Effects of coarse chalk dust particles (2.5-10 μm) on respiratory burst and oxidative stress in alveolar macrophages

Prevalence and risk factors of chronic respiratory symptoms in public and private school teachers in north-western Ethiopia: results from a multicentre cross-sectional study

OBJECTIVE

This study aimed to investigate the prevalence and risk factors of chronic respiratory symptoms among school teachers in Gondar city, north-western Ethiopia.

DESIGN

A school-based cross-sectional study was conducted from April to May 2019. A self-administered British Medical Research Council Questionnaire was used to assess chronic respiratory symptoms. Data were entered into Epi Info V.7 and Stata V.14 was used for analysis. A multivariable logistic regression analysis was conducted to identify factors associated with chronic respiratory symptoms. The association was determined using adjusted OR (AOR) with a 95% CI at a value of p<0.05.

SETTING

The study was conducted in public and private schools in Gondar city.

PARTICIPANTS

A total of 822 teachers participated in this study.

OUTCOME MEASURES

The primary outcome is the prevalence of chronic respiratory symptoms.

RESULTS

The total response rate was 97.4%. The majority, 532 (64.7%) of the participants, were male. The mean age (±SD) of the respondents was 36.69 (±6.93) years. The total prevalence of chronic respiratory symptoms in the previous 12 months among teachers in Gondar city was found to be 31.14% (95% CI 27.99% to 34.43%). A family history of respiratory problems (AOR=1.90; 95% CI 1.07 to 3.37), an overweight body mass index (AOR=2.57; 95% CI 1.57 to 4.21), exposure to secondhand cigarette smoke at home (AOR=9.85; 95% CI 4.77 to 20.33), use of chalk (AOR=1.97; 95% CI 1.25 to 3.09), and failure to open windows during class (AOR=2.15; 95% CI 1.02 to 4.52) were risk factors for chronic respiratory symptoms.

CONCLUSION

This study concluded that the prevalence of chronic respiratory symptoms was high among teachers. Making a smoking-free zone, avoiding smoking in public places, improving the ventilation conditions of the classrooms and controlling the chalk dust are all necessary actions to take to reduce chronic respiratory symptoms.

Fine chalk dust induces inflammatory response via p38 and ERK MAPK pathway in rat lung

Chalk teaching is widely used in the world due to low cost, especially in some developing countries. During teaching with chalks, a large amount of fine chalk dust is produced. Although exposure to chalk dust is associated with respiratory diseases, the mechanism underlying the correlation between chalk dust exposure and adverse effects has not fully been elucidated. In this study, inflammation and its signal pathway in rat lungs exposed to fine chalk dust were examined through histopathology analyses; pro-inflammatory gene transcription; and protein levels measured by HE staining, RT-PCR, and western blot analysis. The results demonstrated that fine chalk dust increased neutrophils and up-regulated inflammatory gene mRNA levels (TNF-α, IL-6, TGF-β1, iNOS, and ICAM-1), and oxidative stress marker (HO-1) level, leading to the increase of inflammatory cell infiltration and inflammatory injury on the lungs. These inflammation responses were mediated, at least in part, via p38 and extracellular regulated proteinase (ERK) mitogen-activated protein kinase (MAPK) signaling mechanisms. In contrast, N-acetyl-L-cysteine (NAC) supplement significantly ameliorated these changes in inflammatory responses. Our results support the hypothesis that fine chalk dust can damage rat lungs and the NAC supplement may attenuate fine chalk dust-associated lung inflammation.

Trace Elemental Characterization of Chalk Dust and Their Associated Health Risk Assessment

It is evident that chalk produces dust on use, i.e., particulate matter, which will alter the air quality of classrooms and can cause health hazards in teachers. The possible causes for health effects of chalk dust on teachers are still unclear. Hence, the aim of this study is to estimate the concentration of trace elements (Al, Cr, Mn, Fe, Co, Ni, Si, Pb) in chalk dust collected from classrooms by using ICP-MS. Both suspended and settled chalk dust was collected from selected classrooms. Suspended chalk dust was collected with PM2.5 filter paper using fine dust sampler, and settled chalk dust was collected by placing petriplates at a distance of 3 m from the board for a duration period of 30 min. Scanning electron microscopy images of chalk dust were taken up. Potential health risk analysis was also assessed. Results showed that Al, Fe, and Mn are in higher concentration (>1000 μg kg^-1) in both settled and suspended chalk dust. Cr, Mn, Fe, Co, and Ni were beyond the minimal risk levels in both settled and suspended chalk dust. There are no minimal risk levels for the elements Al, Si, and Pb. The concentration of trace elements in suspended chalk dust was higher than that in settled chalk dust. The SEM images of PM2.5 filter papers (suspended chalk dust) showed that all pores of the sampled filter papers are clogged with chalk dust. The few SEM images of the settled chalk dust showed fibrous shape which is associated with good-quality chalk whereas others showed circular and more aggregated nature of chalk dust from low-quality chalk from which the dust production will be very high. As observed from the result that the trace elements concentration was high in the suspended chalk dust, the fact can be correlated with the SEM images which have shown high density of absorbed chalk dust. With reference to human health risk, dermal exposure was the main route of exposure followed by inhalation and ingestion. Al (aluminum), Fe (iron), Si (silicon), and Mn (manganese) are the major contributors for the non-carcinogenic effects. For all the elements, the carcinogenic effect calculated (LADD) is within the global acceptable limit (10^-6-10^-4).