In the ′80s, microplastics replaced these natural ingredients in many products, both in formulations and in the packaging of cosmetic products, due to their versatility. They were used for various functions, including viscosity regulation, film forming, opacifying, bulking, and exfoliating. [\[7\]](https://pmc.ncbi.nlm.nih.gov/articles/PMC11587687/?utm_source=chatgpt.com#cssc202401065-bib-0007) For example, polyethylene glycols (PEGs) were used as humectants and moisturizers, [\[8\]](https://pmc.ncbi.nlm.nih.gov/articles/PMC11587687/?utm_source=chatgpt.com#cssc202401065-bib-0008) polyacrylates as film‐forming agents, [\[9\]](https://pmc.ncbi.nlm.nih.gov/articles/PMC11587687/?utm_source=chatgpt.com#cssc202401065-bib-0009) and polyamides to lend substantivity to hair and skin. [\[10\]](https://pmc.ncbi.nlm.nih.gov/articles/PMC11587687/?utm_source=chatgpt.com#cssc202401065-bib-0010) However, the first bans regarding marine litter began with the increase in plastic pollution. Countries and organizations have become more aware of the negative impact of plastic and microplastics on the environment. In 2015, the “Microbead‐Free Waters Act” was the first ban on microbeads. Subsequently, prohibitions or restrictions on microbeads or microplastics in cosmetic and personal care products were implemented. ## 2\. Microplastics in Cosmetic Formulations – A Real Threat for the Environment and Human Health In the last decade, microplastics (MPs) have emerged as a significant environmental and health problem worldwide. MPs are defined as small plastic particles ranging in size from 0.1 to 5 mm. [\[15\]](https://pmc.ncbi.nlm.nih.gov/articles/PMC11587687/?utm_source=chatgpt.com#cssc202401065-bib-0015) Microplastics derive from a variety of sources, including discarded plastic, the textile, and cosmetic industries. The generation of plastics and microplastics associated with the cosmetic industry is currently one of the most serious environmental issues, reinforced also by the increased number of consumers and the high demand in this sector. [\[16\]](https://pmc.ncbi.nlm.nih.gov/articles/PMC11587687/?utm_source=chatgpt.com#cssc202401065-bib-0016) Microplastics can be found in primary form, as constituents of cosmetic formulations, such as exfoliating agents, or as secondary plastics, derived from cosmetic packaging. Among the primary sources, personal care products, including cleansing products, makeup cosmetics, shower gel, facial cleanser, hand sanitizer, soap, toothpaste, sunscreen and shampoo represent significant sources of microplastics in the environment. [\[17\]](https://pmc.ncbi.nlm.nih.gov/articles/PMC11587687/?utm_source=chatgpt.com#cssc202401065-bib-0017) These microplastics are specially designed and optimized in a spherical shape, to reduce skin scratches or disruption of the natural skin growth process. The use of microplastics in various personal care products has expanded beyond their initial scrubbing effects to include important functions such as binders, bulking agents, emulsifiers, film formers, viscosity regulators, opacifying agents, glitters, skin conditioning, tooth polishing in oral care, gellants in denture adhesives, moisturizers, sun filters, and stabilizers. [\[18\]](https://pmc.ncbi.nlm.nih.gov/articles/PMC11587687/?utm_source=chatgpt.com#cssc202401065-bib-0018) The plastic ingredients used for the scrubbing function are commonly referred to as plastic microbeads. Microbeads made of polyethylene are the most common application, although polyurethane, polypropylene, polyethylene terephthalate, polymethyl methacrylate and nylon are used. [\[19\]](https://pmc.ncbi.nlm.nih.gov/articles/PMC11587687/?utm_source=chatgpt.com#cssc202401065-bib-0019) The advantages of using plastic microspheres for washing and exfoliation include their soft peeling effect, associated with good skin tolerance. They have a broad range of positive properties, they are chemically inert substances, odourless, non‐sensitizing and non‐irritating. [\[20\]](https://pmc.ncbi.nlm.nih.gov/articles/PMC11587687/?utm_source=chatgpt.com#cssc202401065-bib-0020) ## 4\. Major Microplastics in Cosmetic Formulations As previously mentioned, cosmetic powders are among the most relevant raw materials for the achievement of final formulations with specific properties distinguishable by the end consumer. The small size, shape, and chemistry of these materials are the characteristics that influence most of their properties. Microplastics have led to a drastic change in the performance of formulations, improving sensory attributes, albeit at the expense of sustainability. Table 2 summarizes the principal microplastics exploited in cosmetic products, showing their chemical formula and main effects in formulations.