Fatty Acid Methyl Esters in Agrochemical, Textile, and Chemical Manufacturing Waste: Compositional Variability, Physicochemical Drivers, and Human Health Risk Assessment

Abstract

ABSTRACT This study provides one of the first systematic evaluations of fatty acid methyl esters (FAMEs) as lipid‐fraction markers in industrial waste matrices in sub‐Saharan Africa, addressing an important gap in environmental monitoring of biofuel‐related contaminants. FAMEs were quantified in five industrial waste types ( n = 5 replicates per site) using gas chromatography–mass spectrometry (GC–MS) with a DB‐5MS column, electron ionization at 70 eV, and external calibration ( R 2 > 0.995). Hexadecanoic acid methyl ester was the dominant compound across all waste profiles (7.37–9.87 ± 0.13–0.73 mg/g), followed by methyl stearate (4.55–6.41 ± 0.11–0.31 mg/g) and 15‐tetracosenoic acid methyl ester (4.89–6.97 ± 0.02–0.25 mg/g). Analysis of variance (ANOVA) revealed significant inter‐waste variability ( p < 0.05 for 24 of 27 compounds), indicating strong source‐specific compositional heterogeneity. Correlation analysis showed moderate positive relationships between total FAMEs, pH, and electrical conductivity, whereas hierarchical clustering identified two distinct chemical regimes. Human health risk assessment showed non‐carcinogenic hazard quotients ranging from 1.23 × 10 −6 to 1.35 × 10 −4 , below the regulatory threshold of 1.0. Carcinogenic risks were reported as 0.00E+00 due to unavailable slope factors in the US Environmental Protection Agency (US EPA) Integrated Risk Information System (IRIS), not confirmed safety. Limitations include small sample size, deterministic risk modeling, and incomplete toxicological data. These findings establish baseline data for FAME monitoring and support risk‐informed waste valorization strategies.