## 1 Introduction  
Nitrogen [N] fertilization plays a critical role in modern agriculture, contributing to increased crop yields and the improved quality of plant production [1]. N, as a fundamental nutrient, supports plant growth; however, excessive use is associated with significant environmental and human health risks. Improper management of synthetic fertilizers, particularly N-based ones, can lead to soil and groundwater contamination, which has serious implications for ecosystem well-being and public health [1]. Excess N that is not assimilated by plants migrates from the soil to groundwater in the form of NO3-[2]. This phenomenon results from processes such as leaching and irrigation, which facilitate the transfer of N to surface and groundwater, leading to their contamination [1, 2]. The degradation of biodiversity and the health of aquatic ecosystems can therefore exert indirect health effects, impacting food quality and the availability of safe, natural resources. A notable consequence of water contamination is the consumption of drinking water with elevated nitrate [NO3-] levels, which poses a risk of developing the so-called \"blue baby syndrome\" (methemoglobinemia) in infants [3]. This condition can lead to serious disturbances in oxygen transport within the body. Furthermore, prolonged dietary exposure to NO3-, resulting from the consumption of plant products that have been intensively fertilized with N and exhibit high concentrations of nitrogenous compounds, may promote the formation of carcinogenic nitrosamines [NOCs][2, 4]. This situation is particularly concerning, as NO3- tends to accumulate most in the leafy parts of plants, including leaves and stems, due to these tissues' high metabolic demand and NO3- storage capacity [5]. Several key regulatory bodies mandate NO3- testing and set maximum limitsfor NO3\({}^{-}\) levels in specific high-risk crops, especially leafy greens, due to the health risks associated with excessive NO3\({}^{-}\) consumption [1,5,6]. The European Union [EU] has some of the most comprehensive regulations on NO3\({}^{-}\) levels in vegetables, particularly leafy greens such as spinach, lettuce, and arguula [6]. The European Commission's Regulation No 1881/2006 sets maximum allowable NO3\({}^{-}\) concentrations for certain fresh vegetables, with separate limits for produce grown in different conditions [i.e., open field vs. greenhouse] and seasons, as NO3\({}^{-}\) levels tend to be higher in winter-grown crops [5,6]. Recent studies have highlighted the risks associated with NO3\({}^{-}\) accumulation in vegetables, particularly leafy greens [spinach, lettuce, arguula, swiss chard], due to the intensive use of N-based fertilizers [7]. NO3\({}^{-}\) levels are influenced by factors like light, temperature, and fertilization methods, with leafy vegetables grown in controlled environments accumulating especially high levels [7]. Sustainable farming practices and improved environmental management can help reduce NO3\({}^{-}\) levels, ensuring safer consumption levels [5,6,7]. In addition, the EU has implemented the \"Farm to Fork\" [F2F] strategy as part of the European Green Deal [8,9]. This strategy aims to reduce the use of chemical fertilizers by 20% by 2030, addressing the negative impact of agriculture on the environment and human health [10,11]. A key component of this initiative is the reduction of N fertilizer applications, which, while posing challenges for farmers, could contribute to environmental quality improvement and a decrease in health threats. More particularly, the F2F strategy consists of four axes of action: (i) sustainable food production, (ii) sustainable food processing and distribution, (iii) sustainable food consumption, and (iv) food loss and waste prevention [10]. A specific goal of the first axis of the strategy is to achieve reductions of 20% in nutrient inputs and 50% in nutrient losses, including N, without deteriorating soil fertility [9,10,11].