Abstract:
Disinfection is intended to improve drinking water quality and human health. Though,
disinfectants may transform organic matter and form disinfection by-products (DBPs), many of
them branded as cyto and genotoxic in nature. Traditionally, research focuses on the effects of
DBPs to human health, but cytogenic and genotoxic impacts on aquatic organisms still remained
ill defined. Which is why, current study examines the potential toxic effect of chloroform and
iodoform (DBPs) on common carp (Cyprinus carpio), selected as a model organism. Healthy
fish specimens were exposed to various concentrations of chloroform and iodoform primarily
based on LD50 values, where acute toxicity was monitored for 96 h. The LD50 was determined to
be 3 and 90 mg/L for iodoform and chloroform respectively. Headspace SPME analysis through
gas chromatography was conducted to assess either applied doses (75.5 – 87.5 and 2.1 -2.9 mg/L
for chloroform and iodoform respectively) effects fish blood samples or not. Genotoxicity was
monitored using Comet assay. Tail length, tail DNA and olive tail moment values were
quantified to be significant (P<0.05) as compared to control. Results shows that the mean tail
length values for iodoform (11, 17,25,33,41 μm) was significantly higher than chloroform (6, 12,
15, 18.3,22 μm) at all observed concentrations. Cytotoxicity through hematology and
biochemistry showed a dose-response relationship. Statistically significant (p<0.05) decrease in
all blood parameters {(white blood cells (WBC), red blood cells (RBC), platelets (PLT),
hematocrit (Hct), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH),
mean corpuscular hemoglobin concentration (MCHC) and hemoglobin (Hgb)} was observed
with increase dose concentration and exposure time. The change was more significant in case of
iodoform at all administered doses in comparison to chloroform analogue. The changes in
biochemical indices (glucose, total protein and alanine aminotransferase) were also statistically
significant (p<0.05). But, ALT secretion was significantly increased (93±0.05 and 82.8 ±0.1U/L)
at higher concentration compared to control (56±0.1U/L), suggesting liver damage. Thus, results
demonstrated that iodoform was statistically more damaging as compared to chloroform.
Keywords: Biochemical count, chloroform, comet assay, cytotoxicity, disinfectant by-products, genotoxicity,
hematology, iodoform.
