Zinc Oxide
(in 9,632 products)

Potential Risk Index®:

ISCE InhaleISCE SwallowISCE ContactISCE Environment
PRI Legend

About:

Functions:
1. Astringent - Causes the contraction of body tissues, typically of the skin.
2. Binder / Stabilizer - Retains the physical characteristics of food/cosmetics and ensure the mixture remains in an even state.
3. Colorant - Pigments or dyes that are added in order to change or enhance the color.
4. Dietary / Nutritional Supplement - Vitamins, minerals, proteins, fatty acids or probiotics that improves nutritional intake
5. Drug / Medicine - Treats, alleviates, cures, or prevents sickness. As officially declared by a governmental drug/medicine regulatory body
6. Fragrance / Fragrance Component - Provides or enhances a particular smell or odor.
7. Opacifier - Makes the mixture less transparent or translucent
8. Sunscreen - Physical sunscreens work by deflecting or scattering UV rays. Chemical sunscreens work by absorbing and dissipating the UV rays as heat.
Zinc Oxide (ZnO) is safe for use as a physical sunscreen ingredient.
Physical sunscreens typically work by reflecting and scattering UV rays from the sun.
Zinc Oxide and its nanoparticles (ZnO NPs <100nm) have registered very little to negligible skin penetration and hence it poses no threat to human health.
Long-term oral exposure in mice also showed minimal toxicity and in human cells, ZnO NPs have demonstrated to be able to induce the death of cancerous cells while having no effect on normal cells. It has also proven to have some antiviral activity against the herpes simplex virus. [1]
Recent Findings:
Zinc oxide is commonly used as a sunscreen or an antibacterial ingredient.
Skin penetration of zinc oxide through sunscreen application is limited: “Dermal penetration of TiO2 (titanium dioxide) and ZnO NPs (zinc oxide nanoparticles) did not occur at or above the limit of detection of the used experimental methods” [2]
“This is in accordance with the conclusions that were made by the EU Scientific Committee on Consumer Safety that stated that both kinds of nanoparticles are safe to use for dermal applications up to a concentration of 25% in cosmetic products [SCCS (Scientific Committee on Consumer Safety), 2012; SCCS (Scientific Committee on Consumer Safety), 2014]” [2]
In a study conducted on 48 mice for 35 weeks concluded that there is “minimal toxicity” from 50-500mg/kg nano-ZnO (nano zinc oxide), at 5000 mg/kg, there is “significantly enhanced mRNA expression of zinc metabolism-related genes” and “caused toxicity on development, and altered the zinc metabolism and biodistribution in mice”. [3]
Zinc tends to accumulate in “in the liver, pancreas, kidney, and bones (tibia and fibula) after receiving 5000 mg/kg nano-ZnO diet” it may also affect liver iron content and pancreas manganese levels. [3]
The effects of nano-ZnO are varied, as it “can easily enter cells and introduce oxidative stress, although it has been reported that nano-ZnOs exhibited high biocompatibility with human cells and high selectivity”. [3]
“ZnO-NPs are reported by several studies as non-toxic to human cells” despite their “significant antimicrobial activities when particle size is reduced to the nanometer range” it “exhibits distinct bactericidal mechanisms” with “good biocompatibility to human cells”. [4]
“ZnO-NPs possess high catalytic and high photochemical activities. ZnO possesses high optical absorption in the UVA (315–400 nm) and UVB (280–315 nm) regions”. [4]
“Zinc oxide nanoparticles exhibit a strong preferential ability to kill rapidly dividing cancerous T-cells (28–35x) but not normal cells”. [5]
In a study conducted on human volunteers aged 20-30 over a period of 5 days, it was found that repeated application of ZnO-NPs sunscreen showed no evidence of "any skin penetration and local toxicity". [6] This includes same site application every hour for 6 hours and same site application once every day for 5 days. [6] “In conclusion, repeated application of zinc oxide to the skin, as used in global sunscreen products, appears to be safe, with no evidence of zinc oxide penetration into the viable epidermis nor toxicity in the underlying viable epidermis”. [6] In a similar study, it was "demonstrated that the epidermal penetration of zinc was negligible following topical application of this nanoparticulate formulation to human epidermis in vitro." and "whilst the debate on general nanoparticle safety continues, the case for safe, non-penetrating, transparent, topical ZnO sunscreen formulations appears to be strengthening". [7]
Zinc oxide also prevents dental demineralization. [8] [9] In a study involving 20 participants using a toothpaste slurry containing zinc over 14 days, the results were statistically significant, with a "49% greater inhibitory efficacy on dentine demineralization over the control". [8] The compound, zinc oxide-eugenol (ZOE) can also be used as an oral cement, where the "zinc from zinc oxide–eugenol cements can effectively inhibit MMP-2 (matrix metalloproteinases) and MMP-9 proteolytic activities", preventing "tissue destruction during periodontal disease". [9]
Scientific References:
2. Dermal Absorption of Nanomaterials Titanium Dioxide and Zinc Oxide Based Sunscreen (The Danish Environmental Protection Agency, 2015, ISBN: 978-87-93352-53-7)
3. Effects of Long-Term Exposure to Zinc Oxide Nanoparticles on Development, Zinc Metabolism and Biodistribution of Minerals (Zn, Fe, Cu, Mn) in Mice (PLoS One. 2016; 11(10): e0164434. Published online 2016 Oct 12. doi: 10.1371/journal.pone.0164434)
4. Review on Zinc Oxide Nanoparticles: Antibacterial Activity and Toxicity Mechanism. (Nano-Micro Letters, 7(3), 219–242. doi:10.1007/s40820-015-0040-x)
5. Zinc oxide nanoparticles as selective killers of proliferating cells (Int J Nanomedicine. 2011; 6: 1129–1140. Published online 2011 May 30. doi: 10.2147/IJN.S16581)
6. Support for the Safe Use of Zinc Oxide Nanoparticle Sunscreens: Lack of Skin Penetration or Cellular Toxicity after Repeated Application in Volunteers. (J. Investig. Dermatol. doi:10.1016/j.jid.2018.08.024)
7. Human Skin Penetration of Sunscreen Nanoparticles: In-vitro Assessment of a Novel Micronized Zinc Oxide Formulation. (Skin Pharmacol. Physiol., 20(3), 148–154. doi:10.1159/000098701)
8. Inhibition of dentine demineralization by zinc oxide: In vitro and in situ studies. (Dent. Mater. J., 21(12), 1170–1177. doi:10.1016/j.dental.2005.02.006)
9. Inhibition of human pulpal gelatinases (MMP-2 and MMP-9) by zinc oxide cements. (J. Oral Rehabil., 31(7), 660–664. doi:10.1111/j.1365-2842.2004.01297.x)
Regulatory References:
1. South Korea - Ministry of Food and Drug Safety - Prohibited/Restricted Chemicals
- Ref: 1405
2. EU CosIng Annex IV, COLORANTS ALLOWED IN COSMETIC PRODUCTS [2017]
- Ref: IV/144
3. EU CosIng Annex VI, LIST OF UV FILTERS ALLOWED IN COSMETIC PRODUCTS [2017]
- Ref: VI/30, VI/30a
4. Association of Southeast Asian Nations Annex VII, Allowed UV Filters
- Zinc oxide, Zinc Oxide (nano)
5. Association of Southeast Asian Nations Annex IV - Part 1, Allowed Colorants
- CI 77947
6. US FDA Generally Recognized As Safe (GRAS) (21 CFR 182) [2017]
- § 182.8991 - Zinc oxide
7. International Fragrance Association Transparency List [2015]
- Zinc oxide (zno)

