Organic UV filters are currently considered to be emerging contaminants that could pose risks to human health (Ao et al., 2018). They have become ubiquitous as they are used both in the manufacturing processes of different materials such as plastics to increase their resistance to degradation phenomena (Rani et al., 2017; Santana et al., 2021) and in sun protection products. Numerous studies show that it is possible to find measurable quantities in various biological fluids such as urine, seminal fluid, breast milk or serum (Carpiento et al., 2010; Zang et al., 2013; Ao et al., 2018; Li et al., 2019: Frederiksen et al., 2021, Grgić et al., 2021). UV filters are also found in house dust and in vegetable crops, especially tomatoes (Ramos et al., 2020). The most serious findings concern surface waters (Wu et al., Mitchelmore et al., 2019, Wu, O'Malley) and the implication of UV filters in coral bleaching (Schneider et al., 2019; Fivenson et al., 2020; Watkins et al., 2021). The most studied UV filters are benzophenones, octyl methoxycinnamate, octocrylene, salicylates, homosalate and octyl salicylate.
It is commonly accepted that the UV filters found in the environment arise from the use of sun protection creams in leisure activities (Yaran et al., 2021). Our study shows that the presence of UV filters is in fact much broader and not limited to sun protection products. The only cosmetic products that are virtually free of UV filters are 'hygiene' products and some 'personal care' products (hand creams). The only shampoos we found formulated with UV filters are special shampoos intended for dyed hair (Loke and Jachowicz 2005). As for the two shower gels in our sample, one contains benzophenone-4 and the other a mixture of octyl methoxycinnamate, butyl methoxydibenzoylmethane and octyl salicylate. The role of these filters is to stabilise, in the one case, two azo dyes and, in the other, guaiazulene, which is known for its photodegradation products (Fiori et al., 2008). It is interesting to note that lip balms and lipsticks, for which ingestion takes place during the day after application (Loretz et al., 2005), and hand creams, likely to be transferred to the mouth and to come into contact with food, rarely or never contain UV filters.
The other categories of cosmetic products studied are very different. In recent years, many moisturising and anti-ageing products, as well as make-up products, have been formulated containing UV filters (Seité and Fourtanier 2008; Séhédic et al., 2009; Randhawa et al., 2016). An SPF value may or may not be given on the packaging. In the latter case, the user is not informed of the presence of filters in the products they are using. Moreover, the way this type of product is used differs from using a sun protection product. For a day cream or foundation, the quantity applied is less than 2 mg/cm² and there is no reapplication every 2 hours as with a sun protection product.
In the interests of public health, it would seem worthwhile to limit the use of UV filters to the formulation of sun protection products alone. If we consider the four filters found in the products in our sample, namely butyl methoxydibenzoylmethane, octyl methoxycinnamate, octocrylene and octyl salicylate, we can see that many undesirable effects can be attributed to them. With regard to butyl methoxydibenzoylmethane, cases of contact allergies were published as early as the end of the 1980s (Alomar 1989; Parry et al., 1995). Estrogenic, anti-androgenic, anti-progestenic and anti-thyroid activities have been demonstrated for octyl methoxycinnamate in rodents, but the mechanisms by which this filter could induce these activities have not yet been elucidated (Lorigo et al., 2018). A study by Janjua et al. suggested a difference in the pharmacokinetics of octyl methoxycinnamate between males and females, and a possible chronic effect after daily exposure to this filter. Contact photoallergy to octocrylene was reported in 4% of 1031 adult patients who underwent patch testing for photoallergic contact dermatitis (EMCPPTSA 2012), but its occurrence appears to be strongly related to prior sensitisation to topical ketoprofen (de Groot and Roberts 2014; Loh and Cohen 2016).
From an environmental point of view, numerous studies highlight that octocrylene, octyl methoxycinnamate and octyl salicylate can be identified and measured in almost all water sources worldwide and emphasise that these filters are difficult to remove by standard wastewater treatment techniques. These same filters have been identified in various species of fish, so it may also have implications for the food chain (Schneider and Lim 2019). In this context, in 2018 Hawaii became the first state in the US to pass legislation banning the sale of sunscreen products containing UV filters benzophenone-3 and octyl methoxycinnamate, found in nearly 75% of sunscreen products on the US market, due to environmental concerns about coral reef bleaching (Narla and Lim 2020). It would undoubtedly be more relevant to stop using UV filters in some cosmetic products that are used daily, especially since known alternatives already exist, such as antioxidants for anti-ageing products (Puizina 2008), or the use of adapted packaging when it is a question of protecting the formula itself from potential degradations by UV (Alves et al., 2022).