EWG Original Research
California Proposes Safe Level for Roundup More Than 100 Times Lower Than EPA Limit
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Olga V. Naidenko, Ph.D., Senior Science Advisor for Children's Environmental Health

Wednesday, June 21, 2017

 

In a landmark rule with global repercussions, California state scientists are preparing to issue the world's first health guideline for Monsanto's glyphosate herbicide based on its cancer risk. The state’s proposed safe level is more than 100 times lower than the the federal Environmental Protection Agency’s legal allowance for the average-sized American​. 

Glyphosate is the key ingredient in Roundup, the most heavily applied weed killer in the history of chemical agriculture. Use of glyphosate has exploded in the last 15 years, as Monsanto has promoted genetically modified Roundup Ready seeds to grow crops that aren't harmed by the herbicide. In the U.S. alone, more than 200 million pounds of Roundup are sprayed each year, mostly on soybeans and corn. 

In March 2015, the International Agency for Research on Cancer – part of the World Health Organization, with no regulatory authority – reviewed human cancer studies and determined that glyphosate is “probably carcinogenic” to people. Based on that finding, the California Office of Environmental Health Hazard Assessment, or OEHHA, announced its intention to add glyphosate to the state's Proposition 65 list of chemicals known to cause cancer.

By itself, that listing would be a big blow to Monsanto, because it would require cancer warning labels on containers of Roundup and on foods that have high residues of glyphosate. Monsanto is appealing the decision in state court, but in the meantime the OEHHA has moved forward in setting a so-called No Significant Risk Level of the amount of glyphosate people could safely consume each day.  


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1. California’s proposed limit vs. the amount allowed by EPA

California's proposed No Significant Risk Level is 1.1 milligrams of glyphosate daily for an adult weighing 70 kilograms, or 154 pounds. The EPA's safe level, or Reference Dose, is 2 milligrams per kilogram of body weight, which for that same adult would be 140 milligrams a day – 127 times the level proposed by California.

Monsanto argues that California should not restrict glyphosate at all. The company's written comments on OEHHA's proposal say the agency should “determine that glyphosate exposure at any level poses no significant risk." At a public hearing in June, a lawyer representing Monsanto said the No Significant Risk Level should be “infinite.”

As reported by The New York Times, Monsanto has long lobbied the EPA to halt an investigation into the safety of glyphosate. In lawsuits against Monsanto brought by cancer victims, an EPA official who was in charge of evaluating the herbicide's cancer risk has been accused of aiding Monsanto's efforts to kill the agency's investigation.

California's proposed limit under Proposition 65 is the dose of glyphosate expected to cause no more than one case of cancer in every 100,000 people who ingest it over a lifetime. EWG strongly supports the state's move to set a health-protective limit for glyphosate based on cancer risk. But we believe the state should go further and set a much lower limit for glyphosate at no more than 0.01 milligrams per day.

Why California should lower the No Significant Risk Level for glyphosate

  1. The risk level for glyphosate should include a tenfold safety factor to account for glyphosate exposures to children and the developing fetus. An analysis published by California state scientists in 2009 on in-utero and early life susceptibility to carcinogens, points out that existing risk assessment approaches do not “adequately address the possibility that risk from early-in-life exposures may differ from that associated with exposures occurring in adulthood.” This report also noted that an adjustment factor of 10 is appropriate for calculating lifetime cancer risk in humans arising from carcinogen exposures that occur in utero.

    A safety factor of 10, supported by OEHHA’s own research, would account for potential increased susceptibility to glyphosate exposures occurring before birth and in the early years of life.

  2. A tenfold children’s health safety factor is also supported by the recommendations of the 1993 National Research Council Report, Pesticides in the Diets of Infants and Children, which highlighted that children are both exposed to more pesticides than adults and are more susceptible to the toxic effects of pesticides, particularly those that cause cancer.

    The 1996 Food Quality Protection Act specifically required pesticide risk assessors consider the special susceptibility of children to pesticides by using an additional tenfold safety factor.

    In 2009, the National Research Council again emphasized the importance of applying an adjustment factor to account for humans’ varying susceptibility to cancer. This authoritative report says that some people may be 10 to 50 times more susceptible to cancer than others, and advises public health agencies to include a factor of up to 25 to account for this variation.

    A tenfold safety factor for children’s health is thus fully supported by both the national pesticide law and by the recommendations of the country’s top experts.

