Trace metal accumulation in automotive garage soils of Jimma Town Ethiopia and its potential health implications

Abstract Garages generate waste streams—including used oils, metal fragments, brake and tire debris, and fluid spills—that introduce trace metals into surrounding soils. This study quantified chromium (Cr), zinc (Zn), and copper (Cu) in topsoils from six garages (G1-G6) in Jimma town, Oromia Region, Ethiopia, through the collection and analysis of 21 composite topsoil samples (0–10 cm depth, including three controls). Metal concentrations were determined using Microwave-Induced Plasma Atomic Emission Spectrometry (MP-AES) following aqua regia digestion. Soil Zn and Cu concentrations at all six investigated garages systematically exceeded World Health Organization (WHO) target soil values (Zn: 50 mg/kg; Cu: 36 mg/kg), with Zn reaching up to 677.50 mg/kg (G1) and Cu reaching 686.25 mg/kg (G6). Concurrently, Cr concentrations at sites G4 (140.00 mg/kg) and G6 (123.75 mg/kg) exceeded the WHO target value for soil (100 mg/kg). Based on comparison with established soil guidelines and known toxicity thresholds, these elevated concentrations suggest potential health concerns for workers and residents exposed via direct contact, dust ingestion, or secondary exposure to home-grown produce. The spatial pattern and magnitude of contamination support anthropogenic sources associated with automotive repair activities as the primary drivers of metal accumulation. These findings underscore the urgent need for regulatory interventions, including paved workshop floors, hazardous waste containment, and routine soil monitoring in commercial repair zones.