Nitrates significantly impact human health and the environment. Drinking water and vegetables are considered the main sources of exposure to exogenous nitrates for humans. This study aimed to estimate and assess the health hazards from nitrate contamination present in drinking water and vegetables for infants in the north of the Gaza Strip. A total of 252 samples were collected from groundwater and drinking water, and 15 vegetable samples were analyzed with a spectrophotometer. In addition, an ELISA kit was used to determine methemoglobin in 87 infant blood samples. According to the findings of this study, the nitrate concentration in groundwater was in the range from 58.3 mg/L to 178.4 mg/L. Meanwhile, the nitrate levels in drinking water were found to be between 10 and 17 mg/L. As for vegetables, carrots (237.20 ± 53.23 mg kg⁻¹), potatoes (246.80 ± 81.42 mg kg⁻¹), and zucchini (275.86 ± 58.87 mg kg⁻¹) had varying nitrate concentrations. Lastly, the study revealed that methemoglobinemia was present in 32.2% of infant samples in the study area. This study concluded that 97% of groundwater in desalination plants exceeded WHO guidelines (>50 mg/L), and the values of nitrates in drinking water showed the existence of nitrate contamination. Among vegetables, zucchini has the highest nitrate content. Exposure to drinking water and vegetables contaminated with nitrate increased the percentage of methemoglobin levels in infants.