Related Experiment Video
Updated: Jan 3, 2026
Author Spotlight: Exploring Microglial Interactions with Stress-Response Circuitry Using the Limited Bedding and Nesting Model
Published on: July 12, 2024
Bedding-generated particulate matter: implications for rodent studies
Neelakshi Hudda1, John L Durant1,2, Alexandra Nemeth3
1Department of Civil and Environmental Engineering, Tufts University, Medford, MA, USA.
Objectives:
Rodents used in scientific research are typically housed in cages containing natural bedding materials. Despite extensive evidence of biological harm from inhaled particulate matter (PM), relatively little work has been performed to measure bedding-generated PM exposure in caged animals used in basic science research. Our objectives were to determine whether bedding-generated PM was present in significant concentrations in rodent cages and to identify the main factors affecting the accumulation and attenuation of bedding-generated PM inside cages.
Materials And Methods:
We measured PM2.5 concentrations in cages containing common bedding materials (pine, aspen, paper, and corncob) with filter top isolator absent or present on the cages. PM2.5 concentrations were monitored with rats inside cages as well as during artificial manipulation of the bedding (designed to simulate rodent activity).
Results And Discussion:
Upon rodent digging or mechanical/manual stirring, all four bedding materials produced significant increases in PM2.5 concentrations (as much as 100-200 µg/m3 PM2.5, 50- to 100-fold higher than during periods of no rodent activity), and concentrations in cages fitted with filter tops were an order of magnitude higher than in cages without filter tops. Elevated concentrations were sustained for longer durations in cages with filter tops (5-10 minutes) compared to cages with only bar lids (0-2 minutes).
Conclusions:
These results indicate that standard laboratory housing conditions can expose rodents to substantial levels of PM2.5. Bedding-generated PM has potential implications as an environmental agent in rodent studies.
Insights
Rodent bedding releases significant particulate matter (PM2.5) when disturbed, posing a risk to research animals. Filter tops exacerbate PM2.5 exposure, highlighting environmental concerns in laboratory animal housing.
Area of Science:
- Laboratory animal science
- Environmental health
- Toxicology
Background:
- Rodents in research often use natural bedding materials.
- Inhaled particulate matter (PM) is known to cause biological harm.
- Limited research exists on PM exposure from bedding in rodent cages.
Purpose of the Study:
- To quantify bedding-generated PM concentrations in rodent cages.
- To identify factors influencing PM accumulation and reduction within cages.
Main Methods:
- Measured PM2.5 levels in cages with pine, aspen, paper, and corncob bedding.
- Assessed PM2.5 with and without filter top isolators.
- Monitored PM2.5 during simulated rodent activity and with rats present.
Main Results:
- All bedding types generated significant PM2.5 increases (50-100 fold) upon disturbance.
- Cages with filter tops showed 10x higher PM2.5 concentrations than those without.
- Elevated PM2.5 levels persisted longer (5-10 min) in filter-top cages.
Conclusions:
- Standard laboratory housing exposes rodents to substantial PM2.5.
- Bedding-generated PM is a critical environmental factor in rodent studies.
