Analysis of welding fumes: A short note on the comparison between two sampling techniques

It is well established that welding fumes contain toxic substances, and that its composition is dependent on multiple factors, such as nature of the welding process and chemical compositions of the welding consumables and base materials. In order to prevent accidents and, thus to contribute to the safety of protection of welders, the establishment of a database on welding fume components is considered as essential. This has led to the development and upgradation of sampling techniques of welding fumes. Up to now, few standard techniques exist in this area. This study describes the results of the analysis of welding fumes, in terms of heavy metals, for a set of welding electrodes commonly used in carbon steel manufacture. Sampling was done by two different techniques: using the one currently known as “fume box” and common techniques in workplace atmospheres.     

The Exploitation and Environmental Legacy of Amphibole Asbestos : A Late 20th Century Overview

The risk to human health associated with the inhalation of amphibole asbestos has become devastatingly ap- parent this century. The most commonly utilised asbestiform amphiboles, crocidolite (blue asbestos) and amosite (brown asbestos), are implicated in a variety of diseases related to cell damage within the respiratory tract and adjacent areas. Blue and brown asbestos fibres have a morphology and mineralogy which makes them more biopersistent and biochemically reactive than chrysotile (white asbestos). The long-term pres- ence of such fibres within and around the lungs can result in fibrous scarring, lung cancer, and is the major cause of the once extremely rare tumour known as diffuse malignant mesothelioma. Therefore, despite the fact that asbestiformamphiboles comprise approximately 5%of industrially utilised asbestos (the rest being chrysotile), they have been disproportionately pathogenic. Almost all amphibole asbestos sold on the world market was mined from Palaeoproterozoic ironstones in either the northern Cape Province (blue) or Trans- vaal (brown and blue) areas in South Africa. Production peaked from 1966–1978 when around 2 million tons of crocidolite and1million tons of amosite were produced and exported to be used mainly in asbestos-based cement products and many types of building materials. Crocidolite mixed with chrysotile was commonly used in pressure pipes and gaskets, whereas amosite mixed with chrysotile was especially suitable for gut- ters, roofing, and insulation boards. Amid- to late 20th century amphibole asbestos-related cancer epidemic has consequently struck not only mining and milling communities in producer countries, but many groups of workers (and their relatives and neighbours) exposed to amphibole asbestos-bearing materials in importer countries. Although belated closure and reparation of the mines and imposition of threshold safety limits in the workplace will eventually stem this epidemic the death toll has not yet peaked. Given the long latency period (decades) typical of mesothelioma and bronchogenic carcinoma and the fact that amphibole asbes- tos-bearing materials are still present in some buildings, asbestos-related cancer will inevitably continue to be a major cause of death in many countries worldwide well into the next century.     

Health risk assessment and oxidative stress in workers exposed to welding fumes

The aim of this study was designed to determine the influence of welding fumes on oxidative stress in humans and the role of metals. A questionnaire was designed to collect information regarding personal characteristics, including age, weight, height, and medical history; life style such as smoking status and exercise habits; and occupational history such as working history, working environment, employment duration, and use of protective equipment. Body mass index (BMI) in kg/m² was then calculated for each participant. Blood samples were also drawn to determine malondialdehyde (MDA) levels and various metals in plasma. Significantly higher plasma MDA (4.08 µg/L) was observed as compared to controls (1.61 µg/L). Blood metal analysis also showed elevated level of metals in welders for cadmium, chromium, lead,and nickel. Data indicated that workers occupationally exposed to welding fumes for prolong periods possessed higher metal levels associated with increased oxidative stress as evidenced by elevated MDA levels.     

State-of-the-science assessment of non-asbestos amphibole exposure: Is there a cancer risk?

