Potential health risks from heavy metal via dietary intake of water spinach (ipomoea aquatica) from selected farms in Selangor, Malaysia

Water spinach (Ipomoea aquatica) is one of the most common leafy vegetables that are consumed by Malaysians daily. Many would assume that all vegetables are nutritious and safe for human consumption, however they are uninformed that some vegetables may be contaminated with heavy metals and other contaminants. Since food is the major intake source of heavy metals in humans, excessive ingestion of heavy metals beyond the safe limit can lead to various diseases. This study determines the concentration of heavy metals (Cd, Pb, Cu, Fe, and Zn) in water spinach (Ipomoea aquatica) that was cultivated from four selected farms in Selangor, Malaysia. The potential human health risk via dietary intake of water spinach was also evaluated. Sample preparation was done using acid digestion method. A graphite furnace atomic absorption spectrophotometer (GFAAS) analysis was applied to determine the concentration of heavy metals. Heavy metals concentrations in water spinach ranged from 5.2 – 8.79 mg/kg for Cd, 12.77 – 37.98 mg/kg for Pb, 8.01 – 12.82 for Fe, 0.37 – 34.88 mg/kg for Cu, and 6.5 – 22.4 mg/kg for Zn. The overall mean concentration of heavy metal in water spinach measured in ascending order was Cd (7.19 mg/kg) < Fe (9.90 mg/kg) < Cu (13.96 mg/kg) < Zn (15.42 mg/kg) < Pb (28.86 mg/kg). The concentration of Zn, Fe, and Cu are within the acceptable limit set by the Malaysia Food Regulations 1985 and FAO/WHO except for Cu levels in water spinach cultivated at Farm 1. However, Pb and Cd had greatly exceeded the safe limit. A comparison of selected heavy metal contaminants from the study area using one-way analysis of variance (ANOVA) was conducted to compare the effect of location of farms on heavy metal concentration in water spinach. Heavy metals Cd, Fe, Pb and Cu, among the study area is statistically significant (p < 0.05). Based on the health risk assessment, consumption of water spinach from all selected farms has a relatively high non-carcinogenic (HI > 1) and carcinogenic risk (TCR > 10⁻⁶ ). This concludes that the continuous consumption of water spinach from these farms poses health hazards to their consumers. Regular monitoring should be done in order to avoid the excessive accumulation of heavy metals in food products, especially vegetables, in agricultural farms.