Bioconcentration of Heavy Metals in Rhynchophorus phoenicis larvae from three gas-flaring communities in Gbarain and Ekpetiama clans, Bayelsa State: Implications for food safety and human health

Rhynchophorus phoenicis larvae are a popular dietary protein in the Niger Delta, but oil-industry activities and gas flaring may contaminate their habitats. Heavy metals like lead (Pb), cadmium (Cd), chromium (Cr), zinc (Zn) and copper (Cu) in larvae collected between June–September, 2023 from three sites: Gbarain (industrial, Station A), Tombia village (peri-urban, Station B), and Agudama-Ekpetiama (reference/control, Station C) were quantified. A total of 180 mature larvae (60 per site) were harvested, depurated, oven-dried, digested (HNO₃:HClO₄) and analyzed by atomic absorption spectrophotometry. Morphometrics (30 individuals per station subsample) showed significantly greater length and fresh mass in Gbarain (64.8 ± 5.6 mm; 8.73 ± 1.10 g) than Tombia (58.2 ± 4.9 mm; 7.12 ± 0.95 g) and Agudama-Ekpetiama (61.1 ± 5.0 mm; 7.85 ± 1.02 g) (ANOVA, F ≥ 8.7, p < 0.001). Mean heavy metal concentrations (mg/kg) were highest in Gbarain: Pb 1.86, Cd 0.28, Cr 0.94, Zn 45.2, Cu 6.8; followed by Tombia: Pb 0.95, Cd 0.12, Cr 0.41, Zn 51.6, Cu 5.7; and Agudama-Ekpetiama: Pb 0.42, Cd 0.05, Cr 0.18, Zn 29.7, Cu 3.2. Food safety guidance values were exceeded in Gbarain for Pb (92%), Cd (78%), Cr (85%), Cu (46%) and Zn (10%), while Tombia showed exceedances for Zn (22%), with minimal cases in Agudama-Ekpetiama (≤5%). Elevated Pb and Cd pose potential consumer risks. The findings identify R. phoenicis larvae as sensitive bioindicators of terrestrial contamination and call for routine monitoring and emission control in gas-flaring regions.