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Toxic Effects of Dimecron to Labeo Rohita Ham. Fingerlings During Acute and Chronic Exposures: Histopathological Changes

M. Akhter
Department of Zoology, Dhaka University, Dhaka 1000, Bangladesh

A.R. Mollah
Department of Zoology, Dhaka University, Dhaka 1000, Bangladesh

M.M. Kadir
Department of Zoology, Dhaka University, Dhaka 1000, Bangladesh

M.A. Khaleque
Department of Fisheries, Dhaka

Abstract/ Executive Summary:

The exposure to the highest dimecron cone. (8 mg/l) resulted in severe histopathological changes in different tissues of Labeo rohita fingerling. Cell necrosis, cytoplasmic vacuolation and pycnotic nuclei were major abnormalities observed in liver tissue. The degeneration of glomeruli and proximal tubules, cytoplasmic vacuolation and focal haemorrhagic area were noted in case of kidney tissues. Major changes observed in intestinal tissues were degeneration of villi, disintegrity of mucosal layers, necrosis of epithelial cells etc. However, hypertrophy of cells and granulation of cytoplasm were major histopathological changes observed in fish at lower dimecron concs. (4 mg/l).

Keywords: Toxicity, Dimecron, Histopathology, L. rohita

Location: Dhaka University.

Start Date:

End Date:

Program Area: Pest Management

Commodity: Carp fish

Objectives:

To investigate changes in liver, kidney and intestinal tissue of L. rohita in chronic exposure to dimecron.

Methodology:

The experimental system consisted of 6 circular earthen tumblers and were of 40 litres capacity each. Oxgenation of individual tumbler was done by using air stones connected to a air compressor. Fingerlings of Labeo rohita were used as test animal and they were fed with mixture of rice bran and oil cake, twice daily at the rate of 2% body weight. Feeding was stopped two days before the commencement of toxicity trial. The pesticide concentration of "Dimecron 100SCW"- a widely used pesticide used in the present study, were selected arbitrarily on the basis of information obtained from a parallel bioassay study with same fish. In that particular study, the LC₅₀ of the dimecron found to be approximately 20 mg/l. A conc. of 8 mg/l dimecron did not kill the fish during a 4-day exposure period, thought a level of 8 mg/l dimecron might not kill the fish during a prolonged exposure period but may induce noticeable stress response. The logic behind selecting this cone. was thus to demonstrate the toxic effects in the selected parameters. A further cone. of 4 mg/l was used to ascertain whether such a lower cone. is still able to produce stress on fish. After acclimation, six groups of fish, two groups served as control while other groups, in duplicate, were challenged by dimecron. The dimecron cone. in the tumblers were achieved by adding calculated amount of freshly prepared stock solution of the toxicant directly in to the respective tumblers. The experiment was run for 42 days. The fish was inspected several times a day and any dead found was removed immediately. A natural photoperiod of approximately 12 hours dark: 12 hours light was available. At the termination of the experiment, the fish were sacrificed and kidney, liver, intestine and stomach were dissected and preserved for histopathological study. Tissue samples were taken from all treatment groups. For each treatment, at least 6 fish were sampled randomly. For consistency, a fixed sections of the organ systems were sampled. After washing in physiological saline, the tissue samples were fixed in 10% buffered formalin and left for at least one week before further processing. Tissue processing: Fixed tissue were cut into suitable pieces and labeled. The processing involved passing the tissue through different alcohol grades for dehydration. Processed tissue were then blocked in suitable moulds with molten wax and allowed to cool on a cool plate. The blocks were trimmed in order to bring the tissue to the surface of the block. Serial sections of 3-5 micron thickness were cut on a Leitz-wetzlar microtome using Richert Jung disposable microtome blades. Sections were collected on prewashed wet glass slides. The slides were then marked and dried and no adhesive was used. Stained tissue sections were observed under an Olympus compound microscope and photomicrographs from representative histological sections were taken on Leitz-wetzlar photomicroscope.

Source of Information: Bangladesh J. Fish. Res., 5(1), 2001: 37-44

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

The present study detected many abnormalities in tissues caused by dimecron exposure, even at the lower concentration of dimecron used, although changes were less severe indicating that this level of dimecron is not safe from histopathological point of view. It is interpreted on the basis of histopathology that severe imbalance in many physiological process might have occurred in dimecron exposed fish.

Knowledge Management: Journal