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Exposures and urinary biomonitoring of aliphatic isocyanates in construction metal structure coating.
International Journal of Hygiene and Environmental Health ( IF 6 ) Pub Date : 2020-02-28 , DOI: 10.1016/j.ijheh.2020.113495
Anila Bello 1 , Yalong Xue 2 , Rebecca Gore 3 , Susan Woskie 1 , Dhimiter Bello 4
Affiliation  

Background

Isocyanates are highly reactive chemicals used widely in metal structure coating applications in construction. Isocyanates are potent respiratory and skin sensitizers and a leading cause of occupational asthma. At present, there is no cure for isocyanate asthma and no biomarkers of early disease. Exposure reduction is considered the most effective preventive strategy. To date, limited data are available on isocyanate exposures and work practices in construction trades using isocyanates, including metal structure coatings.

Objectives

The primary objectives of this work were: i) to characterize isocyanate inhalation and dermal exposures among painters during metal structure coating tasks in construction; and ii) to assess the adequacy of existing work practices and exposure controls via urinary biomonitoring pre- and post-shift.

Methods

Exposures to aliphatic isocyanates based on 1,6-hexamethylene diisocyanate (1,6-HDI) and its higher oligomers (biuret, isocyanurate and uretdione) were measured among 30 workers performing painting of bridges and other metal structures in several construction sites in the Northeastern USA. Exposure assessment included simultaneous measurement of personal inhalation exposures (n = 20), dermal exposures (n = 22) and body burden via urinary biomonitoring pre- and post-shift (n = 53). Contextual information was collected about tasks, processes, materials, work practices, personal protective equipment (PPEs) and exposure controls, work histories, and environmental conditions.

Results

Breathing zone concentrations were the highest for biuret (median, 18.4 μg/m3), followed by 1,6-HDI monomer (median, 3.5 μg/m3), isocyanurate (median, 3.4 μg/m3) and uretdione (median, 1.7 μg/m3). The highest exposures, measured during painting inside an enclosed bridge on a hot summer day, were: 10,288 μg/m3 uretdione; 8,240 μg/m3 biuret; and 947 μg/m3 1,6-HDI. Twenty percent of samples were above the NIOSH ceiling exposure limit for 1,6- HDI (140 μg/m3) and 35% of samples were above the UK-HSE ceiling for total isocyanate group (70 μg NCO/m3). Isocyanate loading on the gloves was generally high, with a median of 129 μg biuret/pair and maximum of 60.8 mg biuret/pair. The most frequently used PPEs in the workplace were half-face organic vapor cartridge (OVC) respirators, disposable palmar dip-coated polymer gloves, and cotton coveralls. However, 32% of workers didn't wear any respirator, 47% wore standard clothing with short-sleeve shirts and 14% didn't wear any gloves while performing tasks involving isocyanates. Based on biomonitoring results, 58.4% of urine samples exceeded the biological monitoring guidance value (BMGV) of 1 μmol hexamethylene diamine (HDA)/mol creatinine. Post-shift geometric mean HDA normalized to specific gravity increased by 2.5-fold compared to pre-shift (GM, 4.7 vs. 1.9 ng/mL; p value, < 0.001), and only 1.4-fold when normalized to creatinine.

Conclusions

Exposure and biomonitoring results, coupled with field observations, support the overall conclusions that (i) substantial inhalation and dermal exposures to aliphatic isocyanates occur during industrial coating applications in construction trades; that (ii) the current work practices and exposure controls are not adequately protective. High urinary creatinine values in the majority of workers, coupled with significant cross-shift increases and filed observations, point to the need for further investigations on possible combined effects of heat stress, dehydration, and nutritional deficiencies on kidney toxicity. Implementation of comprehensive exposure control programs and increased awareness are warranted in order to reduce isocyanate exposures and associated health risks among this cohort of construction workers.



中文翻译:

建筑金属结构涂料中脂肪族异氰酸酯的暴露和尿液生物监测。

背景

异氰酸酯是高反应性化学品,广泛用于建筑的金属结构涂料应用中。异氰酸酯是有效的呼吸道和皮肤敏化剂,是职业性哮喘的主要原因。目前,尚无治愈异氰酸酯哮喘的方法,也没有早期疾病的生物标志物。减少接触被认为是最有效的预防策略。迄今为止,关于异氰酸酯暴露和使用异氰酸酯(包括金属结构涂料)的建筑行业中的工作实践的有限数据可用。

目标

这项工作的主要目的是:i)表征在建筑过程中进行金属结构涂层作业时画家中异氰酸酯的吸入和皮肤暴露情况;ii)通过在轮班前和轮班后进行尿液生物监测评估现有工作规范和暴露控制的适当性。

方法

在东北地区几个建筑工地对桥梁和其他金属结构进行喷漆的30名工人中,测量了基于1,6-己亚甲基二异氰酸酯(1,6-HDI)及其更高级低聚物(缩二脲,异氰脲酸酯和uretdione)的脂族异氰酸酯的暴露量。美国。暴露评估包括同时测量个人吸入暴露(n = 20),皮肤暴露(n = 22)和通过尿液生物监测班次前后的身体负担(n = 53)。收集了有关任务,过程,材料,工作实践,个人防护设备(PPE)和接触控制,工作历史以及环境条件的上下文信息。

结果

缩二脲的呼吸区浓度最高(中位数为18.4μg/ m 3),其次是1,6-HDI单体(中位数为3.5μg/ m 3),异氰脲酸酯(中位数为3.4μg/ m 3)和脲二酮(中位数) ,1.7μg/ m 3)。在炎热的夏天在封闭的桥梁内涂漆时测得的最高暴露量为:10,288μg/ m 3脲二酮;8,240μg/ m 3双缩脲; 和947μg/ m 3 1,6-HDI。样品的百分之二十是上面的天花板NIOSH暴露极限为1,6- HDI(140微克/米3的样品)和35%的人的UK-HSE天花板总异氰酸酯基(70微克NCO /米以上3)。手套上的异氰酸酯含量通常很高,中位数为129μg双缩脲/对,最大为60.8 mg缩二脲。工作场所中最常用的PPE是半面有机蒸气呼吸器(OVC)呼吸器,一次性手掌浸涂的聚合物手套和棉质连体工作服。但是,在执行涉及异氰酸酯的任务时,有32%的工人没有戴呼吸器,有47%的人穿着标准服装和短袖衬衫,还有14%的人没有戴手套。根据生物监测结果,有58.4%的尿液样本超过了1μmol六亚甲基二胺(HDA)/ mol肌酐的生物监测指导值(BMGV)。与移位前相比,归一化至比重的移位后几何平均HDA增加了2.5倍(GM,4.7对1.9 ng / mL; p值,<0.001),而归一化至肌酐时,仅为1.4倍。

结论

暴露和生物监测的结果,再加上现场观察,支持了以下总体结论:(i)在建筑行业的工业涂料应用过程中,大量吸入和皮肤接触脂肪族异氰酸酯;(ii)当前的工作实践和暴露控制没有足够的保护性。大多数工人的尿肌酐值较高,加上班次有明显的交叉变化,并有观察结果,这表明需要进一步研究热应激,脱水和营养不足对肾脏毒性的综合影响。有必要实施全面的接触控制程序和增强意识,以减少该建筑工人群中的异氰酸酯暴露量和相关的健康风险。

更新日期:2020-02-28
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