Aquatic pollution by pesticides and/or herbicides, either through
run-off from agricultural land, or by direct applications such as spray
drift, aerial spraying and by discharge as effluents from manufacturing
industries, is recognized as strong biological poisons. Now, it becomes
a threat to non-target aquatic organisms such as fin-fish and shellfish. Now-a-days, the application of herbicides into the aquatic
bodies increases several folds to control the invasive plant species
such as water hyacinth and hydrilla etc. Glyphosate is the most
effective modern third generation, broad-spectrum herbicide andwidely used both in agriculture and paddy-cum-fish-culture system inrecent times. It is a non-selective, cost- effective and post-emergence
herbicide. Glyphosate is a weak organic acid; its chemical name
is N-(phosphonomethyl) glycine. Glyphosate is soluble in water (12
g/l at 25o
C) but insoluble in most organic solvents. Glyphosate
is readily degraded both from water and soil by soil microbes to
aminomethylphosphonic acid (AMPA) and carbon dioxide (CO2
).
Due to strong adsorptive characteristics, glyphosate and AMPA are not
likely to move to groundwater but have the potency to contaminate
surface water. Glyphosate is in the toxicity class of III (on I to IV scale,
where IV is least dangerous) for oral and inhalation exposure.
Cytopathological study provides a fast and efficient process
to delineate the health status of organisms exposed to xenobiotic
substances. Currently, histopathological biomarkers are used
extensively for documenting and quantifying exposure level, as well as
expressing the effects of environmental stressors. A number of studies
on histopathological biomarkers in the evaluation of fish health exposed
to contaminants, both in the laboratory and field studies were reported.
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