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Is Roundup Safe?

One of the questions I get asked most often out on the road concerns Roundup, the most commonly used weed killer on the market today. With the active ingredient known as glyphosate, more than 100 million pounds of the product is spread on American landscapes. 

The product is manufactured by Monsanto and distributed by the Scotts MiracleGro company under an extremely profitable licensing agreement. You may recall in earlier advertising that the companies told us the product perished in the environment after seven days. Now the ads tell us that one application lasts four months long. So if you spray that crack in your driveway for dandelions that might be poking up through, do you really feel comfortable having your children or pets walking over that area for the next few months? I hope not.

This article posted today by Environmental Health News should be a wakeup call to anyone who is considering using Roundup:

June 22, 2009

Weed killer kills human cells. Study intensifies debate over ‘inert’


Used in yards, farms and parks throughout the world, Roundup has long

been a top-selling weed killer. But now researchers have found that

one of Roundup’s inert ingredients can kill human cells, particularly

embryonic, placental and umbilical cord cells. The new findings

intensify a debate about so-called “inerts” — the solvents,

preservatives, surfactants and other substances that manufacturers add

to pesticides. Nearly 4,000 inert ingredients are approved for use by

the U.S. Environmental Protection Agency.

By Crystal Gammon

Environmental Health News

Used in yards, farms and parks throughout the world, Roundup has long

been a top-selling weed killer. But now researchers have found that

one of Roundup’s inert ingredients can kill human cells, particularly

embryonic, placental and umbilical cord cells.

The new findings intensify a debate about so-called “inerts” — the

solvents, preservatives, surfactants and other substances that

manufacturers add to pesticides. Nearly 4,000 inert ingredients are

approved for use by the U.S. Environmental Protection Agency.

Glyphosate, Roundup’s active ingredient, is the most widely used

herbicide in the United States.  About 100 million pounds are applied

to U.S. farms and lawns every year, according to the EPA.

Until now, most health studies have focused on the safety of

glyphosate, rather than the mixture of ingredients found in Roundup.

But in the new study, scientists found that Roundup’s inert

ingredients amplified the toxic effect on human cells—even at

concentrations much more diluted than those used on farms and lawns.

One specific inert ingredient, polyethoxylated tallowamine, or POEA,

was more deadly to human embryonic, placental and umbilical cord cells

than the herbicide itself – a finding the researchers call


“This clearly confirms that the [inert ingredients] in Roundup

formulations are not inert,” wrote the study authors from France’s

University of Caen. “Moreover, the proprietary mixtures available on

the market could cause cell damage and even death [at the] residual

levels” found on Roundup-treated crops, such as soybeans, alfalfa and

corn, or lawns and gardens.

The research team suspects that Roundup might cause pregnancy problems

by interfering with hormone production, possibly leading to abnormal

fetal development, low birth weights or miscarriages.

Monsanto, Roundup’s manufacturer, contends that the methods used in

the study don’t reflect realistic conditions and that their product,

which has been sold since the 1970s, is safe when used as directed.

Hundreds of studies over the past 35 years have addressed the safety

of glyphosate.

“Roundup has one of the most extensive human health safety and

environmental data packages of any pesticide that’s out there,” said

Monsanto spokesman John Combest. “It’s used in public parks, it’s used

to protect schools. There’s been a great deal of study on Roundup, and

we’re very proud of its performance.”

The EPA considers glyphosate to have low toxicity when used at the

recommended doses.

“Risk estimates for glyphosate were well below the level of concern,”

said EPA spokesman Dale Kemery. The EPA classifies glyphosate as a

Group E chemical, which means there is strong evidence that it does

not cause cancer in humans.

In addition, the EPA and the U.S. Department of Agriculture both

recognize POEA as an inert ingredient. Derived from animal fat, POEA

is allowed in products certified organic by the USDA. The EPA has

concluded that it is not dangerous to public health or the


The French team, led by Gilles-Eric Seralini, a University of Caen

molecular biologist, said its results highlight the need for health

agencies to reconsider the safety of Roundup.

“The authorizations for using these Roundup herbicides must now

clearly be revised since their toxic effects depend on, and are

multiplied by, other compounds used in the mixtures,” Seralini’s team


Controversy about the safety of the weed killer recently erupted in

Argentina, one of the world’s largest exporters of soy.

Last month, an environmental group petitioned Argentina’s Supreme

Court, seeking a temporary ban on glyphosate use after an Argentine

scientist and local activists reported a high incidence of birth

defects and cancers in people living near crop-spraying areas.

