Airborne arsenic and urinary excretion of metabolites of inorganic arsenic among smelter workers

Summary The relationship between airborne concentrations of arsenic and the urinary excretion of inorganic arsenic metabolites (inorganic arsenic + methylarsonic acid + dimethylarsinic acid) have been studied among smelter workers exposed to arsenic trioxide. The urinary concentrations of arsenic metabolites were found to increase steadily during the first day of the working week (after 2–3 d off from work), whereafter they reached a steady state. The concentration in the late evening after a day of exposure was very similar to that in the early morning after. Both were well correlated to the total daily excretion. In the second part of the study, comprising 18 subjects, the first-void morning urine of each participant was collected for 2 to 3 d during the steady-state phase. Total concentration of arsenic in the breathing zones was measured by personal air samplers. Airborne arsenic (8-h values) varied between 1 and 194 g As/m³, and urinary arsenic between 16 and 328 g As/g creatinine. With the urinary arsenic concentrations (mean values of 2–3 d for each subject) plotted against the corresponding airborne arsenic concentrations, the best fit was obtained by a power curve with the equation y = 17 x x^0.56. However, four of the participants were found to excrete far more (105–260%) arsenic in the urine than possibly could have been inhaled, most likely due to oral intake of arsenic via contaminated hands, cigarettes or snuff. If these four were excluded, the best fit was obtained by a straight regression line with the slope 2.0 and the intercept 29 g As/g creatinine (coefficient of correlation 0.92; P < 0.001).     

Relation between airborne arsenic trioxide and urinary excretion of inorganic arsenic and its methylated metabolites.

The relation between exposure to As2O3 fumes and dust, and the urinary excretion of inorganic arsenic metabolites (monomethylarsonic acid, dimethylarsinic acid, unchanged inorganic arsenic) has been studied in 18 workers from a sulphuric acid producing plant. The concentration of arsenic in the breathing zone of each worker was measured during five consecutive days and urine samples were obtained after one shift and before the next. The collection efficiency of the air sampling system exceeded 95%. The time weighted average exposure (TWA) concentrations of As2O3 ranged from 6 to 502 micrograms As/m3 and were log normally distributed. Although exposure probably occurred by ingestion as well as inhalation, statistically significant correlations (log scales) were found between airborne TWA of As2O3 and the inorganic arsenic metabolites in urine collected immediately after the shift, or just before the next shift. For a TWA of 50 micrograms As/m3, the mean concentration of the sum of the three inorganic arsenic metabolites in a postshift urine sample amounted to about 55 micrograms arsenic/g creatinine (95% confidence interval (95% CI) 47-62). Higher estimates of urinary arsenic reported by other authors are probably due either to the influence of dietary organoarsenicals when total arsenic is measured in urine or to a low retention efficiency of the air sampling system for As2O3 in the vapour phase.     

Relation between airborne arsenic trioxide and urinary excretion of inorganic arsenic and its methylated metabolites.

The relation between exposure to As2O3 fumes and dust, and the urinary excretion of inorganic arsenic metabolites (monomethylarsonic acid, dimethylarsinic acid, unchanged inorganic arsenic) has been studied in 18 workers from a sulphuric acid producing plant. The concentration of arsenic in the breathing zone of each worker was measured during five consecutive days and urine samples were obtained after one shift and before the next. The collection efficiency of the air sampling system exceeded 95%. The time weighted average exposure (TWA) concentrations of As2O3 ranged from 6 to 502 micrograms As/m3 and were log normally distributed. Although exposure probably occurred by ingestion as well as inhalation, statistically significant correlations (log scales) were found between airborne TWA of As2O3 and the inorganic arsenic metabolites in urine collected immediately after the shift, or just before the next shift. For a TWA of 50 micrograms As/m3, the mean concentration of the sum of the three inorganic arsenic metabolites in a postshift urine sample amounted to about 55 micrograms arsenic/g creatinine (95% confidence interval (95% CI) 47-62). Higher estimates of urinary arsenic reported by other authors are probably due either to the influence of dietary organoarsenicals when total arsenic is measured in urine or to a low retention efficiency of the air sampling system for As2O3 in the vapour phase.     

