The world's most widely used herbicide has been detected in the air and water on some agricultural areas well beyond the times of year when it is applied, suggesting the potential for environmental and health impacts, two studies by the U.S. Geological Survey found.
The research focused on tracking glyphosate, the active ingredient in Monsanto's Roundup herbicide, in Mississippi and Iowa.
"The real significance of this study is the documentation that it is present in the streams year-round in warm areas like Mississippi where it is used on crops from spring to fall," Paul Capel, a study co-author and head of the agricultural chemicals team at the U.S. Geological Survey, told msnbc.com. "It is also present most of the time in the air and rain most of the time."?
"The almost continual occurrence of the chemical suggests that subtle environmental impacts be considered and investigated," he added.
Capel said glyphosate was found in every stream sample examined in Mississippi in a two-year period and in most air samples taken.
"So people are exposed to it through inhalation," said Capel.
In Iowa, on the other hand, levels were not observed outside of the growing season. Capel attributed that to several factors, including a relatively shorter growing season and a colder climate.
"The direct toxicity of glyphosate to humans and animals is very low, so the direct effect is not significant," he said, but what's needed are more tests to determine if glyphosate might be harmful to people and the ecosystem over long-term, low-level exposure.
"The concentrations of glyphosate in rain and stream water is relatively high compared to most other conventional herbicides," Capel said, noting that glyphosate was commonly observed at concentrations about 10 times greater than the other herbicides. "But to put it into perspective, the concentrations are still 1,000 times lower than nitrate or sediment."
The study comes on the heels of several others released recently that raise concerns about the rise of resistant "super weeds," and other unintended consequences of Roundup on soil and animals.
It is difficult and costly to test for the presence of glyphosate, which is used to control weeds on farm fields, golf courses and in residential yards. As a result, little research has been done on its occurrence in waterways and the air, according to Capel.
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"This study is one of the first to document the consistent occurrence of this chemical in streams, rain and air throughout the growing season," said Capel. "It is used so heavily and studied so little."
The USGS studies were published late last month in the journals Environmental Toxicology and Chemistry, and Pest Management Science.
Monsanto introduced glyphosate to the world in 1974 branded as Roundup, and has made billions of dollars over the years from Roundup herbicides as well as from the "Roundup Ready" corn, soybeans and cotton the company has genetically engineered to survive dousings of glyphosate.
Most of the corn, soybeans and cotton grown in the United States are part of the Roundup Ready system.
The USGS said more than 88,0000 tons of glyphosate were used in the United States in 2007, up from 11,000 tons in 1992. The big increase in usage has spurred concerns on many fronts, most recently from farmers and environmentalists noting the rise of "super weeds" that are resistant to Roundup.
Fast-growing, glyphosate-resistant weeds are choking out crops in some areas, and some scientists say research shows harmful effects of glyphosate products on soil organisms and plants.
The Environmental Protection Agency is reviewing the registration for glyphosate and the data gathered by the U.S. Geological Survey has been submitted to the EPA, said Capel.
The EPA has set a deadline of 2015 for determining if glyphosate should continue to be sold or in some way limited. The EPA is working closely with regulators in Canada as they also assess the ongoing safety and effectiveness of the herbicide.
Monsanto spokeswoman Kelli Powers said the company was reviewing the study. The EPA had no immediate comment on the study.
Reuters and msnbc.com's Miguel Llanos contributed to this report.
Source: http://www.msnbc.msn.com/id/44357983/ns/us_news-environment/
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