Tiny “nanoparticles” found in diesel fumes and a host of everyday products ranging from cosmetics to paint have direct and potentially dangerous effects on the heart, a new study has shown.

A unique experiment conducted by German scientists confirmed that certain small-scale chemical particles can increase heart rate, upset heart rhythms and interfere with the heart’s electrical activity.

Reinhard Niessner’s team used an isolated rodent heart flushed with artificial blood to test for effects on heart function.

The nanoparticles were injected into the nutrient solution taking the place of blood to simulate their entry into the circulation via the lungs.

Although the doses were around 100 times greater than those experienced in the real world, the findings provide clear biological evidence for the first time of what common nanoparticles can do to the heart.

“There’s lots of ongoing research into the toxicology of nanoparticles, but so far people have only carried out tests on cells,” said Prof. Niessner, from Munich Technical University. “This is the first hint from a higher organ level of what may happen.”

He added: “It might explain why so many people died in the London smog.”

More than 12,000 people may have had their lives cut short by the Great Smog in December 1952, when airborne pollutants mostly from burning coal choked the city.

A number of population studies have suggested that pollutant particles small enough to penetrate the lungs can lead to premature death. One of the most harmful, known as PM10s, are shed in large numbers by diesel engine exhausts.

The small size of nanoparticles means they collectively have a large surface area, which can produce unusual properties not seen in the same material at larger scales.

This makes them ideally suited to certain industrial applications. For instance, the highly reflective surfaces of titanium dioxide nanoparticles makes them appear brilliant white. The substance is therefore widely used in white paints and sunscreens.

Another type of nanoparticle, known as “carbon black”, is extensively used in car tyres and plastics, as well as dyes for printers and copying machines. More than eight million tons of carbon black is produced worldwide each year.

The testbed heart, known as a Langendorff heart, was exposed to a range of different nanoparticles. They included titanium dioxide, spark-generated carbon – a model for diesel pollutants – carbon black, and silicon dioxide. In addition, aerosol silicas that act as thickening agents in cosmetics and polystyrene nanoparticles were tested.

Carbon black, spark-generated carbon, titanium dioxide and silicon dioxide all produced a 15 per cent increase in heart rate with altered ECG values which did not normalise after exposure was ended.

Aerosol silicas and polystyrene did not appear to have any effect on heart function.

The research suggests that nanoparticles stimulate the release of noradrenaline, a nerve signalling chemical, from nerve endings in the inner wall of the heart.

Noradrenaline increases heart rate and also plays an important role in the central nervous system, suggesting that nanoparticles might also affect the brain.

“Here we have, for the first time, a viable instrument for testing the effects of nanoparticles on the heart,” Prof. Niessner said. “The next thing we want to do is find out why some nanoparticles influence the heart function, while others do not influence the heart at all.”

The new heart model may be especially useful in medical research looking at using nanoparticles to transport therapeutic agents to disease sites in the body. Most early prototypes are carbon- or silicate-based, but their biological effects are still largely unknown.

Sign up to our free newsletters

Get the best updates straight to your inbox:
Please select at least one mailing list.

You can unsubscribe at any time by clicking the link in the footer of our emails. We use Mailchimp as our marketing platform. By subscribing, you acknowledge that your information will be transferred to Mailchimp for processing.