Profile of urinary arsenic metabolites during pregnancy

Chronic exposure to inorganic arsenic (In-As) from drinking water is associated with different health effects, including skin, lung, bladder, and kidney cancer as well as vascular and possibly reproductive effects. In-As is metabolized through the process of methylation, resulting in the production and excretion of methylated species, mainly monomethylarsenate (MMA) and dimethylarsenate (DMA). Because a large percentage of the dose is excreted in urine, the distribution of urinary In-As, MMA, and DMA is considered a useful indicator of methylation patterns in human populations. Several factors affect these patterns, including sex and exposure level. In this study, we investigated the profile of urinary In-As, MMA, and DMA of pregnant women. Periodic urine samples were collected from early to late pregnancy among 29 pregnant women living in Antofagasta, Chile, who drank tap water containing 40 micro g/L In-As. The total urinary arsenic across four sampling periods increased with increasing weeks of gestation, from an initial mean value of 36.1 to a final value of 54.3 micro g/L. This increase was mainly due to an increase in DMA, resulting in lower percentages of In-As and MMA and a higher percentage of DMA. Our findings indicate that among women exposed to moderate arsenic from drinking water during pregnancy, changes occur in the pattern of urinary arsenic excretion and metabolite distribution. The toxicologic significance of this is not clear, given recent evidence suggesting that intermediate methylated species may be highly toxic. Nevertheless, this study suggests that arsenic metabolism changes throughout the course of pregnancy, which in turn may have toxicologic effects on the developing fetus. Key words: arsenic, arsenic metabolism, arsenic methylation, Chile, pregnancy, urinary arsenic.     

Association between arsenic exposure from a coal-burning power plant and urinary arsenic concentrations in Prievidza District,Slovakia

To assess the arsenic exposure of a population living in the vicinity of a coal-burning power plant with high arsenic emission in the Prievidza District, Slovakia, 548 spot urine samples were speciated for inorganic As (Asinorg), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), and their sum (Assum). The urine samples were collected from the population of a case-control study on nonmelanoma skin cancer (NMSC). A total of 411 samples with complete As speciations and sufficient urine quality and without fish consumption were used for statistical analysis. Although current environmental As exposure and urinary As concentrations were low (median As in soil within 5 km distance to the power plant, 41 micro g/g; median urinary Assum, 5.8 microg/L), there was a significant but weak association between As in soil and urinary Assum(r = 0.21, p < 0.01). We performed a multivariate regression analysis to calculate adjusted regression coefficients for environmental As exposure and other determinants of urinary As. Persons living in the vicinity of the plant had 27% higher Assum values (p < 0.01), based on elevated concentrations of the methylated species. A 32% increase of MMA occurred among subjects who consumed homegrown food (p < 0.001). NMSC cases had significantly higher levels of Assum, DMA, and Asinorg. The methylation index Asinorg/(MMA + DMA) was about 20% lower among cases (p < 0.05) and in men (p < 0.05) compared with controls and females, respectively.     

某新建火电厂锅炉化学清洗有害因素职业暴露评价及防护

目的针对作业人员可能接触的化学毒物进行职业暴露分析,将健康风险进行分级和定量评价,提出可采取的职业卫生控制措施,降低人员接触风险,保护劳动者健康。方法以职业卫生相关法规及风险矩阵半定量分析评估模型为基础进行计算和综合分析。结果该新建火电厂投入使用前锅炉清洗涉及到的化学药品人员接触风险水平较高,氨、联氨、硫酸、氢氧化钠的风险级别均为4级,应予以关注和防护。结论在实施有效的工程控制,提供必要的个人防护用品,制定应急救援预案,配备现场应急救援设施和用品,制定和实施安全、正确的工作程序后,可有效降低风险水平。     

某燃煤电厂职业病危害调查与分级

为了解某燃煤电厂的职业卫生现状,确定其是否符合卫生学要求,按规范标准检测作业场所有害因素浓度(强度),并对粉尘、噪声、毒物作业进行分级。结果粉尘、毒物分级均为0级;噪声作业0级占25.81%,Ⅰ级岗位占35.48%,Ⅱ级岗位占38.71%。粉尘点合格率(短时间浓度超标)与危害分级两者出现不符的情况下,以粉尘职业危害分级结果确定危害程度较合适。     

某电厂燃煤发电机组职业病危害因素分析

调查显示,某电厂燃煤发电机组主要存在粉尘、化学性毒物和噪声等职业病危害因素,工作场所粉尘浓度样品合格率为71.19%,噪声强度合格率为53.33%,毒物检测结果均符合职业接触限值,连续2年健康检查异常检出率分别为39.97%和49.85%,有职业损伤发生。提示该电厂粉尘和噪声危害分布广泛,对作业人员的危害客观存在,除加强职业病预防措施外,还需要开展企业健康促进工作。     

