This post is the fourth in a series o​n insights into exposure assessment as presented at AIHce 2016 in Baltimore, Md. References to specific products or services do not constitute endorsement by AIHA or The Synergist.

A recent NIOSH exposure assessment of dermal exposures in lead battery plants revealed just how pervasive lead contamination can be in the workplace…and beyond.

“The OSHA exposure limit for lead is 50 micrograms per cubic meter of air as a time-weighted average over an eight-hour shift. It is a very, very little quantity, and when you rub it into a palmar surface it essentially becomes invisible,” said Dr. Bradley King, a certified industrial hygienist for NIOSH, while presenting at AIHce 2016. “You cannot make a visual determination simply by thinking that you can see it on your hands. It’s just not possible when it is rubbed onto surfaces for workers to really visually identify that their hands are really contaminated at that level.”

In fact, researchers found that lead was hiding in plain sight on far more than just workers’ hands. Here are some of the surprising findings of the NIOSH assessment:

• Lead skin contamination was detected on some lead battery plant workers at the beginning of the workday, leading researchers to believe that workers’ hands were not sufficiently decontaminated on the previous workday.
  
• The residual lead raised concerns that exposure extends beyond the workplace. Contaminated workers could be contaminating their cars and homes, leading to the potential exposure of family members, including children.
  
• Researchers also discovered that levels of lead around workers’ mouths increased throughout the course of the day, suggesting an ingestion hazard.
  
• When the saliva of lead battery plant workers was tested, researchers similarly detected increasing levels of lead in their saliva. The test group of workers was ingesting lead throughout the day, potentially contributing to systemic toxicity.
  
• For the majority of workers tested in one plant – five out of six – lead contamination on their hands actually increased from before lunch to after lunch. Why? Researchers believe there was considerable lead contamination in the eating environments.
  
• In fact, several surfaces in eating areas were found to be contaminated with lead, including the steam table, cafeteria tables, cutting boards, doorknobs, and railings.
  

Ultimately, the exposure assessment concluded that hand washing with soap and water was insufficient for removing lead from hands. Sharp PbO particles are very small and easily become lodged in the skin. In addition, lead becomes trapped in the topography of skin. Both phenomena make lead difficult to remove with soap and water.

NIOSH-developed hand wipes as a removal method for toxic metals proved to be more effective than soap and water, and were also gentle on the skin and non-abrasive. The NIOSH-developed wipe resulted in 99.8 percent lead removal efficiency.