Do you know that we could be breathing in four billion nanoparticles per minute? And be none the worse for it? There are numerous sources of such particles in everyday living, and our lungs have learned to cope with these and we continue to live (and prosper).
Does that mean that nanoparticles, natural and engineered, are absolutely safe? Hardly. Asbestos fiber has caused deaths in hundreds of thousands. Even the London smog has caused deaths estimated at a few thousands in one year. Apparently, the capacity of our lungs to tolerate air-borne particles is limited.
There is also the fact that unlike naturally occurring particles, to which our lungs have become accustomed over a long period, engineered nanoparticles are something new which our lungs have no experience of. Just like engineered chemicals, our body might not be all that ready to deal with the new particles.
Dosages can also matter. A single nanoparticle, even if somewhat dangerous, might not have any impact on our health. Even a billion nanoparticles do not amount to much in terms of substance. However, when the substantial content of the nanoparticles absorbed increase, even otherwise harmless particles might become toxic.
These and other interesting thoughts are the content of a recent post at 2020science.org.
