long-term statin use affects cognition function and dementia remain elusive. However, increasing concern exists that statins may be a causative factor for cognitive problems. These adverse effects appear to be rare and likely represent a yet-to-be-defined vulnerability in susceptible individuals.</p><p><b>Conclusions:</b>The association between plasma lipids and cognition, the mechanism of the influence of plasma lipids on cognitive function, and the association between statins and cognitive function are complex issues and currently not fully understood. Future research aimed at identifying the mechanisms that underlie the effects of plasma lipids and statins on cognition will not only provide important insight into the causes and interdependencies of cognitive impairment and dementia, but also inspire novel strategies for treating and preventing these cognitive disorders.</p>

Hypertension-Induced Cerebral Small Vessel Disease Leading to Cognitive Impairment / 中华医学杂志(英文版)

<p><b>Objective</b>Alzheimer's disease and vascular dementia are responsible for more than 80% of dementia cases. These two conditions share common risk factors including hypertension. Cerebral small vessel disease (CSVD) is strongly associated with both hypertension and cognitive impairment. In this review, we identify the pathophysiological changes in CSVD that are caused by hypertension and further explore the relationship between CSVD and cognitive impairment.</p><p><b>Data Sources</b>We searched and scanned the PubMed database for recently published literatures up to December 2017. We used the keywords of "hypertension", "cerebral small vessel disease", "white matter lesions", "enlarged perivascular spaces", "lacunar infarcts", "cerebral microbleeds", and "cognitive impairment" in the database of PubMed.</p><p><b>Study Selection</b>Articles were obtained and reviewed to analyze the hypertension-induced pathophysiological changes that occur in CSVD and the correlation between CSVD and cognitive impairment.</p><p><b>Results</b>In recent years, studies have demonstrated that hypertension-related changes (e.g., small vascular lesions, inflammatory reactions, hypoperfusion, oxidative stress, damage to autoregulatory processes and the blood-brain barrier, and cerebral amyloid angiopathy) can occur over time in cerebral small vessels, potentially leading to lower cognitive function when blood pressure (BP) control is poor or lacking. Both isolated and co-occurrent CSVD can lead to cognitive deterioration, and this effect may be attributable to a dysfunction in either the cholinergic system or the functionality of cortical and subcortical tracts.</p><p><b>Conclusions</b>We explore the currently available evidence about the hypertensive vasculopathy and inflammatory changes that occur in CSVD. Both are vital prognostic indicators of the development of cognitive impairment. Future studies should be performed to validate the relationship between BP levels and CSVD progression and between the numbers, volumes, and anatomical locations of CSVD and cognitive impairment.</p>

Carotid Atherosclerosis and Cognitive Impairment in Nonstroke Patients / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>As a vascular risk factor, carotid atherosclerosis is crucial to cognitive impairment. While carotid intima-media thickness, carotid artery plaque, and carotid stenosis can reflect carotid atherosclerosis in different stages, this review aimed to explore researches on the role of carotid intima-media thickness, carotid artery plaque, and carotid stenosis in the progress of cognitive impairment in nonstroke patients and tried to illustrate the possible mechanisms.</p><p><b>DATA SOURCES</b>We searched the PubMed database for recently published research articles up to July 2017, with the key words of "carotid atherosclerosis," "carotid intima-media thickness," "carotid plaque," "carotid stenosis," "nonstroke," and "cognitive impairment."</p><p><b>STUDY SELECTION</b>Articles were obtained and reviewed to analyze the role of carotid atherosclerosis such as carotid intima-thickness, carotid plaque, and carotid stenosis in the progress of cognitive impairment in nonstroke patients and the possible mechanisms.</p><p><b>RESULTS</b>In recent years, most studies proved that by evaluating carotid atherosclerosis with ultrasonography, carotid atherosclerosis accounts for the development of cognitive decline in nonstroke patients. Carotid atherosclerosis not only impairs the subtle general cognitive function but also decreases the specific domains of cognitive function, such as memory, motor function, visual perception, attention, and executive function. But, it is still controversial. The possible mechanisms of cognitive impairment in nonstroke patients with carotid atherosclerosis can be classified as systemic global cerebrovascular function, small-vessel diseases, and the mixed lesions.</p><p><b>CONCLUSIONS</b>Carotid atherosclerosis can be used to predict the risk of cognitive impairment. Furthermore, diagnosing and treating carotid atherosclerosis at early stage might help clinicians prevent and treat vascular cognitive impairment in nonstroke patients.</p>

