Industrial Hygiene Centre of Excellence, Huntsman, Everslaan 45, B-3078 Everberg, Belgium.
Int J Hyg Environ Health. 2010 Nov;213(6):475-88. doi: 10.1016/j.ijheh.2010.08.011. Epub 2010 Sep 18.
It is well known that the use of MDI (methylene diphenyldiisocyanate) as an alternative for formaldehyde-based resins is seen as a responsible option to reduce formaldehyde emissions for CWP (Composite Wood Products) in buildings. However, there are concerns raised regarding the exposure risk of workers. The purpose of this article is to provide the reader with factual information to demonstrate that the use of MDI compared to other agents used in CWP production processes does not pose increased inhalation exposure risks for workers. Personal and area air measurements were carried out at nine Composite Wood Panel plants throughout Europe to assess potential inhalation exposures to MDI and wood dust as Total Inhalable Particulates (TIP). In total, 446 pairs of samples were collected for MDI and TIP of which 283 pairs were personal samples and the remaining 163 pairs were area samples collected at key locations along the production line. This data together with published formaldehyde exposure data has been used to evaluate the exposure safety margin opposite what are considered relevant occupational exposure limits.
The methods used for sampling and analysing MDI and TIP are based on internationally accepted methods, i.e. MDHS 25/3 (or ISO 16702) for MDI, and MDHS 14/3 for TIP.
The job functions with an increased exposure profile for TIP were the cleaners, drying operators and quality control staff, and for MDI, the cleaners and quality control staff. The areas with an increased exposure profile for TIP are the conveyor area from OSB blender to former area and the OSB press infeed, and for MDI the OSB weigh belt and OSB former bin area.
The exposure safety margin opposite the selected exposure limits can be ranked as MDI>TIP>formaldehyde (high margin of safety to low margin of safety), indicating that the use of MDI also reduces the exposure risks to workers during production of CWP compared to formaldehyde. By reducing the airborne TIP concentrations, a respiratory sensitiser, MDI workplace concentrations in general can be reduced further. This can be achieved by improving design and/or maintenance and testing programmes of existing control measures, which should be in place already to effectively control exposure to TIP and formaldehyde. The airborne concentration of MDI at workstations situated after pressing (curing) is regarded as extremely low and likely mainly constituted by workplace emissions from elsewhere in the plant.
众所周知，使用二异氰酸酯（亚甲基二苯基二异氰酸酯）替代基于甲醛的树脂，被视为减少建筑用复合木制品（CWP）中甲醛排放的负责任选择。然而，人们对工人的暴露风险提出了担忧。本文的目的是为读者提供事实信息，以证明与 CWP 生产过程中使用的其他制剂相比，使用 MDI 不会增加工人的吸入暴露风险。在整个欧洲的 9 家复合木板厂进行了个人和区域空气测量，以评估 MDI 和木尘作为总可吸入颗粒物（TIP）对潜在吸入暴露的影响。总共采集了 446 对 MDI 和 TIP 样本，其中 283 对是个人样本，其余 163 对是在生产线关键位置采集的区域样本。这些数据与已发表的甲醛暴露数据一起，用于评估相对于被认为是相关职业暴露限值的暴露安全裕度。
用于采样和分析 MDI 和 TIP 的方法基于国际公认的方法，即 MDI 采用 MDHS 25/3（或 ISO 16702），TIP 采用 MDHS 14/3。
TIP 暴露水平较高的工作职能是清洁工、干燥操作员和质量控制人员，而 MDI 则是清洁工和质量控制人员。TIP 暴露水平较高的区域是从 OSB 搅拌机到前区和 OSB 压机进料区的输送带区域，而 MDI 则是 OSB 称重带和 OSB 前料仓区。
相对于所选暴露限值，暴露安全裕度可以排列为 MDI>TIP>甲醛（高安全裕度到低安全裕度），这表明与使用甲醛相比，在生产 CWP 期间，使用 MDI 还可以降低工人的暴露风险。通过降低空气中 TIP 浓度，可以进一步降低 MDI 的工作场所浓度，而 TIP 是一种呼吸敏化剂。这可以通过改进现有控制措施的设计和/或维护和测试计划来实现，这些措施已经到位，可以有效控制 TIP 和甲醛的暴露。位于压制（固化）后的工作站处的 MDI 空气浓度被认为极低，可能主要由工厂其他地方的工作场所排放构成。
