A comparative evaluation of the effectiveness of wipe sampling materials to remove beryllium from differently textured surfaces using zinc oxide as a surrogate

Abstract

Wipe sampling is a commonly used method for testing a surface for beryllium or other metal particle contamination. Existing wipe sampling methods have only been validated for smooth surfaces. On rough surfaces contaminant particles may be located behind surface projections where they would not be collected by the wipe. This could lead to an underestimate of surface contamination levels. Worker exposure to surfaces contaminated with beryllium could contribute to beryllium sensitization leading to chronic beryllium disease. Likewise, exposure to surfaces contaminated with other toxic metals could have their own health effects. This study investigated the efficiency of collecting 1–5 μm diameter zinc oxide particles by five commercially available wipe materials (SKC Smear Tabs, Whatman® 41 filter paper, Kimtech Prep* ScottPure* Critical Task Wipers, Ghost Wipes, and Hygenall LeadOff wipes) from surfaces of different roughness (sandpaper of 60–6,000 grit). Zinc oxide was used as a surrogate for beryllium because of its much lower toxicity. Overall, the wipes were most efficient at collecting particles from the fine grits and poor at collecting particles from the coarse grits. The Smear Tabs and Whatman filters performed poorly in both durability and particle collection efficiency. In both respects, the superior performers were the Ghost Wipes and LeadOff wipes. However, even in the best case, the wipe still left behind 20% of the particles. These results indicate that underestimating metal particle contamination levels is a serious possibility when conducting wipe sampling on textured surfaces.