Spectrophotometric determination of silicon tetrahydride in the air of workplace / 华中科技大学学报（医学）（英德文版）

A new, simple and sensitive method was developed for the determination of silicon tetrahydride in the air of workplace in this study. The alkaline resin-based spherical activated carbon was used to collect sample of silicon tetrahydride at workplace. Silicon tetrahydride was then desorbed from active carbon in 100°C hot water. After reacting with ammonium molybdate, oxalic acid and 1,2,4-trichlorobenzene alpha-naphthol amino sulfonic acid under acid condition, silicon tetrahydride was transformed into silicon molybdenum blue. The absorbance of silicon molybdenum blue was quantitatively measured at the wavelength of 680 nm. The results showed that the average sampling efficiency and desorption efficiency were 97.53% and 94.94%, respectively by this method. Detection limits were 0.054 μg/mL for the spectrophotometric method and 0.14 mg/m(3) for the determination of silicon tetrahydride in the air of workplace (sampling volume was 7.5 L). The conversion rate of silicon tetrahydride gradually decreased when storage time of samples was extended. The descent rate of sample was less than 10% when the sample was sealed for 7 days in the room temperature. It was concluded that this spectrophotometric method can be successfully used to determine silicon tetrahydride in the worksites.

Spectrophotometric determination of silicon tetrahydride in the air of workplace / 华中科技大学学报（医学）（英德文版）

A new, simple and sensitive method was developed for the determination of silicon tetrahydride in the air of workplace in this study. The alkaline resin-based spherical activated carbon was used to collect sample of silicon tetrahydride at workplace. Silicon tetrahydride was then desorbed from active carbon in 100°C hot water. After reacting with ammonium molybdate, oxalic acid and 1,2,4-trichlorobenzene alpha-naphthol amino sulfonic acid under acid condition, silicon tetrahydride was transformed into silicon molybdenum blue. The absorbance of silicon molybdenum blue was quantitatively measured at the wavelength of 680 nm. The results showed that the average sampling efficiency and desorption efficiency were 97.53% and 94.94%, respectively by this method. Detection limits were 0.054 μg/mL for the spectrophotometric method and 0.14 mg/m(3) for the determination of silicon tetrahydride in the air of workplace (sampling volume was 7.5 L). The conversion rate of silicon tetrahydride gradually decreased when storage time of samples was extended. The descent rate of sample was less than 10% when the sample was sealed for 7 days in the room temperature. It was concluded that this spectrophotometric method can be successfully used to determine silicon tetrahydride in the worksites.

Size-dependent biological effects on vascular endothelial cells induced by different particulate matters / 华中科技大学学报（医学）（英德文版）

The contribution of particles to cardiovascular mortality and morbidity has been enlightened by epidemiologic and experimental studies. However, adverse biological effects of the particles with different sizes on cardiovascular cells have not been well recognized. In this study, sub-cultured human umbilical vein endothelial cells (HUVECs) were exposed to increasing concentrations of pure quartz particles (DQ) of three sizes (DQPM1, <1 μm; DQPM3-5, 3-5 μm; DQPM5, 5 μm) and carbon black particles of two sizes (CB0.1, <0.1 μm; CB1, <1 μm) for 24 h. Cytotoxicity was estimated by measuring the activity of lactate dehydrogenase (LDH) and cell viability. Nitric oxide (NO) generation and cytokines (TNF-α and IL-1β) releases were analyzed by using NO assay and enzyme-linked immunoabsorbent assay (ELISA), respectively. It was found that both particles induced adverse biological effects on HUVECs in a dose-dependent manner. The size of particle directly influenced the biological activity. For quartz, the smaller particles induced stronger cytotoxicity and higher levels of cytokine responses than those particles of big size. For carbon black particles, CB0.1 was more capable of inducing adverse responses on HUVECs than CB1 only at lower particle concentrations, in contrast to those at higher concentrations. Meanwhile, our data also revealed that quartz particles performed stronger cell damage and produced higher levels of TNF-α than carbon black particles, even if particles size was similar. In conclusion, particle size as well as particle composition should be both considered in assessing vascular endothelial cells injury and inflammation responses induced by particles.

