Investigation of the Cytotoxic Effect of Thorium on MRC-5 Cells

Abstract

Thorium is a naturally occurring radioactive metal belonging to the actinide group. It is found at low levels in water, soil, rocks, plants and animals. Thorium is used as a nuclear fuel in nuclear technology, and its compounds are used in industry, chemistry, mining, ceramic production and high-quality lens production. It also occurs naturally in different sources, including phosphate fertilizers used in agriculture. Its increasing role in the nuclear and defense industries poses a risk to human health as a result of occupational and accidental exposure. Thorium enters the body mainly through inhalation of contaminated dust. Studies conducted on workers have found that inhaling thorium dust will cause an increased the risk of developing lung diseases such as lung cancer. This study aimed to determine the cytotoxic effect of thorium on normal human lung fibroblast cells (MRC-5) exposed to thorium in vitro. For this purpose, MRC-5 cells were cultured in a 96-well plate (1x105 cells/well; 200 µl) containing 150 µM thorium (the stock solution was 1000 µg/ml in 5% HNO3). Cell viability (cytotoxicity status) was evaluated by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, yellow tetrazole (MTT) analysis method after 48 h of incubation. As a result of the MTT test, cell viability was determined as %99.52 in cells treated with 150 μM thorium. Accordingly, it was concluded that 150 μM thorium is not cytotoxic on MRC-5 cells. However, in later studies, it was decided to examine the cytotoxic effect of thorium at higher doses