Microplastics & Personal Care Products (silent endocrine disruptors)  

Microplastics are miniscule plastic fragments, fibers or beads with a diameter which is ranging from 100 nm to < 5 mm. If the particle size is < 100 nm then it is a nanoplastic. Microplastics are usually associated with being strong vectors of hydrophobic organic contaminators such as polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls PCBs.

Microplastics are divided in to two categories as primary and secondary which primary indicates the plastic pelltes, beads ad fibers. Also, the exfoliators integrated into personal care and cosmetic products are a primary microplastics source. Cosmetic formulations release approximately 0.5%-5% primary microplastic and with a single use, they may release 4500-94,500 microbeads.

Secondary microplastics are the most common and the know way of microplastic formation which is through macroplastic degradation and weathering. These two – weathering and degradation – can be so effective to the point where macroplatics might run into powdery materials.

In addition to these, since microplastics have a hydro-phobic nature and a high surface-volume ratio, the accumulation of organic contaminants such as PCBs and PAHs along with trace metal contaminants become easy through adsorption. They provide a wide surface, especially in aqueous environments, which results in the higher accumulation of organic contaminants when the water medium is compared with surrounding waters. For instance in Japan, accumulated PCBs and PBDs on plastic pellets have been recorded as 10⁵- 10⁶ times higher than those exist in surrounding waters. There are various environmental factors that could alter this combination as it is listed in Figure 2.  

The extensive use of personal care products (PPCBs) have caused abundant existence of them in environment resulting in the co-occurrence with microplastics. These synthetic materials consist of extremely complex materials which becomes harmful secondary byproducts after degradation and resists in the environment.

Figure 1 : Pathways of Microplastic Formation

Figure 2 : Personal Care Products and Microplastics

Microplastics covered with organic contaminants as aformentioned might travel miles away with the hostness of microplastic surface and lead their contaminance to the various aquatic biotas. They can pollute pristine ecosystems or they can be taken by marine and aquatic organisms. Since they are miniscule particles which easily float, they can be ingested by various animals through another animal which is a prey (accumulation) or directly with water flow.

Approximately 14.6% of fish sample sets coming from Saudi Arabian Red coast were contaminated by microplastics. In this set, the highest contamination belonged to Parascolopsis eriomma which is a species feeding on benthic invertebrates. In another case, Van Cauwenberghe and Janssen indicated the evidence of two commercial grown biavalves as Mytilus edulis and Crassotrea gigas. According to results of this study, European shellfish consumers can ingest up to 11,000 microplastics annually. 

Furthermore, a study in China reported that 84% of the oysters which were selected for sampling set were contaminated with microplastics (average of 0.62particles/g). Later the investigated mussel Mytilus edulis have a shown difference between pre-cooked and supplied live types in the scope of microplastic concentration. Pre-cooked mussels was reported as they had higher concentration of microplastics than live supplied ones. This might indicate that the pre-cooking process contains much microplastics than the natural environment.

A study conducted by Cho et al. (2019) examined the four types of commercial bivalves which are from 3 major cities of South Korea and it was obtained that population consumes 212 particules / person/year from shellfish in a year. Aformentioned studies and researches demostrate microplastics (wastes and other contaminants as well) are finding a pathway to our diet.

Figure 3 : Uptake of Microplastics

After microplastics made their way into our diets through the organisms we consume they cause various problematic effects on our bodies. Although in these studies have shown a low concentration, when this concentration exposure becomes chronic; the negative impact is inevitable. On the other hand, impact caused by this contamination first effects the ‘host’ animal.

We are under the threat of constant exposure to these materials through our diets, and the organisms we consume are also in danger. For instance, according to a study conducted on oysters, their fecundity – means the ability of producing the ‘next generation’- growth of the offspring at larva stage were lowered because of the microplastic presence.

 

Figure 4 : Oocytes Number Change After Microplastic Exposure

In the frame of this study, the reproductive indices of oysters were strongly –negatively- impacted including 23% reduction in sperm velocity in exposed oysters which might results in the low ability to fertilize oocytes. Oyster oocyte number was also significantly diminished as it can be seen in the Figure 4.

As aforementioned, uptaken microplastics can retain through the ecosystem – and therefore in food chain – by accumulating which results in disturbing whole system gradually. They accumulate in ‘lipid’ zones which makes them harder to be gotten rid of. When they accumulate in the body until the so-called ‘threshold’ level, the impact might be invisible to our eyes however their chronic effect is highly disruptive and carcinogenic. 

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