Heavy Metals Concentration in Water Convolvulus (Ipomoea aquatica and Ipomoea reptans) and Potential Health Risk

Abstract

Water convolvulus (Ipomoea aquatica and Ipomoea reptans) or their Malay name “kangkung” is tropical, semiaquatic, and fast-growing vegetables belonging to the morning glory family. They are among the green leafy vegetables widely consumed by Malaysian population. However, excessive use of fertilizer and pesticides in “kangkung” cultivation and contaminated source of irrigation may cause harm to the human health. Samples of Ipomea were collected from local wet market and supermarket, and digested and analyzed by Atomic Absorption Spectrophotometer (AAS). There were significant differences of heavy metal concentration for zinc, copper, manganese, and nickel in both species. The average concentration of Fe, Mn, Zn, Cu, and Ni in I. aquatica was found to be 270.20, 91.14, 32.95, 3.99, and 1.79 mg/kg, respectively, while Fe, Mn, Zn, Cu, and Ni in I. reptans was 275.97, 212.63, 87.33, 18.56, and 3.14 mg/kg, respectively. The daily intake of aforementioned heavy metals was within the safe limit values under Malaysia Food Regulations 1985 and World Health Organization’s provisional tolerable daily intake. Subsequently, the Health Risk Index (HRI) for daily intake of Fe, Zn, Cu, and Ni was less than 1 except for Mn (HRI > 1) indicating possible health effect upon consumption. The use of fertilizers and pesticides should be monitored, and regular sampling of the vegetables is recommended to minimize the heavy metal uptake by water convolvulus, thus reducing human exposure.