HEALTH AND CARCINOGENIC RISKS ASSOCIATED WITH HEAVY METAL CONCENTRATIONS FROM FOREIGN AND LOCAL TEA BRANDS SOLD IN RETAIL STORES WITHIN GOMBE METROPOLIS, NIGERIA

This study quantified and compared concentrations of seven heavy metals (cadmium [Cd], chromium [Cr], copper [Cu], iron [Fe], nickel [Ni], lead [Pb], and zinc [Zn]) in fourteen foreign and locally processed black and green tea brands sold in retail stores within Gombe Metropolis, Nigeria, and estimated the associated non-carcinogenic and carcinogenic health risks. Tea samples were acid-digested and analysed by atomic absorption spectrophotometer. Measured concentrations were compared with NAFDAC (2025) and Chinese National Food Safety Standard (2022) limits, and Welch's t-test was used to compare foreign and local tea groups. Non-carcinogenic risk was estimated using the Target Hazard Quotient (THQ) and Hazard Index (HI), while carcinogenic risk was estimated using the Incremental Lifetime Cancer Risk (ILCR) model. Cadmium concentrations (0.192-2.147 mg/kg) exceeded the NAFDAC maximum limit (0.1 mg/kg) in all sampled brands, with local black tea recording the highest group mean (0.589 mg/kg), driven by one local brand (GTL-B015-4; 2.147 mg/kg). Chromium and copper concentrations were within permissible limits, while lead exceeded the NAFDAC limit (0.5 mg/kg) in one foreign black tea brand. Welch's t-test showed no significant difference between foreign and local tea for most metals except nickel (t = 2.46, p = 0.042). Hazard Index values exceeded for all four tea groups, driven mainly by cadmium, indicating a potential non-carcinogenic health risk for habitual tea drinkers in Gombe. ILCR values indicated a potentially carcinogenic risk for all tea brands as all groups exceeded the tolerable threshold, indicating an unacceptable carcinogenic risk. The findings of the study suggest that there is heavy metal contaminations in the study area, particularly cadmium in local black tea, which poses a public health concern in Gombe Metropolis and highlight the need for stricter regulatory monitoring and enforcement of heavy metal limits in tea marketed in Nigeria.