Okuku Eric, Maureen Kombo, Catherine Mwalugha, Purity Chepkemboi, Mary Mbuche, Kenneth Otieno

Kenya Marine and Fisheries Research Institute

What are microplastics and why are they a concern

Contrary to popular opinion, microplastics (MPs) have been around since the late 1800s, when they were first discovered in soil samples. The exponential growth of plastic production has since caused the amounts of MPs particles in our environment to skyrocket. Defined by the United Nations Environment Programme as tiny plastic pellets, fragments and fibres measuring less than 5 mm in size, MPs come from a multitude of sources;, primary microplastics that are tiny particles designed for commercial use, such as toothpaste and cosmetics, as well as microfibers shed from clothing and other textiles, such as fishing nets whereas secondary microplastics are particles that result from the breakdown of larger plastic items, such as water bottles (Plate 1). Their small size allows them to pass through water filtration systems, resulting in their dramatic increase in the oceans and lakes where they can devastate organisms and local economies. Microplastics reach marine environments through a variety of pathways including wind, rivers, wastewater and stormwater (Plate 2). 

Plate 1: Global % contribution of microplastics sources (Source Boucher and Friot, 2017)

Plate 2: Global contribution of different microplastic pathways (Source Boucher and Friot, 2017)

Microplastics affect marine life in a variety of ways. They can be mistaken as food by unsuspecting organisms, leading to the ingestion of toxic substances and physical damage to the digestive tract of the animals as they are present in an array of colors and shapes and could potentially be mistaken as food sources. They also act as carriers of other contaminants, including microorganisms and substances, and can leach chemicals and other toxins into the food chain. MPs can also be introduced into the food chain due to their prevalence in surface waters, where marine zooplankton, small, free-floating aquatic microorganisms, often spend most of their time when feeding. Zooplankton are an essential food source for secondary consumers, such as fish and cetaceans, which can create a pathway for microplastics to enter the food chain, posing a danger to secondary producers, apex predators and potentially human health. In addition to direct impacts on marine life, microplastics can indirectly affect Kenya’s economy. The presence of MP in fish can affect seafood safety and negatively impact those who rely on fishing as a source of livelihood and income.

Where are they found in Kenya?

Microplastics are everywhere. Studies in Kenya have shown that over 90% of the microplastics present were fibres, with fragments and films making up the remaining 10%. suggesting high contamination of the ocean with these microplastics, likely arising from textiles, fishing nets used by local fishermen and bleaching of colored plastics. Areas such as Mikindani and Nyali Bridge have been reported to have high concentrations of microplastics linked to increased amounts of solid waste from surrounding industrial and domestic sectors. A recent study reported a concentration range of 0.02 to 2.04 items per cubic meter in 6 sites along the Kenyan Coast. The likely input is River Sabaki, which receives large amounts of packaging plastic waste from the Dandora dumpsite via the Nairobi River. 

A study conducted in the Kenyan exclusive economic zone waters reported the presence of MP between 110 and 255 items per cubic meter mainly from land-based sources in Kilifi, Malindi, Ngomeni, and Kipini, as well as riverine input from Sabaki and Tana that emptied into the ocean. Furthermore, the study reported PP (polypropylene) as being the dominant polymer present. This could be explained by the fact that PP is commonly used to manufacture items such as food containers, plastic tableware, disposable cups, plates and jugs, which are mainly used in urban centers and hotels adjacent that eventually reach the ocean where they are further broken down into MPs. A more striking finding is the transboundary transportation of MP with a past study encountering MPs in Dabaso, a nature reserve located in Watamu Marine National Park at concentrations as high as those of creeks near Mombasa town despite the fact that this is a protected area with limited human activity. The transboundary nature of MP results from their ability to travel great distances and highlights the need for global efforts to reduce plastic pollution.

The information currently available on MP is still scanty. Further research is still needed to gain a better understanding of their occurrence, distribution and their potential implications on the health of marine organisms and the environment as a whole

How do we deal with microplastic pollution?

There are two approaches to reducing the amount of microplastic in the environment. First, avoid having offspring by eliminating the parents’ approach. Avoiding, refusing and eliminating unnecessary, problematic and non-recyclable plastic packing will eliminate macro-plastics from the environment thereby reducing the chances of their degradation into microplastics. The second approach is a total ban on products with micro-bids.

To address issues of plastic pollution, Kenya recently launched National Marine Litter Management Action Plan 2022-2031 and National Strategy on Plastics and Microplastics in 2020 which outlines steps that must be taken to reduce the use of plastic and microplastics including developing a national policy and legal framework for plastic and microplastic management, promoting waste reduction and recycling initiatives, and enforcing existing regulations. Some of the key recommendations aligned to these steps for reducing microplastics in the environment include 1) Reducing the use of single-use plastics and promoting the use of biodegradable packaging; 2) Implementing proper waste management; 3) Strictly enforcing laws prohibiting the dumping of plastics into the ocean; 4) Raising awareness on the dangers of plastics and microplastics and the importance of reducing or avoiding their use and 5) Collaboration between governments and other organizations to develop efficient and effective microplastic removal from waste and stormwater.

We hope these measures will help reduce the amounts of microplastics in the marine environment, aid in protecting Kenya’s marine life and support the blue economy drive. Let’s be the generation that takes a stand against microplastics and works to safeguard the ocean’s diverse biological resources for long-term sustainability including supporting our planet’s economy.

Selected reading

  1. Boucher, J., & Friot, D. (2017). Primary microplastics in the oceans: a global evaluation of sources (Vol. 10). Gland, Switzerland: Iucn.
  2. Kerubo, J. O., Muthumbi, A. W., Onyari, J. M., Kimani, E. N., & Robertson-Andersson, D. (2020). Microplastic pollution in the surface waters of creeks along the Kenyan coast, Western Indian Ocean (WIO). Western Indian Ocean Journal of Marine Science, 19(2), 75-88.
  3. Kosore, C. M., Ojwang, L., Maghanga, J., Kamau, J., Shilla, D., Everaert, G., … & Shashoua, Y. (2022). Microplastics in Kenya’s marine nearshore surface waters: Current status. Marine Pollution Bulletin, 179, 113710.
  4. Kosore, C., Ojwang, L., Maghanga, J., Kamau, J., Kimeli, A., Omukoto, J., … & Ndirui, E. (2018). Occurrence and ingestion of microplastics by zooplankton in Kenya’s marine environment: first documented evidence. African Journal of Marine Science, 40(3), 225-234.
  5. Okuku, E. O., Kiteresi, L. I., Owato, G., Mwalugha, C., Omire, J., Otieno, K., … & Mulupi, L. (2020). Marine macro-litter composition and distribution along the Kenyan Coast: The first-ever documented study. Marine Pollution Bulletin, 159, 111497.
  6. Onyango, W. A. (2020). Types and abundance of microplastics in macro-invertebrates along the Kenyan coast (Doctoral dissertation, University of Nairobi).