الفهرس 
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Abstract
Pesticides are one of the most important synthetic chemicals which have a role in the environmental pollution. Among the pesticides group, there was the herbicides which are used in the periodic irradication of weeds and undesirbie plants. Herbicides pollute the water either directly by its use for irradication of the aquatic weeds grow in tilapia ponds or indirectly by its leaching from the treated lands to the adjacent agricultural water canal.
Drainage water are used for filling the ponds in fish farm with
subsequent harmful effects on aquatic animals specially fish. The present study aimed to determine the possible toxicological effects of the herbicide glyphosate on Nile tilapia fish “Oreochromis niloticus” exposed to, 1/5, 1/10 and 1/20 LC5O, in a comparison to control group. This study is divided into three main parts:
* The first part:
A survey study for detection of glyphosate in land drainage water
samples collected from different governorate. The highest glyphosate level was found in Giza governorate, followed by El-Kalubia governorate, then El-Sharkia governorate and the last one was El Monofia governorate.
* The second part:
Determination of 96-hour LC5O of the herbicide glyphosate. The
acute toxicity of glyphosate (96-hr LC5 0) was 10.14 ppm for 0. Niloticus fish.
* The third part:
In this part, eighty fishs were divided into four equal groups, the
first group used as control, the other three groups were administered glyphosate in water at the dose level of 2.14, 1.07 and 0.54 ppm for two months. Blood samples were collected every 15 days for haematological investigations RBCs and WBCs count, Hb%, PCV%, MCH, MCHC, MCV and differential leukocytic count. At the end of the experiment, sera samples were taken for biochemical analysis, and blood sampling for determination of the respiratory function of the blood were taken. Fresh tissue samples were taken from liver, kidney, spleen, gill, heart, brain and intestine for histopathological examination. Mutagencity testing of glyphosate and estimation of its residues in muscles and liver of the treated fish were preformed.
Glyphosate caused a significant decrease of RBCs and PCV of fish treated with 1/5 LC5O (2.14 ppm) and 1/10 LC5O (1.07 ppm) after 15 and 30 days. While, in fish treated with 1/20 LC5O( 0.54 ppm), non significant decrease was recorded.
The hemoglobin (Hb) content showed a significant decrease after
15 and 30 days in fish treated with 2.14 ppm glyphosate, while that
treated with 1.07 showed a significant decrease after 30 days. The third group treated with 0.54 ppm showed a non significant decrease. The MCH, MCHC and MCV were changed to compansate the changes in RBCs, Hb and PCV.
Glyphosate caused a significant decrease of WBCs in fish exposed to 2.14 ppm and non significant decrease in fish exposed to 1.07 and 0.54 ppm. The differential leucocytic count showed significant decrcase of lymphocytes in fish treated with 2.14 ppm after 45 and 60 days and after 60 days in fish exposed to 1.07 ppm while fish treated with 0.54 ppm showed non significant changes.
Also, differential leukocytes count showed significant increase of
heterophile in fish treated with 2.14 and 1.07 ppm at the end of the
experiment. Other leukocytic cells (Basophiles and Eosinophiles) showed hesitated or non significant changes compared to control group. The biochemical study on fish’s sera indicated a significant
increase in the activity of alkaline phosphatases, ALT, and AST in the sera of all treated fish groups. Also a significant increase in urea and creatinine levels in fish exposed to 2.14 and 1.07 ppm was recorded. The fish group treated with 0.54 ppm showed non significant change. The venous blood P02 decreased after 2 months while PCO2 and PH showed non significant changes, this decrease in P02 may be due to gill dysfunction.
The HCO3 and base excess may changed irregularly in venous
blood which may be due to the disturbarces in the physiological state of the intoxicated fish. Chromosornal analysis of treated fish showed a non significant increase in structural aberrations (gaps, break, fragment, deletion, centro meric attenuation), numerical aberrations (aneuploidy and polyploidy) and condensation or stickness. These results, indicate that glyphosate didn’t induce mutagenic effects to 0. niloticus fish.
The residues of glyphosate in muscles and liver were estimated by
HPLC with levels higher than the permissible limit.
The histopathological study in liver showed presence of sever
vacuolar and hydropic degeneration of the hepatocytes, dilatation of the central vein and portal vessels with hyperplasia of the bile ductal epitheliurn. Kidneys showed congestion of renal blood vessels with, vacuolar and hydropic degeneration of the renal tubules. Spleen showed congestion of splenic blood vessels with activation of the melane macrophage centers. Gills showed congestion of blood vessels, hyper plasia of gill larnella and gill larnellar fusion. Brain showed neural degeneration with congestion of the cerebral blood vessels. Heart showed congestion of myocardial blood vessels with lymphocytic cellular infiltration. Intestines showed catarrhal enteritis.