This little guy is atrazine, the most widely used herbicide in the US (about 76 million pounds annually). Generally, it is used in corn and soybean farming; it is incredibly effective in preventing weeds and grass coming up between the plants….requires no tilling (i.e. no work) = no erosion/runoff. Industrials farmers love this stuff.
Atrazine typically has a relatively short half life, about 30 -100 days in soil. It breaks down via chlorination or by microbes to cyanuric acid…which is a carbon and nitrogen source in the soil.
Atrazine is also highly solubilized in water…often traveling into streams, runoff, and rainwater.
So why should I care?…Atrazine has been shown to be a potent endocrine disruptor in animals (at various doses). It has the chemical ability to transform testosterone into estrogen (mainly shown in fish, amphibians, and reptiles). Essentially, it can induce hermaphroditic behavior. It almost goes without saying that this change is devastating, especially to immune system resulting in increased mortality rates (again shown most predominantly in amphibians).
That being said, the EPA maintains the safety of atrazine when used properly and in low concentrations. Syngeta, the manufacturer, also maintains its safety.
I’ll be posting a more detailed analysis of atrazine effects in water. But for now, here are a number of links to more resources.