Hanley Kevin W, Andrews Ronnee, Bertke Steven, Ashley Kevin
a Industrywide Studies Branch, Division of Surveillance, Hazard Evaluations and Field Studies National Institute for Occupational Safety and Health , Cincinnati , Ohio.
b Chemical Exposure and Monitoring Branch, Division of Applied Research and Technology, National Institute for Occupational Safety and Health , Cincinnati , Ohio.
J Occup Environ Hyg. 2015;12(11):774-84. doi: 10.1080/15459624.2015.1047022.
The National Institute for Occupational Safety and Health has conducted an occupational exposure assessment study of manganese (Mn) in welding fume of construction workers rebuilding tanks, piping, and process equipment at two oil refineries. The objective of this study was to evaluate exposures to different Mn fractions using a sequential extraction procedure. Seventy-two worker-days were monitored for either total or respirable Mn during stick welding and associated activities both within and outside of confined spaces. The samples were analyzed using an experimental method to separate different Mn fractions by valence states based on selective chemical solubility. The full-shift total particulate Mn time-weighted average (TWA) breathing zone concentrations ranged from 0.013-29 for soluble Mn in a mild ammonium acetate solution; from 0.26-250 for Mn(0,2+) in acetic acid; from non-detectable (ND) - 350 for Mn(3+,4+) in hydroxylamine-hydrochloride; and from ND - 39 micrograms per cubic meter (μg/m(3)) for insoluble Mn fractions in hydrochloric and nitric acid. The summation of all Mn fractions in total particulate TWA ranged from 0.52-470 μg/m(3). The range of respirable particulate Mn TWA concentrations were from 0.20-28 for soluble Mn; from 1.4-270 for Mn(0,2+); from 0.49-150 for Mn(3+,4+); from ND - 100 for insoluble Mn; and from 2.0-490 μg/m(3) for Mn (sum of fractions). For all jobs combined, total particulate TWA GM concentrations of the Mn(sum) were 99 (GSD = 3.35) and 8.7 (GSD = 3.54) μg/m(3) for workers inside and outside of confined spaces; respirable Mn also showed much higher levels for welders within confined spaces. Regardless of particle size and confined space work status, Mn(0,2+) fraction was the most abundant followed by Mn(3+,4+) fraction, typically >50% and ∼30-40% of Mn(sum), respectively. Eighteen welders' exposures exceeded the ACGIH Threshold Limit Values for total Mn (100 μg/m(3)) and 25 exceeded the recently adopted respirable Mn TLV (20 μg/m(3)). This study shows that a welding fume exposure control and management program is warranted, especially for welding jobs in confined spaces.
美国国家职业安全与健康研究所对两家炼油厂中从事罐体、管道和工艺设备重建工作的建筑工人焊接烟尘中的锰（Mn）进行了职业接触评估研究。本研究的目的是使用连续萃取程序评估对不同锰组分的接触情况。在受限空间内外进行手工电弧焊及相关活动期间，对72个工作日的总锰或可吸入锰进行了监测。采用一种实验方法对样品进行分析，该方法基于选择性化学溶解性按价态分离不同的锰组分。在温和的醋酸铵溶液中，全时段总颗粒物锰的时间加权平均（TWA）呼吸带浓度范围为可溶锰0.013 - 29微克每立方米；在醋酸中锰（0,2 +）的浓度范围为0.26 - 250微克每立方米；在盐酸羟胺中锰（3 +,4 +）的浓度范围为未检出（ND） - 350微克每立方米；在盐酸和硝酸中不溶锰组分的浓度范围为ND - 39微克每立方米。总颗粒物TWA中所有锰组分的总和范围为0.52 - 470微克每立方米。可吸入颗粒物锰TWA浓度范围为：可溶锰0.20 - 28微克每立方米；锰（0,2 +）为1.4 - 270微克每立方米；锰（3 +,4 +）为0.49 - 150微克每立方米；不溶锰为ND - 100微克每立方米；锰（各组分总和）为2.0 - 490微克每立方米。综合所有工作来看，受限空间内和受限空间外工人的总颗粒物TWA几何均值（GM）浓度，锰（总和）分别为99（几何标准差GSD = 3.35）和8.7（GSD = 3.54）微克每立方米；受限空间内焊工的可吸入锰水平也高得多。无论颗粒大小和受限空间工作状态如何，锰（0,2 +）组分含量最高，其次是锰（3 +,4 +）组分，通常分别占锰（总和）的>50%和约30 - 40%。18名焊工的接触量超过了美国政府工业卫生学家会议（ACGIH）规定的总锰阈限值（100微克每立方米），25名焊工的接触量超过了最近采用的可吸入锰阈限值（20微克每立方米）。本研究表明，有必要实施焊接烟尘接触控制和管理计划，尤其是针对受限空间内的焊接工作。