Safety and Hazards (UN GHS):

1. Suspected of damaging fertility or the unborn child (H361)
2. Causes damage to organs (H370)
3. Very toxic to aquatic life (H400)
4. Very toxic to aquatic life with long lasting effects (H410)

Potential Health Concerns For:

1. Asthenozoospermia (PubMed ID:27111109)
2. Atherosclerosis (PubMed ID:22166487)
3. Atrophy (PubMed ID:27111109)
4. Chemical and Drug Induced Liver Injury (PubMed ID:25680694)
5. Chromosome Breakage (PubMed ID:32600046)
6. Heavy Metal Poisoning (PubMed ID:20934491)
7. Hyperplasia (PubMed ID:23832296)
8. Hypersensitivity (PubMed ID:25127755)
9. Inflammation (PubMed ID:17301066)
10. Lung Injury (PubMed ID:17301066)
11. Necrosis (PubMed ID:24120544)
12. Oligospermia (PubMed ID:27111109)
13. Pneumonia (PubMed ID:22240982)
14. Poisoning (PubMed ID:21964423)
15. Weight Loss (PubMed ID:28212817)

Potential Health Benefits For:

1. Albuminuria (PubMed ID:22116744)
2. Hyperbilirubinemia (PubMed ID:29024620)
3. Sunburn (PubMed ID:21642632)
4. Wounds and Injuries (PubMed ID:7899834)

User Comments:

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