[[7]](https://pmc.ncbi.nlm.nih.gov/articles/PMC11587687/?utm_source=chatgpt.com#cssc202401065-bib-0007), [[80]](https://pmc.ncbi.nlm.nih.gov/articles/PMC11587687/?utm_source=chatgpt.com#cssc202401065-bib-0080) ### Table 2. Main formulation effects of principal microplastic in cosmetic products. | Microplastic | Formulation effects | | --- | --- | | !graphic file with name CSSC-17-e202401065-g011.jpg | Abrasive, film‐forming and viscosity‐regulating | | Polyethylene (PE) | | | !graphic file with name CSSC-17-e202401065-g016.jpg | Exfoliating and viscosity‐regulating | | Polypropylene (PP) | | | !graphic file with name CSSC-17-e202401065-g018.jpg | Brightness/mattifying regulators, carrier of actives, film‐forming and texturizing | | Polymethyl methacrylate (PMMA) | | | !graphic file with name CSSC-17-e202401065-g008.jpg | Binding, bulking, hair and skin conditioning, long‐lasting, moisture‐resistance and texturizing | | Polytetrafluoroethylene (PTFE) | | | !graphic file with name CSSC-17-e202401065-g003.jpg | Absorbent, film‐forming, mattifying and texturizing | | Polyethylene Terephthalate (PET) | | | !graphic file with name CSSC-17-e202401065-g007.jpg | Bulking, conditioning, opacifying, texturizing and viscosity controlling | | Polyamides (Nylon) | | | !graphic file with name CSSC-17-e202401065-g006.jpg | Binding agent, film‐forming, hair fixing and conditioning and viscosity controlling | | Polyurethane (PU) | | | !graphic file with name CSSC-17-e202401065-g010.jpg | Absorbent, binding agent, emollient, emulsifying filming, hair and skin conditioning, opacifying and viscosity controlling | | Polyacrylates | | | !graphic file with name CSSC-17-e202401065-g014.jpg | Emulsifying, hair and skin conditioning, humectant and solvent | | Polyethylene glycols (PEGs) | Polypropylene glycols (PPGs) | | | !graphic file with name CSSC-17-e202401065-g002.jpg | Film‐forming, hair and skin conditioning, opacifying and texturing | | Polymethylsilsesquioxane | | Open in a new tab - Polyethylene (PE) is one of the most widely used synthetic polymers and is easy to produce. PE consists of repetitive units of ethylene groups, which give the polymer flexibility and strength. Indeed, the relative polymerization can yield branched or linear structures, leading to the production of high‐density polyethene (HDPE), low‐density polyethene (LDPE), and linear low‐density polyethene (LLDPE), each contributing to different performances. In cosmetics, PE is a film‐forming and viscosity‐regulating agent. Specifically, PE microparticles were used in formulations for facial and body scrubs as an exfoliating agent. But since 2018, they have been banned from cosmetic products due to their impact on marine ecosystems. [\[80\]](https://pmc.ncbi.nlm.nih.gov/articles/PMC11587687/?utm_source=chatgpt.com#cssc202401065-bib-0080) - Polypropylene (PP) is a thermoplastic homopolymer produced from 1‐propene, a gas derived from petroleum and natural gas. PP is known for its lightweight nature and resistance to corrosion, wear, and moisture. This polymer is used as a viscosity‐controlling agent in foundations and nail polishes – also, employed as an exfoliant in some formulations. [\[80\]](https://pmc.ncbi.nlm.nih.gov/articles/PMC11587687/?utm_source=chatgpt.com#cssc202401065-bib-0080) - Poly(methyl methacrylate) or PMMA is a transparent thermoplastic polymer obtained from methyl methacrylate. In cosmetics, this polymer is used in nail polish, lip gloss, and mascara due to its film‐forming aptitude. PMMA microparticles are also used as absorbent agents for transporting active ingredients and as brightness/mattifying regulators, reducing imperfections caused by ageing. Additionally, they modulate the texture of formulations due to their small size.\ [7, 80, 82\] - Polyacrylates are a family of synthetic polymers made up of acrylate monomers, which are used as film‐forming, antistatic, binding, hair fixative, and suspending agents.\ [7, 82\] There are various acrylate copolymers such as styrene‐acrylates copolymers, used as colour opacification and filming agents; and ethylene/acrylate copolymers, used as a binding, emulsion stabilizing, thickening, film‐forming, and opacifying agent.