Microplastics as emerging contaminants: method development, ecotoxicity testing and biomonitoring in South African water resources

N Mgaba, ON Odume, PK Mensah and N Griffin
April 2019-March 2022

Water Research Commission

Increases in the production of plastic materials globally have led to their ubiquity in the environment. To date, plastics of all sizes have been reported in all type of environments: marine, freshwater, terrestrial, agricultural lands, drinking water, and air. The ubiquity of plastic materials within the environment, coupled with the fact that they are not easily degradable, has raised serious concerns about the ecological and human health risk they pose. Current empirical evidence suggests that the ecological and human health risk posed by plastics is influenced by several factors: the physical and chemical properties of the plastic material, the vulnerability of the impacted biological agent, and the concentration and distribution of plastics in the environment. In South Africa, microplastics have reportedly occurred in river systems, but not much work has been done to examine the potential toxicity and effects of microplastics on biological systems at environmentally realistic concentrations. To this end, methods for quantifying the effects of microplastic or their toxicity have not been well established, although standard toxicity testing methods could be adapted. This project thus fills an important knowledge gap by investigating the occurrence and distribution of microplastics in the Swartkops and Buffalo River systems in the Eastern Cape, as well as the ecotoxicity of microplastics and plasticisers on selected test organisms at environmentally realistic concentrations.

Project aims:

The following are the specific aims of the project:

1. To convene a project inception workshop and update a literature review on microplastics in freshwater environments based on national and international reports, focusing on ecotoxicity testing for human health and environmental risk assessment.

2. To develop (or adapt) methods for quantification and characterisation microplastics in freshwater systems, as well as methods for assessing the toxicity of microplastics (as chemical and physical stressors) using selected test freshwater organisms through multiple life stages.

3. To evaluate the potential toxicity of microplastics as chemical stressors due to the presence of additives (e.g., plasticisers) based on novel endpoints using selected test organisms through multiple life stages.

4. To evaluate the potential toxicity of microplastics as physical stressors, considering different shapes and sizes of microplastic particles, based on novel endpoints using selected test organisms through multiple life stages.

5. To apply the developed (or adapted) toxicitybased methods for assessing the environmental risks of microplastics (as chemical and physical stressors) in selected South African river systems (Swartkops and Buffalo rivers) using selected test organisms, through multiple life stages.

6. To compile a communique and policy document on the toxicity of microplastics in the environment as well as recommendations for microplastics monitoring in freshwater ecosystems.

Last Modified: Wed, 14 Aug 2024 15:05:15 SAST