What NANOPARTICLES are
A nanoparticle particle is defined as a particle of matter that is between 1 and 100 nanometres (nm) in diameter. They may also be labeled as “ultrafine particles” (UFP).
WHERE YOU CAN FIND THEM + WHY MADEWITH DOESN’T ALLOW THEM
Nanoparticles are used in SPF, lotions, and a variety of other body care products. You won’t find the label “nanoparticles” used; you will usually find them labeled as nanonized zinc, nanonized titanium, etc. Because it is an expensive technology, they are generally found in high-end brands. lThey have been shown to be easily absorbed into the body, breaching the dermal layer. They are barely (if at all) regulated and almost never labeled. Particles of such small size also come with the risk of carrying other dangerous particles with them. We believe much more testing must be done, since ingredients at nano-size may behave differently than larger-scale ingredients of the same molecular structure.
WHERE THEY’RE BANNED OR RESTRICTED
While not currently restricted or banned, the governments of Canada, The United States, and the European Union have set up organizations to further study the effects of nanoparticles in cosmetic products.
The European Commission and the REACH act do require nanoparticle warning labels on products.
Furthermore, the FDA has offered guidance on using nanoparticles, warning “nanomaterials can have chemical, physical, and biological properties that differ from those of larger scale particles with the same chemical composition, and the use of nanomaterials in cosmetic products may raise questions about the safety of the product for its intended use.” 
WHERE WE'RE GETTING OUR INFORMATION
 FDA. Guidance for Industry: Safety of Nanomaterials in Cosmetic Products. (2014). https://www.fda.gov/regulatory-information/search-fda-guidance-documents/guidance-industry-safety-nanomaterials-cosmetic-products#III.C
 Focal Point Research Inc. Canada: The regulation of nanoparticles in cosmetics & drugs. (2018). https://www.focalpointresearch.net/canadian-regulatory/canada-regulation-nanoparticles-cosmetics-drugs
 NIH. NCBI. Toxic potential of materials at the nanolevel. (2006). https://www.ncbi.nlm.nih.gov/pubmed/16456071
 Journal Of Health Sciences. Nanoparticles transferred from pregnant mice to offspring can damage the cranial and congenital nerve systems. (2009). http://jhs.pharm.or.jp/data/55(1)/55_95.pdf
 NIH. NCBI. Long-term clearance kinetics of inhaled ultrafine insoluble iridium particles from the rat lung, including transient translocation into secondary organs. (2004). https://www.ncbi.nlm.nih.gov/pubmed/15204761