الفهرس 
acknowledgmentOnly 14 pages are availabe for public view
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Abstract
Hazards of Environmental Contamination Through Indiscriminate and Widespread use of a variety of anthropogenic chemicals have attracted global attention. An evaluation of the potential toxic effects of these chemicals on aquatic ecosystem usually begins with routine laboratory tests using standard test organisms. Artemia has drawn interest as a marker organism for environmental pollution. Its natural characteristics (high prolificacy, short life cycle, and the possibility to be maintained under laboratory conditions) make Artemia an ideal animal model for toxicity testing.
In this study, 24 h acute toxicity tests were conducted using instar II-III nauplii of Artemia salina to assess the toxicity of four insecticides; chlorpyrifos, profenofos, malathion, and fenpropathrin, two pharmaceuticals; diclofenac sodium and 17α-ethynylestradiol, and two detergents; sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB). The mean LC50 values indicated high toxicity of insecticides and were 7.34, 12.49, 56.11, and 16.16 mg/L for chlorpyrifos, profenofos, malathion, and fenpropathrin, respectively. Pharmaceuticals showed low toxicity with mean LC50 values of 216.57 and 405.85 mg/L for diclofenac sodium and 17α-ethynylestradiol, respectively. Detergents were highly toxic with mean LC50 values of 9.07 and 11.72 mg/L for SDS and CTAB, respectively.
In vivo and in vitro bioassays on biomarkers of exposure to chemical pollution; AChE and GST were conducted to detect the adverse affects of these chemicals on A. salina.
The AChE and GST activity values measured in unexposed A. salina nauplii were 14 ± 1.23 and 38 ± 2.64 nmol/min/mg protein, respectively.
The in vivo results showed that AChE was clearly inhibited by organophosphorus insecticides. AChE inhibition reached 87% and 82% at concentration of 2 mg/L in chlorpyrifos and profenofos exposed nauplii, respectively. Malathion caused a 32% inhibition at a concentration of 50 mg/L. The pyrethroid insecticide fenpropathrin caused a maximum AChE inhibition of only 9% at 10 mg/L. The pharmaceuticals; diclofenac sodium and 17α-ethynylestradiol had no effect on AChE activity. The detergents; SDS and CTAB at a concentration of 5 mg/L caused a maximum AChE inhibition of 33% and 26%, respectively.
The in vitro results were similar to those obtained in vivo. AChE inhibition reached 91%, 84% and 67% at maximum concentration of 100µM for chlorpyrifos, profenofos and malathion, respectively. No inhibition was measured for fenpropathrin, diclofenac sodium or 17α-ethynylestradiol. In vitro AChE inhibition for SDS and CTAB reached 47% and 38%, repectively, at the maximum concentration.
No effect on in vivo or in vitro GST activity was observed when Artemia salina nauplii were exposed to the tested insecticides, pharmaceuticals or detergents.
In conclusion, the present study proved that the brine shrimp assay could be a simple and accurate method to assess the aquatic toxicity profile of any toxicant.
The inhibition of AChE activity following exposure of the organism to the organophosphorus insecticides; chlorpyrifos, profenofos, and malathion was highly effective as a specific biomarker of exposure and/or effect, depending on the concentration. AChE was also clearly inhibited by the detergents; SDS and CTAB indicating that the neurotoxic effects consequent to detergents exposure can be of particular ecotoxicological interest.
On the other hand, GST was ineffective as a biomarker of the tested insecticides, pharmaceuticals and detergents exposure.
Concerns over the possible environmental effects of low level continuous aquatic exposure to pharmaceuticals call for the need of chronic toxicity testing to investigate the potential long-term ecotoxicological effects.
In addition, further investigations are recommended to study the effects of extensively used chemicals using sediment toxicity tests and to evaluate water quality of highly polluted areas by direct toxicity assessment.