Liu et al. (2012Liu W, Wang X, Lai W, Yan T, Wu Y, Wan M, et al. Sunburn protection as a function of sunscreen application thickness differs between high and low SPFs. Photodermatol Photoimmunol Photomed . 2012;28(3):120-6.) |
SPF values and amount of product |
Sunscreens with SPF of 4, 15, 30, and 55 were tested in vivo at application levels of 0.5, 1.0, 1.5, and 2.0 mg/cm2
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Sunscreens in the 4 to 15 SPF range showed a linear dose-response relationship with application level. Higher SPF (30 and 55) showed exponential relationship between protection and layer thickness. |
Couteau et al. (2012Couteau C, Paparis E, El-Bourry-Alami S, Coiffard LJ. Influence on SPF of the quantity of sunscreen product applied. Int J Pharm . 2012;437(1-2):250-2.) |
SPF values and amount of product |
In vitro measurements of SPF of well-known products from the market. |
74% of products tested fulfilled their claims in terms of efficacy. Sunscreens based on inorganic formulas alone did not allow SPF values above 30 to be reached. Higher levels of protection can only be achieved through the association of both organic and inorganic formulas. Reductions in the amount of product applied caused a proportional reduction in SPF. |
Couteau et al. (2016Couteau C, Diarra H, Coiffard L. Effect of the product type, of the amount of applied sunscreen product and the level of protection in the UVB range on the level of protection achieved in the UVA range. Int J Pharm. 2016;500(1-2):210-6.) |
SPF values, product type (oil and emulsion) and amount of product |
PF-UVA in vitro measurements of well-known products from the market (15 sun oils and16 emulsions). |
Emulsions correlated exponentially with the amount applied, providing better protection in the UVA range than oils with the same performance. The UVA range also depended on SPF. There was a reduction in the SPF-UVA factor of 2.2, on average, when the value was halved. |
Pissavini and Diffey (2013Pissavini M, Diffey B. The likelihood of sunburn in sunscreen users is disproportionate to the SPF. Photodermatol Photoimmunol Photomed . 2013;29(3):111-5.) |
SPF values, amount and uniformity of application |
A simulation model was developed to estimate the variation in protection provided by a sunscreen on exposed skin surface of consumers. |
The simulation showed that the extent of erythematous areas of skin in SPF15 sunscreen users was two times greater compared with those using SPF30 sunscreen. The proper amount and spreading ability of the sunscreen proved essential factors to ensure protection. |
Ou-Yang et al. (2012Ou-Yang H, Stanfield J, Cole C, Appa Y, Rigel D. High-SPF sunscreens (SPF >/= 70) may provide ultraviolet protection above minimal recommended levels by adequately compensating for lower sunscreen user application amounts. J Am Acad Dermatol . 2012;67(6):1220-7.) |
SPF values and amount of product |
SPF values were measured in vivo for 6 sunscreen products with label SPF values ranging from 30 to 100, applied at 0.5, 1.0, 1.5, and 2.0 mg/cm2. |
Sunscreens with SPF 70 or above provided additional clinical benefits when applied by consumers, even at typically used concentrations. Sunscreens with SPF 30 or 50 may not provide the same level of protection. |
Williams et al. (2018Williams JD, Maitra P, Atillasoy E, Wu MM, Farberg AS, Rigel DS. SPF 100+ sunscreen is more protective against sunburn than SPF 50+ in actual use: Results of a randomized, double-blind, split-face, natural sunlight exposure clinical trial. J Am Acad Dermatol . 2018;78(5):902-10.e2.) |
SPF values |
The protection against sunburn provided by SPFs 100+ and SPF 50+ in conditions of actual use was clinically assessed using erythema score. |
SPF 100+ sunscreen was significantly more effective against sunburn than SPF 50+ sunscreen in actual use conditions. |
Alvarez Roman, R et al. (2001Alvarez-Roman R, Barre G, Guy RH, Fessi H. Biodegradable polymer nanocapsules containing a sunscreen agent: preparation and photoprotection. Eur J Pharm Biopharm. 2001;52(2):191-5.) |
Sunscreen Formulation |
The ability of OMC-nano capsules to protect guinea pig skin against UVB radiation was evaluated. |
Sunscreen preparations OMC-NC-gel and OMC-gel significantly reduced UV-induced erythema compared to corresponding OMC-free formulations. |
Portilho and Leonardi (2019Portilho L, Leonardi GR. The real protection of facial sunscreens. Br J Dermatol. 2019;182(4):1050-1052.) |
SPF values, amount and type of product |
Actual amount, SPF and UVAPF of six different facial sunscreens were evaluated in vivo. |
The application amount of facial photo-protectors was lower than the recommended value of 2 mg/cm². The misleading protection claimed by some types of sunscreen is a risk to public health as the protection indicated on the label was not reached. |