某燃煤发电机组热电联产项目职业病危害预评价

目的 确定该拟建项目产生的职业病危害因素,分析其危害程度及对劳动者健康的影响,评价职业病危害防护措施及其效果,提出职业病危害的关键控制点.方法 采用检查表法、类比法进行综合分析评价.结果 类比企业41个毒物检测点,合格率为100.0％;51个粉尘检测点,合格率为82.4％;69个噪声检测点,合格率为85.5％;3个工频电场检测点全部合格.结合某燃煤发电厂实地考察的情况预测该项目建成投产后,其职业病危害的关键控制点是燃料的储存、装卸和灰渣运输工、汽机巡检工、水处理系统工作人员、锅炉巡检工岗位.结论 该拟建项目作业场所中的职业病危害因素有毒物、噪声、粉尘、工频电场新建设项目只有将各项职业病防护措施落实到位,才能使该项目投入生产后将可能存在和产生的职业病危害因素的浓度(或强度)控制在国家规定的职业接触限值范围内.该拟建工程项目从职业卫生角度分析是基本可行的.     

Methylmercury in mosquitoes around a large coal-fired power plant in central Ohio

Emissions from coal-fired power plants are the major anthropogenic source of mercury (Hg) in the environment. Because emitted Hg can be deposited near the source, concerns arise about the effects of coal-burning facilities on levels of toxic methylmercury (MeHg) in biota near such sources. We investigated the potential impact of a large Hg-emitting (450 kg in 2005) coal-fired power station in Conesville, Ohio, on MeHg levels in adult mosquitoes near the plant. In July 2010, mosquitoes were sampled at 23 locations within a 60-km radius of the plant and at three reference sites distant from major combustion sources of Hg. Nearly all of the Hg in mosquitoes appeared in the form of MeHg (mean=91%). Concentrations of MeHg in mosquitoes were unrelated to either distance or direction from the Conesville plant and did not differ from those at the three reference sites. Moreover, measured levels of MeHg in mosquitoes near Conesville are in good agreement with those predicted from an empirical relationship to wet atmospheric Hg fluxes alone. This suggests that either little of the Hg emitted from the Conesville plant is deposited locally or near-source deposition of Hg does not have a significant impact on MeHg in mosquitoes and, by extension, other insects with similar life histories in the local food web.     

Geographical and temporal differences in the urinary excretion of inorganic arsenic: a Belgian population study.

OBJECTIVE: This Belgian study assessed the geographical and temporal differences in the exposure of the population to inorganic arsenic, a known carcinogen. METHODS: In the CadmiBel study (1985-9) the 24 h urinary arsenic excretion was measured, as an index of recent exposure, in industrialised cities (Liège: n = 664, Charleroi: n = 291), in a rural control area (Hechtel-Eksel: n = 397), and in rural districts in which the population had possibly been exposed through the drinking water or the emissions of nonferrous smelters (Wezel: n = 93, Lommel: n = 111, and Pelt: n = 133). In the PheeCad study, in 1991-5, the rural areas (n = 609) were re-examined together with an urban control area (Leuven: n = 152). RESULTS: The CadmiBel results showed that after adjustment for sex, age, and body mass index, the 24 h arsenic excretion was on average low in Liège (91 nmol), Charleroi (155 nmol), Hechtel-Eksel (144 nmol), and Wezel (158 nmol), whereas the highest excretions were found in Lommel (570 nmol) and Pelt (373 nmol). During the PheeCad study, the mean 24 h arsenic excretion in the rural areas ranged from 81 to 111 nmol. This was lower than six years earlier and similar to the excretion in the control town (108 nmol). Longitudinal studies in 529 people living in the rural areas confirmed that their 24 h arsenic excretion had decreased (P < 0.001) from 222 to 100 nmol. As well as the drinking water, industry was likely to be a source of the increased exposure in Lommel and Pelt in 1985-9, because at that time the urinary arsenic excretion did not follow the regional differences in the arsenic content of the drinking water, because the fall in the arsenic excretion over time coincided with the implementation by industry of stricter environmental regulations, because in individual subjects the urinary arsenic excretion was inversely correlated with the distance to the nearest smelter, and because an increased arsenic excretion was only found downwind from the main smelter. The official network that monitors the arsenic concentration in airborne and fall out dust did not detect the high exposure in Lommel and Pelt between 1985 and 1989. CONCLUSION: This study highlights the necessity to validate environmental monitoring programmes by directly estimating the internal exposure of the population.     

