Crunching the numbers - Atrazine just isn't worth the risk

A rigorous economic report has found Syngenta – the maker of the toxic herbicide atrazine – greatly exaggerated the costs of eliminating the weed-killing chemical. It turns out that when independent experts (not paid by Syngenta) crunch the numbers, a ban on atrazine would simply not result in corn yields falling any significant amount. But even using Syngenta’s dire predictions, the effect on corn prices to consumers would hardly be noticeable. (See the Synapse full report, and Executive summary. It was funded by NRDC)

Syngenta formed the “Atrazine Benefits Team”, that greatly exaggerated the effectiveness of atrazine, partly through failing to completely analyze the alternatives, including other chemicals, low-chemical, and non-chemical alternatives.  And, they failed to account for the fact that if crop yields were reduced then the price would likely rise – simple supply and demand.

Talk about “chicken littles”, running around as if the sky will fall if atrazine is taken off the market. In fact, Syngenta’s own numbers predict about a 5% decrease in corn production, with an associated 8 percent rise in corn prices – overall leading to more money in farmer’s pockets. Using Syngenta’s estimates, price increases would only affect the largest buyers of corn—primarily ethanol producers and animal feedlots. The resulting impact on consumer prices for gasoline and beef would only amount to pennies per gallon or pound, respectively, in exchange for significant health and environmental benefits.

Syngenta has been caught before, paying third-party experts-for-hire to spin the evidence of harm from atrazine. See  here for detailed report by the Center for Media and Democracy's PR Watch.

I’ve written a fair bit about the hazards and health concerns with atrazine. It’s popular because it controls a broad spectrum of weeds, including broadleaf and grassy weeds, by inhibiting photosynthesis. Atrazine was originally approved by EPA in 1958 and is now used at about 75 million pounds annually on corn (86% of atrazine in pounds), sorghum (10%), and sugarcane (3%), golf courses and lawns (1%).

Laboratory studies provide evidence that atrazine may be doing some serious damage to male gonads, even at low doses, causing demasculinization and feminization in male vertebrates – fish, amphibians, reptiles, and mammals. In at least one laboratory report, atrazine-exposed male frogs were so completely feminized that they successfully mated and produced viable offspring with normal males (not exposed to atrazine).

It’s not only damage to test animals, but human health that may also be compromised by atrazine. That’s because it is an endocrine disrupting chemical (EDC), interfering with hormone activity. EPA acknowledges that atrazine is an endocrine disrupting chemical.

Health effects linked to endocrine disrupting chemicals include: breast and prostate cancer, reproductive organ abnormalities, diabetes and obesity, reduced sperm counts, pregnancy loss, and neurological problems. And, that’s something that global health experts are taking seriously!

In 2013, a report by the United Nations Environment Programme (UNEP) and the World Health Organization (WHO) identified endocrine disrupting chemicals linked to health impacts worldwide and called endocrine disruptors “a global threat that needs to be resolved”. Researchers from around the globe called for more research and collaboration. Dr. Linda Birnbaum, Ph.D., D.A.B.T., A.T.S., Director of the National Institute of Environmental Health Sciences (NIEHS), published an article this year titled, When environmental chemicals act like uncontrolled medicine, reviewing the existing science demonstrating health impacts on the endocrine system from chemicals including pesticides that pollute our environment.

Leading scientific experts from around the world, including editors of top scientific journals, have written about the need to make policy decisions that protect human health and our environment from the global public health threat of endocrine disrupting chemical pollution. Atrazine – released directly out into the environment at 60 to 80 million pounds annually in the U.S. – seems like an obvious place to start.

Appendix: Atrazine science review – human health risks

In 2010 EPA reviewed some of the data linking atrazine with human health risks, and raised concerns regarding the potential for atrazine to impair reproductive health in both men and women, and lead to birth defects. Specific concerns included: delayed menopause in women; increased risk of gestational diabetes in pregnant women; and poor sperm quality in men.  These studies used particularly reliable measures of atrazine exposure from personal measurements such as in blood or urine. (See my blog here for details)

In EPA’s 2010 review there were also several studies correlating an elevated risk of low birth weight and abdominal wall or other birth defects in infants with atrazine exposures during fetal development. The fact that several different studies reported an overlapping array of birth defects raises the level of concern. It is worth a note that these studies did not have direct measurements of atrazine from the mothers and babies in the studies, but instead relied on less-certain exposure estimates based on measurements of atrazine in surface and ground water, conception timed during period of high atrazine use, and mothers residing in areas of high atrazine use. (See my blog here for details)

Although the data available at that time were not strong enough in EPA’s opinion to draw conclusions with certainty, it raised some red flags, and stimulated more research. Now, that newer research is published in peer reviewed scientific journals, and it supports the earlier findings regarding atrazine and birth defects.

In 2012 and 2013, a team of researchers from the University of Texas School of Public Health, the Texas Department of State Health Services, and the Baylor College of Medicine reported an association between atrazine exposure during pregnancy and an elevated risk of specific birth defects, including abdominal wall defects (gastroschisis) that were reported in earlier studies, male genital malformations (including hypospadias, cryptorchidism, and small penis size), and malformations of the nose (choanal atresia and stenosis). The team estimated maternal exposure based on atrazine use by county using a sophisticated method developed by government researchers at the US Geological Survey (USGS), which uses both private and public government pesticide use data aggregated by the US Department of Agriculture. This information was then linked to each pregnant woman based on the county that she lived in.  It is interesting that the effects on the abdominal wall were only seen with babies born to older mothers (over age 25), suggesting that the effect may be missed in other studies if the data isn’t sorted by maternal age.

The Texas researchers noted that the observed male genital malformations were not dose-dependent. In fact, the study reported more cases associated with counties having medium use rates of atrazine (1.5 to about 50 pounds per square mile), rather than low (0 to 1.5 lbs./sq. mi) or high (over about 50 lbs./sq. mi) use rates. Effects like these that don’t follow the typical linear dose-response curve (increasing dose leads to increasing effect) are not unusual for chemicals like atrazine that disrupt hormones. A 2011 review available science reports that atrazine has consistent harmful effects on male gonads across vertebrate classes.

In 2012 Researchers in Kentucky estimated atrazine exposure during fetal development by matching pregnant mothers with county-level data on drinking water levels of atrazine. That team reported an increased risk of preterm birth in counties with the highest levels of atrazine in drinking water. This is a medical concern because preterm babies often suffer more illnesses and need more medical attention than full-term births.

A French team of researchers published a study in 2011 that used personal measurements of atrazine in the urine of 579 pregnant women to calculate individual atrazine exposure, and found that exposure to atrazine increased the risk of having a baby with a small head circumference and low birth weight, both of which are associated with increased medical complications. Since atrazine was banned for use in Europe in 2003, the women’s atrazine exposure is likely from persistent environmental contamination – atrazine can last for years or even decades in the environment.

The men and women that apply pesticides –and their families - are most at risk of being exposed to high levels. A 2012 study reported on 29 commercial pesticide applicators, finding that the more atrazine they handled - number of pounds, number of acres treated, number of days applying pesticide - the more atrazine ended up in the dust within their homes. Atrazine is unintentionally transported from the workplace into the home on their body, clothes, shoes, and vehicles. Once in the home, infants, children, and pregnant women can be exposed to atrazine. Take-home exposures to workplace hazardous chemicals have long been established, and pesticides are no exception.

About the Authors

Jennifer Sass

Senior Scientist, Federal Toxics, Health and Food, Healthy People & Thriving Communities Program

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