The distinction between amphibole asbestos fibers and non-asbestos amphibole particles has important implications for assessing potential cancer risks associated with exposure to amphibole asbestos or amphibole-containing products. Exposure to amphibole asbestos fibers can pose a cancer risk due to its ability to reside for long periods of time in the deep lung (i.e., biopersistence). In contrast, non-asbestos amphibole particles are usually cleared rapidly from the lung and do not pose similar respiratory risks even at high doses. Most regulatory and public health agencies, as well as scientific bodies, agree that non-asbestos amphiboles possess reduced biological (e.g., carcinogenic) activity. Although non-asbestos amphibole minerals have been excluded historically from Federal regulations, non-asbestos structures may be counted as asbestos fibers on the basis of dimensional criteria specified in analytical protocols. Given the potential to mischaracterize a non-asbestos structure as a “true” asbestos fiber, our objective was to assess whether exposure to non-asbestos amphiboles that may meet the dimensional criteria for counting as a fiber pose a cancer risk similar to amphibole asbestos. We reviewed analytical methods as well as the mineralogical, epidemiological, and toxicological literature for non-asbestos amphiboles. No evidence of demonstrable cancer effects from exposure to non-asbestos amphiboles that may be counted as fibers, under certain assessment protocols, was found. Data gaps (industrial hygiene data for amphibole-exposed cohorts), inconsistencies (analytical laboratory methods/protocols used to count fibers), and sources of potential bias from misclassification of exposure were identified.     

Fume emissions during gas metal arc welding

The control of exposure to welding fumes is of increasing importance in promoting a healthy, safe and productive work environment. This article describes the effects of shielding gas composition on the amount and composition of welding fumes produced during gas metal arc welding (GMAW). The amount of fumes generated during welding was measured for steady current over a range of wire-feed speeds and arc voltages using the standard procedures contained in ANSI/AWS F1.2 [American Welding Society. ANSI/AWS F1.2. Laboratory method for measuring fume generation rates and total fume emission of welding and allied processes. Miami, Florida; 1992]. Results of these measurements show that the fume formation rates (FFRs) increase with CO₂ and O₂ in the shielding gas mixture. The lowest FFRs were obtained with the mixtures of Ar?+?2%CO₂ and Ar?+?3%CO₂?+?1%O₂. The highest FFRs were obtained with the mixtures of Ar?+?18%CO₂ and Ar?+?5%CO₂?+?4%O₂. The welding fumes contains mainly iron, manganese, silicon, titanium and sodium under oxide forms. The fume cluster particles have dimensions between 0.5 and 2?µm. The FFR was found to be governed by the transfer modes of molten metal, i.e. the current intensity and arc voltage, as well as by the shielding gas mixtures composition. Thus these parameters have to be taken into consideration before designing a welding process. Whenever possible, users of GMAW should use the lowest current intensity. However, when this is not possible, due to the constraints of process productivity, welders should use higher currents, but with Ar?+?2%CO₂ and Ar?+?3%CO₂?+?1%O₂ shielding mixtures, which will lead to smaller fume emissions.     

Industries and lung cancer: A population-based case-control study in British Columbia

An investigation was conducted to identify high-risk industries for histological subtypes of lung cancer based on a large population-based case-control study in British Columbia, Canada. Occupational histories and information on smoking and relevant covariates were collected from 14,755 male incident cancer cases. Industrial risk factors for 2998 lung cancer cases, including histological subtypes were assessed by logistic regression using other cancer cases, excluding smoking-related cancers, as controls. An excess risk of lung cancer was found among workers in mining, metal manufacturing, and electric power systems for all histological-subtypes, and construction, water transport, health services for specific histological subtypes. Industrial associations that are unique to histological subtypes of lung cancer were identified. Future research needs to focus on confirming these histological associations, and identifying the risk from key exposures found within these industries (e.g. medical radiation, electromagnetic fields, and cooking fumes).     

