14 DAY TRIAL // The greediness of the farmers has gone up to the point when they would like to see just corn and nothing else on a cornfield.
And atrazine is one of the most widely employed allies, possibly the most employed herbicide worldwide and one of the most common contaminants in ground and surface water, a long-lived poison encountered even at the poles.
But atrazine does not stop to weeds and is provoking die-offs in stream salamanders, as found by a group investigating the role of atrazine in global amphibian declines.
Moreover, atrazine's toxicity may not be seen in short-term studies, and even extremely low levels of the chemical can be harmful in the long run.
"We are concerned that most studies used to make pesticide registration decisions and to derive safe concentrations last for about four days," said Jason R. Rohr, research associate at the Penn State Institutes of Energy and the Environment.
"They often do not consider recovery processes, persistent effects of chemical exposure, or interactions among individuals within and between species that can affect our estimates of safe chemical concentrations."
Rohr's team at the University of Kentucky, Lexington, exposed streamside salamander larvae to either 4, 40, or 400 parts per billion of atrazine until metamorphosis, the stage where the aquatic larvae lose their gills and develop lungs that enable them to breathe air.
The team tracked their survival to near sexual maturity, about 500 days, and found that the two highest levels rose salamander mortality during exposure.
The larvae mortality benefited the survivors who faced decreased competition-related mortality after metamorphosis.
But this advantage was weak in comparison to the persistent atrazine effects that kept on causing mortality after exposure ceased.
Compared to non exposed salamanders, those surviving the atrazine exposure had a much less survival level 421 days after the exposure.
The net effect of atrazine exposure was even worse later in life than during the exposure.
"The biggest surprise was that it took nearly a year to detect the effects of atrazine at 4 parts per billion, which is just 1 part per billion above the maximum allowable level in drinking water set by the U.S Environmental Protection Agency," said Rohr.
"What this tells me is that we need to consider the long-term effects of chemicals, and that exposure to atrazine during formative stages might have permanent effects on these salamanders; that increases their risk of mortality," he added.
Researchers believe atrazine is an endocrine disruptor, impairing production of hormones that are crucial to normal bodily functions.
Atrazine levels as low as 0.1 parts per billion were found to inflict male frogs to develop both male and female organs by changing their production of sex hormones.
Atrazine could be implied in global amphibian decline.
"Salamanders, and amphibians in general, are crucial to ecosystems, as both predators and prey. They can be seen as bioindicators of environmental stress and harbingers of risk to other animals as well as humans," explained Rohr.