Scientists there also linked genetic malformations in amphibians to

glysophate. In addition, last year in Sweden, a scientific team found

that exposure is a risk factor for people developing non-Hodgkin


Inert ingredients are often less scrutinized than active pest-killing

ingredients. Since specific herbicide formulations are protected as

trade secrets, manufacturers aren’t required to publicly disclose

them. Although Monsanto is the largest manufacturer of glyphosate-

based herbicides, several other manufacturers sell similar herbicides

with different inert ingredients.

The term “inert ingredient” is often misleading, according to Caroline

Cox of the Northwest Coalition for Alternatives to Pesticides, a non-

profit environmental group based in Oregon.

Federal law classifies all pesticide ingredients that don’t harm pests

as “inert,” she said. Inert compounds, therefore, aren’t necessarily

biologically or toxicologically harmless – they simply don’t kill

insects or weeds.

Kemery said the EPA takes into account the inert ingredients and how

the product is used, whenever a pesticide is approved for use. The

aim, he said, is to ensure that “if the product is used according to

labeled directions, both people’s health and the environment will not

be harmed.” One label requirement for Roundup is that it should not be

used in or near freshwater to protect amphibians and other wildlife.

But some inert ingredients have been found to potentially affect human

health. Many amplify the effects of active ingredients by helping them

penetrate clothing, protective equipment and cell membranes, or by

increasing their toxicity. For example, a Croatian team recently found

that an herbicide formulation containing atrazine caused DNA damage,

which can lead to cancer, while atrazine alone did not.

POEA was recognized as a common inert ingredient in herbicides in the

1980s, when researchers linked it to a group of poisonings in Japan.

Doctors there examined patients who drank Roundup, either

intentionally or accidentally, and determined that their sicknesses

and deaths were due to POEA, not glyphosate.

POEA is a surfactant, or detergent, derived from animal fat. It is

added to Roundup and other herbicides to help them penetrate plants’

surfaces, making the weed killer more effective.

“POEA helps glyphosate interact with the surfaces of plant cells,”

explained Negin Martin, a scientist at the National Institute of

Environmental Health Sciences in North Carolina, who was not involved

in the study. POEA lowers water’s surface tension–the property that

makes water form droplets on most surfaces–which helps glyphosate

disperse and penetrate the waxy surface of a plant.

In the French study, researchers tested four different Roundup

formulations, all containing POEA and glyphosate at concentrations

below the recommended lawn and agricultural dose. They also tested

POEA and glyphosate separately to determine which caused more damage

to embryonic, placental and umbilical cord cells.

Glyphosate, POEA and all four Roundup formulations damaged all three

cell types. Umbilical cord cells were especially sensitive to POEA.

Glyphosate became more harmful when combined with POEA, and POEA alone

was more deadly to cells than glyphosate. The research appears in the

January issue of the journal Chemical Research in Toxicology.

By using embryonic and placental cell lines, which multiply and

respond to chemicals rapidly, and fresh umbilical cord cells,

Seralini’s team was able to determine how the chemicals combine to

damage cells.

The two ingredients work together to “limit breathing of the cells,

stress them and drive them towards a suicide,” Seralini said.

The research was funded in part by France’s Committee for Research and

Independent Information on Genetic Engineering, a scientific committee

that investigates risks associated with genetically modified

organisms. One of Roundup’s primary uses is on crops that are

genetically engineered to be resistant to glyphosate.

Monsanto scientists argue that cells in Seralini’s study were exposed

to unnaturally high levels of the chemicals. “It’s very unlike

anything you’d see in real-world exposure. People’s cells are not

bathed in these things,” said Donna Farmer, another toxicologist at


Seralini’s team, however, did study multiple concentrations of

Roundup. These ranged from the typical agricultural or lawn dose down

to concentrations 100,000 times more dilute than the products sold on

shelves. The researchers saw cell damage at all concentrations.

Monsanto scientists also question the French team’s use of laboratory

cell lines.

“These are just not very good models of a whole organism, like a human

being,” said Dan Goldstein, a toxicologist with Monsanto.

Goldstein said humans have protective mechanisms that resist

substances in the environment, such as skin and the lining of the

gastrointestinal tract, which constantly renew themselves. “Those

phenomena just don’t happen with isolated cells in a Petri dish.”

But Cox, who studies pesticides and their inert ingredients at the

Oregon environmental group, says lab experiments like these are

important in determining whether a chemical is safe.

“We would never consider it ethical to test these products on people,

so we’re obliged to look at their effects on other species and in

other systems,” she said. “There’s really no way around that.”

Seralini said the cells used in the study are widely accepted in

toxicology as good models for studying the toxicity of chemicals.

“The fact is that 90 percent of labs studying mechanisms of toxicity

or physiology use cell lines,” he said.

Most research has examined glyphosate alone, rather than combined with

Roundup’s inert ingredients. Researchers who have studied Roundup

formulations have drawn conclusions similar to the Seralini group’s.