Assessment of exposure to ceramic fibers during insulation operations in a thermoelectric power plant]

Refractory ceramic fibre concentrations were measured during renewal of the insulation lining of a turbine located in a large power plant. Personal and stationary samples were collected during operations, which involved installing and ripping out standard and pre-coated and pre-shaped ceramic fibre blankets. Operation-length average (OLA) and TWA exposure levels were about 500 F/l and about 100 F/l, respectively, for installing and ripping out operations where non-coated blankets were handled. In these cases specific task-associated personal exposure levels up to 1000 F/l were measured. Personal exposure levels up to as much as 10 times lower were observed in operations involving pre-coated and pre-shaped blankets. The average concentration levels from area samples were always lower than those from personal samples, and showed a downward gradient with the distance from the source. Given the current carcinogenic classification of refractory ceramic fibres (class 2, European), the necessity is stressed of introducing adequate working practices and control measures (adoption of pre-coated and pre-shaped fibrous materials whenever possible, confinement of working area, use of local air extractions ventilation with HEPA filter unit, use of garments for personal protection and respirators, use of wetting or binding liquids prior to removal, quick cleaning of debris from working area), in order to keep the exposure levels and the number of potentially exposed workers to the minimum.     

A pathway-based analysis of urinary arsenic metabolites and skin lesions

Inorganic arsenic is metabolized to monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). Limited evidence suggests that the ability to fully metabolize arsenic into DMA influences susceptibility to disease. To determine whether percentage of MMA was predictive of disease, the authors used data from a case-control study conducted in Bangladesh (2001-2003). Persons who were diagnosed with keratosis, melanosis, Bowen's disease, or squamous cell carcinoma were matched on age, sex, and village to persons without these conditions. This analysis was restricted to persons who had no missing data on covariates (859 cases, 868 controls). A path analysis was used to evaluate simultaneously the association between the percentage of all urinary arsenic metabolites and the odds of skin lesions using PROC CALIS in SAS, version 9.1 (SAS Institute, Inc., Cary, North Carolina) and Mplus, version 6.1 (Muthén & Muthén, Los Angeles, California). The odds of skin lesions were significantly associated with log(10) percentage of MMA (adjusted odds ratio (OR(adj)) = 1.56, 95% confidence interval (CI): 1.15, 2.12) but not log(10) percentage of inorganic arsenic (OR(adj) = 1.06, 95% CI: 0.75, 1.50) or log(10) percentage of DMA (OR(adj) = 1.07, 95% CI: 0.33, 3.46). This novel analysis confirmed that persons who excrete a higher proportion of MMA have a greater risk of skin lesions after data are adequately controlled for urinary arsenic metabolites, current arsenic exposure, and other risk factors.     

Use of outpatient clinics as a health indicator for communities around a coal-fired power plant.

The permit to operate the first coal fired power plant in Israel was issued with the condition that a comprehensive network to monitor its effects on the environment, health, and agriculture must be installed and operated around the plant. The health monitoring system consists of four studies, which started 1 year prior to the operation of the plant and were carried out for 10 years. In the framework of the health monitoring system, a study of requests for health services was carried out. In this survey, 8 clinics of the Sick Fund, served by 16 physicians, were followed up. The clinics were located as near as possible to air pollution monitoring stations and represent expected different levels of pollution. A health recorder summarized each day's visits to each physician and tabulated the total visits for each day and the visits due to respiratory tract complaints. Multivariate stepwise regressions on total as well as on respiratory complaints were carried out. The independent variables in the regressions were sulfur dioxide, meteorological parameters (such as temperature and humidity), and flu epidemics. Temperature was almost always significantly correlated with respiratory complaints, but less correlated with total visits among, adults and children. Sulfur dioxide, most meterological parameters and flu epidemics were not meaningful explanatory factor in the regressions. Ambient air pollution levels did not exceed the Israeli air quality or the more stringent local air quality standards, the monthly and annual average sulfur dioxide and nitrogen oxides values were very low.     

