Determination of combined acute toxic effects of well water hardness and fluoride using the embryos of Danio rerio (zebrafish)
No Thumbnail Available
Date
2024
Journal Title
Journal ISSN
Volume Title
Publisher
Faculty of Science, University of Kelaniya Sri Lanka
Abstract
Water hardness is expressed as the concentration of dissolved minerals, mainly calcium and magnesium which are naturally present in both ground and surface water sources. Water hardness and fluoride levels in drinking water have significant impacts on human health. The synergistic effect of total hardness and fluoride is considered to be one of the major hypotheses for Chronic Kidney Disease of unknown etiology (CKDu) in Sri Lanka. The kidney accumulates more fluoride than other soft tissues, which may contribute to the origin and progression of kidney disease. Water hardness can affect early development as it alters the availability of essential ions for physiological processes. This study was conducted to evaluate the total hardness and fluoride levels in well water from Agunukolapelassa and determine the acute toxic effect of different hardness and fluoride combinations on embryonic development using zebrafish. Thirty well water samples were collected randomly. Highest total hardness was measured as 158.67 ± 0.05 mg/L (H1) and lowest was 16.00 ± 0.10 mg/L (H2) while fluoride was ranged between 1.93 ± 0.00 mg/L (F1) to 0.16 ± 0.00 mg/L (F2). Four different solutions were prepared by combining the above concentrations solution 1 (H1, F1), solution 2 (H1, F2), solution 3 (H2, F1), and solution 4 (H2, F2). Hardness solutions were synthetically prepared using MgCl2 and CaCl2, fluoride solutions were prepared using NaF. Distilled water was used as the control. Zebrafish embryos after 2 hours of post fertilization (hpf) were exposed to different solutions, thirty per each and triplicated. Mortality, hatching rates, heart rates and morphological abnormalities were observed using a light microscope (10×4) until 96 hpf. The highest mortality, 27.8% was recorded in solution 1 and others were 15.5%, 20.0% and 8.8% respectively. The hatching rate was recorded after 54 hpf and it was 3.3%, 16.6%, 11.1% and 22.2% for each solution. Heart rate was lowest in solution 1 as 84 beats per minute (bpm) and highest in solution 4 as 100 bpm. Subsequently, control showed 0% mortality, 80% hatching rate and 140 bpm heart rate at the same time. Around 40% of embryos showed morphological abnormalities such as yolk sack oedema and bent body axis in solutions 1 and 3. Oedema in belly region indicates the damaged pronephros, which alters the kidney function in embryos. Results emphasize the adverse developmental effects of total hardness and fluoride combinations on embryos as it increases mortality, reduces hatching rate and heart rate. Especially higher levels of fluoride induce having physical deformities, organ damages and reduce blood flow in embryos. These effects on early development can reduce embryonic viability, organ functioning and survival in the natural environment.
Description
Keywords
Fluoride, Hatching rate, Heart rate, Mortality, Total hardness
Citation
Imanthi K. P. A.; Wanigasuriya J. K. P.; Perera P. P. R.; Jayasundara N.; Manage P. M. (2024), Determination of combined acute toxic effects of well water hardness and fluoride using the embryos of Danio rerio (zebrafish), Proceedings of the International Conference on Applied and Pure Sciences (ICAPS 2024-Kelaniya) Volume 4, Faculty of Science, University of Kelaniya Sri Lanka. Page 32