Susncreens and FFA: What do we really know so far?

Sunscreens and Frontal Fibrosing Alopecia (FFA): What do we really know so far?

The 2016 publication by Dr Messenger’s group that the incidence of sunscreen use in FFA was greater than that of patient without FFA has lead to a marked increase in research in this area. Some studies have suggested that susncreens and facial moisturizers are somehow related to the disease. Other studies have suggested they are not. 

The interest in facial products as a culptrit in FFA is very much a part of active study. Allergy testing (Patch testing) in patients with FFA shows a high prevalence of sensitization to cosmetic ingredients but not to a specific culprit. This suggests that patient with FFA could potentially be using more cosmetic products than the general population. 

The 2019 Cranwell and Sinclair Study

Cranwell and Sinclair published an intriguing study in 2019 of a patient who reported improvement in her FFA after stopping sunscreen use. Many potential explanations can be given - and we do not know really which is correct.

At the preset time, titanium dioxide sits on the top of the list as ingredients that may be causing problems in FFA. The data is by no means crystal clear and more studies are needed. It is important to understand that titanium dioxide is often added to susncreens and facial products because it has very desirable properties such as being a thickening agent, being a a pigment and being a sunscreen.  

 What you may not be aware is that titanium dioxide has significant ‘photocatalytic activity’ when it is exposed to UV irradiation. It’s certainly possible, but not yet fully proven that when ultraviolet radiation hits the skin of someone wearing a titanium dioxide containing sunscreen that there is some sort of tissue damage. Whether patients with FFA are more predisposed to tissue damage compared to someone who does not have FFA is really not clear. Most of us don’t come home after a period of being out in the sun with concerns that we’ve had tissue damage from wearing our sunscreens. Clearly we’re in the earliest stages of understanding what this all means. In most modern cosmetics, these zinc and titanium dioxide particles are actually coated ot make them less reactive. The cosmetics industry is very much aware of these properties of titanium and zinc.

Nowadays, many cosmetic products consist of very tiny particles (called nanoparticles) of titanium and zinc dioxide. They are in fact so small some are only 40 nm in size. It has been proposed that with such as small size it is possible for these product to enter skin and hair cells.

Recent studies have shown that our hairs do have titanium dioxide in them. A recent study by Thompson and colleagues tested hair shafts from 16 women with biopsy-proven FFA using scanning electron microscopy with energy-dispesive X-ray spectroscopy (SEM/EDX). Each of the study subjects had a hair plucked form the hairline and the content was analyzed. Interestingly, titanium was identified in all 16 hair shafts. But three control patients who did NOT have FFA were also found to have hair shafts continaing titatium dioxicde. This data does not prove that titanium is involved and shows that the relationship is far more complex. 

Why would sunscreens be involved?

It’s not clear how sunscreens would be involved in FFA. One possibility that has been raised is that this tiny titaniusm dioxide penetrates down to the isthmus (upper part of the hair follicle) and then trigger a lichenoid reaction. Another possibility is that these sunscreens block out the anti-inflammatory benefits effects of sunlight (Yes, sunlight can be anti-inflammatory).

REFERENCE

1) Aldoori N, Dobson K, Holden CR et al. Frontal fibrosing alopecia: possible association with leave-on facial skin care products and sun- screens; a questionnaire study. Br J Dermatol 2016; 175:762–7. 

2) Cranwell WC and Sinclair R. Frontal fibrosing alopecia: regrowth fol- lowing cessation of sunscreen on the forehead. Australas J Dermatol 2019; 60:60–1. 

3) Debroy Kidambi A, Dobson K, Holmes S et al. Frontal fibrosing alopecia in men: an association with facial moisturizers and sun- screens. Br J Dermatol 2017; 177:260–1. 

4) Moreno-Arrones OM, Saceda-Corralo D, Rodrigues-Barata AR et al. Risk factors associated with frontal fibrosing alopecia: a multicentre case–control study. Clin Exp Dermatol 2019; https://doi.org/10. 1111/ced.13785.