Fragmented Plastics in Food and Food Packaging

Studies have shown the presence of micro- and nanoplastics in fishes and sea mammals. Table 6.1 summarizes the list of research on food and food products. As per the reports published, the number of various species contaminated with fragmented plastics is very high, with more than 690 aquatic species of both edible and non-edible nature [49]. Although the chances of non-edible species reaching the human diet is very remote, their presence in the ecological balance cannot be denied. Only 200 edible species from marine sources and one from a terrestrial source has been considered [89]. Only one study is reported, by Lwanga et al., that concludes chicken gizzards to contain micro- or nanoplastics [50].

It has been shown that plastic fragments are present in 35% of the plankton eating fishes. On average, 2.1 fragments per fish were found [51]. In a study of Brazilian estuaries by Possatto et al., 18%—33% of catfish showed to have fragmented plastic particles in their stomachs [52]. It has been reported that the fragmented plastics can sediment at the bottom of the sea and species living in the dark zone of oceans are also susceptible to consuming micro- and nanoplastics [53].

Hollman et al. reported that in the benthic region of the sea, mostly crustaceans and polychaetes live. He also concluded that a trophic level transfer and bioaccumulation may also work here [54].

It is common to use fish guts for preparing animal feed, mostly in the poultry farms. Although, there is no report about possible contamination of animal husbandry, which uses fish waste products as animal feed. This area has a scope of research and the possibility of gaining some vital data about contaminated edible animals reaching the human diet. According to the European Food Safety Authority (EFSA) [5], blue mussels (Mytilus edulis) cultivated for human consumption are exposed to microplastics of 2-10 pm. This is in accordance with the conclusion of Browne et al. [55]. The EFSA report also concludes about the possible presence of microplastics in bivalves, fishes and shrimps. Presence of microplastics in common mussels was also reported by Li et al. [56-58]. In their study, Li and co-workers concluded that the contamination level was higher in wild mussels than farmed ones, and processed mussels were more contaminated with microplastics than nonprocessed mussels [56].

Liebezeit released two research studies reporting contamination of honey by micro- and nanoplastics in samples from producers and supermarkets. The first of the two studies concluded an average presence of 166±147 fibers/kg and 9±9 fragments/kg of honey

TABLE 6.1 List of Reported Studies on Food Contamination by Fragmented Plastics

made available from different countries [39,40]. Cellulose fibers and chitin fragments were found as particulate matter in honey. In the second of the two studies by Liebezeit, the honey samples from Germany were found to contain microplastics in the range of 40-660 fibers/kg of honey and 0-38 fragments/kg of honey [39,40,47]. However, the authors did not classify the fragments. Miihlschlegel et al. studied honey from Switzerland for possible contamination by fragmented particles; they also suggested possible precautions for minimizing them [41].

Contamination of salts is directly related to the microplastics in aquatic environments. Karami et al., in their studies, confirmed the presence of significant amounts of micro- and nanofragmented plastics in salt samples. Karami et al., also studied 17 different brands of salts available in a Malaysian market and concluded the presence of microplastics by Raman spectroscopy [44]. In another study by Giindogdu, microplastics were confirmed in Turkish salt by p-Raman spectroscopy [42]. Kosuth et al. studied commercialized salt samples made available from US grocery stores and confirmed the presence of significant amounts of microplastics [43]. Yang and co-workers studied sea, rock and lake salt from China and concluded the presence of 7-680 particles/kg [45]. One study by Liebezeit and Liebezeit reported possible contamination of sugar by microplastics. They concluded that unrefined sugar had the highest number of fragmented particles and fibers [39]. Karami et al., also studied canned sprat and sardine brands made available from 13 different countries. By exploiting Raman spectroscopy, the researchers concluded an average presence of 1-3 particles in four out of 20 brands [46]. Liebezeit et al. also studied and confirmed the possible presence of microplastics in German beers [47]. A similar kind of study was conducted with beers from the United States by Kosuth et al. and confirmed the presence of microplastics in US beers [43].

Mason et al. studied 259 bottled waters from nine different countries for possible contamination by micro- and nanoplastics. It was also concluded that most of the contamination would be from packaging sources [59,60]. In a similar study by Schymanski et al., 22 singleuse bottled waters were compared with reusable plastic bottles for contamination with microplastics. The authors concluded 8.4 times greater contamination in reused bottles than single-use bottles [48]. Kosuth et al. studied tap water collected from 14 different countries and concluded that the average presence of microplastics was 0-61 particles/L [43].

Packaging materials usually contain chemical constituents, additives, monomers, etc. which may, upon contact with food, leach into the food product [61,62]. However, such contamination is not a spontaneous process. Currently nanotechnology is being applied to almost every scientific and nonscientific field. Nanoparticles are now used for designing food packaging that can improve the shelf life and freshness of the product [63]. There is a strong possibility of migration of such nanoparticles from packaging material to food upon contact [64].