Water in Napa - Moms Across America

Glyphosate in Napa Valley Groundwater


Contact: Carol Nagle
Title: Label GMOs Napa County Co-coordinator
Phone: 707-226-2147

Glyphosate in Napa Valley Groundwater:

3.3 Times Higher Than What is Allowed in European Drinking Water 

Napa, CA., October 4, 2016

glyphosate_and_grape_vines.jpgIn a joint partnership, Label GMOs Napa County and the Napa County Green Party did what the U.S. government has not been doing-- tested local water supplies for glyphosate, the active ingredient in Roundup, the most commonly used herbicide in the world.

Although the Safe Drinking Water Act was originally passed by Congress in 1974 to protect public health by protecting drinking water and its sources, including rivers, lakes, reservoirs, springs, and groundwater wells, the federal government does not test for glyphosate.

“The Safe Drinking Water Act requires the testing for pesticides, and they do for about 200; however, none of them test for glyphosate,” wrote Dr. Don Huber, Emeritus Professor of Plant Pathology at Purdue University, in an email on April 29th of this year.

Therefore, on July 6th, 2016, the groups took three water samples from three different water sources in the Napa Valley-- a sample from the Napa River, taken at the Oak Knoll bridge in Napa; a sample of municipal tap water from outside a home in Yountville, which gets its water from Rector Reservoir; and a sample of unfiltered well water from outside a home on Hedgeside Avenue in Napa.  The groups shipped the samples via overnight mail to Microbe Inotech Laboratories in St. Louis, Missouri to be tested for glyphosate.


The results of these tests indicated that while the sample from the Napa River did not contain a detectable level of glyphosate (<0.05 parts per billion or ppb), and the sample of municipal water in Yountville contained only a small amount of glyphosate (0.091 ppb), the well water contained 0.729 ppb, which is lower than what is allowed in the United States at 700 parts per billion but is higher than what has been shown to cause harm and three times higher than what is allowed in drinking water in the European Union at 0.1 ppb. 

Scientists have shown that 0.1 ppb of glyphosate, also a patented antibiotic, kills beneficial gut bacteria, which make up 70% of the immune system in humans.(1) In addition, scientists have shown that only 0.1 parts per trillion of glyphosate stimulates the growth of breast cancer cells.(2) 

Moreover, many other toxic compounds are used in these glyphosate-based herbicides.  These other compounds have recently been shown by French scientist Gilles-Eric Seralini to be 1000 times more toxic than glyphosate alone, as well as endocrine and nervous system disruptors, making the current allowable levels of glyphosate too high to protect human health.​(3)

Given the low levels of glyphosate that have consistently been found in municipal water supplies compared to the higher levels found in groundwater, Dr. Michael Antoniou, geneticist at King’s College in London, stated via email, “What we can detect in human urine has to be coming from food and man-made drinks, such as wine and beer, rather than tap water.”

Glyphosate is sprayed in vineyards throughout Napa County in the winter when the vines are dormant.  According to the California Department of Pesticide Registry, 50,417 pounds of glyphosate were applied on Napa County vineyards in 2013 alone, the last reported year.  

In March 2016, Moms Across America reported that tests of ten wines from the California North Bay, including wines from Napa County, all contained varying levels of glyphosate.  At the Acres USA Conference in 2011, Dr. Huber stated that the glyphosate is likely absorbed through the roots and bark of the grapevines and is then translocated into the leaves and grapes, making its way into the wine itself.


“These test results point to two environmental issues in Napa County-- herbicide use and over-extraction of groundwater, both primarily due to agriculture,” said Amy Martenson, Co-coordinator for Label GMOs Napa County.

“It is not surprising that glyphosate would be in higher concentrations in groundwater versus surface water, because groundwater is stored in alluvial aquifers, similar to reservoirs, that do not get the flushing actions that surface flows get,” stated Chris Malan, watershed advocate and Napa County Green Party County Council Member.  “As people extract more and more groundwater, the contaminants become more and more concentrated, which is devastating to future generations who will need to depend on clean aquifers."

Concerned about the amount of pesticide use in Napa County, the negative impacts to the environment and human health, and its likely connection to Napa County’s high cancer rate, Label GMOs Napa County and the Napa County Green Party have called on local officials to reduce pesticide use by taking the following actions:

  1. Follow the lead of other environmentally progressive cities and counties in the U.S., and ban the use of pesticides on all publicly-owned lands, except if needed to protect the health, safety, and welfare of its residents.

  2. Direct the Agricultural Commissioner to use his authority under AB 947 to create school protection zones, banning pesticide use a quarter of a mile around all schools.

  3. Make organic certification a criteria for all new Williamson Act contracts, which give tax breaks to landowners in the Agricultural Preserve and Agricultural Watershed to keep their land in agriculture; these contracts could be tied to organic farming practices and sound environmental stewardship but currently are not.

(1) Current Microbiology. The Effect of Glyphosate on Potential Pathogens and Beneficial Members of Poultry Microbiota In Vitro. (2013). Shehata, AA, Schrodl, W, Aldin, AA, Hafez, HM, and M. Kruger.
(2) Food and Chemical Toxicology. Glyphosate Induces Human Breast Cancer Cells Growth via Estrogen Receptors. (2013). Thongprakaisang, S, Thiantanawat, A, Rangkadilok, N, Suriyo, T, and J. Satayavivad.

 (3) International Journal of Environmental Research and Public Health.  Co-­Formulants in Glyphosate-Based Herbicides Disrupt Aromatase Activity in Human Cells below Toxic Levels. (2016). Defarge, Nicolas, Takacs, Eszter, Lozano, Veronica Laura, Mesnage, Robin, Spiroux de Vendomois, Joel, Seralini, Gilles-­Eric, and Andras Szekacs.

Be the first to comment

Please check your e-mail for a link to activate your account.

Follow Us Here