Size-dependent biological effects on vascular endothelial cells induced by different particulate matters / 华中科技大学学报（医学）（英德文版）

The contribution of particles to cardiovascular mortality and morbidity has been enlightened by epidemiologic and experimental studies. However, adverse biological effects of the particles with different sizes on cardiovascular cells have not been well recognized. In this study, sub-cultured human umbilical vein endothelial cells (HUVECs) were exposed to increasing concentrations of pure quartz particles (DQ) of three sizes (DQPM1, <1 μm; DQPM3-5, 3-5 μm; DQPM5, 5 μm) and carbon black particles of two sizes (CB0.1, <0.1 μm; CB1, <1 μm) for 24 h. Cytotoxicity was estimated by measuring the activity of lactate dehydrogenase (LDH) and cell viability. Nitric oxide (NO) generation and cytokines (TNF-α and IL-1β) releases were analyzed by using NO assay and enzyme-linked immunoabsorbent assay (ELISA), respectively. It was found that both particles induced adverse biological effects on HUVECs in a dose-dependent manner. The size of particle directly influenced the biological activity. For quartz, the smaller particles induced stronger cytotoxicity and higher levels of cytokine responses than those particles of big size. For carbon black particles, CB0.1 was more capable of inducing adverse responses on HUVECs than CB1 only at lower particle concentrations, in contrast to those at higher concentrations. Meanwhile, our data also revealed that quartz particles performed stronger cell damage and produced higher levels of TNF-α than carbon black particles, even if particles size was similar. In conclusion, particle size as well as particle composition should be both considered in assessing vascular endothelial cells injury and inflammation responses induced by particles.

Correlation between increased circulating endothelial progenitor cells and stage of non-Hodgkin lymphoma / 华中科技大学学报（医学）（英德文版）

This study aims to examine the levels of circulating endothelial progenitor cells (cEPCs) in the peripheral blood of patients with non-Hodgkin lymphoma (NHL) and their correlation with the tumor stage. Forty-one patients with biopsy-proven NHL and 16 healthy individuals were recruited. Peripheral blood mononuclear cells (PBMCs) were isolated by density gradient centrifugation, and cEPCs were characterized by triple staining using antibodies against CD133, CD34 and vascular endothelial growth factor receptor-2 (VEGFR-2, CD309) and quantified by flow cytometry. In NHL patients, the number of cEPCs was significantly greater than in control group (P=0.000). The cEPCs counts in patients with NHL of stage III-IV were significantly greater than in stage I-II (P=0.010). FACS analysis revealed that the number of cEPCs in NHL patients had no correlation with the gender (P=0.401) or the pathological category (P=0.852). It was suggested that the over-expression of cEPCs in NHL patients may serve as a novel biomarker for disease progression in NHL.

Association between CHRNA3 rs1051730 genotype and lung cancer risk in Chinese Han population: A case-control study / 华中科技大学学报（医学）（英德文版）

Recent population-based genome wide association studies have revealed potential susceptibility loci of lung cancer at the region of chromosome 15q25.1 containing nicotinic acetylcholine receptor genes. The loci increasing lung cancer risk has been widely identified in Caucasians, but whether this association also exists in Asians and whether this association is a direct role or mediated via tobacco smoking indirectly has not been fully established. We conducted a case-control study comprising of 210 histologically confirmed lung cancer cases and 200 healthy controls to examine rs1051730 genotyping, a single nucleotide polymorphism receiving much attention recently, and its influence on lung cancer risk as well as nicotine dependence in a Chinese Han population. Our results showed that the heterozygous C/T genotype and minor allele T conferred a significant higher risk of lung cancer than the CC homozygotes and allele C (adjusted OR=2.25, 95% CI=1.04-4.89, P=0.040 and OR=2.18, 95% CI=1.02-4.67, P=0.045 respectively). However, no association between the smoking habit and the CHRNA3 rs1051730 polymorphism was observed in this study. The results suggested that the rs1051730 polymorphism may modify susceptibility to lung cancer via a smoking-independent manner among Chinese Han population. Additional studies in vitro and in vivo are warranted to further elucidate the impact of rs1051730 on lung cancer susceptibility.

