Abstract
M.Sc. (Chemistry)
Nanotechnology is the synthesis and manipulation of matter at nanometre scale where materials exhibit unique physicochemical properties thus attracting application in industrial processes and consumer products. Research activities around nanotechnology over the past two decades have focused on the synthesis and application of engineered nanomaterials (ENMs) and this has resulted in the increase of the number of nano-enabled products (NEPs) entering the global markets. With this rising in the number of NEPs, there are also concerns in the scientific community and the general public about the safety of ENMs towards humans and environmental recipients. Evidence emerging from literature shows that ENMs can be toxic to aquatic organism. However, such studies have exposed the test organisms to pristine ENMs which might be different to ENMs as they are used in the real world. Currently in South Africa, there is a data gap on the sources of nanopollutants that the environment and humans can be exposed to.
This study sought to identify and to prioritise NEPs (explicitly declared by the manufacturer) that are available in South Africa according to their exposure potential for the environment. Once prioritised, a select number of NEPs were studied further by characterisation of the physicochemical properties of the incorporated ENMs. A total of 264 NEPs were identified in this study distributed across the health and fitness (66.7%), electronics and computer (15.2%), home and garden (10.6%), appliances (3.8%), automotive (2.7%) and the food and beverages (1.1%) use categories. The chemical type of ENM was declared in 63% of the identified NEPs with titanium, carbon, silver and silica based ENMs being the most applied. These ENMs were almost exclusively applied in the health and fitness products such as personal care and cosmetics, sunscreens, sporting goods and clothing. In the remaining 37% of the products, the chemical identity of the ENM was not declared by the manufacturer or it was poorly defined. By using the location of ENMs in NEPs, the estimated concentration, usage rate and release factor (RF), it was found out that 63.6% of NEPs exhibited high potential for environmental exposure and it was mostly personal care and cosmetics, sunscreens and cleaning liquids.
Six NEPs (3 sunscreens (Sun 1–3), 2 moisturising creams (MC 1–2), 1 pair of socks (Tex 1)) which exhibited high exposure potential to the environment were then selected to confirm the manufacturer’s claim of the presence of ENMs and for characterisation of ENMs. The “nano-claim” was confirmed (size analysis by transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA)) in all the samples, except in the pair of socks where the...