Occupational exposure to quarry dust and progressive systemic toxicity in animal models exposed to two quarry sites in Ebonyi State, Nigeria

Abstract

Assessment of the health risks of occupational exposure to quarry dust is a public health priority, because quarry industry workers are usually exposed to respirable particulates of the dust over a long duration, which could have serious harmful effects to respiratory and non-respiratory organ systems. This study investigated some organs and biochemical effects of long-term exposure to quarry dust using a randomized controlled animal model. Seventy-two (72) male guinea pigs (800 - 1200 g) were exposed to quarry dust at Umuoghara and Amoffia-Ngbo quarry sites in Ebonyi State, Nigeria, for the durations of 3, 6, 9, and 12 months. The animals were randomly divided into three groups of 24 animals each and labeled UMR for Umuoghara quarry site, AMN for Amoffia-Ngbo quarry dust-exposed, and CTR for the control. Each was further subdivided into four subgroups (n = 6) corresponding to exposure durations of 3, 6, 9, and 12 months. Biochemical parameters including renal indices, cardiovascular biomarkers, and broncho-alveolar lavage (BAL) fluid markers were evaluated at the end of these periods. The results indicated duration-dependent elevations in serum creatinine, urea, uric acid, electrolytes, cardiac troponin I (cTnI), creatine kinase (CK), lactate dehydrogenase (LDH), total cholesterol (TC), low density lipoprotein (LDL) cholesterol, triacylglycerol (TAG), and BAL fluid LDH, alkaline phosphatase (ALP), and total protein, with corresponding reductions in high density lipoprotein (HDL)-cholesterol. Toxic effects were consistently more severe in AMN animals. These findings demonstrate that prolonged quarry dust exposure induces progressive multi-organ toxicity which could be attributed to oxidative stress, inflammation, toxic metal accumulation and particulate matter-induced mechanical stress in tissues. These findings indicate a significant occupational health risk associated with working in a quarry sites.