Arsenic poisoning results from the postharvest use of calcium carbide to ripen Citrus sinensis (L.) Osbeck. fruits

Abstract

The use of calcium carbide (CaC2) to ripen Citrus sinensis (L.) Osbeck and other non-climacteric fruit is prevalent in parts of the Global South. However, little to no information exists about the potential effects and risks associated with such practices. Hence, it is necessary to determine if contaminants like arsenic that are associated with CaC2 accumulate significantly in orange juices after they are ripened with the chemical. Fresh mature but unripe C. sinensis were harvested from an orchard in Benin City, Nigeria, and exposed to the different concentrations (1.0, 2.5, and 5.0 g) of dry and wet CaC2 in small lidded cylindrical containers with a surface area of 1507.96 cm2. In each container, three oranges were placed while the control setup was allowed to naturally ripen. The control oranges began to ripen on the 7th day, with severe colour loss, whereas the oranges treated with 5.0 g CaC2 (dry) began to ripen on the second day. However, there were already signs of rotting by the sixth day. Even though the orange exposed to 5.0 g CaC2 (wet) began to ripen after 24 h, there were no symptoms of fruit degradation after one week. Moreover, in oranges ripened with CaC2, there was a large deposition of arsenic. The dried and wet-CaC2-exposed oranges showed no significant variations in arsenic accumulation. It was found that the oranges contain 2.15 mg/L juice and 2.06 mg/L peel material. The use of CaC2 for fruit ripening is discouraged and could contribute to reducing the incidence of cancer, skin lesions, poor cognitive development, and non-communicable diseases like diabetes caused by arsenic exposure.