For example, in 2005, University of Pittsburg ecologists added Roundup

at the manufacturer’s recommended dose to ponds filled with frog and

toad tadpoles. When they returned two weeks later, they found that 50

to 100 percent of the populations of several species of tadpoles had

been killed.

A group of over 250 environmental, health and labor organizations has

petitioned the EPA to change requirements for identifying pesticides’

inert ingredients. The agency’s decision is due this fall.

“It would be a big step for the agency to take,” said Cox, “but it’s

one they definitely should.”

The groups claim that the laws allowing manufacturers to keep inert

ingredients secret from competitors are essentially unnecessary.

Companies can determine a competitor’s inert ingredients through

routine lab analyses, said Cox.

“The proprietary protection laws really only keep information from the

public,” she said.

About The Author

Paul Tukey

An international leader of the green movement, Mr. Tukey is a journalist, author, filmmaker, TV host, activist and award-winning public speaker, who is widely recognized as North America's leading advocate for landscape sustainability and toxic pesticide reduction strategies.

Number of Entries : 1023
  • Gloria Day

    I’ve been saying for years that people use RoundUp like Windex. I’ve never considered it safe. People want everything instantly and at their convenience. It is time to re-educate for the safety and the health of all living beings at risk from the harmful effects of this product.

  • Handy Haydon

    While living in the Dallas area I stopped using Roundup and processed fertilizers about 12 years ago and have been committed to organics and building the soil up. We were early clients of Michael Bosco-Soils Alive who introduced us to this approach.

    We moved to Southwest Missouri, about four years ago, and built a home in the Ozark Mountains still committed to continuing the organics approach. We have recently been faced with the need to restart an area where we have been trying to grow native (wildflowers, native grasses) primarily from seed. The problem is it has been taken over by Johnson grass and other non-desirable weeds and grasses. Probably a left over of the construction process that disturbed the native glade and savannah landscape

    All this to say….What is my alternative, if not Roundup?

  • Catherine

    My husband and I own a small garden center in Monument, Colorado. We discontinued the sale of Roundup several years ago. We just did not feel it was safe, no matter what the studies said about it not having any residual dangers. I am glad it it is finally coming to light.

  • Paul Tukey

    Handy Haydon asked about an alternative to Roundup and there are several organic or more earth-friendly options in the marketplace. Look for Nature’s Avenger on-line or in local stores. has several options, too, including herbicidal soaps:

  • LnddMiles

    Pretty cool post. I just stumbled upon your blog and wanted to say
    that I have really liked reading your blog posts. Anyway
    I’ll be subscribing to your blog and I hope you post again soon!

    • Scott Scholl

      In reference to getting rid of Johnson Grass. Till or dig it out or spray with 20% vinegar when it is hot and dry. And soil improvement eliminates weeds. So do a soil test and improve that soil. That is what it is all about. Weeds are there for a reason, they are a natural way to improve the soil. Disturbed areas will have the not so pleasant plants coming in so replant/reseed the natives and green manures. Also spray with liquid organic fertilizers for faster soil improvement. I use a wide variety of them. They are cheaper and better than solid organic products.

  • sage bio-pesticide

    It’s disturbing to me that Monsanto is creating “round-up ready”seeds. I suppose that it’s their way of justifying spraying round-up in food crops.

    • Paul Tukey

      The vast majority of the corn and soybeans that we consume in the U.S. are grown from genetically modified seeds sold by Monsanto. The seeds are resistant to Roundup, which means that the crops can be sprayed with Roundup.

      This technology was supposed to reduce the overall amount of pesticides used, but in fact the amount of pesticides needed has expanded exponentially. Nature, which always wins, is developing Roundup-resistant weeds in response to Monsanto’s technology.

  • Manuka Honey Soaps

    You are right, people should listen to what you are saying because are absolutely right. :-D

  • ksb

    NPR reported the other day that:
    “Monsanto Co., the world’s biggest seed maker, said Wednesday it lost $19 million in the first quarter as global sales of its Roundup herbicide sank in the face of generic competition.”

    Full article …

  • Slappy

    “It’s disturbing to me that Monsanto is creating “round-up ready”seeds. I suppose that it’s their way of justifying spraying round-up on food crops.” You think!!!!! I have always had issues with “inerts” not labled. I use similar products; but roundup, which I do not use, is a total vegetation killer. That should tell you something right there. Back to the seeds. It scares me to think that the seed has been genetically engineered to resistant a product like that. And now we are consuming some of those crops. Another example is Scott’s turfgrass seeds. They are coated with fungicides and herbicides to combat the pest during germination. It’s a marvel of science, but not on my must use list.

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