The blue dye causes harmful chemical reactions in fish cells that damage their blood, and the more damage there is, the lower the blood’s oxygen-carrying ability becomes.
Scientific Claim
Sub-lethal methylene blue exposure in Labeo rohita is associated with a significant increase in lipid peroxidation (MDA levels up to 7.8 ± 0.6 nmol/g), indicating oxidative damage to cells, which correlates strongly with reduced hemoglobin levels (r = -0.89, p < 0.01).
Original Statement
“Oxidative stress markers, quantified as malondialdehyde (MDA), surged to 7.8 ± 0.6 nmol/g in high-dose groups, correlating strongly with Hb% reduction (r = -0.89, p < 0.01)”
Evidence Quality Assessment
Claim Status
overstated
Study Design Support
Design cannot support claim
Appropriate Language Strength
association
Can only show association/correlation
Assessment Explanation
The abstract implies ROS-mediated damage as causal, but the study design cannot confirm mechanism. Only correlation between MDA and Hb% is demonstrated.
More Accurate Statement
“Sub-lethal methylene blue exposure in Labeo rohita is associated with a significant increase in lipid peroxidation (MDA levels up to 7.8 ± 0.6 nmol/g), indicating oxidative damage to cells, which is strongly correlated with reduced hemoglobin levels (r = -0.89, p < 0.01).”
Evidence from Studies
Supporting (1)
The study found that a small amount of methylene blue made the fish’s cells get damaged by harmful chemicals, and at the same time, their blood couldn’t carry as much oxygen — and these two things were strongly linked.