Trace and Potentially Toxic Elements in Canned Tuna Marketed in Eastern Saudi Arabia: ICP-OES/LIBS Method Comparison and Dietary Exposure Assessment

Abstract

Canned tuna is nutritionally valuable but may contain trace elements introduced through the marine environment, processing, or packaging. This study quantified fourteen elements in 14 commercial canned-tuna products marketed in Dammam and Al Khobar, Eastern Saudi Arabia, using inductively coupled plasma optical emission spectrometry (ICP-OES) and orthogonal double-pulse laser-induced breakdown spectroscopy (ODP-LIBS). Scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) spectroscopy were used for complementary structural characterization. Brand-level ICP-OES concentrations (mean ± SD, mg/kg) included Pb 0.549 ± 0.530, Cd 0.095 ± 0.048, Hg 0.264 ± 0.155, and Al 84.736 ± 54.903. For contextual screening, eight of 14 samples contained Pb above 0.30 mg/kg, five contained Cd above 0.10 mg/kg, and all had Hg below 1.0 mg/kg; these comparators are used for screening rather than a formal Saudi regulatory compliance determination. Method comparison showed very high Pearson correlations for Zn, Pb, Al, Cd, Cr, Fe, Mg, Na, and Ca, but correlation did not imply interchangeability. Lin’s concordance correlation coefficient was high for Pb (0.994), Al (0.996), Zn (0.989), Fe (0.972), Na (0.997), and Ca (0.960), but substantially lower for Hg (0.211), Ni (0.145), Cu (0.265), and Co (0.310), reflecting systematic element-specific bias in LIBS. Dietary exposure was recalculated using the manuscript’s stated external scenario of 7.35 g tuna/week and 61.6 kg body weight. Mean weekly exposures were 0.0655 µg/kg bw for Pb, 0.0113 for Cd, 0.0315 for Hg, and 10.11 for Al. Under this low-consumption scenario, Hg represented approximately 1.97% of the JECFA methylmercury PTWI and Al approximately 0.51% of the JECFA aluminium PTWI; the current JECFA lead PTWI has been withdrawn. The results support continued monitoring of Pb and Cd concentrations in canned tuna and indicate that LIBS may be useful as a rapid screening tool for selected elements after matrix-specific validation, but it should not be considered analytically interchangeable with ICP-OES for all analytes.