# Blyproducts as a Sustainable Source of Cosmetic Ingredients
## 1 Introduction  
Consumer awareness of environmental impact and sustainability has significantly influenced the market, leading to a noticeable change in the consumption of green products, particularly within the Asian-Pacific region [1]. This shift is driven by various external factors that contribute to changing consumer behavior, such as heightened awareness of green consumerism, evolving marketing trends, and cultural and social influences, such as normative beliefs and the roles of social groups. In addition, personal factors, including age, life stage, wealth, and even religious beliefs, also play a pivotal role in determining the extent of a consumer's commitment to environmentally friendly products [1, 2].  
For the cosmetic industry, the rising consumer demand for sustainability and green solutions created two challenges to be solved. The first is the incorporation of natural compounds in products, thus responding to consumer demands for greener and more natural products, and the adjustment required during the production process for this to occur. The second, and the one which represents a more radical shift for the cosmetics industry, is the need to find new and sustainable sources of bioactive natural compounds. With this need and companies pushing knowledge boundaries in the search for new and sustainable sources of compounds, one solution emerged: byproducts [3, 4].  
Byproducts are, by definition, incidental or secondary products of the manufacture process and were once considered as wastes or residues without any added value, but nowadays they are considered secondary sources of bioactive and technological relevant compounds. In the context of sustainability, byproducts have gained significant importance as they are now key contributors to various industries, including cosmetics, due to their sustainability, green credentials, and effective role in diminishing primary industries' footprint and wastes [5, 6]. The increased presence and utilization of byproducts-derived compounds is seen as a key contributor to the future sustainable development of industries, especially in terms of reducing their environmental impact, with its relevance being formalized on a global level by the UN with its 2030 Agent for Sustainable Development, particularly in the responsible consumption and production goals [6]. For the cosmetic industry in particular,the use of byproducts-derived compounds will be of great importance and benefit, as their introduction will contribute substantially to the industry's sustainability drive and goals. Through the minimization of the waste generated and the reduction in the industries' reliance on new raw materials, the overall environmental impact of the cosmetics sector will be lessened, and byproducts will become a cornerstone in the development of future sustainable cosmetics [7]. Considering the inherent complexity of byproducts-derived compounds' incorporation into cosmetics, this review aims to provide an encompassing visualization of byproducts of animal and plant sources from which ingredients can be extracted and which can be used or are already in use in cosmetics, advantages of their incorporation, and the various additional considerations, such as applicable legislation and consumer awareness, that have to be taken into account on this topic.