Svedberg Urban, Johanson Gunnar
Occupational and Environmental Medicine, Sundsvall Hospital, SE85186 Sundsvall, Sweden;
Ann Occup Hyg. 2013 Nov;57(9):1128-37. doi: 10.1093/annhyg/met033. Epub 2013 Jul 3.
More than 500 million ocean freight container units are shipped annually between countries and continents. Residual levels of fumigants, as well as naturally occurring off-gassing chemicals emanating from the goods, constitute safety risks, which may affect uniformed workers upon entering the container. The aim of this study was to assess workers' exposure during stripping of containers and is the first study of its kind. First, an experimental tracer gas method was investigated to determine its usefulness to approximate real exposures from gaseous fumigants and off-gassing volatile organic compounds (VOCs). Nitrous oxide was injected and left to distribute in the closed containers. The distribution of the tracer gas and initial (arrival) concentrations of off-gassing volatiles were measured prior to opening the containers. Second, personal exposure (breathing zone) and work zone air monitoring of both tracer gas and VOCs were carried out during stripping. Adsorbent tubes, bag samples, and direct-readings instruments (photoionization detector and Fourier transform infrared spectrometry) were used. The distribution studies with nitrous oxide, and the high correlation between the former and VOCs (r(2) ~ 0.8) during stripping, showed that the tracer gas method may well be used to approximate real exposures in containers. The average breathing zone and work zone concentrations during stripping of naturally ventilated 40-foot containers were 1-7% of the arrival concentrations; however, peaks up to 70% were seen during opening. Even if average exposures during stripping are significantly lower than arrival concentrations, they may still represent serious violations of occupational exposure limits in high-risk containers. The results from this and previous studies illustrate the need to establish practices for the safe handling of ocean freight containers. Until comprehensive recommendations are in place, personnel that need to enter such containers should, in addition to appropriate personal protective equipment, have access to equipment for measuring contaminants and for applying forced ventilation when necessary.
每年有超过5亿个海运集装箱在各国和各大洲之间运输。熏蒸剂的残留水平，以及货物自然散发的脱气化学品，构成安全风险，可能会影响进入集装箱的工作人员。本研究的目的是评估工作人员在拆解集装箱过程中的接触情况，这是同类研究中的首例。首先，研究了一种实验性示踪气体方法，以确定其用于估算气态熏蒸剂和脱气挥发性有机化合物（VOCs）实际接触量的有效性。注入一氧化二氮并使其在封闭的集装箱内分布。在打开集装箱之前，测量示踪气体的分布以及脱气挥发物的初始（到达）浓度。其次，在拆解过程中对示踪气体和VOCs进行了个人接触（呼吸带）和工作区空气监测。使用了吸附管、袋式样品和直读仪器（光离子化检测器和傅里叶变换红外光谱仪）。一氧化二氮的分布研究以及拆解过程中前者与VOCs之间的高度相关性（r(2)约为0.8）表明，示踪气体方法很可能可用于估算集装箱内的实际接触量。在自然通风的40英尺集装箱拆解过程中，呼吸带和工作区的平均浓度为到达浓度的1-7%；然而，在打开集装箱时出现了高达70%的峰值。即使拆解过程中的平均接触量明显低于到达浓度，但在高风险集装箱中，它们仍可能严重违反职业接触限值。本研究及先前研究的结果表明，需要制定安全处理海运集装箱的操作规程。在全面的建议出台之前，除了配备适当的个人防护设备外，需要进入此类集装箱的人员还应能够使用测量污染物的设备，并在必要时进行强制通风。
