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
- 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.
- 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.
- 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.