Comparison of the urinary excretion of arsenic metabolites after a single oral dose of sodium arsenite,monomethylarsonate, or dimethylarsinate in man

Summary The urinary elimination of the metabolites of arsenic has been followed up as a function of time in volunteers who ingested a single oral dose of arsenic (500 g As) either as sodium arsenite (As_i), monomethylarsonate (MMA), or cacodylate (DMA). The excretion rate increased in the order As_i < DMA < MMA. After 4 days, the amount of arsenic excreted in urine represents 46, 78, and 75% of the ingested dose in the case of As_i, MMA and DMA, respectively. With regard to the in vivo biotransformations, it is concluded that DMA is excreted unchanged; MMA is slightly (13%) methylated into DMA while roughly 75% of the arsenic excreted after ingestion of As_i is methylated arsenic (about 1/3 as MMA and about 2/3 as DMA).This study was supported by a grant from the Commission of the European Communities     

Urinary levels of 1-hydroxypyrene in children residing near a coal-fired power plant

Background

The effects of emissions from coal-fired power plants on children's exposure to polycyclic aromatic hydrocarbons (PAHs) are not well understood.

Objectives

This study aimed to evaluate the sources and the urinary levels of 1-hydroxypyrene, a biomarker of exposure to PAHs, among children living in proximity to a coal-fired power plant.

Methods

Study areas consisted of two high exposure and two low exposure communities, at different distances and directions from a large coal-fired power plant in central Taiwan. Study subjects included 369 children aged 1–13 years and randomly selected from each community. Each child's urinary 1-hydroxypyrene concentration was measured by a high-performance liquid chromatography-fluorescence detector method. Samples of ambient air were analyzed for PAHs using a gas chromatography–mass spectrometry method. Information on important factors was collected by an interview using a structured questionnaire. Multiple regression analysis was used to assess factors significantly associated with urinary 1-hydroxypyrene levels.

Results

Levels of PAHs in ambient air in the high exposure communities were higher than those in the low exposure communities. Children living in high exposure communities had higher mean urinary 1-hydroxypyrene concentrations than those in low exposure communities (0.186 and 0.194 vs. 0.113 and 0.122 μmol/mol-creatinine, respectively). The difference in urinary 1-hydroxypyrene levels between the high exposure communities and one low exposure community remained significant after adjusting for age, gender, environmental tobacco smoke, dietary exposure, and traffic.

Conclusions

Children living in communities downwind of and in proximity to the coal-fired power plant had significantly increased urinary 1-hydroxypyrene levels.     

A study of factors influencing urinary arsenic excretion in exposed workers

This study was designed to evaluate the influence of occupational and non-occupational factors on urinary arsenic excretion in workers exposed to iAs (inorganic arsenic) in the dismantlement of a factory which once produced fertilisers. We measured iAs and its methylated metabolites in 108 urinary samples of workers exposed to iAs in July 2006. A total of 13.9% of the samples showed levels higher than the Biological Exposure Index (BEI) of 35 μg/l (mean value 23.9 μg/l). After the improvement of working conditions, in August–October 2006 we collected urinary samples from each of the 108 workers enrolled. We also administrated a questionnaire, in order to investigate the influence of occupational and non-occupational factors on the urinary arsenic excretion. A significant difference was observed in relation with seafood consumption and age stratification. We have found a significant reduction of urinary arsenic excretion between the two phases of biological monitoring, probably due to appropriate hygiene work-related interventions.     

典型燃煤电厂周边蔬菜重金属累积特征及人体健康风险

目的探讨和分析燃煤电厂重金属排放对周边蔬菜质量安全的影响。方法选取典型燃煤电厂,分析其东南西北4个方向、5 km范围内(基于不同气象条件下的最大浓度的落地距离)叶菜类、豆类和茄果类蔬菜中As、Cd、Cr、Cu、Hg和Pb重金属累积特征,并使用膳食暴露模型评估该地区蔬菜重金属污染的人体健康风险。结果调查的10种蔬菜中,叶菜类、豆类和茄果类Cu超标率分别为17.4%、14.3%和14.3%,叶菜Hg和Cr超标率分别为21.7%和17.4%,其他蔬菜重金属均未超出相应的国家食品卫生标准限值。儿童摄入Cu的非致癌风险值平均为1.09,其他金属对暴露人群的非致癌风险值均小于1.0,但该区域蔬菜中多种重金属对成人和儿童的总非致癌风险值分别为2.18和3.00。结论该区域蔬菜的重金属污染程度整体较低,燃煤电厂排放并没有造成周边蔬菜重金属的严重污染。该燃煤电厂周边蔬菜中除Cu累积对人体会造成非致癌风险,其他金属无明显的健康危害,但复合污染风险需重视。