Fundamental Study of Welding Fume Inhalation

描述（由申请人提供）：焊接被用作美国工业所有分支中金属部件高质量连接的强大制造方法。呼吸影响、金属烟雾热、癌症以及对肾脏、神经系统、生殖系统和皮肤的影响都与焊接烟雾接触有关。最近的人口普查数据表明，美国有超过80万名工人全职从事焊接或相关工艺，而据估计，有超过100万人间歇性地进行焊接，作为他们工作期望的一部分。尽管有许多焊接工艺用于各种应用，但使用手持电极的手工金属电弧焊（MMA）和使用连续焊丝的金属惰性气体（MIG）焊接应用于低碳钢、不锈钢和铝屈服组合，其被70%的焊接人口实践。我们建议确定焊接烟雾的吸入浓度作为与MMA过程相关的暴露的真实测量。迄今为止，在现场或在非常有限的程度上在实验室条件下进行的焊接烟雾暴露研究，评估了工人呼吸区的区域暴露或个人暴露。很少有研究评估焊工头盔内外的烟雾浓度。然而，没有研究试图定量地确定焊接烟尘的吸入浓度作为焊接工艺参数的函数，例如基材/电极组合、焊接电流和电压以及焊工与源区域的距离。本提案中概述的实验设计和数据分析解决了这一关键数据缺口。将使用真人大小的假人头部和肩部进行拟议实验，使用呼吸机泵通过口腔模拟呼吸。将调整潮气量和呼吸频率，以符合休息或进行正常体力劳动的男性的特征值。在使用焊接和受试者相关参数组合的一系列实验期间，将佩戴焊接头盔的假人暴露于暴露室中的MMA焊接烟雾。将一个过滤盒放入口中，并将焊接烟雾收集在37 mm过滤器上，将对其进行重量分析，以确定颗粒质量和吸入浓度。还将通过分别使用37 mm卡匣和BGI旋风分离器同时对头盔外的空气进行采样，估计呼吸区中吸入浓度与头盔外总/可吸入烟雾浓度的比值。一个中心复合实验设计与一些定量和定性参数将被用作实验设计的基础，以有效地和系统地确定最有影响力的参数影响吸入，总/可吸入的焊接烟雾浓度。这基本上是二次经验表面响应模型，以确定吸入浓度沿着与总/可吸入烟雾浓度和影响焊接参数之间的关系。这些结果将增强我们对焊接烟雾吸入剂量的理解，这是健康影响研究的更好暴露指标。此外，这项研究将提供必要的信息，用于评估焊接烟尘个人或区域暴露测量的生物学意义，并可能提供深入了解焊接烟尘的现行暴露标准（TLV-TWA）的生物学相关性。

DESCRIPTION (provided by applicant): Welding is used as a powerful manufacturing method for the high quality joining of metallic components in all branches of US industries. Respiratory effects, metal fume fever, cancer, and effects on kidneys, nervous system, reproductive system and skin have been associated with welding fume exposures. The recent census data indicate that over 800,000 workers in the United States are involved in welding or allied processes full time, while it is estimated that more than one million perform welding intermittently as part of their work expectations. Although there are many welding processes employed for various applications Manual Metal Arc (MMA) welding using hand-held electrodes and Metal Inert Gas (MIG) welding using continuous wire applied to mild steel, stainless steel, and aluminum yield combinations which are practiced by 70% of the welding population. We propose to determine the inhaled concentration of welding fume as a true measure of exposure associated with the MMA process. To date, welding fume exposure studies in field or, in a very limited extent, under laboratory conditions either assessed the area exposures or personal exposures in the breathing-zone of workers. Very few studies have evaluated fume concentration inside and outside of the welder helmet. However, no studies have attempted to quantitatively determine the inhaled concentration of welding fumes as a function of welding processing parameters such as base material/ electrode combination, welding current and voltage, and distance of the welder from the source area. The experimental design and data analysis outlined in this proposal addresses this critical data gap. The proposed experiments will be performed using a life-size head and shoulders of a manikin for which breathing will be simulated through the mouth using a ventilator pump. The tidal volumes and breathing frequencies will be adjusted to correspond to the characteristic values for men at rest or performing normal physical work. The manikin, wearing a welding helmet, will be exposed to MMA welding fumes in an exposure chamber during a series of experiments using a combination of welding and subject-related parameters. A filter cassette will be placed inside the mouth and welding fumes will be collected on 37-mm filters, which will be analyzed gravimetrically to determine the particulate mass and inhaled concentration. The ratio of inhaled concentration to total/respirable fume concentration outside of the helmet in the breathing-zone will also be estimated by concurrently sampling the air outside of the helmet using a 37-mm cassette and a BGI cyclone, respectively. A central composite experimental design with a number of quantitative and qualitative parameters will be used as a basis of experimental design in order to efficiently and systematically determine the most influential parameters affecting inhaled, total/respirable concentration of welding fumes. This is basically a quadratic empirical surface-response model to determine the relationship between inhaled concentration along with total /respirable fume concentration and influential welding parameters. These results will enhance our understanding of the inhaled dose of welding fumes, which serve as a better exposure metric for health effects studies. In addition, this study will provide necessary information for evaluating biological significance of welding fume personal or area exposure measurements and may provide insights into the biological relevance of the current exposure standard (TLV-TWA) for welding fumes.