In recent years, the amount of plastic in the environment has become a global concern. With the world population approaching eight billion, more and more plastic and plastic-derived products are being used and discarded. An estimated 367 million tonnes (367 billion kg) of plastic were produced in 2020 alone – about 12 tonnes (12,000kg) of plastic waste produced every second that year.
With about 2.5 million tonnes of plastic waste annually, Nigeria ranks ninth globally among countries with the highest contributions to plastic pollution. Unfortunately, over 88% of the plastic waste generated in Nigeria is not recycled. Instead, much of it ends up in water bodies – rivers, lakes, drains, lagoons and the ocean.
Waste comes in sizes ranging from macroplastic (pieces larger than 25 millimetres in diameter) to nanoplastic (less than 1,000 nanometers). It takes various forms, such as polyethylene terephthalate (used for food packaging, beverages, and personal care products), polyvinyl chloride (used in plumbing pipes, flooring, and clothing) and polystyrene (used for food packaging, laboratory materials, toys and computer housing).
Microplastic particles (less than 5mm long) have been shown to be potential vectors of disease agents. Plastic has been reported in cooking salt, stool and drinking water (tap, bottled, and sachet), with potential risks to human health.
Sustaining life in water and on land is among the United Nations Sustainable Development Goals. This makes it necessary to have a clear idea of where the plastic pollution is coming from, what harm it is causing and what the authorities can do about it.
Plastic waste in Nigeria
We conducted a systematic review of academic studies on plastic pollution in the environment in Nigeria. There were relatively few. As at 30 May 2021 there were only 26 such studies in Nigeria, compared to 62 peer-reviewed studies on the Arctic Ocean. Between 1987 and September 2020, there were 59 studies on the African aquatic environment.
We looked for the main sources and types of plastic waste in Nigeria and their biological effects. We identified big research gaps but were able to make some recommendations.
The studies indicate that water sachets and shopping bags are the major constituents of plastic waste in Nigeria. Educational institutions, markets and households are among the major routes. They are indirect routes of entry of plastic waste, particularly into water bodies in Nigeria.
The sources of plastic waste included tyre wear, cigarette butts and electronic waste (mobile phone components, electronics, electrical appliances). Others were fishing ropes, biosolids, cosmetics, clothing, food packs, and cellphone bags. Microplastic particles were found in some insects, snails and fish sampled from water bodies as well as in table salt (mostly in Southern Nigeria).
Further research is needed to establish holistic evidence of plastic pollution from all sources across the six geopolitical zones in Nigeria.
We also need to know more about its effect on agricultural soils, air, plants, animals, drinking water and human health as well as the socio-economic and psycho-social impact.
Despite these gaps, the evidence for land-based sources indirectly polluting water bodies and the oceans is a concern.
With increasing evidence of climate change in Nigeria, such as floods, the chances for transfer of plastic waste from indirect sources into the aquatic environment are higher.
The low level of recycling – less than 12% – and inadequate waste collection pose a huge threat to plastic pollution management in Nigeria.
Some African countries have taken steps to curb plastic waste discarded into the environment. They are gradually eliminating or banning single-use plastics. They have also made producers more responsible through buy-back programmes.
Education about plastic pollution management should start at the elementary level and continue into adulthood.
The informal sector also has a role in curbing plastic waste in the environment. Policies and incentives, backed by robust enforcement, should target plastic producing companies to encourage polymer replacement and recycling.
Researchers need up-to-date facilities and funds to evaluate plastic footprint and the risk to animals and humans. They should explore trans-disciplinary approaches to curbing plastic pollution, including using innovative technologies.