Erionite series minerals: mineralogical and carcinogenic properties

Erionite is a human and animal carcinogen and one of the most toxic minerals known. Erionite deposits have been reported in many countries; however, it is only in the area of three villages of Cappadocia, Turkey, that environmental exposure to erionite has been demonstrated to be the cause of an epidemic of the disease mesothelioma. In the USA, no cases of mesothelioma have been reliably proven to be the result of erionite exposure, though the possibility exists. Erionite samples from three villages of the Cappadocia region were characterized mineralogically and compared with three different standards from the USA. Micro morphological details of erionite minerals using a high-resolution field-emission SEM showed that microstructures of "bundles", "fibers", and "fibrils" are important physical properties of fibrous erionite minerals. Typical lung burden of erionite and asbestos fibers were compared in terms of number of fibers. Assuming the lung burden of fibers in a human mesothelioma victim is about 1 mg, and the hazardous fibers are approximately 1 mum in diameter and 10 mum long, that milligram contains approximately 40 million asbestos and 50 million erionite fibers. These microstructures of erionite minerals draw attention to the concepts of surface area or surface-area-to-volume ratio and their relationship to the carcinogenicity of the mineral. The larger surface area creates a wider platform for mineral-cell interaction and thus more possibilities of proliferative transformation of mesothelial cells. Consequently, understanding the exact mineralogical properties will help determination of the true carcinogenic mechanism(s) of the mineral for prevention and possibly treatment of malignant mesothelioma.     

Printed in great Britain Cr(VI) and other metallic mutagens in fly ash and welding fumes†

Particulate samples taken from both the indoor (working) and outdoor (community) environments contain a wide range of metallic trace elements most of which are mutagenic in at least one of the short term tests for genotoxicity currently in use. Because of the demonstrated presence of a short lived biologically active species (Cr(VI)), and the uncertainty with which the results of the screening of metallic compounds in short term tests can be interpreted in terms of human risk, great care must be taken to assure the appropriate collection, storage, and chemical and biological assay of such material. The sensitivity of the results for fly ash and welding fumes to variations in these protocols is demonstrated and discussed.     

Characteristics of heavy metal absorption of river bed sludge components

Chronic inhalation of aerosols of different Cd compounds by rats gave sufficient evidence that inhaled Cd is a lung carcinogen in rats. In contrast, the evidence in humans has been termed limited that inhaled Cd causes lung cancer in occupationally exposed humans. In order to assess the carcinogenic potential of ambient air concentrations of Cd, the accumulated dose of Cd in lung tissue from a rat inhalation study was modelled taking into account deposition and retention of Cd in the lung. A lung Cd—cancer incidence relationship could then be established, and an equivalent human exposure could be calculated using man specific pulmonary Cd retention and deposition data for Cd containing particle sizes in the ambient air. Linear interpolation to low doses showed that the pulmonary carcinogenic risk from inhalation of environmental airborne Cd is generally very low, but may reach about 1 × 10^‐4 in polluted industrialized areas. Combined exposures to Cd plus other carcinogens or air pollutants may increase the risk considerably. Cd in cigarette mainstream smoke was estimated to contribute less than 5 % of the total lung cancer risk from smoking cigarettes. However, the influence of co‐exposure to other compounds in cigarette smoke is not known and should be taken into account.     

The assessment of the malignant mesothelioma cases and environmental asbestos exposure in Sivas province, Turkey

One of the most significant diseases related to environmental asbestos exposure is malignant mesothelioma (MM). Sivas province is located in the Central Anatolia where asbestos exposure is common. We aimed to study clinical, demographical and epidemiologic features of the patients with MM in Sivas, along with the history of asbestos exposure. In total, 219 patients with MM who were diagnosed in our hospital between 1993 and 2010 were retrospectively analyzed in terms of demographical and clinical features. Rock, soil and house plaster samples were taken from the habitats of those patients and were evaluated with optical microscopy and X-ray diffraction methods. The age of the patients ranged between 18 and 85 years. The male-to-female ratio was 1.4:1. Most of the patients confirmed an asbestos exposure history. The most frequent symptoms of the patients were chest pain (60 %) and dyspnea (50 %). The gap between the start of first symptoms and the diagnosis date was approximately 4 months in average. The plaster materials used in most of the houses were made up of mainly carbonate and silicate minerals and some chrysotile. Ophiolitic units contained fibrous minerals such as serpentine (clino + orthochrysotile) chiefly and pectolite, brucite, hydrotalcite and tremolite/actinolite in smaller amounts. MM is not primarily related to occupational asbestos exposure in our region, and hence, environmental asbestos exposure may be indicted. Yet, single or combined roles and/or interactions of other fibrous and non-fibrous minerals in the etiology of MM are not yet fully understood and remain to be investigated.     

