Fundamental Study of Welding Fume Inhalation

描述（由申请人提供）：焊接是一种强大的制造方法，用于美国所有工业部门的金属部件的高质量连接。呼吸系统影响、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暴露有关。最近的人口普查数据表明，美国有80多万工人全职从事焊接或相关工艺，而据估计，有100多万人间歇性地从事焊接工作，这是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，但使用手持式电极的手工金属电弧（MMA）焊接和使用连续焊丝的金属惰性气体（MIG）焊接应用于低碳钢，不锈钢和铝的屈服组合，70%的焊接人口采用这种焊接方法。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实验室条件下进行的焊接烟雾暴露研究要么评估了工人呼吸区的区域暴露，要么评估了工人呼吸区的个人暴露。很少有研究评估了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雾吸入浓度与焊接工艺参数（如基材/电极组合、焊接电流和电压以及焊工与源区的距离）的关系。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。拟议的实验将使用真人大小的头部和肩部的人体模型进行，呼吸将通过口腔使用呼吸机泵进行模拟。潮汐量和呼吸频率将被调整，以符合休息或进行正常体力工作的男性的特征值。在一系列结合焊接和受试者相关参数的实验中，戴着焊接头盔的人体模型将暴露在暴露室内的MMA焊接烟雾中。将在口内放置一个过滤盒，将37毫米的过滤器收集焊接烟雾，并对其进行重量分析，以确定颗粒质量和吸入浓度。吸入浓度与呼吸区头盔外总/可呼吸烟雾浓度的比率也将通过分别使用37毫米卡式和华大基因旋风同时采样头盔外的空气来估计。为了有效、系统地确定影响焊接烟雾吸入、总浓度/可吸入浓度的最重要参数，将采用具有多个定量和定性参数的中心复合实验设计作为实验设计的基础。这基本上是一个二次经验表面响应模型，用于确定吸入浓度以及总烟雾浓度/可呼吸烟雾浓度与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，这可以作为健康影响研究的更好的暴露度量。此外，本研究将为评估焊接烟雾个人或区域暴露测量的生物学意义提供必要的信息，并可能为当前焊接烟雾暴露标准（TLV-TWA）的生物学相关性提供见解。

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.