Comparative toxicity of exfoliating products containing microplastics and alternative particles from Nepal

Plastic pollution is a global problem, with numerous studies focusing on the effects of\nmicroplastics (1- 1000 μm). Cosmetic products like exfoliators have been identified as an\nimportant source of primary microplastics. After abundant reports on the hazards caused by\nmicroplastics, subsequent banning or voluntary removal from cosmetics is going on, causing them\nto be replaced by the non- plastic alternative particles. However, the replacement by so- called\nnatural particles seems to be just a marketing strategy and lacks enough research verifying if they\nare actually safer than microplastics.\nThe present study investigated the chemical and particle toxicity of eight exfoliators containing\nmicroplastics and alternative particles used in Nepal. This was addressed by means of two in vitro\nand one in vivo assay. The bioluminescent bacteria Photobacterium leiognathi was exposed to 2-\n300 μg product and particles extracts and luminescence inhibition was measured. The recombinant\nyeast strain Saccharomyces cerevisiae containing a gene coding for human estrogen receptor alpha\nwas exposed to 500 μg product and particle extract and estrogenicity was measured. Daphnia\nmagna neonates (< 24 h old) were exposed to 2- 45 μm microplastic and alternative particles at\n0.8 – 500 mg/L for 21-days and survival and reproduction was examined.\nThe chemical toxicity from products was higher than the particle toxicity for bacteria with no\nsignificant differences among microplastic and alternative particles. Most of the ingredients in the\nproducts were unknown and thus the observed toxicity could not be attributed to any specific\nchemical. In the YES, only one sample that contained parabens was estrogenic in the product\nextract but not the particle extract. Both types of particles did not show any adsorbance. From in\nvivo assay, the alternative particles had stronger effects in the lethality of D. magna whereas\nmicroplastics caused higher reproductive effects.\nBased on the findings of this study, alternative particles cannot be considered safer than\nmicroplastics and with regards to products from Nepal, chemicals used in the cosmetics seem to\nbe of more concern. Since this study analyzed only exfoliators, study on effects of other classes of\ncosmetics using environmentally relevant concentrations and other bioassays needs to be done in\nthe future.