Environmental Safety and Ecotoxicological Assessment of GEIOS Nitrogen Hybrid Gas Nanofoam for Enhanced Quantum Geothermal Stimulation: OECD, REACH, US EPA, and WHO Compliance Testing Demonstrating Not-Classified Hazard Status, Risk Quotient of 0.000

This study presents a comprehensive environmental impact assessment and ecotoxicological evaluation of the GEIOS nitrogen hybrid gas nanofoam, a proppant-free, water-minimising stimulation fluid for Enhanced Quantum Geothermal (EQG) applications. The four-component formulation (inert nitrogen carrier gas plus gamma-Al2O3 and amorphous SiO2 nanoparticles) was tested against a battery of OECD Test Guidelines (TG 201, 202, 203, 211, 218, 471, 439), ASTM E2524-08 nanoparticle protocols, US EPA, EU REACH, and WHO benchmarks. All acute and chronic aquatic endpoints (LC50/EC50/NOEC) exceeded 1,000 mg/L in water-column assays and 10,000 mg/kg dry weight in sediment tests, yielding a Globally Harmonized System status of Not Classified for both environmental and acute toxicity. The Ames test was negative in all five strains up to 5,000 ug/plate, and reconstructed human epidermis retained 94.2% viability (non-irritant). A conservative worst-case groundwater release scenario produced a risk quotient (RQ) of 0.0004, more than three orders of magnitude below the negligible-risk threshold and five to six orders of magnitude below conventional slickwater and crosslinked-gel fluids (RQ 10 to 1,000). Leachate aluminium reached only 0.04 mg/L (below the 0.2 mg/L WHO guideline and US EPA secondary standard), with silica within natural background and no detectable organic contaminants in TCLP tests. Electron and X-ray microscopy showed no cellular internalisation in tested organisms, with nanoparticles dissolving at reservoir temperatures into naturally occurring gibbsite, boehmite, and orthosilicic acid. The system achieved a GREEN rating across all thirteen regulatory checks and an approximate 90% reduction in aggregate environmental impact relative to conventional fracturing fluids, while reducing induced-seismicity acoustic emission events by 49%. Laboratory findings are reported alongside recommended multi-year field monitoring requirements for operational validation.