Adsorption of progesterone onto microplastics and its desorption in fish following digestion with simulated gastric and intestinal fluids

The sorption of hydrophobic organic compounds onto microplastics is relatively well reported in the literature, while their desorption remains poorly investigated, especially in biological fluids. The present study investigated the sorption and desorption of progesterone on polyethylene (PE), polypropylene (PP), and polystyrene (PS) microplastics. A sorption efficiency of 357.1 mg g-1 was found for PE and PS, and 322.6mg g-1 for PP. Sorption experiments indicated that adsorption would certainly happen via surface sorption and a potentially pore-filling mechanism. The desorption was carried out in Simulated Gastric Fluid (SGF) and Simulated Intestinal Fluid (SIF). It has been found that the desorption was higher in SIF as compared to SGF, due to micelle formation in SIF promoting the pollutant solubilization. This study indicates that the ingestion of microplastics could be considered as an additional route of exposure to pollutants and therefore emphasizes pollutant bioavailability for aquatic organisms.

Adsorption of progesterone onto microplastics and its desorption in simulated gastric and intestinal fluids

Florian Frédéric Vincent Breider, Dominique Grandjean, Yang Liu, Thibault Béranger Masset, Cécilia Laetitia Carla Siri

The sorption of Hydrophobic Organic Compound (HOC) onto microplastics is relatively well reported in the literature, while their desorption remains poorly investigated, and especially in biological ﬂuids. The present study investigated the sorption and desorption of progesterone on polyethylene (PE), polypropylene (PP) and polystyrene (PS) microplastics. The sorption experiments showed that the equilibrium was reached in a few hours for all plastics. A sorption efﬁciency of 357.1 µg/g was found for PE and PS and 322.6µg/g for PP. Sorption experiments indicated that adsorption would happen certainly via surface sorption and potentially pore-ﬁlling mechanism. The desorption was carried out in Simulated Gastric Fluid (SGF) and Simulated Intestinal Fluid (SIF), whose formulations were more complex than similar models reported so far. It has been found that the desorption was higher in SIF compared to SGF, surely due to micelle formation in SIF promoting the pollutant solubilization. Sorption of pepsin onto microplastics has also been revealed, suggesting a competition between pollutant and pepsin for sorption sites and a potent reduction of pollutant solubilization. This study indicates that microplastics ingestion could be considered as as additional route of exposure of pollutants and therefore emphasizes pollutants bioavailability for aquatic organisms.

2021

Bioavailability of steroid hormones sorbed on microplastics for aquatic organisms through biological fluids

Florian Frédéric Vincent Breider, Yang Liu, Thibault Béranger Masset, Cécilia Laetitia Carla Siri

Many studies have reported that hydrophobic organic contaminants have the ability to sorb on microplastics in aquatic ecosystem via different mechanisms of sorption. However, a lack of studies investigating desorption of such contaminants in organism fluids has been disclaimed. The bioavailability of potential risk-compounds for aquatic organisms has to be assessed. It has been largely reported that adsorption onto microplastics is directly linked with hydrophobicity property of contaminants; the more hydrophobic the pollutant, the higher the sorption capacity. However, it is expected that the least hydrophobic molecules desorb more easily from microplastics. In our study, steroid hormones with different hydrophobicities, namely progesterone and testosterone, are used and their respective desorption from different types of microplastics is investigated in gastric and gut fluids. The idea is to discern if the ingestion of microplastics by organisms might promote desorption of potential sorbed micropollutants and therefore their bioavailability for such species. By using more complex composition of gastric and intestinal fluids separately and then sequentially, the purposes are to reproduce realistic digestive conditions and furthermore determine the organ which is the most prompt to enhance bioavailability of pollutants. Our results show that a higher desorption efficiency (58.6-73.0%, depending on plastic types) is reached in intestinal fluid than in freshwater (31.1-53.6%) or in gastric fluid (18.7-43.9%). Bile salts in intestinal fluid form micelles able to promote the solubilization of pollutants. Adsorption of pepsin onto microplastics has also been revealed, suggesting a competition between pollutant and pepsin for sorption sites and a potent reduction of pollutant solubilization. Our results indicate that progesterone daily intake via microplastics exposure is equal to 16.0μg/kg/day upon intestinal digestion, which represents about 13% of daily intake via water exposure. This observation suggests that ingestion is an additional route of exposure of pollutants and therefore emphasizes pollutants bioavailability for aquatic organisms.

2020

Bioaccessibility of Organic Compounds Associated with Tire Particles Using a Fish In Vitro Digestive Model: Solubilization Kinetics and Effects of Food Coingestion

Florian Frédéric Vincent Breider, Dominique Grandjean, Luke Christopher Harris, Thibault Béranger Masset, Kristin Schirmer

Tire and road wear particles (TRWP) account for an important part of the polymer particles released into the environment. There are scientific knowledge gaps as to the potential bioaccessibility of chemicals associated with TRWP to aquatic organisms. This study investigated the solubilization and bioaccessibility of seven of the most widely used tire-associated organic chemicals and four of their degradation products from cryogenically milled tire tread (CMTT) into fish digestive fluids using an in vitro digestion model based on Oncorhynchus mykiss. Our results showed that 0.06–44.1% of the selected compounds were rapidly solubilized into simulated gastric and intestinal fluids within a typical gut transit time for fish (3 h in gastric and 24 h in intestinal fluids). The environmentally realistic scenario of coingestion of CMTT and fish prey was explored using ground Gammarus pulex. Coingestion caused compound-specific changes in solubilization, either increasing or decreasing the compounds’ bioaccessibility in simulated gut fluids compared to CMTT alone. Our results emphasize that tire-associated compounds become accessible in a digestive milieu and should be studied further with respect to their bioaccumulation and toxicological effects upon passage of intestinal epithelial cells.

2022

Bioavailability of steroid hormones sorbed on microplastics for aquatic organisms through biological fluids

Florian Frédéric Vincent Breider, Yang Liu, Thibault Béranger Masset, Cécilia Laetitia Carla Siri

2020