  3. Finally, for carcinogens in drinking water, California applies a one-in-a-million standard: no more than one expected case of cancer in every one million people who drink the contaminated water daily for a lifetime. EWG urges the state to use the one-in-a-million standard for setting the No Significant Risk Level for all glyphosate exposures.

In sum, applying the tenfold children’s health factor and a one-in-a-million cancer risk standard, EWG believes that the No Significant Risk Level for glyphosate should be no more than 0.01 milligram, or 10 micrograms, per day. This maximum intake limit should apply to all exposures.

For drinking water, health guidelines take the safe intake amount as a point of departure and divide it by an estimated average 2-liter drinking water consumption per day. For glyphosate, this health guideline corresponds to a limit of no more than 5 micrograms per liter, or parts per billion.

 

2. Other human health concerns about glyphosate

A 2015 EWG analysis mapped the year-to-year growth in glyphosate use on American farmland from 1992 to 2012. According to the Department of Agriculture, in 2014, approximately 240 million pounds of glyphosate were sprayed in the U.S. As a result of widespread spraying, glyphosate has now been found to contaminate air, water and soil across vast expanses of the U.S., and also shows up in the food Americans eat every day.

Biomonitoring studies in different states, especially in the Midwest, found glyphosate in the bodies of children and pregnant women. According to initial data from an ongoing study in Indiana, women who were more heavily exposed to glyphosate during pregnancy were more likely to give birth to premature babies that weighed less than average. 

It's unknown how much glyphosate is in Americans' bodies, because federal agencies responsible for pesticide safety have neither tested nor mandated testing for glyphosate in food, drinking water or bodily fluids. Glyphosate has not been included in government-sponsored pesticide residue programs. In 2014, the Government Accountability Office called for glyphosate to be added to the list of pesticides tested on foods annually, and urged the USDA and the Food and Drug Administration to strengthen pesticide monitoring overall. The FDA began testing a limited number of foods for glyphosate last year. The program was scuttled after only a few months, but reportedly has resumed.

The EPA’s 2012 assessment of glyphosate estimated that American adults could be ingesting more than 5 milligrams of glyphosate every day – five times more than California's proposed limit and 500 times more than EWG recommends. Because data on glyphosate levels on food are very limited, the EPA assessment could be a significant underestimate of real-life exposures.

Biomonitoring studies of adults and children in agricultural and non-agricultural areas consistently find glyphosate in urine, indicating that glyphosate from food is absorbed into the body. Farmers and rural families are exposed to greater amounts of glyphosate compared to people in other parts of the nation. A 2007 study by the National Institute for Occupational Safety and Health found that both parents and children in farm families had two to three times more glyphosate in their bodies compared to those in non-farming families.

 

3. Roundup triggers ‘superweeds’

Roundup is worth a lot to Monsanto: an estimated $4.76 billion in sales and $1.9 billion in profit in 2015. Almost all of the corn, soybeans, cotton and sugar beets grown in the U.S. are now genetically engineered to be Roundup Ready.

But the overuse of Roundup has triggered the spread of more than a dozen glyphosate-resistant “superweeds” that force industrial farmers to spray other herbicides that are often more toxic.

GMO crops are not the only use of this toxic chemical. Roundup kills weeds but not certain genetically engineered grasses. It is sold in stores for residential application around homes and yards, and is widely sprayed along roadways and in parks, commercial properties and plant nurseries. Glyphosate is also sprayed at the end of growing season on some food crops that are not genetically engineered to resist the weed killer, including wheat, oats, barley and dry beans. EWG advocates that federal and state agencies prohibit the application of glyphosate shortly before harvest season. 

 

4. What lies ahead

The long-term sustainable solution to mitigate the risks of glyphosate is supporting a transition away from food production that is dependent on chemical pesticides and toward a system that uses organic practices, and more sophisticated, prevention-based pest and weed management systems.

Every five years, the EPA must review pesticides' registrations, or use permits. Glyphosate is due for re-registration in 2017, which should be an opportunity to tighten or eliminate its use. But the EPA's recent reversal of its scheduled ban on chlorpyrifos, a neurotoxic insecticide, shows it can't be trusted to do an objective evaluation. 

While prospects for tighter regulation or a ban of glyphosate are slim under current EPA Administrator Scott Pruitt, who personally overturned the chlorpyrifos ban, public pressure remains crucial. Americans must tell the EPA and state agencies that it's time for glyphosate to go. Chemicals that can cause cancer do not belong in America’s food supply.