2026-03-302026-03-302025-12-18https://repositorio.ifal.edu.br/handle/123456789/1470Quality of life is directly related to dietary habits, including fluid intake. In this context, it is essential that drinking water be free from chemical and biological contaminants. The ingestion of water containing nitrate concentrations above established limits may cause adverse effects on human health. Among these effects, methemoglobinemia—also known as blue baby syndrome—stands out. This condition occurs due to the oxidation of hemoglobin iron from the ferrous state (Fe²⁺) to the ferric state (Fe³⁺), resulting in the formation of methemoglobin, which is unable to efficiently transport oxygen. This alteration compromises tissue oxygenation and may lead to symptoms such as fatigue, headache, and shortness of breath. In addition, chronic exposure to nitrate has been associated with an increased risk of gastric cancer due to the endogenous formation of potentially carcinogenic N-nitroso compounds (nitrosamines) in the gastrointestinal tract. This study aimed to monitor nitrate (NO₃⁻-N) concentrations in groundwater from the Barreiras–Marituba aquifer system in Maceió, Alagoas State, Brazil, between 2022 and 2025, based on laboratory data and statistical analyses, and to assess compliance with the limits established by Brazilian Ministry of Health Ordinance GM/MS No. 888/2021. The results indicated that the Barreiras–Marituba aquifer system exhibits different degrees of nitrate contamination, with higher and persistent concentrations in the lower part of the city, ranging from 10.65 to 46.86 mg NO₃⁻-N/L, and moderate but increasing values in the upper part, between 4.20 and 26.70 mg NO₃⁻-N/L. A significant proportion of the samples exceeded the maximum permissible limit of 10 mg NO₃⁻-N/L, evidencing the influence of anthropogenic sources associated with inadequate sanitation infrastructure. These findings indicate a risk to public health, particularly due to the potential occurrence of methemoglobinemia and gastric cancer, and reinforce the need for permanent environmental education actions and sanitation improvements as strategies aligned with the Sustainable Development Goals.ptAttribution-NonCommercial-NoDerivs 3.0 BrazilCiências BiológicasMetemoglobinemiaCianoseNitrato - Contaminente emrgenteÁguas subterrâneasNitrate - Emerging contaminantMethemoglobinemiaGroundwaterTrabalho de Conclusão de CursoCIENCIAS BIOLOGICAS