Significance of introduced pollutants (plastic bags) on natural Systems

Shafiq Nedala, April 2017


Makerere University Waste Management Research Association (MUWMRA)

Department of Environmental Management

What are plastics?

Plastics are non-biodegradable, synthetic polymers derived primarily from Petro-fossil feedstock and made-up of long chain hydrocarbons with additives joined together by a process polymerization (Tapkire 2014; Abdel-Rahman et al, 2015; Bashir, 2013). According to (Muthu et al, 2012) polyethylene – High Density, Low Density, linear low-density polyethylene (LLDPE) are the raw materials widely used for the manufacture of plastic bags.

Why the increased use of plastics?

Plastics especially carrier bags have been used in many sectors including agricultural industry, manufacturing industry, transport, business and in construction industries as packaging and storage material. According to Dikgang and Visser (2010), the popularity for use of plastic bags among retailers and consumers worldwide in recent decades is due to their functionality, strength, and low cost. Furthermore plastic bags seem to be slender, light and hence are easy to carry (Muthu et al, 2012). Unlike for metals and paper, Ramaswamy and Sharma (2011) reported that they are resistant to moisture. A combination of the above factors and its characteristics of being nonreactive with most chemical compounds contribute to their increased adoption by chemical and manufacturing industries hence an increased global demand.

The effects to animals and the environment.

Generally plastics have been reported to have caused a number of environmental issues.  They are blamed for increased pollution of soil, water bodies especially the great oceans, seas, lakes, rivers and swamps, biodiversity loss, diseases, food insecurity and climate change. Xanthos and Walker (2017) reported that 5.25 trillion metric tons of plastic wastes float on the Pacific Ocean with the biggest portion contained in the northern gyre. This phenomenon poses ecological threats to both sea ecosystems and sea food consumers.

In soil plastic bags impede water movement affecting soil moisture the distribution and movement of moisture. They limit movement of soil macro organisms such as earthworms and arthropods that aid in soil aeration. Movement of plant roots is impaired resulting into crop failure resulting into food insecurity. Resource poor farmers in Africa find it difficult to cultivate soils laden with plastics, consequently prompting rural urban migration of the able bodied youth. These factors coupled with others such as climate change, limited technology, poor soils and poverty can best explain the low agricultural productivity in sub-Saharan Africa.

Fish fry have been reported to prefer eating micro particles of plastics than food in the oceans. According to report by The Telegraph dated 3rd-June-2016, a study of European perch larvae for the first time found that exposure of European perch larvae to high concentration of micro plastics stunts growth and alters their feeding habits leading them to ignore their natural food sources such as the swimming zooplanktons.  Andersson (2014) reported that experiments on the Norway lobster, Nephros norvegicus, an important catch for Scotlands fishing industry, showed that 100% of the lobsters fed with micro plastics-containing fish carried themselves micro plastics 24 hours later. On land and in water, Bashir (2013) reported that animals such as cows, sheep, goats, sea turtles, fish, sharks,, whales, birds, and others inhale or ingest plastic bags each year, with over 100,000 animals killed by entanglement over a 3 year period.  The ecological effects of this bio-accumulation of plastics in the food chain may cause massive kills of organisms at higher trophic levels leading to extinction and biodiversity loss.

Plastics are very dangerous when consumed in food. Environmental exposure to a widespread compound such as (monomers, acrylonitrile, and vinyl plasticizers) used to make common plastic food containers interferes with cell division in the eggs of female mice according to (Bashir, 2013). A similar effect has been reported in humans and may also result into a genetic condition called aneuploidy. This condition is the leading cause of mental retardation and birth defects in humans, including Down’s syndrome (Bashir, 2013). Burning plastics as a disposal method introduces Dioxins and Furans, two highly toxic compounds into the environment. Dioxins belong to persistent organic pollutants (POPs) and are highly cancerous. Short-term exposure to Dioxins results in for example TCDD (

In Africa, increased incidences of malaria have been linked to plastic bags and bottles and the impacts are more eminent in areas with poor waste disposal methods. Plastics collect water in rainy seasons creating breeding zones for mosquitoes. This together with climate change phenomena exacerbate the prevalence of malaria disease hence claiming lots of lives of children below 5 years and expectant mothers. Sanitation disease such as cholera have been reported to somewhat have stemmed from plastic bag use. For example in the urban-poor settlements around Kampala, locals have used plastic bags as mobile toilets commonly known as “flying toilets”. Disposal of feacal waste into plastic bags poses a double risk to both human health and the environment. That is to say feaces are highly associated with diseases such cholera, diarrhea, dysentery, and parasitic worms which are life threats while plastics in the environment impair ecosystem functioning.

