Sunscreens to Avoid the Skin Damage
As we are heading towards the summer season we are stocking up the sunscreens to avoid the skin damage. Sunscreens block harmful Ultraviolet rays (UV) of sun. Skin is the largest organ and the protective barrier to the outside environment and can absorb whatever is applied over it including sunscreens.
They can do more harm than good, if contains toxic chemicals. Chemicals cross the skin barrier and enter bloodstream circulating and reaching to every single fiber in body, wrecking the immunity and endocrine system. However, knowing what is in the sunscreen can help not to grab anything over the shelf.
Sunscreens are broadly categorized as chemical and physical sunscreens. Chemical sunscreens have avobenzone, octinoxate and oxybenzone as active ingredients. They absorb UV radiations like a sponge. Whereas, physical or mineral sunscreens have nano-sized Zinc Oxide (ZnO) or Titanium Oxide (TiO2) particles that deflect the UV rays, in other words they act like a shield. FDA has approved ZnO and TiO2 nanoparticles to be used in sunscreens and “generally recognized as safe and effective” (GRASE).
Nanoparticles in sunscreen are safe or not?
ZnO and TiO2 are natural sun-screening agents providing broad-spectrum UV protection. TiO2 works synergistically with Zinc Oxide. Nanoparticles as approved by FDA do not pose any threat, but their long term effects are yet to be exposed. So far there is no claim as if they are harmful in longer run. Material to be nano-sized comes within the range of 1-100 nm. A nanometer is 10-9 m that is one billionth of a meter; a human hair is 80,000-100,000 nm wide.
Bulk materials and nanomaterials have different behaviors. Large size particles of zinc and titanium appear as amorphous white powder that contributes a white finish to the sunscreen when applied over the skin, but their nano-sized particles (25-50nm) behave differently; they have enhanced clarity. Nanoparticles of both metals are more stable than other UV absorbing chemicals, hence less re-application. Moreover, both are low allergen and low irritant material.
When applied over the skin, how far they penetrate depends on the size of the particle. Researches shoe that TiO2 powder when inhaled causes lung cancer in rats, but its topical application is so far safe, besides they are used in very low concentrations. Sunscreens having these nanoparticles usually do not penetrate past the first layer of skin. Penetration of 19-110 nm sized ZnO particles in humans (bloodstream) is <0.01%.
Research on human and animal skin has suggested that systemic absorption is unlikely. Furthermore, human immune cells are capable to absorb and break Zinc oxide nanoparticles.
Considering the available studies sunscreens having nanoparticles are very effective. Also their long-term usage by far is safe and effective. Additionally the concentration of Titanium oxide and Zinc oxide nanoparticles is very low. There is more risk with avoiding sunscreen than those posed by nanoparticles.
by: Marria Ghalib