ST. LOUIS (KGO) -- A lab test of ten California wines concluded they all contained trace amounts of the active ingredient from some weed-killers, glyphosate. Whether that is cause for concern is a matter of great dispute.
We know how important this issue is to so many people, so we traveled to St. Louis to see the lab that performed the tests. We also spoke to scientists, including a toxicologist from the Monsanto Company, which first patented glyphosate in the 1970's.
Wines from the prime growing regions of Napa, Sonoma and Mendocino Counties were tested at Microbe Inotech Labs in St. Louis, Missouri.
Dan Noyes: "How many of those wines had glyphosate?"
Dr. Bruce Hemming, Microbe Inotech Labs: "All 10 did."
Noyes: "All ten."
Hemming: "All ten."
Dr. Bruce Hemming and his team have been testing foods and beverages for glyphosate for years. Critics charge that these preliminary tests don't prove there's glyphosate in the wine. Doctor Hemming agrees more tests are needed, but stands by his results.
Noyes: "How confident are you that there was glyphosate in these wines?"
Hemming: "Very confident that the glyphosate is present."
Glyphosate is the most popular weed killer in the world, the active ingredient in hundreds of products, including Roundup, widely used on big farms and in home gardens. In fact, Dan Noyes found a bottle in his own supplies at home. And it's often used at vineyards.
Jennifer Putnam is the Executive Director of Napa Valley Grape Growers. She questions the results of the St. Louis tests, which were sponsored by an anti-pesticide group called "Moms Across America", but says she welcomes more testing. "Nobody's more interested in a healthy environment of the vineyard than us," Putnam said.
For decades, Roundup has enjoyed a reputation as a safe alternative to harsher chemicals, but today it's at the heart of a scientific controversy.
Roundup maker Monsanto says that over 40 years, there have been hundreds of studies on glyphosate.
"The consensus is that it is a-- will pose no unreasonable risk to human health and the environment when used according to label directions," said Monsanto Toxicologist Dr. Donna Farmer.
Dr. Farmer disputes the validity of the wine tests, but adds that even if there is glyphosate in the wine, it's way too little to cause harm.
Farmer said, "A person, say a 150-pound person would have to drink around 8,000 regularly sized bottles of wine in one day to meet the allowable daily intake for glyphosate."
The U.S. EPA says that for a 150-pound person, it's safe to consume 120 milligrams of glyphosate per day, the amount we showed in a teaspoon.
But some scientists are concerned that the EPA levels are much too high. Dr. Michael Antoniou of Kings College in London has been testing glyphosate in his lab. He said, "There is an increasing body of evidence that levels of glyphosate exposure below regulatory set safety limits anywhere in the world given enough time can result in potentially serious disease."
In a paper published this year, Dr. Antoniou and 13 other scientists express concern that at the levels Americans are now consuming, glyphosate may pose "heightened cancer risk". And they cite controversial studies that linked glyphosate to "higher risks to the kidneys and liver" in laboratory rats. They say more tests are urgently needed.
Dr. Antoniou added, "Then we can get to the bottom of whether what we are exposed to can be causatively linked to disease or not."
In past years various regulatory bodies, including the State of California and the U.S. EPA, had concluded that glyphosate did not pose a cancer risk to humans. But, last year the World Health Organzation's cancer research agency classified glyphosate as a probable carcinogen. Then, the State of california said it wants to list it as a known carcinogen which would require special labeling on products. Monsanto has filed a lawsuit against the state over the measure.
Now, the group that sponsored those lab tests, "Moms Across America", is calling for a ban on glyphosate.
Working with Dr. Hemming's lab, they've found glyphosate in wine, breast milk, urine and drinking water. Other groups have found it in eggs, oatmeal, bread, and even highly-regulated German beer.
Zen Honeycutt from Moms Across America said, "We're talking about the widespread contamination of all different kinds of crops and that really needs to stop."
Already, many California vineyards are growing grapes without glyphosate or other conventional weed killers. For vineyard consultant Daphne Amory, weeds are good.
"They're there for a reason," said Amory. "The vine needs companion plants to help it thrive and do its job."
Biodynamic farming is based on the idea that the right weeds help retain water and nutrients. One drawback is that it's labor intensive.
Jennifer Putnam from the Napa Valley Grape Growers said, "If you do away with the tool of being able to use glyphosate, we go back to a lot more labor and we go back to shovel work."
Dr. Hemming concluded there was glyphosate in the organic and biodynamic wines he tested, but at much lower levels than conventional California wines. One theory is that it may have drifted from conventional vineyards.
Just 11 days ago, the EPA posted a report on its website announcing that glyphosate is "not likely to be carcinogenic to humans", and then, three days later, they pulled it off the web. They said their evaluation is not final and told the I-Team, "The agency is working through some important scientific issues on glyphosate."
I-Team investigates controversy over weed killer and California wine