Plastics have contributed to climate change mainly because they are petroleum products. Increased demand for plastic bags globally results to increased oil extraction, which together with utilization of other petroleum products contribute to acute rise of greenhouse gas emissions such carbon dioxide to the atmosphere. U.S. alone utilizing over 100 billion bags annually, which is equivalent to throwing away over 12 million barrels of oil per annum (Bashir, 2013). Muthu et al. (2012) estimated that the introduction of a levy on plastic bags in China could save about 2.4 − 3.0 million tons of crude oil every year and cut 7.6 − 9.6 million tons of carbon dioxide emissions every year. The above illustration serve as evidence to show that plastic bag use has a great contribution to climate change in the modern world.


What have governments done?

Apparently many states have recognized plastic bags as one of the most dangerous pollutants that need to be avoided from their environments. This has been demonstrated in a number of ways such as formulation of laws that completely ban plastic bag use, levying heavy taxes, recycling, reusing and recovery, and landfilling. For example The New York City proposed charge on all carrier bags as a model for U.S. Cities (Romer and Tamminen, 2013) to manage single use plastic bags and this proposal entailed formulation of plastic bag ordinance. In Africa countries such as Uganda, Rwanda and South Africa, have banned “single use” plastic shopping bags whereas other countries like Kenya are considering a bag tax or a ban. Some countries have dearly invested in recycling of plastic bags for example China while others have merely done nothing. More examples of countries that have banned use of single use plastic shopping bags include China, Italy, Mexico City, and Delhi.

Uganda in particular

The law against single use plastic bags in Uganda especially those below 30microns was passed in 2007 by the parliament. However, implementation of this law has been chocked with a multitude of factors including politics, limited financing, and the national goal agenda that is “Vision 2040-Transforming Uganda into a middle income state”. This goal mainly focuses on economic development through job creation for the youth and less emphasis to environmental management. This has been clearly observed in the three attempts by NEMA with the most current and outstanding operation in 2015 which entailed activities such confiscation of plastics bags from the major super markets around Kampala. However this operation was seized due to political atmosphere and contradiction between two government agencies that is Ministry of Trade, Tourism and Industry and NEMA Uganda.


Use of plastic bags and their eco-impacts will continue growing globally due to their flexibility, cheapness during manufacturing and other factors discussed in this paper. Their consequence on wildlife, domestic animals, human health and the environment are significantly pressing and therefore quick responses are required to curtail this unknown evil with more emphasis on behavioral change through awareness, recycling, reusing and recovery.



Abdel-Rahman, E. H., Harbi12, M. A., Abdellatif, E. M., & Alnagrabe, S. Environmental Assessment of Polyethylene Bags: A Case Study in Khartoum State, Republic of Sudan.

Bashir, N. H. (2013). Plastic problem in Africa. Japanese Journal of Veterinary Research, 61(Supplement), S1-S11.

Dikgang, J., & Visser, M. (2010). Behavioral response to plastic bag legislation in Botswana (No. dp-10-13-efd).

Tapkire, G., Patil, P., & Kumavat, H. R. (2014). Recycled Plastic used in Concrete Paver Block.

Ramaswamy, V., & Sharma, H. R. (2011). Plastic bags–Threat to environment and cattle health: A retrospective study from Gondar City of Ethiopia. The IIOAB Journal, 2(1), 7-12.

Muthu, S. S., Li, Y., Hu, J. Y., Mok, P. Y., & Ding, X. (2012). Eco-Impact of Plastic and Paper Shopping Bags. Journal of Engineered Fabrics & Fibers (JEFF), 7(1).

The Telegraph 3rd June 2016,  Last reviewed on 5th-May-2017

Xanthos, D., & Walker, T. R. (2017). International policies to reduce plastic marine pollution from single-use plastics (plastic bags and microbeads): A review. Marine Pollution Bulletin.

Romer, J. R., & Tamminen, L. M. (2013). Plastic Bag Reduction Ordinances: New York City’s Proposed Change on All Carryout Bags as a Model for US Cities. Tul. Envtl. LJ, 27, 237.

[1]Nedala S. © 2017

Plastic bags pollution

[1] Nedala Shafiq is an environmental scientist   pursuing a Bachelor`s degree in Environmental Science at Makerere University.



3 thoughts on “Significance of introduced pollutants (plastic bags) on natural Systems

  1. The question that hits my mind is “what exactly can replace plastic bags ?” as an alternative with out posing a thread to our environment in relation to climate change

    Liked by 1 person

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