The government has set up a task team to look at imposing a total ban on microbeads - the tiny plastic beads used in cosmetics, toothpaste and sandblasting.
This comes after a Water Research Commission study found microplastic pollution in tap water in Johannesburg and Tshwane, as well as in all rivers tested in Gauteng and in borehole water in the North West province.
The study, conducted by researchers at North-West University, recommended a ban on the manufacture, importation and use of microbeads in South Africa.
In response, the Department of Environmental Affairs (DEA) has set up a task team of officials from the departments of trade and industry, health and science and technology to examine the possibility of phasing in a microbead ban.
The task team is also in consultation with the plastics and cosmetic industries.
DEA spokesperson Albi Modise said the department had "moved quickly to engage extensively on the possibility of a complete ban of microbeads, particularly the petroleum-based microbeads".
One of the proposals that the team has made so far is for an amendment of the Foodstuffs, Cosmetics and Disinfectants Act, administered by the Department of Health, which would ban microbeads in these substances.
Modise said the task team had consulted the Cosmetic Toiletry and Fragrance Association to get its position on the manufacturing, import and use of microbeads in various products.
"The association has expressed the same concerns as those of DEA, and is working with the European Union and other local research institutes to look at alternatives into microbeads," he said.
Several countries have banned, or plan to ban, the manufacture or importation of toiletries containing microbeads. Those where a ban came into effect in 2018 include Canada, France, New Zealand, Sweden, Taiwan, the United Kingdom and the United States of America.
Others, such as India, Ireland and Italy, have drafted legislation for the ban to come into effect later.
Microbeads were only some of the microplastics that the study found in rivers, boreholes and tap water. Microplastics - defined as plastic particles less than 5mm in size - have two primary sources: plastic pellets used as raw material by the plastics industry, and microbeads used in the cosmetic industry, particularly in exfoliants and toothpaste.
Secondary sources are the billions of bits of plastic broken off from larger plastic objects that have become degraded after being discarded.
Microbeads are added to a variety of toiletries, including shower gels, toothpastes, facial scrubs and exfoliants, to give them "scrubbing power".
They are usually less than 2mm in size, with some so small they are not visible to the naked eye.
Professor Henk Bouwman, one of the researchers in the study, said a worrying source of microbeads was sandblasting.
"If used in sandblasting they can not only get into water but also into the air and so into people's lungs. If they are a certain size they can stick onto the alveoli in the lungs," he said.
Microbeads from toiletries are washed down the drain and into sewerage treatment plants, which are not designed to capture such tiny particles. These end up in rivers and the sea when treated sewage effluent is discharged.
It is not known how microbeads and other microplastics got into tap water in Gauteng.
Bouwman recommended in his study that the "pathways" of microplastic pollution of freshwater be studied.
South Africa is not alone in having tap water contaminated by microplastics. A study by Orb Media this year of tap water from more than a dozen countries found microplastic contamination in 83% of the samples. The US had the highest contamination rate with 94% of tap water samples containing microplastic, and the UK, Germany and France the lowest rate at about 72%.
Another study, released this year, found that bottled water also contained microplastic particles. An analysis of 259 bottles from 11 brands in nine countries found an average of 325 plastic particles for every litre of bottled water sold. Only 17 bottles contained no microplastics.
No studies have been done on the health effects of ingested microplastics on humans.
Bouwman said one of the worries was that toxins like DDT and persistent organic pollutants attached themselves to plastic, and were absorbed into plastic.
It is not known whether these toxins move from the plastic into the body of the animal or human once it has been ingested.