Hidden Contaminants on the Menu – Market and Socioeconomic Profiles of Emerging Contaminants in Fish of Nutritional Importance Revealed by µ-Raman

The occurrence of anthropogenic materials in commercially important fish provides relevant information on environmental exposure in coastal urban systems. This study investigated materials detected in the gastrointestinal tracts of croaker (Micropogonias furnieri) and horse mackerel (Trachurus trachurus) marketed in Santos, Brazil, and Maputo, Mozambique, integrating µ-Raman spectroscopy, frequency analysis, and correspondence analysis with market categories and market-associated socioeconomic profiles. µ-Raman analysis yielded 65 material and compound spectral assignments, including carbonaceous materials, synthetic polymers, cellulosic materials, pigments, dyes, and other chemical signatures. Carbon and graphite were the most frequent components, while polyethylene terephthalate (PET) and polyester-related materials predominated among synthetic polymers. Both study areas showed comparable spectral-occurrence patterns, particularly for PET, graphite, and cellulosic materials. Global chi-square tests showed no statistically significant dependence between material occurrence and either market categories or socioeconomic profiles. However, adjusted standardized residuals and correspondence analysis revealed localized distributional patterns involving specific materials and market categories, which should be interpreted as exploratory rather than causal relationships. Integrating µ-Raman spectroscopy and multivariate analysis provides a useful framework for characterizing chemically diverse materials associated with gastrointestinal exposure in commercially important fish. Because we analyzed only gastrointestinal tissues, the findings do not demonstrate contamination of edible muscle tissues, human dietary exposure, or health risk.