Comparison between active (pumped) and passive (diffusive) sampling methods for formaldehyde in pathology and...

Area of Science:

• Occupational Health and Safety
• Industrial Hygiene
• Environmental Monitoring

Background:

• Formaldehyde is a common occupational hazard, particularly in laboratory settings.
• Accurate exposure assessment is crucial for protecting worker health.
• Evaluating different sampling methods is essential for reliable monitoring.

Purpose of the Study:

• To determine occupational formaldehyde exposures in pathology and histology laboratories.
• To compare formaldehyde concentrations measured by active and passive sampling methods.
• To assess the reliability of passive samplers against established occupational exposure limits.

Main Methods:

• Collected paired active (Supelco LpDNPH tubes) and passive (ChemDisk Aldehyde Monitor 571) air samples.
• Analyzed samples using NIOSH NMAM 2016 for active and OSHA Method 1007 for passive methods.
• Collected 66 sample pairs (49 personal, 17 area) over an 8-hour time-weighted average (TWA).

Main Results:

• Most samples complied with the OSHA Permissible Exposure Limit (PEL) of 0.75 ppm.
• A significant majority of both active (78%) and passive (88%) samples exceeded the NIOSH Recommended Exposure Limit (REL) of 0.016 ppm.
• Passive samplers generally overestimated formaldehyde concentrations compared to active samplers (73% higher).
• No underestimation was observed, contrary to OSHA Method cautions regarding methanol in formalin.

Conclusions:

• Passive samplers can be useful for demonstrating compliance with OSHA PELs due to their tendency to overestimate.
• However, individual passive sample results should be interpreted cautiously due to potential discrepancies with active methods.
• The study suggests passive samplers are reliable for assessing formaldehyde exposure in these specific laboratory settings, even with low methanol content in formalin.