Microbial and dust toxicities in the classroom increase the risk of teachers’ work-related symptoms: a cross-sectional study

Thesis event information

Date and time of the thesis defence

Place of the thesis defence

Leena Palotie auditorium 101A (Aapistie 5 A). Remote access: https://oulu.zoom.us/j/63522718099

Topic of the dissertation

Microbial and dust toxicities in the classroom increase the risk of teachers’ work-related symptoms: a cross-sectional study

Doctoral candidate

Licenciate in Medicine Janne Salin

Faculty and unit

University of Oulu Graduate School, Faculty of Medicine, Research Unit of Internal Medicine

Subject of study

Medicine

Opponent

Professor Tuula Putus, University of Turku

Custos

Docent Hannu Syrjälä, University of Oulu

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Microbial and dust toxicities in the classroom increase the risk of teachers’ work-related symptoms

The causes and pathophysiological mechanisms of building-related symptoms (BRS) are unclear. The aim of this cross-sectional study was to investigate the association between intrinsic in vitro toxicity in classrooms and teachers’ work-related symptoms.

Teachers from 15 Finnish schools responded to the symptom survey. The boar sperm motility inhibition assay, a sensitive indicator of mitochondrial dysfunction, was used to measure the toxicity of wiped dust and cultured microbial fallout samples collected from the teachers’ classrooms.

231 teachers whose classroom toxicity data had been collected responded to the questionnaire. The Poisson regression model showed that teachers’ work-related BRS were 2.8-fold (95% CI: 1.6–4.9) higher in classrooms with highly toxic dust samples compared to classrooms with non-toxic dusts. The rate ratio of work-related BRS was 1.8 (95% CI: 1.1–2.8) for toxic microbial samples. Logistic regression analysis showed that classroom dust toxicity was statistically significantly associated with the following 12 symptoms (adjusted odds ratios in parentheses): nose stuffiness (4.1), runny nose (6.9), hoarseness (6.4), globus sensation (9.0), throat mucus (7.6), throat itching (4.4), shortness of breath (12.2), dry cough (4.7), wet eyes (12.7), hypersensitivity to sound (7.9), difficulty falling asleep (7.6), increased need for sleep (7.7). Toxicity of cultured microbes was associated with nine symptoms (adjusted ORs in parentheses): headache (2.3), nose stuffiness (2.2), nose dryness (2.2), mouth dryness (2.8), hoarseness (2.2), sore throat (2.8), throat mucus (2.3), eye discharge (10.2), increased need for sleep (3.5).

The toxicity of classroom dust and airborne microbes in boar sperm motility inhibition assay significantly increased teachers’ risk of work-related symptoms. The results support the hypothesis based on previous literature showing that exposure to boar sperm-toxic substances can cause mitochondrial dysfunction, oxidative stress, immunological inflammation, activation and sensitization of chemosensory C-fibers, and neurogenic inflammation. These findings contribute a new perspective to the research field of indoor adverse exposure and pathophysiological processes in exposed, symptomatic individuals.
Last updated: 3.1.2022