Repository logo
 

Faculty of Management Sciences

Permanent URI for this communityhttp://ir-dev.dut.ac.za/handle/10321/13

Browse

Filters

2017 - 20192

Settings

Subject: search.filters.subject.Toxicity

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Recycling and disposal of carbon nanotubes
    (2019-10) Naidoo, Denise Radhamani; Singh, Shalini; Kanny, Krishnan
    Nanoparticles may be released throughout the lifecycle of products. Information on the handling, treatment, toxicity and mobility of carbon nanotubes (CNTs) is currently minimal. The objectives of the study were to determine the practices employed by nano-organisations for recycling and disposal of CNTs, identify quality management tools to aid responsible development and observe the behaviour, toxicity and leaching potential of CNTs. These objectives would support the development of a strategy for managing the potential environmental risks associated with the recycling and disposal of CNT. A mixed method tactic was adopted for this study. In addition to validated protocols based on OECD guidelines for validity and reliability in experimental work, the validity of the review was achieved by obtaining expert knowledge through scholarly articles and the internal consistency. While the reliability of the review was achieved by monitoring the repetitive information from literature sources and Cronbach alpha. Respondents participating in the survey indicated that there are differing practices for the recycling and disposal of engineered materials (ENMs). The toxicity studies revealed that while the nano-clay had a lethal response to earthworms during the pilot toxicity study, the main toxicity study showed that carbon nanotubes did not have a lethal response to earthworms in soil. However, worms were observed to be highly sensitised to increased concentrations of carbon nanotubes. The leaching in a soil column test showed that the movement of carbon nanotubes was inhibited with the largest portion of carbon nanotubes remaining on the surface and in the topmost layers of the soil. Results pointed to contradicting views with regards to environmental risks amongst people working in the field of nanotechnology. For this reason a continued precautionary approach is suggested until standardised legislation has been enforced for nanotechnology. Future work requires a more detailed understanding of the fate, behaviour, uptake and distribution of CNT in the environment. This can be achieved through the sharing of knowledge between nano-facilities.
  • Thumbnail Image
    Item
    The quality of selected food products containing nanosilica additive (E551) in South Africa
    (2017) Thakur, Rookmoney; Singh, Shalini
    The proliferation of nanotechnology, whilst perceived to be positive for human advancement, introduces potential risks when applied to food. Silicon Dioxide (E551), a common food additive made up of particles in the nano-range, is found in spices, salt, sweets and some frozen foods and functions as an anti-caking agent to allow these food products to flow and mix evenly. According to Codex Alimentarius, E551 is generally regarded as safe (GRAS), provided that food manufacturers apply good manufacturing practice (GMP) principles and use the lowest possible amounts necessary. Smaller nanoparticles are more readily taken up by the human body than larger sized particles and could be injurious to human health. While the use of E551 is strictly regulated in some countries, there is growing debate regarding the health and safety implications for consumers and the quality of food. This study examined the quality of selected food products containing E551 (nanosilica) in South Africa (SA). A mixed method paradigm (qualitative and quantitative) and an experimental research strategy were adopted. Respondents were purposefully selected, their participation in this study was voluntary and confidentiality was maintained. Pilot studies were conducted for the semi-structured interviews and the survey, with a sample size of one food expert and three food technologists, respectively. The main study consisted of interviews, a survey and experimental work. The interviews, conducted with five food experts, were recorded and transcribed to ensure credibility. The results were interpreted and analysed against existing literature using thematic content analysis. The findings suggest that it was critical for food manufacturers to demonstrate the safe use of products without posing any safety risks to the consumer and the environment; and for the South African government to address and regulate the application of nanomaterials in food either by legislation or guidelines. The survey was conducted with a sample population of thirty food technologists who reported that public awareness of nanotechnology was limited as many consumers were not familiar with this technology. Descriptive and inferential statistics were used to analyse the quantitative data. Content validity ensured that the survey focused on concepts and constructs that emerged from the review of literature on the application of nanotechnology in food products. Cronbach’s alpha index was used to assess the reliability of the surveys and found α = 0.862 and α = 0.809 for food additives awareness and nanosilica safety in food, respectively. Different characterisation methods, such as Fourier Spectra Infrared Spectroscopy (FT-IR), Energy Dispersive X-ray Spectroscopy (EDX) and X-ray Diffraction (XRD), were used to determine the type and form of silica, and its levels in selected food brands available in SA. This was compared against similar products manufactured and packed in the European Union (EU) and Asia. This study benchmarked against the EU standard because of its more stringent guidelines in the field of nanotechnology and regulations. The results indicate that while the comparative EU food sample conformed to the European Food Safety Association (EFSA) permissible level of 1 %, the South African sample levels were higher. Even though the regulatory standards are different in both countries, the potential health effects remain the same. Significantly, the most prominent finding of this study is that the form of silica in some of the South African and Asian products were crystalline in nature, rather than synthetic amorphous silica (SAS), which is indicative of E551. Thus, it stands to reason that the generalised limit set by Codex Alimentarius was inadequate to regulate and control the quantity and type of E551 used as it varied from each of the selected samples. The identification of traces of crystalline silica is of concern since studies in literature showed that exposure to and ingestion of crystalline silica that was not food grade, is likely to induce perilous health effects such as cancer and fibrosis in humans. In light of this finding on the crystalline nature of silica in the studied brands, it is therefore imperative that specific limits and regulations be put in place and enforceable in SA to ensure that products sold are in line with acceptable standards as found in some developed countries like the United States of America (US) and EU. In view of the above, and to ensure proper monitoring and minimal risk exposure, a risk management framework, a ‘Hazard identification, Access the risks, Control the risks’ (HAC) model, was developed and recommended to ensure that the correct form and type, and limits of silica is used and the associated risk controls applied.