Thermal Emission Toxicity and Qualitative Screening of Volatile Organic Emissions and Hazard Identification from Water Hyacinth Fiber–Cassava Starch Biodegradable Composites

The rapid transition toward sustainable packaging has driven the development of biodegradable polymer composites utilizing agricultural wastes, such as water hyacinth (Eichhornia crassipes) fibers and cassava starch matrices. However, while the environmental biodegradability of such biocomposites is widely studied, the toxicological safety of volatile organic compounds (VOCs) released under thermal exposure remains critically unaddressed. This study evaluated the volatile emission profile and qualitative hazard screening of water hyacinth–cassava starch composite sheets subjected to heat (100 °C for 15 min) simulating hot-food contact conditions. Using Headspace Gas Chromatography–Mass Spectrometry (HS-GC-MS), 26 volatile compounds were tentatively identified based on NIST library mass spectral matching (similarity match factor >80%, corresponding to Metabolomics Standards Initiative Level 2). The identified profile included 9 hazardous chemical species classified by the International Agency for Research on Cancer (IARC). Key hazardous emissions comprised Group 1 human carcinogens (Ethylene oxide 3.60% peak area and Formaldehyde [5.80%]), Group 2A/2B probable/possible carcinogens (Ethylenimine 19.40%, Acetaldehyde 10.50%, Trichloromethane 1.20%, Tetrachloromethane 0.90%, 1,2-Dichloroethane 0.70%, and 1,2-Dibromoethane 0.60%), alongside hepatotoxic Chloromethane (17.10%). It is emphasized that reported peak area percentages represent relative chromatographic abundances under specific headspace thermal desorption conditions and do not reflect absolute mass concentrations. Furthermore, qualitative hazard identification does not constitute a quantitative health risk assessment, as consumer exposure levels and migration limits were not established. The origin of these hazardous species stems from a plausible combination of aquatic bioaccumulation by raw water hyacinth, alkali delignification pre-treatment residuals, thermal fragmentation of the starch–glycerol matrix, and pyrolysis of residual plant proteinaceous biomass. These findings demonstrate that environmental biodegradability does not inherently ensure chemical safety for food contact materials, highlighting the necessity of integrating volatile emission toxicity screening into biopolymer safety standards.