A study has raised concerns over arsenic contamination in Nigerian water sources, with about 85 per cent of mapped sampling sites recording levels above the World Health Organisation’s recommended limit.
The findings, published in the Journal of Applied Sciences and Environmental Management on September 21, 2026, also exposed gaps in water quality monitoring, as more than one-third of the states and the Federal Capital Territory have no published data on arsenic contamination.
According to a statement jointly released by the researchers on Thursday, the researchers reviewed 40 studies conducted across Nigeria, with 35 studies involving 945 water samples included in the analysis.
The highest reported concentration was 4.645 milligrams per litre in Ebonyi State boreholes, about 465 times the WHO limit of 0.01 milligrams per litre.
Abia, Anambra, Kano and Nasarawa were among the other states where elevated concentrations were reported. The review covered water from boreholes, wells, rivers and lakes.
However, the researchers warned that the results did not establish the extent of contamination nationwide because the review was based on available studies, some of which focused on locations already suspected of pollution.
The study’s corresponding author, Excel Obumneme Amaefule, said the lack of testing and links between water quality results and health records made it difficult to determine the scale of the problem.
“We’re not claiming a national crisis. We’re saying Nigeria can’t rule one out, because across much of the country nobody has tested, and nowhere is anyone comparing water results with health data,” Amaefule said.
Dr Babajide Milton Macaulay called for urgent attention to the potential health implications of arsenic exposure.
“The reason arsenic pollution should be treated as a public health emergency is because ingestion, even at numerically low concentrations, could result to significant health concerns.
“Today, many Nigerians are privately managing chronic illnesses, who knows, if it was triggered by the water they’ve been drinking?!” he said.
Romoke Shakirat Ojo, who highlighted the study’s use of geospatial analysis, said government agencies needed to make reliable water quality data publicly available to improve research and inform drinking water policies.
Chioma Dike, a registered nurse and public health nurse, warned that contaminated water could appear safe to households using it daily.
“Water may look perfectly safe while arsenic exposure continues silently. Many families may drink from the same boreholes and wells for years without knowing what is in them,” she said.
The researchers recommended expanding testing to states without published data, requiring water quality assessments for mining and industrial approvals, and establishing a national surveillance system linking environmental measurements with health records.
The WHO has linked prolonged exposure to inorganic arsenic in drinking water to skin abnormalities and increased risks of skin, bladder and lung cancers, as well as cardiovascular diseases and diabetes.