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Pulmonary responses after wood chip mulch exposure
S F Wintermeyer1, W G Kuschner, H Wong
1Division of Occupational and Environmental Medicine, University of California San Francisco 94143-0924, USA.
Abstract:
Organic Dust Toxic Syndrome (ODTS) is a flu-like syndrome that can occur after inhalation of cotton, grain, wood chip dusts, or other organic dusts or aerosols. We investigated whether inflammatory pulmonary responses occur, even after relatively brief, low-level wood chip mulch exposure. Six volunteers were exposed to wood chip mulch dust. Total dust and/or endotoxin levels were measured in five subjects. Pulmonary function and peripheral blood counts were measured before and after exposure in each subject. Bronchoalveolar lavage (BAL) was performed in each subject after exposure, and cell, cytokine, and protein concentrations were measured. Control BAL without previous exposure was also performed on three of the subjects. Three of six subjects had symptoms consistent with ODTS. No clinically relevant or statistically significant changes in pulmonary function tests after exposure were found. Three subjects manifested a marked elevation in neutrophil percentage in their BAL (range, 10 to 57%). When these three subjects underwent control BAL, the postexposure comparison demonstrated an increase in neutrophil levels of 154 +/- 89 x 10(3)/mL (mean +/- standard error; P = 0.22). The mean increase in BAL interleukin-8 levels after exposure, compared with paired control values, was 11.2 +/- SE 2.5 pg/mL (P = 0.047). There was also an increase in BAL interleukin-6 levels that reached borderline significance (6.4 +/- SE 2.0 pg/mL; P = 0.08). Tumor necrosis factor levels were increased in all three subjects' BAL as well (0.4 +/- SE 0.2 pg/mL), but this change was not statistically significant (P = 0.2). Our findings of increased BAL proinflammatory cytokine and neutrophil levels are consistent with the theory that cytokine networking in the lung may mediate ODTS.
Insights
Exposure to organic dusts like wood chip mulch can trigger flu-like symptoms, a condition known as Organic Dust Toxic Syndrome (ODTS). This study found that even brief exposure increased inflammatory markers in the lungs, suggesting a role for cytokines in ODTS.
Area of Science:
- Environmental Health
- Pulmonary Medicine
- Toxicology
Background:
- Organic Dust Toxic Syndrome (ODTS) is an acute, flu-like illness following inhalation of organic dusts.
- The specific pulmonary inflammatory responses to low-level, short-term wood chip mulch exposure remain unclear.
Purpose of the Study:
- To investigate inflammatory pulmonary responses after brief, low-level wood chip mulch exposure.
- To determine if these responses are associated with symptoms of ODTS.
Main Methods:
- Six volunteers were exposed to wood chip mulch dust.
- Pulmonary function tests and peripheral blood counts were assessed pre- and post-exposure.
- Bronchoalveolar lavage (BAL) was performed post-exposure to measure cell counts, cytokines (IL-8, IL-6, TNF-alpha), and protein concentrations.
Main Results:
- Three of six subjects developed ODTS-like symptoms.
- No significant changes in pulmonary function tests were observed.
- BAL analysis revealed elevated neutrophil percentages and increased levels of proinflammatory cytokines, particularly interleukin-8, in symptomatic subjects compared to controls.
Conclusions:
- Brief exposure to wood chip mulch dust can induce pulmonary inflammation characterized by increased neutrophils and cytokines in susceptible individuals.
- These findings support the hypothesis that inflammatory cytokine networking in the lungs plays a role in mediating Organic Dust Toxic Syndrome.