Micro(nano)plastics: A threat to human health? Messika Revel, Amélie Châtel and Catherine Mouneyrac Abstract The presence and effects of plastic debris is increasingly investigated. The majority of studies focuses on microplastics (MPs), but few reports suggest that plastic fragments in the <100 nm size range, referred to as nanoplastics (NPs), may also be formed in the aquatic environment and further to humans. This paper provides a review on routes of human exposure and potential effects of MPs and NPs to human health. MPs/NPs could potentially induce: physical damages through particles itself, and biological stress through MPs/NPs alone or leaching of additives (inorganic and organic). Future research should evaluate trophic transfer of MPs/NPs with their associated chemicals through the marine food web. Addresses Laboratoire Mer, Molécules, Santé (MMS, EA 2160), Université Cath- olique de l’Ouest, Angers F-49000 France Corresponding author: Mouneyrac, Catherine (catherine.mouneyrac@ uco.fr) Current Opinion in Environmental Science & Health 2018, 1:17 – 23 This review comes from a themed issue on Micro and Nanoplastics Edited by Dr. Teresa Rocha-Santos For a complete overview see the Issue and the Editorial https://doi.org/10.1016/j.coesh.2017.10.003 2468-5844/© 2017 Elsevier B.V. All rights reserved. Keywords Microplastics, Nanoplastics, Additives, Food chain, Ingestion. Introduction Today, plastic products can be found in several fields such as health, construction, and textiles. Global pro- duction of plastic has increased significantly, from 1.7 million tons in the 1950s to over 322 million tons in 2016 [1]. Plastic is made of synthetic organic polymers; the majority being polyethylene (PE, high and low density), polystyrene (PS), polypropylene (PP), polyvinyl chlo- ride (PVC), polyurethane (PUR) and polyethylene terephthalate (PET). In addition, additives may be added to plastics to improve their characteristics such as strength, coloration or flame retardant properties. To understand MPs impacts, it is crucial to study their fate and their potential effects and their additives (e.g., Bisphenol A, phthalates, polybrominated diphenyl ethers, and metals or metalloids) which for some of them can be classified as carcinogenic or endocrine disrupting. In recent years, the presence of plastic debris called microplastics (MPs), define as fragments smaller than 5 mm has been reported in diverse aquatic ecosystems [2e4]. Though the presence of nanoplastics (NPs) is difficult to ascertain, due to the inherent technical dif- ficulties, recent studies shown that NPs are also being introduced in important quantities into the natural environment [5e7]. Since plastic items undergo continuous fragmentation, it is likely that MPs could become NPs and some studies suggested that the average size of sampled plastic particles seems to be decreasing [8]. Concerns about toxic impacts of MPs and eventually NPs for human health have been raised, but in- vestigations are still sparse [9]. To compare the number of studies focusing on MPs/NPs effects towards human health or the environment, the number of articles found in Web of science using different keywords (“Micro- plastics human health”, “Microplastics environment”, Nanoplastics human health”, “nanoplastics environ- ment”) was summarized in Fig. 1. Clearly, a much higher number of studies are available on MPs in the environ- ment compared to human exposure (articles published from 2006 to 2017). The aim of this review is to present an overview of the different exposure routes for humans and potential effects of MPs and NPs, including their additives, from commercial items and discarded debris through the food chain. Since to date reports on human health is very sparse, we used previous work from environmental studies on MPs, and engineered nano- particles for NPs to try to predict potential translocation and eventually effect on humans. Routes of human exposure Oral Drinking water The presence of MPs in soil and freshwater ecosystems has been measured, including in locations used as sources of drinking water representing a way of MPs human exposure, particularly if plastic particles can pass through the filtration systems of wastewater treatment [10,11]. It has been estimated that daily discharges could ranged from w50,000 up to nearly 15 million particles [12]. Food chain: marine products Aquatic organisms may be contaminated by MPs (and NPs), either through loaded water or the feeding from other organisms and may serve as a source of human exposure. Concerning bivalves, humans consume the whole soft tissues which may contain microscopic plastic Available online at www.sciencedirect.com ScienceDirect Current Opinion in Environmental Science & Health www.sciencedirect.com Current Opinion in Environmental Science & Health 2018, 1:17 – 23