Locally made utensils as potential sources of heavy metals contamination of water: A case study of some pots made in Nigeria

Abstract

This research work was carried out to determine if locally made utensils can be the sources of water contamination by heavy metals. A reference water of known metal concentration (Distilled water) was heated for 1- 2 hours in both clay and metal pots made in different locations in Nigeria. Geochemical analysis of the heated water from the different variety of pots revealed that the major cations Al (0.109-0.79mg/l), Ca (5.011-16.43mg/l), Fe (0.042-0.178mg/l), K (0.35-2.72), Mg (0.506-2.51mg/l), and Na (1.74-4.88mg/l) have preferentially been released into the heated water displaying significantly elevated concentrations compared to that of the reference water concentrations (0.49mg/l, 6.42mg/l, 0.005mg/l, <DL, 0.54mg/l, 1.88mg/l respectively). On the other hand, water from the metal pots present relatively similar concentrations in the major cations but exceptionally higher concentrations in Al (1.79-14.71mg/l), Ca (5.47-14.15mg/l) and K (4.69-5.91mg/l. With respect to heavy metal concentrations, the heated waters from the clay pots display significantly higher concentrations in As (0.043-0.440mg/l), Tl (0.326mg/l) and Zn (0.801-1.16mg/l) relative to their concentrations in the metal pots (0.072-0.23mg/l), 0.037-0.259mg/l) and 0.67-1.11mg/l). Analysis of geochemical data using a standard pollution index; Contamination Factor (CF) revealed that the water from both the clay and metal pots have been very highly contaminated by As (clay pots (CF for As = 4-44); metal pots (CF for As =7-23). Whereas the water from the metal pots are considerably contaminated by Sb (CF = 0.65-3.35), that from the clay pots are moderately contaminated (CF=0.45-1.9). Both waters from the clay and metal pots are very highly contaminated in Se (CF= up to 7.2). Thus, the continuous long-term usage of locally made utensils for cooking purposes could introduce significant amount of heavy metals into the human body system through the food chain with its attendant human health risks.