Several hospitals have withdrawn a widely used surgical device over fears that it could expose patients to dangerous levels of aluminium, the Guardian has learned.

The device, called enFlow, is used to warm fluids to body temperature before they are infused into patients during surgery. But fluids passed through the device during tests were found to contain hundreds of times the recommended safe limit of aluminium.

The Royal Manchester children’s hospital and Salford Royal are understood to have suspended the use of the device last week after concerns that premature babies and young children could be at risk of neurological damage if exposed to such high levels of the metal.

The device is understood to be used in many hospitals around the UK.

Michael Charlesworth, an anaesthetist at Wythenshawe hospital in Manchester, said: “It’s certainly alarming as a clinician that it’s possible that aluminium could be released into patients in this quantity. I’d imagine hospitals would be reviewing the use of this device.”

The health regulator, the Medicines and Healthcare Regulatory Agency (MHRA), was informed of concerns on 2 January and said the matter was under active investigation.

During surgery, fluids are normally administered to patients to replace lost blood or to prevent dehydration. Before infusion, fluids are generally warmed to body temperature to avoid patients suffering hypothermia.

EnFlow, which is made by the US company Vyaire Medical, is used in thousands of such procedures each day in UK hospitals and has been approved for clinical use in the US and the EU for more than a decade. In some devices, the heating element is coated in a biocompatible seal, but in the enFlow (and some other models) the element is directly exposed to the infusion fluid, like in an electric kettle.

Doctors at a German hospital that was trialling the device were concerned that the element appeared to change colour after a few hours of use, suggesting that a chemical reaction was taking place.

The German team investigated and found that when an electrolyte solution (typically used to replace lost fluids during surgery) was passed through the enFlow and heated, unusually high levels of aluminium were detected. The concentration reached about 7,000 micrograms per litre, hundreds of times above the US Food and Drug Administration’s recommended safe limit of 25 micrograms per litre.

Only traces of aluminium were found when they carried out the same tests using a saline solution, leading to the conclusion that certain fluids may react with the element.

Thorsten Perl, a senior consultant at the University Medical Center Göttingen in Germany and lead author of the research, said: “The finding that a huge amount of aluminium is liberated, at least in the case of this one fluid, is alarming because of the potential toxic effects in the long term.”

When a different brand of warming device with a coated element was tested, low levels of aluminium were found regardless of the fluid used.

So far, patients have not been tested to see whether they have higher levels of aluminium in their blood during treatment with the device. Biological consequences of a patient being exposed to high levels of aluminium are unclear. The known toxic effects are mostly long-term rather than immediate.

“What we don’t know is whether this [device has caused] any long-term clinical problems,” said Charlesworth. “We may never know.”

Newborn babies exposed to aluminium when being fed through an IV drip have been shown to be at risk of delayed brain development and bone problems. Chronic exposure to aluminium, for instance in metalworkers, has been linked to cognitive problems. Higher-than-average concentrations of aluminium have also been observed in the brains of Alzheimer’s patients – although whether the metal contributes to the onset of the disease remains under debate. Aluminium is normally rapidly cleared from the body by the kidneys, but might persist longer in patients with kidney failure.

The Royal Manchester children’s hospital said it had withdrawn the device “purely as a precautionary measure”. Salford Royal is understood to have also suspended use of the device, but the hospital did not respond to a request for comment.

Prof Andrew Klein, a senior anaesthetist at the Royal Papworth hospital NHS trust in Cambridge and editor of the journal Anaesthesia, which published the report, said findings raised broader concerns about medical device regulation and expressed frustration that the MHRA were yet to provide official guidance to doctors.

“Medical devices come on to the market very easily and there seems to be very little oversight once they go on to the market,” he said. “The burden of proof should be to show something is safe.”

An MHRA spokeswoman said: “Patient safety is our highest priority and where necessary we will take action to protect public health. This is an ongoing area of investigation for the agency and we are closely scrutinising this issue, including detailed discussions with both the company and other international regulators.”

Vyaire Medical said the device had undergone a rigorous premarket safety review. “Since its introduction and after millions of uses worldwide, we are not aware of a single incident in a clinical setting where aluminium was observed to have been transmitted to a patient in amounts above scientifically recognised safe limits nor have there been any reported adverse events related to aluminium toxicity,” it said.

“We take our obligation to offer safe and effective products to our customers and their patients very seriously. We are reviewing this matter and working proactively with the applicable regulatory bodies to share our own data and findings. In line with our commitment to safety and quality, we will make changes to the product or its recommended usage if additional review of the data or other findings determine, in collaboration with the applicable regulatory bodies, that such steps are warranted.”