During the last few years, research on toxicologically relevant properties of engineered nanoparticles has increased tremendously. A number of international research projects and additional activities are ongoing in the EU and the US, nourishing the expectation that more relevant technical and toxicological data will be published. Their widespread use allows for potential exposure to engineered nanoparticles during the whole lifecycle of a variety of products. When looking at possible exposure routes for manufactured Nanoparticles, inhalation, dermal and oral exposure are the most obvious, depending on the type of product in which Nanoparticles are used. This review shows that (1) Nanoparticles can deposit in the respiratory tract after inhalation. For a number of nanoparticles, oxidative stress-related inflammatory reactions have been observed. Tumour-related effects have only been observed in rats, and might be related to overload conditions. There are also a few reports that indicate uptake of nanoparticles in the brain via the olfactory epithelium. Nanoparticle translocation into the systemic circulation may occur after inhalation but conflicting evidence is present on the extent of translocation. These findings urge the need for additional studies to further elucidate these findings and to characterize the physiological impact. (2) There is currently little evidence from skin penetration studies that dermal applications of metal oxide nanoparticles used in sunscreens lead to systemic exposure. However, the question has been raised whether the usual testing with healthy, intact skin will be sufficient. (3) Uptake of nanoparticles in the gastrointestinal tract after oral uptake is a known phenomenon, of which use is intentionally made in the design of food and pharmacological components. Finally, this review indicates that only few specific nanoparticles have been investigated in a limited number of test systems and extrapolation of this data to other materials is not possible. Air pollution studies have generated indirect evidence for the role of combustion derived nanoparticles (CDNP) in driving adverse health effects in susceptible groups. Experimental studies with some bulk nanoparticles (carbon black, titanium dioxide, iron oxides) that have been used for decades suggest various adverse effects. However, engineered nanomaterials with new chemical and physical properties are being produced constantly and the toxicity of these is unknown. Therefore, despite the existing database on nanoparticles, no blanket statements about human toxicity can be given at this time. In addition, limited ecotoxicological data for nanomaterials precludes a systematic assessment of the impact of Nanoparticles on ecosystems.

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The potential risks of nanomaterials: a review carried out for ECETOC

Research efforts in the past two decades have resulted in thousands of potential application areas for nanoparticles - which materials have become industrially relevant? Where are sustainable applications of nanoparticles replacing traditional processing and materials? This tutorial review starts with a brief analysis on what makes nanoparticles attractive to chemical product design. The article highlights established industrial applications of nanoparticles and then moves to rapidly emerging applications in the chemical industry and discusses future research directions. Contributions from large companies, academia and high-tech start-ups are used to elucidate where academic nanoparticle research has revolutionized industry practice. A nanomaterial-focused analysis discusses new trends, such as particles with an identity, and the influence of modern instrument advances in the development of novel industrial products.

Industrial applications of nanoparticles

Exposure to the shortest wavelengths in sunlight, ultraviolet light, constitutes a deleterious ecological factor for many microorganisms. The use of secondary metabolites as sunscreens has emerged as an important photoprotective mechanism in certain groups of large-celled microorganisms, such as cyanobacteria, fungi and many protists. In this Review, we describe our current understanding of microbial 'sunscreen' compounds, including scytonemin, the mycosporines and the naphthalene-based melanins. Study of these sunscreens has led to the discovery of new classes of compounds, new metabolic pathways, a deeper understanding of microbial photobiology and the potential for dermatological or biomedical applications.

Microbial ultraviolet sunscreens

Solar light is the primary source of UV radiation for all living systems. UV photons can mediate damage through two different mechanisms, either by direct absorption of UV via cellular chromophores, resulting in excited states formation and subsequent chemical reaction, or by phosensitization mechanisms, where the UV light is absorbed by endogenous (or exogenous) sensitizers that are excited and their further reactions lead to formation of reactive oxygen species (ROS). These highly reactive species can interact with cellular macromolecules such as DNA, proteins, fatty acids and saccharides causing oxidative damage. Direct and indirect injuries result in a number of harmful effects such as disrupted cell metabolism, morphological and ultrastructural changes, attack on the regulation pathways and, alterations in the differentiation, proliferation and apoptosis of skin cells. Processes like these can lead to erythema, sunburn, inflammation, immunosuppression, photoaging, gene mutation, and development of cutaneous malignancies. The endogenous and exogenous mechanisms of skin photoprotection are discussed.

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Ultraviolet light induced alteration to the skin.

The novel organometallic−inorganic diblock copolymer, poly(ferrocenyldimethylsilane)-b-poly(dimethylsiloxane) (PFS-b-PDMS) (block ratio = 1.0:6.0) (Mn = 35 100 g/mol with a narrow molecular weight ...

