Atrazine is an agricultural herbicide that’s widely used by farmers to control broadleaf weeds & grasses that interfere with the growth of corn, sorghum, sugar cane, and other crops. Atrazine is also used as a weed killer on golf courses, Christmas tree farms, and in commercial and residential landscaping. Runoff washes the chemical into streams, rivers, and groundwater; it’s one of the most common pollutants found in American waters.
The chemical is produced by the Swiss agrochemical company Syngenta and was first registered for use in the United States in 1959.
The herbicide has been banned in the European Union since 2004, with individual countries in Europe beginning to ban Atrazine as early as 1991.
Atrazine may protect crops and lawns from certain types of weeds, but it’s a serious problem for other species. The chemical is a potent endocrine disruptor that causes immunosuppression, hermaphroditism and even complete sex reversal in male frogs at concentrations as low as 2.5 parts per billion (ppb)—well below the 3.0 ppb that the U.S. Environmental Protection Agency (EPA) says is safe. A study recently found that 10% of male frogs reared in atrazine laced water turned into females while being exposed to 2.5 ppb of Atrazine.
This problem is particularly acute because amphibian populations worldwide have been declining at such unprecedented rates that, today, nearly one-third of the world's amphibian species are threatened with extinction.
Atrazine has also been linked to reproductive and developmental abnormalities, behavioral changes, increased disease, & reduced survival, growth, immunity, and sensory capacities in aquatic life. There’s also evidence the herbicide harms plants and wildlife.
Epidemiological studies also suggest that atrazine is a human carcinogen and leads to other human health issues. Researchers are finding an increasing number of links between atrazine and poor birth outcomes in humans. A 2009 study, for example, found a significant correlation between prenatal atrazine exposure (primarily from the drinking water consumed by pregnant women) and reduced body weight in newborns. Low birth weight is associated with an increased risk of illness in infants and conditions such as cardiovascular disease and diabetes.
Timing of exposure may be more important than exposure levels. Research shows that low levels of exposure during key periods of pregnancy may interfere with healthy fetal development. The third trimester of pregnancy appears to be most critical, says a recent epidemiological study.
Atrazine also interferes with hormonal activity of humans at extremely low doses, causing:
Reproductive Effects: Because atrazine disrupts hormones, it's not surprising that epidemiological studies find associations between exposure to the herbicide and reproductive effects including increased risk of miscarriage, reduced male fertility, low birth weight, increased chance of any birth defect, and higher incidence of abdominal defects;
Cancer: Evidence for the carcinogenic potential of atrazine is growing — exposure has been linked to elevated risk of breast, thyroid, ovarian, prostate, and other cancers. The recent President's Cancer Panel Report notes that atrazine has possible carcinogenic properties.
IN 2016, CALIFORNIA ADDED ATRAZINE AND RELATED CHEMICALS TO THE PROPOSITION 65 LIST, LISTING THEM AS SUBSTANCES KNOWN TO CAUSE REPRODUCTIVE AND DEVELOPMENTAL TOXICITY.
The public health issue is a growing concern because Atrazine is also the most commonly detected pesticide in American groundwater. As one of the most widely used herbicides in the U.S., it’s found in 94% of U.S drinking water tested by the USDA. An extensive U.S. Geological Survey study also found atrazine in approximately 75% of stream water and about 40% of groundwater samples in the agricultural areas tested.
The highest levels of contamination are in the Midwest where it is widely used on corn fields. USGS monitoring shows drinking water concentrations typically spike during the spring and early summer as rains flush the freshly applied herbicide into streams — and into local water supplies.
According to NRDC's 2010 analysis of the most recent EPA data, drinking water in 67 public systems had peak Atrazine levels above 3 ppb, with one as high as 60 ppb in Ohio. Six water systems had average annual Atrazine concentrations that exceeded the EPA limit entirely. And these figures are for treated drinking water — raw water samples contained even higher concentrations.
Atrazine is not only widely present in the environment, but it’s also unusually persistent.
