Acute and chronic toxicity of potassium bromate (KBrO₃) in zebrafish (<i>Danio rerio</i>): Behavioural and hepatic effects.
KBrO₃ exposure in zebrafish led to significant behavioral and hepatic changes, with a 96-h LC₅₀ value of 1052.6 mg L⁻¹, indicating sublethal effects occur below acute mortality levels.
Where it sits
this study against the rest of the efsubaglutide corpusSummary and findings
This study evaluated the acute and chronic toxicity of potassium bromate (KBrO₃) in zebrafish, focusing on behavioral and hepatic responses. Adult zebrafish were exposed to KBrO₃ for 96 hours to determine median lethal concentration (LC₅₀) values and for 21 days for chronic effects. The 96-h LC₅₀ value for KBrO₃ was estimated as 1052.6 mg L⁻¹.
Abstract
Potassium bromate (KBrO₃) is a known food additive and environmental pollutant with documented oxidative and genotoxic effects in mammals, yet its impact on aquatic organisms remains poorly characterized. To date, studies integrating behavioural, physiological, and histopathological endpoints for KBrO₃ toxicity in zebrafish have been limited. This study aimed to evaluate the acute and chronic toxicity of KBrO₃ in zebrafish (<i>Danio rerio</i>), focusing on behavioural and hepatic responses. Adult zebrafish were exposed to graded concentrations of KBrO₃ for 96 h following OECD Guideline 203 to determine median lethal concentration (LC<sub>50</sub>) values. Behavioural parameters, including swimming speed, exploratory activity, and vertical zone preference, were analyzed. For chronic toxicity, fish were exposed to KBrO₃ for 21 days, and liver tissues were examined histologically following hematoxylin and eosin staining. Random blood glucose was measured immediately post-exposure. The 96-h LC₅₀ value for KBrO₃ was estimated as 1052.6 mg L⁻¹ . Acute exposure was associated with reduced locomotor activity, including decreases in swimming speed and exploration rate, along with increased bottom-zone activity. Chronic exposure (21 days) was associated with elevated blood glucose levels and hepatic alterations including vacuolization, sinusoidal dilation, hepatocellular degeneration, and necrosis. KBrO₃ exposure induced measurable behavioural, physiological, and hepatic alterations in zebrafish, demonstrating that sublethal biological effects occur at concentrations below those causing acute mortality. These findings provide baseline hazard characterization data for KBrO₃ in an aquatic vertebrate model and support future studies aimed at environmental risk assessment and mechanistic evaluation of bromate toxicity.
Background
Potassium bromate (KBrO₃) is recognized for its oxidative and genotoxic effects in mammals, but its impact on aquatic organisms, particularly zebrafish, is not well understood. Previous studies have primarily focused on mammalian models, leaving a gap in knowledge regarding KBrO₃'s effects in aquatic environments. This study aims to fill that gap by assessing both acute and chronic toxicity in zebrafish, which are widely used as a model organism in toxicology.
Methods
Adult zebrafish were exposed to graded concentrations of KBrO₃ for 96 hours to determine median lethal concentration (LC₅₀) values, following OECD Guideline 203. Behavioral parameters such as swimming speed, exploratory activity, and vertical zone preference were analyzed. For chronic toxicity, fish were exposed to KBrO₃ for 21 days, and liver tissues were examined histologically after hematoxylin and eosin staining.
Results
The 96-h LC₅₀ value for KBrO₃ was estimated as 1052.6 mg L⁻¹. Acute exposure resulted in decreased locomotor activity, including reduced swimming speed and exploration rate, alongside increased bottom-zone activity. Chronic exposure for 21 days led to elevated blood glucose levels and significant hepatic alterations, including vacuolization and necrosis.
Interpretation
The findings indicate that KBrO₃ exposure results in both acute and chronic effects on zebrafish, with measurable behavioral and physiological changes occurring at concentrations below those that cause acute mortality. While the study provides important baseline data for environmental risk assessment, the clinical significance of these findings in relation to human health remains unclear. Limitations include the focus on a single species and potential confounding factors not addressed in the abstract.
Key findings
- 96-h LC₅₀ value for KBrO₃ was estimated as 1052.6 mg L⁻¹.
- Acute exposure was associated with reduced locomotor activity, including decreases in swimming speed and exploration rate.
- Chronic exposure (21 days) was associated with elevated blood glucose levels.
- Hepatic alterations included vacuolization, sinusoidal dilation, hepatocellular degeneration, and necrosis.
Limitations
- Not reported in abstract.