Indoor and outdoor air pollution and lung cancer in New Hampshire and Vermont

Indoor and outdoor air pollution is known to contribute to increased lung cancer incidence. This study is the first to address the contribution of home heating fuel and geographical course particulate matter (PM₁₀) concentrations to lung cancer rates in New Hampshire, USA. First, Pearson correlation analysis and geographically weighted regression were used to investigate spatial relationships between outdoor PM₁₀ and lung cancer rates. While the aforementioned analyses did not indicate a significant contribution of PM₁₀ to lung cancer in the state, there was a trend towards a significant association in the northern and southwestern regions of the state. Second, case-control data were used to estimate the contributions of indoor pollution and secondhand smoke to the risk of lung cancer with adjustment for confounders. Increased risk was found among those who used wood or coal to heat their homes for more than 10 winters before the age of 18, with a significant increase in risk per winter. Resulting data suggest that further investigation of the relationship between heating-related air pollution levels and lung cancer risk is needed.     

Low level inhalation experiments with four different cadmium compounds in rats†

This long‐term inhalation study was designed to describe the toxicity and the carcinogenic risk from Cd compounds because it had been shown from former long‐term inhalation studies that cadmium choloride induced primary lung tumors in Wistar rats. It was therefore logical to examine whether other cadmium compounds to which human beings are more frequently exposed have also carcinogenic potency. In a long‐term inhalation study cadmium aerosols consisting of cadmium chloride (CdCl₂), cadmium oxide (CdO) as dusts and fumes, cadmium sulfate (CdSO₄), cadmium sulfide (CdS) and a combination of cadmium oxide/zinc oxide were used. Wistar rats were continuously exposed in inhalation chambers for 18 months 22 hrs a day or for 40 hrs a week. The studies will be terminated at the mean survival life time of the species. The aerosols were generated by several different systems. The particles of the cadmium aerosols have the average mass medium diameters in the range from 0.2 to 0.5 μm.     

Trace element concentration in fine particulate matter (PM<Subscript>2.5</Subscript>) and their bioavailability in different microenvironments in Agra,India: a case study

Exposure to airborne particulate matter results in the deposition of millions of particle in the lung; consequently, there is need for monitoring them particularly in indoor environments. Case study was conducted in three different microenvironments, i.e., urban, rural and roadside to examine the elemental bioavailability in fine particulate matter and its potential health risk. The samples were collected on polytetrafluoroethylene filter paper with the help of fine particulate sampler during August–September, 2012. The average mass concentration of PM_2.5 was 71.23 µg m^?3 (rural), 45.33 µg m^?3 (urban) and 36.71 µg m^?3 (roadside). Elements in PM_2.5 were analyzed by inductively coupled plasma atomic emission spectroscopy. Percentage bioavailability was determined to know the amount of soluble fraction that is actually taken across the cell membrane through inhalation pathway. Cadmium and lead were found to have cancer risk in a risk evaluation using an Integrated Risk Information system.     

镉致癌的分子机制研究进展

镉是一种无处不在的重金属环境污染物,广泛用于工业环境中。普通人主要通过摄食、吸烟及饮水等方式摄入镉。1993年国际肿瘤研究机构(IARC)就已将镉及其化合物列为第1类人致癌物,镉的致癌性被广泛研究,大量研究发现镉会提高肺癌、前列腺癌、乳腺癌、消化道肿瘤等肿瘤的患病风险。但至目前为止,镉的致癌分子机制尚不清楚。大量研究认为镉通过以下几方面致癌:氧化应激、抑制DNA损伤修复、DNA异常甲基化、抑制细胞凋亡、影响细胞周期调控、致多种基因异常表达、雌激素样效应、促进肿瘤干细胞生长、慢性炎症刺激。     

论城市室内环境中气溶胶污染问题

本文全面评述了室内环境中气溶胶的种类来源,化学组成,形成和自然清除机理。空气环境中气溶胶大致可分为：１．燃烧型气溶胶,主要包括各类燃料燃烧产生的烟雾和烟草烟雾等;２．矿物型气溶胶,包括粉尘,飞灰,石棉及其它天然纤维尘等;３．生物型气溶胶,包括植物生气溶胶,如动物皮屑及各类微生物等。     

