How car tyres harm lungs, by researchers

Invisible pollutant found to cause emphysema, DNA damage

AN invisible pollutant produced by car tyres has been found to be even more damaging to lungs than previously thought.

Researchers studying the effects of carbon black have found it causes emphysema and Deoxy Nucleic Acid (DNA)/genetic material damage in smokers – it is produced when cigarettes burn.

But because the specks invisible to the human eye are also produced when car tires wear down they warn that the effects of carbon black have been underestimated.

And the authors highlight why smoking-related lung damage is incurable – because the nanoparticles are impossible to remove once absorbed by the lungs.

The study was published in the journal e-life.

Researchers were studying why the lungs of dead smokers are black on the inside as well as the effects of carbon black on mice.

The authors found that it is the accumulation of tiny carbon black nanoparticles –previously it was thought to have been caused by either tar, aluminium or some other dark pigment.

The finding is all the more extraordinary because the nanoparticles are invisible to the human eye and just 30 to 40 nanometers wide – a human hair is 100,000 nanometers wide.

As well as damaging the lungs, they found that this black material accumulates in part of the immune system called the dendritic cells – causing damage at the genetic level.

The particles were found to cause double breaks in strands of human DNA – a condition that is very difficult for the cell to repair – and lead to chronic inflammation in the lungs.

The carbon black also produced emphysema – lung damage, which causes a chronic shortness of breath – when inhaled by mice.

Dr. James Tour of Rice University, in Houston, Texas, who analysed the effects of carbon black for the journal e-life said the finding has far-reaching implications as many products, such as tires, contain significant amounts of nanoparticulate carbon black.

“I am concerned about how this affects industry. It is going to have to change. As it gets into the air, for example through tire-tread wear, it could affect the public as well, and it is imperative that risk-assessments be conducted.”

The smaller the carbon black particles, the more toxic they were found to be, he said.

Tour and fellow authors write in e-life: “These findings largely explain the persistent and incurable nature of smoking-related lung disease.

“Because no medical means of removing accumulated lung nCB (nanoparticulate carbon black) exists, our findings underscore the need for all individuals and societies to minimize the production of and exposure to smoke-related particulate air pollution and industrial nCB.”

Co-author Professor David Corry of Baylor College of Medicine, Houston who also wrote about the effects of carbon black in the journal Nature Immunology said once breathed in, it was impossible to get rid of the carbon black particles.

He said: “You never get rid of this stuff. It will be important to conduct further studies to fully assess the spectrum of health-risk profile.”