First baseline data on the exposure and risk assessment of Ulva rigida C. Agardh (Chlorophyta) in Sinop, Turkiye

This study aims to determine the extent to which Ulva rigida C. Agardh (green alga) can absorb metals and to what extent it can be used as food or an ingredient. Metal concentrations in U. rigida samples collected from the Sinop coasts were evaluated in relation to the surrounding environment, using Inductively Coupled Plasma - Mass Spectrometry (ICP-MS). The acquired data were assessed in terms of human health and marine environmental health. The average element analysis results of seawater samples were as follows, in order: Mg > Ca > K > Fe > Zn > Pb > Co = Cd > Zn (mg L-1) and Na concentration was found above detection limits. The mean concentrations in sediments across the entire area (eight stations) were found in the order: Ca > Mg > K > Na > Fe > Zn > Cu > Co > Pb > Cd > Hg (mg kg-1). The Bioaccumulation Factor (BAF) and Biota-Sediment Accumulation Factor (BSAF) results for metals were calculated below threshold values. BAF results showed high uptake for Cu, Fe, and Zn, while Cd, Hg, and Pb showed limited translocation. Cu levels varied significantly between stations (5.36-132.67 mg kg-1, p < 0.05), with the highest BSAF values at Tersane and DSI stations, indicating pollution in popular summer-use areas. Pb at Station 4 (Akliman) slightly exceeded low-effect sediment quality guideline (SQG) values, and Zn surpassed the pollution threshold (100 mg kg-1) at recreational stations during summer. Risk assessment revealed that although individual hazard quotients (HQs) were <1, cumulative hazard index exceeded the threshold for infants. Total cancer risk (TCR) values ranged from 1.14x10-6 to 5.02x10-5, suggesting low but non-negligible carcinogenic risk for consumers. The estimated daily intake (EDI) calculations showed that sea lettuce consumption rates for infants, children, and adults were below the reference dose values for Cd, Co, Cu, Fe, Hg, Pb, and Zn. The utilization of U. rigida poses a carcinogenic risk based on the Carcinogenic Risk Index for infants.