Suppression of low-dose hyper-radiosensitivity in human lung cancer cell line A549 by radiation-induced autophagy / 华中科技大学学报（医学）（英德文版）

This study explored the role of radiation-induced autophagy in low-dose hyperradiosensitivity (HRS) in the human lung cancer cell line A549. A549 cells, either treated with an autophagic inhibitor 3-methyladenine (3-MA), or with a vehicle control, were irradiated at different low doses (≤0.5 Gy). The generation of autophagy was examined by laser scanning confocal microscopy. Western blotting was used to detect the expression of microtubule-associated protein l light chain 3B II (LC3B-II). Flow cytometry (FCM) and clonogenic assays were used to measure the fraction of surviving cells at the low irradiation doses. Our results showed that there was a greater inhibition of autophagic activity, but a higher degree of low-dose HRS in A549 cells treated with 3-MA than in control group. Our data demonstrated that radiation-induced autophagy is correlated with HRS in A549 cells, and is probably one of the mechanisms underlying HRS.

Correlation between increased circulating endothelial progenitor cells and stage of non-Hodgkin lymphoma / 华中科技大学学报（医学）（英德文版）

This study aims to examine the levels of circulating endothelial progenitor cells (cEPCs) in the peripheral blood of patients with non-Hodgkin lymphoma (NHL) and their correlation with the tumor stage. Forty-one patients with biopsy-proven NHL and 16 healthy individuals were recruited. Peripheral blood mononuclear cells (PBMCs) were isolated by density gradient centrifugation, and cEPCs were characterized by triple staining using antibodies against CD133, CD34 and vascular endothelial growth factor receptor-2 (VEGFR-2, CD309) and quantified by flow cytometry. In NHL patients, the number of cEPCs was significantly greater than in control group (P=0.000). The cEPCs counts in patients with NHL of stage III-IV were significantly greater than in stage I-II (P=0.010). FACS analysis revealed that the number of cEPCs in NHL patients had no correlation with the gender (P=0.401) or the pathological category (P=0.852). It was suggested that the over-expression of cEPCs in NHL patients may serve as a novel biomarker for disease progression in NHL.

Relationship between the level of waist circumference and the impaired fasting glucose of pre-diabetes / 中华流行病学杂志

<p><b>OBJECTIVE</b>To explore the relationship between the level of waist circumference (WC) and the impaired fasting glucose (IFG) in people working for the Kailuan Enterprise.</p><p><b>METHODS</b>A total of 101 510 subjects from the employees of Kailuan Group who took part in the health examination between 2006 to 2007, with fasting plasma glucose (FPG) < 6.1 mmol/L, no history of diabetes, completed data on FPG and WC examination and without using hypoglycemic agents, were selected as the observation cohort. Subjects who did not participate in the health examination from 2010 to 2011 and had incomplete data were finally excluded, ended up with 52 099 subjects available for final analysis. According to the baseline WC measurements and its quartile in the health examinations during 2006 to 2007, people under observation were divided into four groups (first, second, third and the forth quartile groups). Multiple logistic regression analysis was used to test the relation between the increasing of WC and IFG.</p><p><b>RESULTS</b>(1) The incidence rate of IFG in the obese group was higher than that in non-obese group (10.5% vs. 6.8% , P < 0.01), along with an increasing WC noticed in the 4 quartile groups and the incidence rates of IFG were progressively increased, being 6.0%, 7.1%, 8.6% and 11.0% respectively in the total population(7.0%, 7.9%, 9.1% and 11.4% in males, 2.5%, 4.6%, 6.8% and 9.8% in females). (2)Results from the multiple logistic regression analysis showed that, when compared with the first quartile group, the second, third and fourth quartile groups had increased risks of IFG after adjustment on age, gender and other risk factors in the total population, with the OR values being 1.03, 1.15 and 1.30 respectively. After adjusting the above factors in genders, we also noticed the increased risks of IFG, with the OR value being 1.45, 1.66 and 2.08 in males, while 1.00, 1.09 and 1.23 in females, respectively. The influence of the second and third quartile groups on IFG was not significant in females, however.</p><p><b>CONCLUSION</b>The incidence of IFG showed an increasing trend with the increase of WC.</p>

