Impact of crude oil contamination on green leafy vegetables: nutritional and health risk assessments

Abstract

For decades, crude oil spills have been a serious environmental challenge which have led to the establishment of crude oil remediation intervention values (CRIV) by different national agencies to regulate the release of toxic petroleum hydrocarbons via these spills. To ascertain the suitability of these CRIV in crude oil‐polluted agricultural sites, the impact of five CRIV on the nutritional composition of two green leafy vegetables (GLV) and associated human health risk was investigated using standard analytical procedures. Briefly, high‐performance liquid chromatography was used in determining the composition of the sugars while inductively coupled plasma mass spectrometer and atomic absorption spectrometer were utilized in quantifying the levels of minerals in the harvested samples. This was followed by human health risk assessment based on the evaluation of noncarcinogenic and carcinogenic risks. CRIV at 3000 and 5000 mg/kg total petroleum hydrocarbons (TPH) reduced the fructose and glucose contents of Lactuca sativa whereas the sucrose level was enhanced at 10,000 mg/kg TPH. All the tested CRIV had no statistically significant effect (p > 0.05) on the Na/K ratio of Brassica oleracea as well as the F/G and Ca/P ratios of L. sativa. Among the studied nonessential heavy metals, only the samples' Pb contents were below the FAO/WHO Codex maximum level. Multivariate statistical analysis indicated that the 10,000 mg/kg TPH treatment GLV samples' nutrients were the most impacted by the crude oil stress which also primarily had the highest non‐carcinogenic and cancer risk levels. The investigation revealed the potential of some crude oil concentrations in agricultural sites to alter the physiology of GLV and their nutritional composition. Consequently, use of CRIV at TPH concentration of ≤ 3000 mg/kg is recommended to protect the quality of GLV from such sites and to safeguard against possible cancer risk.