Determination of Petroleum Hydrocarbon Contamination Tolerance Limit by Food Insect (Brachytrupes membranaceus) in Bodo Community, Niger Delta, Nigeria

Petroleum hydrocarbon contaminant passes from contaminated soils to soil-inhabiting food insects and alter the tolerance limit and nutritional contents of the insects. Species samples of adult Brachytrupes membranaceus; an edible insect mostly consumed by children in the Niger Delta region of Nigeria, and its soil substrates were collected from petroleum contaminated habitat-types of 5yr-pipeline, 2yr artisanal refinery-source pollution and unpolluted sites, monthly for 6 months (May-Oct, 2017), using hand and bucket-type soil auger, at Bodo community. The samples were processed in the laboratory for Total Petroleum Hydrocarbon (TPH) and nutritional content, using KJELDAHL method and analyzed by GCFID and UV spectrophotometer analyses, respectively, to investigate human health impact of TPH contamination through insect-pathways. The results indicated that the mean values of the TPH in the soil were 1.35ppm (control), 373.67ppm (pipeline) and 351.37ppm (artisanal refinery) and in the crickets the values were 6.42ppm (control), 355.90ppm (pipeline) and 312.93ppm (artisanal refinery). The TPH in insects collected monthly from the control habitat-type recorded below 100ppm and those insects collected from polluted habitat-type recorded above 100ppm. Four mineral elements, Fe, Ca, Mg and P were detected in crickets collected from the three habitat-types. The habitat-type which contained higher TPH concentration recorded higher values of Fe (pipeline: 349mg/kg), Mg values was higher in artisanal refinery (187.8mg/kg) and P values was higher in the control (283.2mg/kg). The increase in levels of mineral elements, proteins and fat in polluted crickets-habitats over those of non-polluted was abnormal and hydrocarbon-induced and may cause human health implications for cricket consumers. Statistical analyses indicate a significant difference between the concentrations of TPH in the soils and crickets collected from the control and polluted habitat-types but insignificant between that of the soils and crickets collected from the same polluted habitat-types. Results implies that the TPH contained in the crickets exceeded the allowable tolerance limit by Nigerian authority, and had impact on levels of mineral elements.