A lecturer at the University of Education, Winneba (UEW), Dr. Ekpor Anyimah-Ackah, has raised scientific concerns over the US$200,000 pilot deployment of a copper nanoliquid solution by the Environmental Protection Agency (EPA) to clean the heavily polluted Birim River, warning that the intervention could unintentionally introduce new environmental risks.

Dr. Ekpor Anyimah-Ackah says although nanotechnology-based remediation shows promise in controlled laboratory settings, its behaviour in real river systems remains highly unpredictable, particularly in complex, sediment-laden waters affected by illegal mining (galamsey).

According to him, the fundamental scientific risk is that the technology could substitute one pollutant for another rather than eliminate contamination.

“The core problem is this: copper nanotechnology may remove one contaminant while introducing another, and river chemistry makes the net risk hard to predict,” he explained on Wednesday, February 25, in reaction to the project.

The EPA is piloting the nano-copper intervention as part of emergency efforts to restore the Birim River, one of Ghana’s most degraded waterways, largely due to illegal small-scale mining activities.

The river influences water supply for millions of residents in the Eastern Region and beyond, heightening the stakes for any experimental remediation approach.

Dr. Anyimah-Ackah cautioned that success in laboratory conditions does not automatically translate into field safety.

In natural rivers such as the Birim, nanoparticle behaviour can shift dramatically depending on key water chemistry variables, including pH, ionic strength, ionic valence, natural organic matter (NOM), and sediment load.

“One study showed these factors strongly alter agglomeration, sedimentation, dissolution and speciation of CuO nanoparticles,” he said.

In practical terms, he noted, copper nanoparticles in open river systems could clump and settle unpredictably, dissolve and release free copper ions, bind with organic matter, or travel downstream into drinking water systems. He warned that such transformations can simultaneously alter both the effectiveness and toxicity of nano-based treatments.

Beyond chemical instability, the UEW lecturer flagged other dangers associated with copper exposure. While copper is an essential trace element, elevated concentrations can be harmful to aquatic ecosystems.

“Copper is essential at low levels but toxic at higher levels,” Dr. Anyimah-Ackah noted.

He referenced findings consistent with assessments by the United States Environmental Protection Agency indicating that copper exposure in aquatic organisms can lead to acute mortality, reduced growth and survival, reproductive impairment, brain and enzyme dysfunction, metabolic disruption, and blood chemistry changes.

For copper nanoparticles specifically, he stated that recent aquatic toxicology reviews have reported oxidative stress caused by reactive oxygen species, cellular damage, genotoxic effects, and DNA damage signals in fish tissues and gametes.

Environmental advocates warn that the Birim River is already under severe ecological stress, and any additional toxic burden could worsen biodiversity loss.

Dr. Anyimah-Ackah also pointed to Ghana’s regulatory framework. Ghana’s drinking-water specification DGS 175:2021 sets a maximum copper concentration of 2.0 mg/L.

“Any intervention that introduces copper into a drinking-water source must be carefully evaluated against the national standard,” he cautioned.

Water quality experts say continuous monitoring would be required to ensure the nano-treatment does not push concentrations beyond safe limits.

In the broader fight against galamsey pollution, the UEW lecturer urged policymakers to maintain realistic expectations about alternative clean-up methods. He explained that phytoremediation, the use of plants to absorb or stabilise contaminants, is better suited to land rehabilitation than fast-flowing river channels.

“In Ghana’s galamsey context, phytoremediation is best understood as a low-cost, plant-based clean-up and land rehabilitation approach used mainly on mined-out soils, tailings, and riverbank-adjacent degraded areas,” he said.

Dr. Anyimah-Ackah outlined three principal applications currently studied in Ghana. Phytoextraction involves plants absorbing heavy metals into their tissues. Phytostabilisation uses vegetation to immobilise contaminants and reduce erosion, runoff, and dust movement. Ecological reclamation focuses on restoring vegetation cover and rebuilding soil structure on degraded mine lands.

“Ghana studies show this is often more realistic as a medium- to long-term rehabilitation strategy than a quick ‘decontamination’ fix,” he emphasised.

Research in Ghana has identified several plant species with potential for mine-land rehabilitation, including Aspilia africana, Leucaena leucocephala, Senna siamea, Chromolaena odorata, Mimosa pudica, Chrysopogon zizanioides (vetiver), Cynodon dactylon, Paspalum vaginatum, and cover crops such as Centrosema, Stylosanthes, and Mucuna.

However, he stressed these approaches must complement, not replace, source control measures.

“Phytoremediation works best when paired with stopping active pollution, sediment management, and long-term monitoring,” he said.

The EPA’s nano-copper pilot comes amid mounting national pressure to restore Ghana’s polluted rivers, with galamsey widely blamed for heavy metal contamination, extreme turbidity, river siltation, loss of aquatic biodiversity, and rising water treatment costs. Water treatment operators have repeatedly warned that turbidity levels in some rivers now exceed plant design capacity, forcing expensive chemical dosing.

Dr. Anyimah-Ackah is not dismissing innovation outright but is urging a precautionary, evidence-driven approach.

“Any nano-based river intervention must be preceded by rigorous pilot studies under real Ghanaian river conditions, with full ecotoxicological monitoring,” he advised.

As Ghana searches urgently for solutions to the galamsey crisis, the Birim River pilot is expected to attract close scientific and public scrutiny.