If 2022 could not get any worse… a recent study that microplastics were found in human blood recently surfaced, with the study revealing that traces of the particles were discovered in 80% of its tested participants. According to Carrington (2022), the samples tested positive for PET plastic (used in water bottles), polystyrene (used in food packaging) and polyethylene (used in plastic bags).

Thus, this poses the perennial question – how did plastics even end up in our bloodstream? Wright and Kelly (2017) expound on this further, highlighting that although plastic is an inert material, various pathways such as bioaccumulation are key conduits in plastic transmission to humans.Bioaccumulation occurs when toxins accumulate in a food chain, with predators at the top of the food chain (humans!) absorbing the most adverse effects. Small amounts of toxins such as pesticide/anthropogenic pollution that are leached into groundwater and sediments are absorbed by plants which are then consumed by primary consumers in low concentrations. As the toxin cannot be excreted, it is transmitted to secondary predators. As the toxins remain embedded in the tissues of prey at each trophic level in the food chain, toxin concentration is the highest in the predator at the top of the food chain (How are populations affected by conditions in an ecosystem? – OCR 21C, undated).

As emphasised in previous post, plastic pollution is perhaps the Anthropocene’s most pervasive and conspicuous form of pollution. Due to their hydrophobic surfaces, microplastics not only adsorb toxic contaminants polychlorinated biphenyls at high concentrations, they also acquire heavy metals such as lead, zinc, nickel and cadmium.Because of their hydrophobic surface, microplastics can adsorb and concentrate hydrophobic organic contaminants (HOCs) such as polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides and polychlorinated biphenyls (PCBs) to a high degree.19,20 They also accumulate heavy metals such as cadmium, zinc, nickel, and lead.21,22 Microplastics are thus considered as vectors for these pollutants that have proven to cause adverse health effects (Wright and Kelly, 2017).

As appetites for seafood increase amongst humans – 15% of the world’s population consumes 4 fish regularly –  it is no wonder then that its consumption facilitates human exposure to microplastics. After all, almost all marine organisms have the capacity to ingest plastics (Check out my earlier blog posts on plankton consumption of microplastics!). What is especially alarming is the rate of pervasiveness of plastics – Harkin (2020) reports how studies reveal that nanoplastics are transmitted  BBB (blood-brain-barrier) in fish, causing behavioural disorders and brain damage. If marine creatures are affected at such an adverse level, surely the same would apply for humans?

While a seminal discovery, microplastics in our blood stream poses a significant health concern as they contain EDCs (Endocrine Disrupting Chemicals) that include BPA (Bisphenol A), phthalates and pesticides. Moreover, it was unearthed that a substantial number of EDCs – 800, in fact! – possess the capacity to interfere with hormone receptors. Amongst others, EDCs can cause result in higher risks for breast cancer, adverse pregnancy effects, neurological disorders and a greater propensity of foetuses contracting ADHD (Attention Deficit Hyperactivity Disorder) and autism through food transmission by the mother (Harkin, 2020).

Consuming less seafood may seem like the most obvious solution for now, however is that truly sustainable? Perhaps the answer lies in going directly to the source and urging governments to pass stricter legislation on plastic producers and to hold them accountable for the waste they generate. While its efficacy may not account to much, consumers can also limit their use of single-use plastics (BYOB if you can!), participate in beach clean-ups and continue raising awareness of this epidemic as it is clearly getting out of hand.

References

https://www.bbc.co.uk/bitesize/guides/zxgn97h/revision/5#:~:text=Bioaccumulation%20occurs%20when%20toxins%20build,activity%20%2D%20are%20absorbed%20by%20plants.

https://pubs-acs-org.libproxy1.nus.edu.sg/doi/pdf/10.1021/acs.est.7b00423

https://www.theguardian.com/environment/2022/mar/24/microplastics-found-in-human-blood-for-first-time

https://medcraveonline.com/IJCAM/IJCAM-13-00487.pdf