Microplastics have received great attention in the last years all over the world. This increasing interest is mainly due to their potential harmful effects on the biota and humans through the food chain or from contact with contaminated products (2, 3). Furthermore, the negative interactions are also extended to all contaminants (chemical and biological) of which microplastics can be carriers (4, 5, 6), so microplastics could be also infections or toxic chemicals vectors. It was recently estimated that 8 M tons per year of plastics are entering the marine environment, due to accidentally or deliberately dumped litter (7). The awfulness of this situation is due to the non-biodegradability of plastics items that are accumulating in the environment as fragments of decreasing size (microplastics) (7).

Microplastics show a relevant heterogeneity, in terms of chemical classification (type of polymer), size and shape, deriving from several kind of thermal and/or mechanical degradation from macroscopic plastic items (secondary microplastics), furthermore microplastics are contained as intentionally added microparticles for specific functional purposes (primary microplastics) in several kinds of products (4). According to ECHA (2019), microplastics are defined as: "particles containing solid polymers, to which additives or other substances may have been added, with dimensions between 1 nm ≤ x ≤ 5 mm (particles) or fibres with a length between 3 nm ≤ x ≤ 15 mm, with a length/diameter ratio >3”. Biodegradable polymers, polymers with water solubility > 2g/l and natural polymers (not modified except by hydrolysis) are excluded from this definition (8). An extensive definition and description of microplastics is necessary to fully understand their distribution patterns in the environment and also to allow the development of reliable and robust analytical protocols (9), therefore an appropriate description of all the characteristics of microplastics, such as size, chemical nature, colour and shape, is very relevant and useful for understanding the origin and way of distribution in the environment of these contaminants (10).

As previously mentioned, primary microplastics are those that are intentionally added to other products with a specific functional activity, for example exfoliating particles in scrubs or in detergents, opacifiers in cosmetics in cosmetics (4, 11) or glitter in make-up and nail products. Many countries are addressing the primary microplastics problem by introducing national laws to ban or restrict the intentional addition of functional microplastics into various types of products (12), see some examples in the table below (Table 1):

Table 1. (12) National laws to ban or restrict the intentional addition of functional microplastics.

Recently (October 2023) has been published the European Commission Regulation that insert microplastics in the XVII Allegate of REACH (Commission Regulation (EU) 2023/2055) ( ). In this context, great attention is focused on cosmetics and detergents samples, for which the ban regarding to the intentionally added microbeads is already in force and within a few years will be ban also the intentional addition of microparticles in general, firstly in rinse-off products and then also in the live-on (Commission Regulation (EU) 2023/2055)(13).

Furthermore European Commission has published a Proposal for a Regulation of the European Parliament and of the Council on preventing plastic pellet losses to reduce microplastics pollution (14).

Studies of major depressive disorder have been correlated with reduced Lactobacillus and Bifidobacteria and symptom severity has been correlated to changes in Firmicutes, Actinobacteria, and Bacteriodes. Gut microbiota that contain more butyrate producers have been correlated with improved quality of life (1).

A study in healthy women providing probiotic yogurt for four weeks showed an improvement in emotional responses as measured by brain scans (2). A subsequent study by Mohammadi et al. (3) investigated the impacts of probiotic yogurt and probiotic capsules over 6 weeks and found a significant improvement in depression-anxiety-stress scores in subjects taking the specific strains of probiotics contained in the yogurt or capsules. Other studies with probiotics have indicated improvements in depression scores, anxiety, postpartum depression and mood rating in an elderly population (4-7).

Other studies have indicated a benefit of probiotic supplementation in alleviating symptoms of stress. In particular, researchers have looked at stress in students as they prepared for exams, while also evaluating other health indicators such as flu and cold symptoms (1). In healthy people, there is an indication that probiotic supplementation may help to maintain memory function under conditions of acute stress.

In light of what has been described, it is clear that the problem of microplastics is now increasingly relevant and subject to great attention. In addition to finding new technological solutions to eliminate the use of microparticles, it is important to have analytical tools capable of identifying and quantifying them, not only for regulatory purposes, but also to evaluate the new technological solutions.

In this article we offered an informative point on the topic, underlining that an analytical method has been developed in the Innovhub laboratories which allows the possible content of microplastics in cosmetic or detergent samples to be characterized and quantified in concentrations up to four times lower than the limit imposed from the European Regulation.

Alessia Aprea has a PhD in Chemistry. She worked as researcher at University of Calabria and University of Insubria. From 2016 she works at Innovhub-SSI, where she is Project Manager of Microplastics Institutional Project, and FTIR specialist.

Alessia Aprea

Innovhub-SSI, Milano, Italy