Self-Assembly of a Novel Organometallic−Inorganic Block Copolymer in Solution and the Solid State: Nonintrusive Observation of Novel Wormlike Poly(ferrocenyldimethylsilane)-b-Poly(dimethylsiloxane) Micelles

The present invention provides, as a first aspect, a sun protection agent, which is especially suitable for use in pharmaceutical or cosmetic applications, comprising a) a micronised organic UV absor.ber; and one, or preferably both of; b) an oil-soluble, non-micronised UV absorber and/or an inorganic micropigment; and c) a polymeric hollow sphere additive and/or a polymer selected from xanthan and/or polyvinylpyrrolidone. The present invention also provides a sunscreen composition comprising A) 0.1 to 15%, preferably 0.5 to 10% by weight, based on the total composition of a sun screen agent according to the present invention; and B) a cosmetically acceptable carrier.

Uv-protection formulation

The use of sunscreen is embedded in a hierarchy of sun protection strategies consisting primarily of sun avoidance by seeking shade and covering up with clothing. Sunscreens are, however, important means of protection; thus, understanding how they work and knowing their limitations are crucial. This review explains the role of ultraviolet (UV) filters, emollients, emulsifier systems and other components in a sunscreen, as well as trends in formulations in Europe, North America, Latin America, and Asia Pacific. Furthermore, it explains how sunscreen performance in terms of sun protection factor, UVA protection, and other metrics can be simulated. The role of sensory characteristics in assessing and improving compliance is also discussed.In the final chapter, Facts and Fiction, five of the most common myths about sun exposure and sun protection by sunscreen are debunked.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/phpp.12112

Global state of sunscreens

Sunscreens are used to protect the human skin against harmful UV radiation. Today there is a trend toward higher sun protection factors (SPF) and better UVA protection. Methods for the assessment of SPF and UVA protection involve irradiation of the product, and the photostability properties of the sunscreen have an influence on its performance. Sunscreens often contain more than one UV filter. Thus it is important to understand the photostability properties of the complete system. The filter combinations used may exhibit destabilizing, stabilizing or inert interactions. For that reason, besides assessment of the properties of the single filters, photostabilities of binary filter combinations are investigated. Destabilization occurs when two UV absorbers undergo a chemical reaction after absorption of UV radiation. Stabilization may be achieved when the optical density of the system is very high, giving rise to a self-protection effect of the sunscreen film. Photounstable UV absorbers may be additionally stabilized by employing triplet quenchers. Being aware of these mechanisms and applying them for specific UV filter combinations can help in designing efficient sunscreens.

Photostability of UV absorber systems in sunscreens.

The adverse effects of terrestrial solar ultraviolet radiation (UVR) (~295–400 nm) on the skin are well documented, especially in the UVB region (~295–320 nm). The effects of very long-wave UVA (>380 nm) and visible radiation (≥400 nm) are much less known. Sunscreens have been beneficial in inhibiting a wide range of photodamage, however most formulations provide very little protection in the long wave UVA region (380–400 nm) and almost none from shortwave visible wavelengths (400–420 nm). We demonstrate photodamage in this region for a number of different endpoints including cell viability, DNA damage (delayed cyclobutane pyrimidine dimers), differential gene expression (for genes associated with inflammation, oxidative stress and photoageing) and induction of oxidizing species in vitro in HaCaT keratinocytes and in vivo in human volunteers. This work has implications for phototherapy and photoprotection.

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The UV/Visible Radiation Boundary Region (385-405 nm) Damages Skin Cells and Induces "dark" Cyclobutane Pyrimidine Dimers in Human Skin in vivo.

The magnitude and quality of UV protection provided by topical sun products have improved considerably over the past three decades. As our knowledge and understanding of sun protection requirements increases, product and testing technologies advance and new sunscreen molecules and technologies become available. The biannual London Sun Protection Conference has monitored this development over the last two decades. The 2009 edition of the conference (June 3 and 4) was entitled “Perfection of Protection”. This paper, based on our talk given at the conference, tries to answer the question about the “ideal sunscreen” and explores four key requirements of good UV protection regarding where we stand on a ranking scale between poor and perfect, and what still needs to be done. Technology is leading with a rating of 80%, Assessment/measurement follows at 70%, Norms/standards around 50% and Compliance ranks only around 30% between poor and perfect. UV filters are the heart of the product technology. Besides UVB-filters, plenty of UV filters for UVA II and UVA I protection are now available in most parts of the world, except the USA. Although the Sun Protection Factor is well established and various methods have been developed for assessment of UVA protection, the performance measurement of sunscreens is still far from perfect. On the other hand, the high bar for achieving the highest UVA protection in the various classification systems released recently in Europe (2006) and the USA (2007) already helped to increase the protection considerably. The greatest problem however, remains poor compliance. Providing cosmetically pleasing formulations that people like to wear and communicating what sunscreens are and how they work are key elements in improving UV protection.

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Bernd Herzog

Papers

Uv-protection formulation

Global state of sunscreens

Photostability of UV absorber systems in sunscreens.

The UV/Visible Radiation Boundary Region (385-405 nm) Damages Skin Cells and Induces "dark" Cyclobutane Pyrimidine Dimers in Human Skin in vivo.

The long way towards the ideal sunscreen--where we stand and what still needs to be done.