Hardness Toxicity and Multi‐Route, Multi‐Demographic Health Risks of Nitrate‐Contaminated Groundwater: A Call for Sustainable Environmental and Public Health Protection

Abstract Groundwater contamination by nitrate and hardness poses critical challenges to environmental sustainability and public health across many regions. This research pioneers an integrated assessment of nitrate multi‐route exposure for six‐age groups and hardness toxicity in Ghana. Using physicochemical analysis, United States Environmental Protection Agency (USEPA) health risk models, and ArcGIS‐based geospatial mapping, the investigation evaluates impacts across infants (6–12 months), children (5–10 years), teens (10–15 years), young adults (15–20 years), adults (20–60 years), and elderly (>60 years) in the Birimian Province, Wa East and Sawla‐Tuna‐Kalba Districts. Nitrate concentrations reach 720 mg/L in agricultural hotspots; 30.6% of samples exceed the 50 mg/L guideline. Oral hazard quotients exceed safe levels in 41.7% of infant samples. Cumulative hazard indices substantially exceed values reported in comparable Nigerian and Indian studies. Dermal risks remain negligible. Total hardness (TH) reaches 247 mg/L, with most samples exceeding 100 mg/L, suggesting infrastructural and dermatological implications. Geospatial mapping identifies contamination clusters in rural agricultural zones, intensifying environmental justice concerns for communities dependent on polluted groundwater. These findings highlight the need for groundwater management strategies that address multi‐demographic risks and promote environmental sustainability. Implementing precision agriculture to reduce nitrate leaching is recommended to safeguard public health and ensure equitable outcomes in vulnerable regions.