Trace elements concentrations in soil contaminate corn in the vicinity of a cement-manufacturing plant: potential health implications

Abstract

Background: Cultivated lands in the vicinity of industry are vulnerable due to trace element releases from industrial activities. One such situation concerns the surrounding of the largest cement-manufacturing plant in sub-Saharan Africa, located in Obajana, Nigeria.

Objective: This study aimed at examining the trace element concentrations in the soil as they contaminate corn crops in the vicinity of a cement manufacturing plant. A case study of the cement-manufacturing plant located in Obajana, Nigeria is presented.

Methods: We used inductively coupled plasma-mass spectrometer to analyse for total arsenic (As), cadmium (Cd), chromium(Cr), copper (Cu), lead (Pb), and nickel (Ni) concentrations and microwave-induced plasma-atomic emission spectrometer to measure total iron (Fe) and zinc (Zn) contents in 89 samples of corn and surface soil (0-15 cm) from five farmlands including reference farmland and evaluated health hazard of human exposure to the trace elements via the consumption of corn cultivated in the area.

Results: The results showed the average Cr concentrations in µg/g dry weight (±standard error of the mean) in corn ranged from 2.08 ± 0.17 to 3.56 ± 0.65 in all the farmlands including control, while the mean Pb levels in µg/g dry weight (± standard error of the mean) in corn extended from 0.23 ± 0.03 to 0.38 ± 0.02 in the farmlands downwind of the cement plant. The Cr values were several factors higher than the stable concentration range of 0.01 to 0.41 µg/g reported in cereal grains, while the Pb values exceeded the limit of 0.2 µg/g set by the Food and Agriculture Organization of the United Nations/World Health Organization in grains. Lead is a trace element of environmental concern and its average levels in the farmlands downwind of the plant were found to be several orders of magnitude higher than the values in µg/g dry weight (± standard error of the mean) (0.01 ± 0.00 to 0.02 ± 0.00) observed in the farmlands upwind of the plant and were statistically significant (p < 0.0001).

Impact statement: Our findings provide the first health hazard assessment from the consumption of corn cultivated in the vicinity of the largest cement-manufacturing plant in Nigeria as far as we know.

Keywords: Exposure; Farmland; Hazard impact; Human health; Metals; Nigeria.