Journal of Environmental Biology

Histopathological alterations of Nile tilapia, Oreochromis niloticus

in acute and subchronic alachlor exposure

Piyanut Peebua¹, Maleeya Kruatrachue*², Prayad Pokethitiyook¹ and Sombat Singhakaew¹

¹Department of Biology, Faculty of Science, Mahidol University, Bangkok - 10400, Thailand

²Department of Biology, Faculty of Science, and Mahidol University International College, Mahidol University, Bangkok - 10400, Thailand

(Received: December 20, 2006; Revised received: August 03, 2007; Accepted: August 30, 2007)

Abstract: Histopathological alterations in Nile tilapia, Oreochromis niloticus, aged 3 months and subjected to acute and subchronic alachlor exposure were studied by light microscopy. LC50 values of alachlor for 24 hr, 48 hr, 72 hr and 96 hr were 963.6, 563, 448, and 381.9 μg l-1, respectively and the maximum acceptable toxicant concentration (MATC) was 350 μg l-1. Fish were exposed to 381.9 (acute) and 35 μg l-1 (sub-chronic) of alachlor for 24, 48, 72 and 96 hr and 90 days, respectively. Gill lamellae and kidney tubules were the primary target organs for the acute toxic effect of alachlor while in the subchronic exposure, the toxic effect on the gills was less marked than that of the kidneys and liver. Gill alterations included edema of the epithelial cell system, aneurisms with some ruptures, hypertrophy and hyperplasia of epithelial cells. The liver showed hydropic swelling of hepatocytes and vacuolation. Lipid vacuoles were observed in hepatocytes in the second and third month of subchronic exposure. The kidney showed hydropic swelling of tubular cells, lipid vacuole accumulation in many tubules, and nuclear pyknosis. The findings of this study could be used as a guideline for biomonitoring programs on populations of Nile tilapia cultured near alachlor contaminated areas.

Key words: Acute exposure, Alachlor, Histopathological alterations, Oreochromis niloticus, Subchronic exposure

PDF of full length paper is available with author (scmkt@mahidol.ac.th)

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