Dynamic monitoring and analysis of occupational hazards in working environment of foundry plant from 1987 to 2010 / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate the characteristics and changing trend of occupational hazards in the working environment of a foundry plant from 1987 to 2010.</p><p><b>METHODS</b>The foundry plant of a large-scale automobile company in Hubei Province, China was chosen as the study site. The data on occupational hazards in the working environment of the foundry plant in the past years were collected, and additional measurements were performed. The means and geometric means of the concentrations of occupational hazards were calculated. The characteristics and changing trend of occupational hazards from 1987 to 2010 were presented.</p><p><b>RESULTS</b>There were dust, chemical, and physical occupational hazards in the working environment of the foundry plant, with silica dust, noise, and heat stress as the main ones. Dust, mainly silica dust, is found in all aspects of foundry. The mean concentration of silica dust was high (3.2∼8.2 mg/m(3)), exceeding the national occupational exposure limit (1 mg/m(3)). The mean concentrations of silica dust varied across different types of work, with higher levels in cast shakeout and finishing, overhead crane operation, and sand preparation. The mean concentration of respirable dust in the foundry plant was low (0.38 mg/m(3)), not exceeding the national occupational exposure limit (0.7 mg/m(3)). There were high concentrations of grinding wheel dust (10.6 mg/m(3)) and welding fume (5.7 mg/m(3)) in cast shakeout and finishing, exceeding the national occupational exposure limit (8 and 4 mg/m(3)). Coal dust was mainly found in melting as well as cast shakeout and finishing, with higher concentration in the former (4.7 mg/m(3). The main chemical occupational hazard in the environment of the foundry plant was formaldehyde (1.23 mg/m(3)), exceeding the national occupational exposure limit (0.5 mg/m(3)). The concentrations of ammonia, phenol, metal fume, sulfur dioxide, hydrogen sulfide, and phosphine in the foundry plant were low. The mean concentration of polycyclic aromatic hydrocarbons was 0.1405 µg/m(3), with a higher level in pouring. The main physical occupational hazards in the working environment of the foundry plant were noise and heat stress. Noise, mainly steady noise, was distributed in all workshops of the foundry plant, with a mean intensity of 85.1 db (A). Noise levels varied across different types of work, higher in cast shakeout and finishing (89.3 db (A)) and moulding (85.4 db (A)). Heat stress mainly existed in overhead crane operation (35.1°C), pouring (33.3°C), and melting (32.8°C).</p><p><b>CONCLUSION</b>Dust, chemical, and physical occupational hazards co-existed in the working environment of the foundry plant. High concentration of dust was widely distributed in many workshops and across many types of work, but the dust concentration showed a downward trend. Chemical occupational hazards included ammonia, phenol, hydrogen sulfide, and metal fume, most at low concentrations. High-intensity noise was widely distributed in all working positions of foundry process and mainly from equipment operation, collision between parts, and gas injection. High-intensity heat stress mainly existed in overhead crane operation, pouring, and melting.</p>

Protective performance and subjective evaluation of N95 filtering-facepiece respirators / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To evaluate the protective performance of N95 filtering-facepiece respirators (FFRs) used widely in China and to investigate participants' subjective evaluation about them.</p><p><b>METHODS</b>Four models (A1, A2, B1, B2) of N95 FFRs from two manufactures were chosen to measure the filter penetration and inhalation resistance. Inward leakage was measured by Condensation Nuclei Counting method (CNC) in 50 participants selected using the Chinese respirator fit test panel. Each participant was asked subjective feelings after wearing a respirator by questionnaire survey.</p><p><b>RESULTS</b>The filter penetration and inhalation resistance of four FFRs complied with national standard (GB 2626-2006). The geometric mean fit factors (GMFFs) for four models were 20.9, 14.6, 74.0, 49.1 and there passing rates were 4%, 4%, 42%, 10%. All of four models had bad seal performance, especially the passing rate of A1 and A2 were lower than 10%. The self-feelings about the resistance for FFRs had no significant difference (P > 0.05). The results indicated that B (B1 and B2) has a better fit than A (A1 and A2) according to participants' subject evaluation (P < 0.05). The folding style respirator (B2) was significant more comfortable than the cup style respirator (B1). The subjective feeling of respirators leakage by participant was poor consistent with objective inward leakage test. The kappa index was 0.067 (95%CI: -0.029∼0.163, P = 0.18) and the consistent rate was 50%.</p><p><b>CONCLUSION</b>The poor seal performance was the biggest problem of N95 FFRs in Chinese market. Respirators should be resigned or improved rely on Chinese facial features. Dust workers should choice a fit respirator according to the result of objective leakage test rather than subjective feeling of leakage.</p>