An interesting question I have already asked on this link and did not get enough answers

https://www.researchgate.net/post/fate_of_Nanoparticles

Nanotech is a new technology and there are not sufficient research to show the risks and hazards of this newly born Tech. However, since this technology is related with fabrication and manipulating of matter in nanoscale, there are some concerns on how safe these materials are. There are no clear regulations on the use of these materials worldwide. Countries have different views towards Nonotech. safety.

Europe and Canada have laws regulating nanotechnology, but the United States has issued only voluntary guidelines for manufacturers. The U.S. Food and Drug Administration (FDA) passed its final guidance on nanotech in June 2014. It recommends that companies consult with the FDA before taking products to market, and warns that nanotech products may require additional safety reviews on a case-by-case basis. According to the Center for Food Safety, nanoparticles in food or food packaging can gain access to the human body via ingestion, inhalation or skin penetration. Nanoparticles’ small size allows them to circulate through the body when ingested, reaching potentially sensitive target sites, such as bone marrow, lymph nodes, the spleen, the brain, the liver and the heart. After nanoparticles are in the body, some types may have the ability to translocate to various organs and the central nervous system. For example, silver and carbon nanoparticles show up in other parts of the body after inhalation exposure.

You can read the following articles and book:

https://jech.bmj.com/content/72/2/148.abstract

https://www.tandfonline.com/doi/full/10.1080/21553769.2017.1365775

https://books.google.com/books?hl=fa&lr=&id=1nyPDQAAQBAJ&oi=fnd&pg=PA3&dq=nanotechnology+in+human+&ots=NMGKYWzrL2&sig=7craiSCXFaPnx4MSRAArwk4ilYc#v=onepage&q=nanotechnology%20in%20human&f=false

Dear Maher,

A tube of sunscreen, a tennis racquet, an iPod, or any number of other consumer products, and there’s a good chance that it’s been “nano-enabled,” meaning it contains nanoscale particles designed to give it some beneficial feature.

Yet nanotechnology’s spread through the market has been met with mounting concerns over the potential human health effects of these miraculous materials. Because of their small size—100 nano-meters or less—nanomaterials have unique physical properties that can influence their uptake, distribution, and behavior in the body. Indeed, some nano-particles have been shown to penetrate into cells, where they can trigger inflammatory responses and oxidative stress.

No case of human toxicity has been linked to the roughly 2,000 types of nano-materials in commercial use or development today, however, those risks can’t be ruled out.

Predictions about nanotechnology risk have emerged from inhalation research, specifically studies targeting ultrafine soot particles with nanoscale dimensions. Upon inhalation, some of these particles traverse epithelial and endothelial cells to reach the blood and lymph circulation, which carries them to potentially sensitive sites, including the bone marrow, lymph nodes, spleen, heart, and central nervous system. In vitro and animal studies show these particles can—depending on the dose and chemical composition—induce a range of inflammatory effects, whereas epidemiologic findings link them to respiratory and cardiovascular diseases.

All nanoparticles have high surface-to-mass ratios, which makes them uniquely reactive in the body. “Chemical reactions tend to occur at particle surfaces,” . Engineered nanoparticles and soot differ in key ways, however, in particular, soot is heterogeneous in terms of particle size, chemistry, surface characteristics, and other constituents, whereas engineered nano-particles—within product categories—have uniformly identical shapes, including spheres, tubes, wires, rings, and planes. Given their similar high surface-to-volume ratios, both types of particles could trigger comparable biologic effects. Particle uniformity might also influence the kinetics and toxicity of nano-materials in unknown ways.

Ashish