August 2023

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ABSTRACT Atrazine, a Restricted Use Pesticide classified by the EPA, is known to contaminate surface water and groundwater, primarily through agricultural runoff. Elevated levels of atrazine beyond EPA drinking water standards have raised concerns about human health impacts. Atrazine has been linked to adverse reproductive effects in wildlife and amphibians, with water contamination being a significant contributor. Studies have shown that Atrazine is linked to the decline of amphibians and other species. It is a known endocrine disruptor that affects sexual development in amphibians by changing the hormone cycle. Furthermore, ongoing research is exploring its potential as an endocrine disruptor and carcinogen. Despite the risks, atrazine remains popular in agriculture due to its effectiveness in controlling broadleaf and grassy weeds. So why is it used in agriculture so regularly? The mechanism of action is that atrazine disrupts photosynthesis in most broadleaf plants and grasses. Once applied it is taken up by the root system and the leaves moving upward in the plant areas of new growth making the plant dry out and die. While it is very effective in killing weed systems in 14-21 days, atrazine is shown to stay in the soil system for approximately 6 weeks after only one application. In those 6 weeks, many things can occur that can distribute the herbicide into many other locations which can in turn get into human systems. For instance, one of the top concerns is soil runoff getting into human water systems after excessive agricultural watering or even in a natural event of a rainstorm. Another instance would be the aerial application of the herbicide being distributed by the wind to another location the chemical was not initially intended for due iii to wind dispersion. The wind carries contaminants away from their intended source a problem in dry windy rural areas. Another factor that affects this herbicide would be volatilization which can also escape into our atmosphere. All the above factors are important arguments that need to be researched further as a circumstance that can cause human health issues with the distribution and use of atrazine leading to possible human exposure. To investigate its effects on community health, this study focused on two main areas, with particular emphasis on using the standard plant test system, Allium cepa. In the experiment, Allium cepa bulbs were subjected to various concentrations of the herbicide in chemical treatments. Allium cepa, commonly known as green onion, serves as a widely used “test system” for evaluating the impact of different mutagens on organisms globally. This versatile plant species is utilized as a model organism in chemical screening processes and in situ assessments to determine the genotoxicity of environmental contaminants. A.cepa offers several advantageous characteristics for cytological studies, making it an ideal test system. When cultivated hydroponically, it exhibits prolific root growth. The plant's chromosomes are large, well-defined, and present in a limited number (2n=16), allowing for easy analysis from metaphase plates. The second test system used for experimentation was the Daphnia magna. Daphnia as an indicator of environmental pollutants’ sensitivity. Daphnids reflect a high sensitivity to environmental pollutants because they are sensitive to toxicants and indicate water pollution. Daphnids demonstrate reproductive decline, aberrant vertical mobility, and phenoplasticity to name a few when exposed to environmental stressors. Abiotic and biotic stressors include chemical substances, synthetic hormones, acidity, salinity, etc. I iv tested the survival rate of Daphnia at different concentrations of the herbicide and recorded the concentration for the LD50 (Lethal Dose 50). I found that Daphnia exhibited lethality even with the very lowest experimented dose of the herbicide proving thereby the herbicide subjected to this experiment is both genotoxic and lethal to the daphnid and other organisms.



Biology, General


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