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New Study Confirms The Lethal Effect Of Smoking


Many people who pass away from severe emphysema are found, at the time of autopsy, to have black lungs. The discoloured lungs are most strongly associated with people who have smoked heavily or worked in certain industries.

Now medical researchers have a clue as to what causes the black colour. Studies led by David Corry and Farrah Kheradmand, both of Baylor College of Medicine have found that the black material is made up of an insoluble nanoparticulate of carbon. These tiny specks are result of the incomplete combustion of organic material. An example is with tobacco. The particles are around 30 and 40 nanometers in size. A nanometer is one billionth of a meter in length.

Many of the particles are found in the dendritic cells (dendritic cells are a type of human antigen-presenting cell). The particles are small enough to break strands of DNA inside these cells.

Centrilobular emphysema

Centrilobular emphysema

Taking the nanoparticle carbon black material from deceased humans and placing controlled amounts into the noses of mice led to the experimental mice developing emphysema. This highlighted the fact that the tiny particles are hazardous to human health.

The studies showed, unsurprisingly, that the more particles that an animal is exposed to then the worse the effects. The findings also showed that smaller particles do more harm than larger ones.

A burning cigarette has a temperature of between 800 to 920oC; this is hot enough to cause carbon black particle formation. This effect is not only linked to tobacco, for people who work in certain industries, such as the processing of rubber or plastic face a similar hazard. This could lead to new risk assessments being performed. The key risk is that once someone has inhaled a sufficient level of particles, the particles cannot be removed from the lungs and the risk of ill-health is very real.

It might be possible one day to develop drugs to deal with the particles. However, in the meantime, the best measures are to minimize exposure.

The researchers have produced two papers that explain the findings. The first is in eLife, in a paper titled: “Nanoparticulate carbon black in cigarette smoke induces DNA cleavage and Th17-mediated emphysema”.

The second is published in Nature Immunology, which is headed: “The microRNA miR-22 inhibits the histone deacetylase HDAC4 to promote TH17 cell–dependent emphysema”.

About the author

Tim Sandle

Dr. Tim Sandle is a chartered biologist and holds a first class honours degree in Applied Biology; a Masters degree in education; and has a doctorate from Keele University.

  • has

    I thought carbon was supposed to be inert and it was its combination with other inorganic materials that was damaging

    • Allah hu Ackbar

      That is incorrect because it is not the carbon that is the problem it is the fact that it is a nano-scale structure that interferes with cell biology and causes problems because of it’s physical presence, not it’s chemical interactions.

  • André Kruk

    At first glance, I thought centrilobular emphysema was easter bread..

  • thecrud

    So vaporizing may leave nano particles?

    • Reid W Harris III

      Vaporizing at optimal temperatures produces < .1% of the carcinogens found in smoke.

      • Allah hu Ackbar

        Nanoparticles =/= carcinogens. You can have a totally inert material in nanoparticles and it will cause problems due to it’s structure and size alone.

    • Ethan Freimark

      Yes, many e-cigs use a heating element, or atomizer, that includes nickel. The nickel can become part of the aerosol and accumulate in the lungs as nano particles. Nickel is also thought to be a carcinogen, and various nickel compounds are known to be carcinogens.