10/16/2009 05:12 am ET | Updated May 25, 2011

Thirsting for Truth: No "Safe" Level of Atrazine

Last week's New York Times article "Debating Just How Much Atrazine Is Safe In Your Water Glass" highlights the controversy surrounding the agri-chemical weed killer atrazine in our water supply. It's past time to acknowledge that the legal pollution in our water has unacceptable human consequences.

The increase in potency and variety of toxins interacting in our water should make each of us thirsty for the truth, and compel us to challenge the role and viability of achievable toxicity standards.

An ever-growing body of research demonstrates the need for concern (and ultimately action) over this issue. Most notably I find Dr. Tyrone Hayes's experience working for Ecorisk Inc., a consulting company to Syngenta, to be compelling. A professor of integrative biology, Hayes's work exposes the influence corporate interests can have over academic research, and definitively demonstrates the damaging effects of atrazine at low exposure levels. His findings are clear: frogs, who exhibit the same reproductive hormone vulnerability as humans, experience retarded gonadal development and hermaphroditism when exposed to low levels of atrazine.

A study published this spring by a team of doctors and medical researchers in South Korea was inspired by the overlap of areas in the United States where atrazine is frequently used with areas of prevalent obesity. Their findings illustrate an increase in mitochondrial damage and insulin resistance when exposed to low levels of atrazine in drinking water. Without altering food intake or exercise, the rats tested experienced decreased metabolic rates, increased body weight and intra-abdominal fat, suggesting it is not just our food choices that are problematic.

Looking deeper into the issue, Dr.Warren Porter, professor of zoology and environmental toxicology, emphasizes the discord between the reality of your body's response to exposure and the way in which synthetic chemicals are regulated. Policy is outlined on the principle that higher levels of exposure result in higher levels of damage, i.e. "the dose makes the poison." Yet science indicates that a bell-shaped dose response, where very low levels of exposure at particular stages of human development result in drastic developmental damage, better exemplifies our reaction to exposure.

Even atrazine's advocates do not deny the toxicity of the chemical outright -- it is, in fact, a substance created to kill. Proponents downplay its hazard to human health by contending that known exposure levels are safe. Some scientists support the industry viewpoint, which is summarized by Syngenta in the Times article: "the evidence is overwhelming that atrazine does not cause adverse health effects at levels to which people are normally exposed." What level is that? No one knows for sure. The EPA has been ineffective at monitoring and regulating the low levels of exposure that Hayes and Porter found significant. In fact, allowing the use of atrazine, a proven endocrine disruptor, based on "acceptable levels of exposure," fails to protect the health of the environment and people.

Synergistic Exposure and Bioaccumulation: What Is Not Measured

So what's behind these conflicting risk assessments of this widely used agri-chemical?

The EPA standard of acceptable levels of exposure neglects the synergistic, exponential interaction of repeated and multi-sourced exposure. Atrazine, like other endocrine disruptors, concentrates in the fatty tissue of animals. As tertiary consumers we are not only exposed to pollutants in our water supply, but to high concentrations in our food supply due, in part, to biomagnification. Sitting at the top of the food chain, we consume the highest concentrations of toxins. When have fish for dinner, we are also eating every meal of insects and smaller fish that our dinner had to eat. While our bodies may be able to remove the toxins from a small amount of exposure, our bodies are not equipped to clean the exponentially accumulated toxins from our food. The end result is a toxic load greater than our bodies are designed to handle. We need to re-evaluate the false sense of security that a "safe level of exposure" provides.

After Atrazine: Economic Viability

Removing atrazine from the market is a legitimate option, despite claims to the contrary about agriculture's dependency on atrazine to protect corn yields. In 1991, both Germany and Italy terminated the use of atrazine and found no decrease in corn yields or harvested area. The USDA estimates that corn yields here would decrease by about 1%, if farmers did nothing new to manage weeds.

Many farmers, scientists, public leaders and even the chemical companies know that eliminating toxins from our farms entirely does work. Research here at the Rodale Institute's Farming Systems Trial (FST) has shown that organically-grown corn and soybeans outperform crops grown with synthetic fertilizers and pesticides by 30% and 50%, respectively, in drought years, and yield just as much as chemically-dependent crops in normal years. Moreover, a 2003 review of U.S. studies between 1985 and 1993 reported that yields and overall economic returns in organic farming systems were equal to, or higher than, those from chemically-dependent systems.

Given the ineffectiveness of EPA regulation, neglect of standards to encompass synergistic interactions, and the viability of removing atrazine from the market, agricultural and food safety leaders need to take the reasonable step of following the precautionary principle until we can address the risks.

The difficulty in monitoring and regulating atrazine use shows why we must continue to challenge toxicity standards and their illusory guarantee of safety. Quickly phasing out atrazine will reduce the amount of this toxin accumulating in our soils, our water, and our bodies.

To Learn More About the Health Hazards of Atrazine.

To Learn More About Atrazine Alternatives.