Comparative assessment of heavy metal accumulation and potential health risks in lettuce (Lactuca sativa L.) grown with marine macroalgae biofertilizer and chemical fertilizer applications.

Abstract

Macroalgal species can be employed as biostimulants for agricultural production. However, their effects on heavy metal accumulation and associated human health risks remain insufficiently explored, particularly in Turkey. This study aimed to evaluate the agronomic performance, metal accumulation, and potential health risks of lettuce (Lactuca sativa L.) cultivated using a biofertilizer produced from Ulva sp. collected from Mersin Bay (NE Mediterranean Sea) between January 2023 and April 2024, in comparison with a commercial chemical fertilizer and a control treatment. Metal concentrations in macroalgae and lettuce samples were determined, and a health risk assessment was performed based on USEPA guidelines, including estimated daily intake (EDI), hazard quotient (HQ), hazard index (HI), and carcinogenic risk (CR). The results of this study showed that the biofertilizer significantly improved plant growth parameters, with yields comparable to those obtained under chemical fertilizer application. Study findings indicated that measured metal values of lettuce samples for most metals remained below FAO/WHO permissible limits, except for arsenic (As) and lead (Pb). Health risk assessment indicated that HQ and HI values were below 1, suggesting no significant non-carcinogenic risk. In contrast, CR values for chromium (Cr) and nickel (Ni) exceeded the acceptable limit of 10-4 for all treatments, indicating potential long-term carcinogenic risks associated with lettuce consumption.