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Potential toxicity of emerging chemicals of concern used in sanitisers and disinfectants on aquatic organisms : case study of the freshwater snail, Physa acuta
Dissertation (MEng (Chemical Engineering))--University of Pretoria, 2026.
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University of Pretoria
2026
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| _version_ | 1869483893939240960 |
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| access_status_str | Open Access |
| author2 | Daramola, Michael Olawale |
| author_browse | Daramola, Michael Olawale |
| author_facet | Daramola, Michael Olawale |
| collection | Thesis |
| dc_rights_str_mv | © 2024 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Dissertation (MEng (Chemical Engineering))--University of Pretoria, 2026. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/108285 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-07-01T04:06:14.584Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/108285 Potential toxicity of emerging chemicals of concern used in sanitisers and disinfectants on aquatic organisms : case study of the freshwater snail, Physa acuta Daramola, Michael Olawale u13238282@tuks.co.za Khuzwayo, Zakhele Motaung, Lenah Kagiso UCTD Sustainable Development Goals (SDGs) Benzalkonium chloride Disinfectants Sanitisers Physa acuta Titanium Dioxide Nanoparticles Sediment toxicity Species Sensitivity Distribution Dissertation (MEng (Chemical Engineering))--University of Pretoria, 2026. Aquatic contamination is regarded as a significant global concern. However, sediments are the ultimate sinks of particle-bound contaminants. Thus, storing harmful compounds leading to long-term ecological harm and risks to benthic organisms. This study adopted a tiered approach to assess the ecological impact of chemicals commonly found in disinfection and sanitisation products by incorporating screening protocols, statistical modelling, and organism-level experimentation. An initial PBT (Persistence, Bioaccumulation, Toxicity) screening process was used to identify chemicals of potential environmental concern based on their physicochemical properties, environmental behaviour, and documented toxicological profiles. Quaternary ammonium compounds (QACs) were amongst the chemicals of concern, and this is due to their wide use and applications in disinfectants and other products. Secondly, their effects, along with other micro chemicals and nano particles like titanium dioxide, remain poorly understood, especially on invertebrates, which have been neglected in toxicity studies. The compounds that met the set prioritisation criteria, the two QACs, benzalkonium chloride (BAC) and Didecyldimethyl ammonium chloride (DDAC) and the titanium dioxide nanoparticles (nTiO2), were subsequently assessed using insilico Species Sensitivity Distributions (SSDs) constructed from EC50, LC50, and NOEC datasets to estimate HC5 values, identify sensitive taxa, and derive protective concentrations where feasible for Ecological Risk Assessment (ERA). The SSD based ERA was compiled from data extracted from the ECOTOX database and peer-reviewed journals using targeted key words. The hazardous 5th percentile (HC5) was calculated and the PNEC determined from the HC5 from NOEC SSDs to determine the Risk Quotient (RQ) for each chemical. The HC5 values derived from BAC EC50 and LC50 SSD were low at 0.001 µg L-1 and 3.33 µg L-1, respectively, while the HC5 for NOEC was 0.032 µg L-1. Higher values were observed for DDAC with the HC5 recorded as 19.12 µg L-1.and 0.528 µg L-1 for LC50 and NOEC. The HC5 values for nTiO₂ endpoints were comparatively higher and falling within the milligram range, 4 050.4 and 347.4 µg L-1 for LC50 and EC50. A consistent trend across all three chemicals was observed whereby daphnids were identified as the most sensitive species for at least one of the evaluated endpoints for each chemical. The analysis also highlighted the data gaps and under representation of many classes of organisms in ecotoxicity studies, more so sediment dwelling organisms, especially molluscs. Thus, the toxicity studies were conducted on Physa Acuta snails to determine the effects on the apical endpoints, survival, and reproduction, furthermore, investigate the inhibition of glutathione S-transferase (GST) antioxidant enzyme. The results of the 96-h acute exposure studies results showed survival of P. Acuta snails to fall in the range of 96.6% and 100% across the treatment groups with exposure concentrations of up to 800 µg kg −1 and 800 µg L-1 in the sediment and overlaying water, respectively. There were no significant differences in the number of capsules laid by snails over the exposure time compared to the control group that was not exposed to the any of the three chemicals. On the other hand, the number of eggs laid per capsule over the 96 hours was significantly affected. The reproduction effects of the snails in ascending order were: nTiO2 < DDAC < BAC compared to the control. Additionally, results from the biomarker assays revealed significant inhibition of glutathione S-transferase (GST) antioxidant enzyme across all three test groups and across all concentrations compared to the controls. Snails exposed to DDAC exhibited the lowest GST inhibition, except at a concentration of 400 µg kg-1, while those exposed to nTiO2 showed the highest inhibition. These GST test results reveal significant adverse effects at the molecular level that are not immediately apparent at the organism level. This highlights the importance of studying the molecular effects of chemicals, even during short-term exposure periods. Secondly, chronic exposure studies are recommended to better understand the toxicity mechanism of the three chemicals over more real-life environmental scenarios. NRF CSIR University of Pretoria Chemical Engineering MEng (Chemical Engineering) Unrestricted Faculty of Engineering, Built Environment and Information Technology SDG-06: Clean water and sanitation SDG-14: Life below water 2026-02-16T13:29:50Z 2026-02-16T13:29:50Z 2026-05-08 2026-02-06 Dissertation * A2026 http://hdl.handle.net/2263/108285 https://doi.org/10.25403/UPresearchdata.31333531 en © 2024 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | UCTD Sustainable Development Goals (SDGs) Benzalkonium chloride Disinfectants Sanitisers Physa acuta Titanium Dioxide Nanoparticles Sediment toxicity Species Sensitivity Distribution Potential toxicity of emerging chemicals of concern used in sanitisers and disinfectants on aquatic organisms : case study of the freshwater snail, Physa acuta |
| title | Potential toxicity of emerging chemicals of concern used in sanitisers and disinfectants on aquatic organisms : case study of the freshwater snail, Physa acuta |
| title_full | Potential toxicity of emerging chemicals of concern used in sanitisers and disinfectants on aquatic organisms : case study of the freshwater snail, Physa acuta |
| title_fullStr | Potential toxicity of emerging chemicals of concern used in sanitisers and disinfectants on aquatic organisms : case study of the freshwater snail, Physa acuta |
| title_full_unstemmed | Potential toxicity of emerging chemicals of concern used in sanitisers and disinfectants on aquatic organisms : case study of the freshwater snail, Physa acuta |
| title_short | Potential toxicity of emerging chemicals of concern used in sanitisers and disinfectants on aquatic organisms : case study of the freshwater snail, Physa acuta |
| title_sort | potential toxicity of emerging chemicals of concern used in sanitisers and disinfectants on aquatic organisms case study of the freshwater snail physa acuta |
| topic | UCTD Sustainable Development Goals (SDGs) Benzalkonium chloride Disinfectants Sanitisers Physa acuta Titanium Dioxide Nanoparticles Sediment toxicity Species Sensitivity Distribution |
| url | http://hdl.handle.net/2263/108285 https://doi.org/10.25403/UPresearchdata.31333531 |