癌症与土壤环境中Sn元素的关系

利用土壤环境资料中关于锡元素的32335个数据,癌死亡调查资料787080例,研究了胃癌、食管癌、肝癌、宫颈癌、肺癌、大肠癌、白血病、鼻咽癌、乳腺病死亡率与人鲜生活区土壤环境中锡元素的关系,结果表明。食管癌死亡率与生活区土壤中锡元素质量分数的相关性显著,肝癌、宫颈癌、鼻咽癌死亡率与生活区土壤中锻元素质量分数的相关性极显著,而胃癌、肺癌、大肠癌、白血病、乳腺癌死亡率与生活区土壤中锡元素质量分数的相共性下显著。     

云南曲靖地区铜的暴露与肺癌相关性研究

我国云南省曲靖的宣威和富源等地是全世界肺癌高发区,为了研究环境介质中铜(Cu)等重金属的暴露与体内分布特征,探讨Cu与肺癌的相关性,在当地开展肺癌环境流行病学调查,采集宣威和富源高发区人群饮食、饮水以及人体血浆和肺组织样品,微波消解ICP-MS法测定样品中Cu等元素.结果显示,当地居民使用燃料类型是影响肺癌高发的重要因素.高发区人群Cu的日摄入总量低于我国推荐的每日膳食中营养素供给量(RDA).肺癌组血液中Cu含量显著高于对照组,肺癌组织中Cu含量显著高于癌旁组织和正常组织,且肺癌患者的血浆和肺组织中Cu/Zn比值均升高.Pearson相关性分析结果表明,Cu和Ni、Cu和Pb呈显著正相关,提示在致癌作用上具有协同效应;Cu和Fe、Cu和Zn呈显著负相关,提示具有抑制或拮抗作用.多因素Logistic回归结果表明,Cu是肺癌发生的重要影响因素,人体中Cu含量和Cu/Zn比值可为肺癌的早期预防和诊断提供科学依据.     

Pesticide in the Mississippi River floodplain and its possible linkage to colon cancer risk in the US

Result of this study shows that elevated colorectal cancer risk in Mississippi River floodplain of the United States is likely linked to historically high pesticide application. Mississippi River basin produces about 80% of major US crops and has about two-thirds of US pesticides used for agriculture. Historically, heavy pesticide application and agricultural irrigation were reported to result in high pesticide residues in surface water, fish and wells of Mississippi embayment. Risk ratio of colorectal cancer incidence in 86 counties of Mississippi River floodplain was about 29% higher than that of other counties in the 48 contiguous states. Risk ratio of colon cancer mortality in 63 counties of Mississippi embayment was 33% higher than that of other counties in the 48 states between 1999 and 2016. Risk ratios of colorectal cancer incidence and colon cancer mortality in Mississippi River floodplain are higher after smoking and diabetes factors were filtered off. Previous studies have linked exposure to pesticide with type-II diabetes and the latter was linked to increasing colon cancer risk by about 27%. Result here suggests that pesticide may be an independent risk factor directly associated with elevated colon cancer risk in Mississippi River floodplain.     

Scalp hair metal analysis in the assessment of the occupational exposure of arc welders

Eleven metals (Ca, Mg, Fe, Zn, Cu, Mn, Cd, Co, Cr, Ni and Pb) were estimated in hair samples of metal arc welders and a control group with the same socioeconomic background. Nitric acid–perchloric acid wet digestion procedure was adopted for the estimation of endogenous metal contents by ICP-AE technique. The study exhibited the following increasing order of the metal concentrations: Cd??1, dry weight, respectively. On average, the levels of Mn, Ni, Pb and Fe were found to be 1.5–2.4 times higher in the hair of welders compared with controls. Besides age and exposure which were strongly correlated, Cu–Mg, Mn–Mg, Ca–Co and Cd–Zn also showed significantly positive correlations. The identification of metal sources, done by cluster and principal component analyses, revealed four factors: age and exposure; Cu, Mg, Mn and Fe; Ca and Co; Cd, Zn, Ni and Pb. High levels of Fe were found to have a depleting impact on Co levels. The arc welders were feared to accumulate heavy metals in their bodies due to long-term endogenous exposure.