article · Journal of Hazardous Materials Advances
An assessment of 369 groundwater samples investigated nitrate and nitrite contamination using water quality indexing and probabilistic health risk models. The evaluated methods included an entropy-weighted water quality index, a principal component analysis-based groundwater quality index, and exposure assessments for oral and dermal pathways in adults and children. Nitrate levels ranged from 0.005 to 54.50 milligrams per litre, while nitrite concentrations spanned 0.0005 to 13.0 milligrams per litre. Only one sample exceeded the World Health Organization threshold for each compound, representing an exceedance rate of 0.27 percent. Principal component analysis linked both compounds to anthropogenic nitrogen loading. Health evaluations revealed higher vulnerability in children, with four in ten thousand simulated instances exceeding a safe hazard index of one, compared to zero for adults. Ingestion drove over 99 percent of exposure, with nitrate identified as the primary risk driver.
Groundwater is an essential source of drinking water, but contamination from nitrogen compounds poses health threats. By assessing both nitrate and nitrite concurrently through advanced statistical and exposure models, this work reveals that while overall water quality limits are rarely breached, children remain disproportionately exposed to risks, primarily through drinking water. This provides clearer guidance for targeting water safety monitoring.
The abstract describes early-stage environmental risk modelling and water quality indexing methodology rather than a commercial product or service. Water resource authorities, environmental monitoring bodies, and public health agencies could use these combined indexing and probabilistic risk assessment frameworks to refine drinking water safety guidelines and monitoring strategies. However, the abstract does not indicate a direct commercialisation pathway or commercial readiness level.
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Nitrate ( 𝑁 𝑂 − 3 ) and nitrite ( 𝑁 𝑂 − 2 ) are the primary inorganic nitrogen contaminants commonly found in groundwater. Both are typically analysed separately in health risk assessments, using overly simplified exposure assumptions. This study presents a comprehensive multi-parameter groundwater quality and health risk assessment of 369 groundwater samples, with 𝑁 𝑂 − 2 explicitly included in all analytical frameworks in addition to 𝑁 𝑂 − 3 . Three complementary approaches were applied: (i) non-carcinogenic human health risk assessment (HHRA) based on oral ingestion and dermal exposures to water for two demographic groups; (ii) Entropy-weighted Water Quality Index (EWQI); and (iii) Principal Component Analysis based Groundwater Quality Index (PCA-GWQI). Nitrate (NO₃⁻) concentrations ranged from 0.005 to 54.50 mg/L, with a median of 6.94 mg/L, while nitrite (NO₂⁻) concentrations ranged from 0.0005 to 13.0 mg/L, with a median of 0.010 mg/L. Only one groundwater sample exceeded the WHO guideline value for nitrate (50 mg/L as NO₃⁻), and one sample exceeded the WHO guideline value for nitrite (3 mg/L as NO₂⁻), corresponding to an exceedance rate of 0.27% for each contaminant. Nitrate showed a skewness of 1.217 and kurtosis of 1.094, whereas nitrite exhibited a much stronger skewness of 17.793 and kurtosis of 331.849. PCA retained six components that explained 67.54% of the total variance. Nitrate and nitrite loaded strongly on PC6, identifying anthropogenic nitrogen loading and nitrogen transformation as a distinct hydrochemical process. In PCA-GWQI, nitrate and nitrite received weights of 0.0324 and 0.0198, respectively. In contrast, the entropy-weighted index assigned nitrite the second-highest weight of 0.1111, while nitrate received a weight of 0.0243. The probabilistic human health risk assessment showed that children were more vulnerable than adults. The mean combined hazard index was 0.0156 for adults and 0.0365 for children. No adult simulation produced an HI above 1, whereas four of the 10,000 child simulations exceeded 1, corresponding to P (HI > 1) = 0.04%. Ingestion accounted for 99.48% of the adult HI and 99.34% of the child HI. Sensitivity analysis identified nitrate concentration as the dominant risk input, with coefficients of 0.963 for adults and 0.958 for children, followed by nitrite concentrations, with coefficients of 0.305 and 0.294, respectively.
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DOI: 10.1016/j.hazadv.2026.101547
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