ORIGINAL ARTICLE Abstract Background: Indonesia is one of world’s largest producers of coal. Coal fly ash (CFA), a product of the coal combustion process, consists of various minerals and causes toxic effects by inhalation. This study aimed to analyze the toxic effects of CFA inhalation in mice models by examining oxidative stress and inflammation markers in the blood. Methods: A true experimental with post-test control group design was used in this study. Twenty-four mice were randomly divided into three groups including control (P1), CFA inhalation for 24 hours (P2), and CFA inhalation for 30 days (P3). Mice in the P2 and P3 groups were exposed to CFA measuring 0.075 mm with doses equal to 12.5 mg/m3 for 1 hour/day. Malondialdehyde (MDA) and the percentage of blood eosinophils were examined as parameters of toxic effects. One way analysis of variance (ANOVA) test was used to compare the toxic effects between groups. Results: MDA were significantly increased in between groups (p<0.05). The percentage of blood eosinophils in P1 was significantly differenced to P2 and P3 (p=0.04 and p=0.14, respectively), however there was no different than P2 and P3 (p = 0.891). Conclusions: CFA inhalation induces toxic effects through increased oxidative stress and inflammation in mice models. This may indicates health hazards after CFA inhalation. Keywords: Coal fly ash, Inhalation, Mice, Malondialdehyde, Eosinophil Inhalation Toxicity of Coal Fly Ash in Mice Models 150 Coal is one of the most important sources of energy, and make up nearly 40% of the fuel in power plants worldwide (1). Indonesia is the fifth largest coal producing country in the world with a total production of 470.8 tons in 2014 and 392 tons in 2015 (2). Asam-asam power station is a coal fuel power plant in South Kalimantan, Indonesia. The coal combustion process produces ash as a pollutant, consisting of 80% fly ash and 20% bottom ash. Air pollution produced by coal combustion is a larger health risk to society than emissions in water or soil. Health impacts due to coal-fired air pollution include respiratory and cardiovascular system disorders, cancer, growth and development disruption (3,4). Coal fly ash (CFA) inhalation causes toxic effects that are dependents on components, quantity, and frequency. CFA exposure to high intensity in a short time is associated with severe toxicity in the body (5,6). Asam-asam CFA contains various minerals, including relatively high silica (74.2%), iron (14.4%), alumina (5.7%), magnesium (2.03%), and others (5). CFA inhalation induces cell damage due to free radical exposure and increased lipid peroxidation reactions (7). Lipid peroxidation is a complex chain reaction of polyunsaturated fatty acid (PUFA) and reactive oxygen species (ROS) leading to the formation ___________ of hydrogen peroxide which causes the decomposition of aldehyde. Malondialdehyde (MDA), 4-hydroxy-2-noneal (HNE), F2-isoprostanes, and other active compounds are the secondary products of lipid peroxidation reaction. MDA is highly reactive compound and easily penetrates into the tissue, inducing cell disruption. Therefore, MDA is widely used as a biomarker of oxidative stress (8,9). The toxic effects of CFA inhalation can also be seen through abnormalities in blood tests (6). Hematological abnormalities are directly correlated to inflammatory response due to lung tissue damage (10). Blood eosinophil count is one of the inflammatory parameters commonly used by clinicians. Eosinophils on the peripheral blood smear are characterized by round cells with two lobes, purple chromatin and eosinophilic granules. Eosinophilia is associated with decreased lung function and has been linked to airway degeneration (6, 11). Our study aimed to analyze the toxic effects of CFA inhalation in mice models. In this case, MDA levels were an oxidative stress parameter and peripheral blood eosinophil counts were an indicator of inflammatory response. This true experimental study with post-test control group design was conducted in January-March 2020 at Lambung _________________ INTRODUCTION * Correspondence to: Dewita Rahmantisa Putri, MD, Department of Pulmonology and Respiratory Medicine, Faculty of Medicine, Lambung Mangkurat University,Veteran Sungai Bilu 317, Banjarmasin, Indonesia, 70122 Phone: +628115127165, Email: drahmantisa@gmail.com DEWITA RAHMANTISA PUTRI 1* , LATIFATU CHOIRUNISA 1 , AND ISA ANSORI 1 1 Department of Pulmonology and Respiratory Medicine, Faculty of Medicine, Lambung Mangkurat University, Veteran Sungai Bilu 317, Banjarmasin, Indonesia, 70122 How to cite this article: Putri DR, Choirunisa L, Ansori I. Inhalation Toxicity of Coal Fly Ash in Mice Models. Asia Pac J Med Toxicol 2020; 9(4):150-153. CFA inhalation toxicity in mice D.R. Putri et al. METHODS