Assessment of respiratory and reproductive impacts of artisanal refinery activities on male Albino Wistar rats: implications for environmental health

Abstract

Abstract Background Artisanal petroleum refining operations have been known to produce a significant volume of air pollutants. The highest concentration of pollutants is generated during the oven heating or crude boiling phase of the operation. The major pollutant is black carbon or soot. Although these operations are widespread, especially in developing countries, the impact of exposure to emissions from artisanal refinery on both respiratory and reproductive health remains poorly understood. Objective This study is aimed to examine the effects of controlled subacute exposure to carbon soot emissions generated during the oven heating phase of the refining process, on the respiratory and reproductive systems of male albino Wistar rats. Methods To simulate the exposure conditions found in artisanal refineries, we developed a replicable fabrication of an artisanal refinery combustion system fitted with an exposure chamber for in vivo studies. 6–8 weeks old adolescent albino Wistar rats were divided into four groups (A, B, C, & D), with group A acting as the general control group and was not exposed to any carbon soot particulate matter. Group B, C, and D were exposed subacutely for four hours each day for 3, 7, 14, 21, and 28 days to varying emission concentrations. Daily exposure measurements were determined using Aeroqual Series 300 Gas Monitor, and average exposure concentration of carbon soot particulate matter (PM 2.5 ), for each exposed group were given as: (1.221 ± 0.169 mg/m 3 , 1.290 ± 0.214 mg/m 3 1.282 ± 0.235 mg/m 3 ). Animals from each group were euthanised on Day 3, 7, 14, 21, and Day 28, respectively. Tissue samples of the lungs and testis were collected for immunohistochemistry and oxidative stress analysis. Discussion /Conclusion : Cytoarchitecture of the lungs and testis via histology and immunohistochemistry, showed inflammatory cell infiltration, thickened alveolar walls, diminished alveolar spaces, hyperaemia, and bronchial epithelial hyperplasia in the lungs of Group B, C, and D animals that were exposed to soot. While cytoarchitecture of the testis revealed a distortion of the Leydig cells, vacuolations and mild vacuolations within the spermatid layer, loss of flagella, and some distortion of seminiferous tubule in the lumen. Notable increase in the mean expression and significant P -values determined by one-way analysis of variance (ANOVA), followed by Tukey’s post hoc test, were observed on Day 14–28 ( P < 0.05) for tumour-necrosis-factor alpha (TNF-α), Day 21–28 ( P < 0.001) for malondialdehyde (MDA), and Day 21 ( P < 0.001) for superoxide dismutase (SOD) expression in the lungs of each of the experimental Group (B, C, D) when compared to the control Group A. Our study provides valuable insights into the health risks associated with exposure to carbon soot particulate matter, thus underscoring the urgent need for necessary control measures to curb air pollution as a result of artisanal refinery activities.