Toxicity study of diethyl phthalate on Clarias gariepinus fingerlings

Abstract

Diethyl Phthalate (DEP) is used as a plasticizer, a detergent base, in aerosol sprays, as a perfume binder
and after shave lotion. It is known to be a contaminant of fresh water and marine ecosystem. Therefore,
a study was designed to determine the acute toxicity effects of DEP on a fresh water fish, Clarias
gariepinus fingerlings. The fish was treated with 50, 75, 100 and 150 µg/l. DEP was dissolved in distilled
water to determine the LC50. There was 100% mortality observed in 150 µg/l. The LC 50 of DEP was
estimated at log toxicant concentration as 2.217, 2.734, 3.435 and 3.931 µg/l at 24, 48, 72, 96 h and
1.871µg/l for the total death. This shows that the impacts are dose and time dependent with respect to
marked reduction in mortality rate. At sub-lethal concentrations of the test substance at 30, 40, 60 and
80 µg/l in a renewal bioassay system, the water and the test compound were changed intermittently.
One group was maintained as a control in dechlorinated water. There was significant difference (P <
0.05) in brain and muscle AchE activity compared to the control. The liver ACP activity was statistically
significant (P < 0.05) at day 15 while the muscle ACP in other treatment groups showed no significant
difference (P > 0.05). Liver AST showed no significance in all treated groups (P > 0.05) and liver ALT
activity was statistically significant (P < 0.05) at day 30 only. The haematological parameters (HB, PCV,
RBC and WBC) carried out showed that haemoglobin and erythrocyte levels estimated in all treatment
groups to the duration of exposure showed no significant difference (P > 0.05) compared to the control.
The park cell volume showed a significant difference (P < 0.05) at day 30 only. The leucocyte count
throughout the exposure period showed that the mean values are statistically significant (P < 0.05) at
day 15 only compared to the control. The mean cell volume (MCV) showed a significant difference at
day 15 (P < 0.05) whereas mean cell haemoglobin (MCH) and mean cell haemoglobin concentration
(MCHC) showed no significant difference (P > 0.05) throughout the exposure period. No significant
difference was seen between the lymphocytes and the neutrophils. In day 0 and 15 only, the monocytes
and the lymphocytes showed a significant difference (P < 0.05). The gill damages indicated toxicity of
DEP with raised lamella, oedema of the lamella epithelia, loss of lamellar epithelium, mild oedema and
raising of the filament. The liver damage showed focal necrosis and vacuolization, hepatocyte
degeneration in the liver. These alterations may have long term effects on that that are continuously
exposed to DEP in the aquatic environment.