Every year, more than half a million pounds of atrazine drift off during spraying and falls back to Earth in rain and snow, eventually seeping into streams and groundwater and contributing to chemical water pollution.
The EPA re-registered atrazine in 2006 and deemed it safe, saying that it posed no health risks for humans. The NRDC and other environmental organizations question that conclusion, pointing out that the EPA's inadequate monitoring systems and weak regulations have allowed Atrazine levels in watersheds and drinking water to reach extremely high concentrations, which certainly puts public health in question and possibly at serious risk.
In June 2016, the EPA released a draft ecological assessment of atrazine, which recognized negative consequences of the pesticide on aquatic communities, including their plant, fish, amphibian, and invertebrate populations. Additional concerns extend to terrestrial ecological communities. These findings concern the pesticide industry, of course, but also many farmers who rely on Atrazine to control hardy weeds.
To make matters worse, the U.S. Environmental Protection Agency (EPA) recently announced that it would allow 50% MORE atrazine in the surface water along the nation’s waterways, despite all of the scientific evidence warning against Atrazine.
“Atrazine is a hundred times worse than glyphosate, the active ingredient in Roundup, because it’s an endocrine disruptor,” said Nathan Donley, a scientist at the Center for Biological Diversity, which has called for a complete ban of the chemical. “It can have huge impacts and should have been banned a long time ago.”
Atrazine has been mired in controversy since Dr. Tyrone Hayes, an industry funded scientist-turned-whistleblower, published a study showing the chemical alters the sex lives of adult male frogs, emasculating most and turning some into females. The feud between Hayes and Syngenta, the biggest manufacturer of atrazine in the U.S., revealed the industry’s zeal to discredit independent scientists, push its own studies, and hold sway in the government’s regulatory process.
In a Civil Eats article, Dr. Hayes reported:
It’s ironic [the EPA] would move to increase the allowable levels after previously coming to the correct conclusion that atrazine is an environmental and biological hazard. Given that research shows that fish and amphibian reproduction and behavior can be damaged by atrazine at levels as low as 0.1 parts per billion (ppb), raising the acceptable levels to 15 ppb is disastrous.
Hundreds of independent lab and field studies have found evidence that opposes Syngenta’s claims. But it was Hayes, a University of California, Berkeley scientist whom Syngenta paid in 1998 to run experiments on atrazine, who fired the first salvo. When he discovered the herbicide altered the sex lives of frogs, the company tried to block the results, Hayes said. And because he refused to toe the company line, the scientist severed ties with Syngenta in 2000. He then repeated the experiments and published a study that showed frogs changed sex by exposure to atrazine at levels 30 times below what the EPA permits in water.
Hayes has since openly fought Syngenta, published other papers, and reported that he had found frogs with sexual abnormalities in atrazine-contaminated sites in Illinois, Iowa, Nebraska, and Wyoming. According to a review by Hayes, the best predictor of whether a study has found atrazine to have significant biological effects was the funding source; when research was funded by the pesticide’s manufacturer, studies have found either no effect or only small effects.
Despite his findings, the EPA approved the continued use of atrazine in 2004. That same year, the European Commission banned the chemical and a class-action lawsuit was filed by several Midwestern cities and towns accusing Syngenta of contaminating their drinking water. The documents unsealed in those lawsuits showed that Syngenta worked to discredit Hayes, with company reps following him to lectures, and attacking him both personally and professionally.
Several other papers also have pointed out flaws in the EPA’s approach to regulating the chemical and the bias embedded in atrazine studies and other publications funded by Syngenta. The researchers in the two studies linked above say the EPA is mired in conflicts of interest and has used only a small portion of the available data to determine a chemical’s impacts, often relying exclusively on industry-supplied studies. In its recent 2012 reassessment of atrazine impacts on amphibians, for example, the EPA relied on a single industry-funded study, while excluding 74 other published studies because they did not meet rigid criteria for study inclusion.
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