“We see the formulations are much more toxic. The formulations were killing the cells. The glyphosate really didn’t do it.” — Mike DeVito, acting chief, National Toxicology Program Laboratory

Monsanto’s Roundup weedkiller may be even worse for human health than we thought.

As reported this week in the Guardian, new tests show that when Roundup’s key active ingredient, glyphosate, is combined with other chemicals to create the final product, the herbicide is more toxic to human cells than glyphosate alone.

As if glyphosate alone weren’t toxic enough.

U.S. Right to Know’s Carey Gillam reported on the first-ever testing, conducted by the U.S. National Toxicology Program (NTP), of glyphosate-based formulations. Previous testing focused exclusively on glyphosate in isolation.

NTP’s acting chief of the National Toxicology Program Laboratory, Mike DeVito, told the Guardian the agency’s work is ongoing but its early findings are clear on one key point. “We see the formulations are much more toxic. The formulations were killing the cells. The glyphosate really didn’t do it,” DeVito said.

Labels mislead, Monsanto pleads ‘proprietary’

That’s bad for farmers who spray Roundup, for people who eat Roundup-contaminated food, or for the millions of humans and their pets who are exposed to Roundup because it runs off into our waterways or is sprayed on parks, playgrounds and neighborhood lawns. According to U.S. Environmental Protection Agency (EPA) latest figures, $9 billion worth of glyphosate-based herbicides were sold in the U.S. in 2012.

Monsanto continues to claim that its product is safe, including the formulation it sells direct to consumers for their lawns and gardens. Beyond Pesticides (BP) and the Organic Consumers Association (OCA) sued Monsanto for misleading consumers about the safety of its flagship herbicide. Monsanto tried to get the lawsuit dismissed, but a federal judge recently ruled in favor of BP and OCA.

The consumer case revolves around glyphosate, not the whole formulation, and Monsanto’s claim on Roundup containers that the product is safe because it “target[s] an enzyme found in plants but not in people or pets.” The lawsuit alleges this statement is false, deceptive and misleading, because the enzyme targeted by glyphosate is, in fact, found in people and pets.

Besides providing new information about glyphosate-based herbicides, the NTP testing also highlights what the public (and interested scientists) don’t know about these herbicides, even though they’ve been on the market for 40 years, because Monsanto won’t tell us.

“We don’t know what the formulation is,” Devito told the Guardian.” That is confidential business information.” According to the Guardian, for testing purposes, scientists sourced some samples from store shelves, picking up products the EPA told them were the top sellers, he said.

Testing the full formulation—why it matters

According to André Leu, international director of Regeneration International and author of “The Myth of Safe Pesticides,” the overwhelming majority of registered pesticide products used in agriculture as insecticides, herbicides and fungicides are formulations of several chemicals. They are mixtures composed of one or more chemicals that are defined as the active ingredient(s) or active principle, and are combined with other mostly toxic chemicals, such as solvents, adjuvants and surfactants—otherwise known as “inerts.”

The active ingredient is the primary chemical that acts as the pesticide and is the only chemical tested, Leu told us. The other chemicals in the mixture are called inerts because they have a secondary role in the formulation.

“The name ‘inert’ is misleading as most of these other compounds are chemically active in their functions in the pesticide formulations. They help to make the active ingredient work more effectively. According to the United States President’s Cancer panel report, many of these ‘inert’ ingredients are toxic; however, they are not tested for their potential to cause health problems.

Many of the solvents, fillers and other chemicals listed as inert ingredients on pesticide labels also are toxic, but are not required to be tested for their potential to cause chronic diseases such as cancer.”

Leu said it should be of “great concern” to everyone that the vast majority of the nearly 1,400 registered pesticide and veterinary products used in the U.S. for the production of food have had no testing for numerous health and environmental problems linked to the exposure to cocktails of chemicals.

“These are the toxicities that cause other health issues such as cancers, cell mutations, endocrine disruption, birth defects, organ and tissue damage, nervous system damage, behavior changes, epigenetic damage, and immune system damage,” Leu said.

In the only study where nine formulated pesticides were tested on human cells at levels well below agricultural dilutions, the research scientists found that eight of the nine formulations were several hundred times more toxic than their respective active ingredients. The researchers stated:

Adjuvants in pesticides are generally declared as inerts, and for this reason they are not tested in long-term regulatory experiments. It is thus very surprising that they amplify up to 1000 times the toxicity of their AP [active ingredient] in 100% of the cases where they are indicated to be present by the manufacturer.”

The only peer-reviewed, lifetime comparison feeding study of a formulated pesticide, in this case Roundup, found that rats fed a diet that contains minute residues of Roundup had significantly higher rates of kidney disease, liver damage, tumors and other negative health effects including endocrine disruption.

Katherine Paul is associate director of the Organic Consumers Association. To keep up with OCA’s news and alerts, sign up here.