07.05.2016  
 

Arsenic, Herbicide Wine Scares Put in Context

In keynote address at ASEV conference toxicology expert explains there's little risk

 
by Andrew Adams
 
wine aresenic toxic ASEV
 
Dr. Carl K. Winter speaks about the risk of arsenic and glyphosate in wine last week during the national conference of the American Society for Enology and Viticulture in Monterey, Calif.
Monterey, Calif.—An average man would need to put back five glasses of wine per day, every day, to consume enough inorganic arsenic to run the risk of causing health problems, according to a leading expert on food and beverage toxicology.

At such a rate of consumption, however, that hypothetical person would likely have several other health concerns that would be more evident than anything related to arsenic. “The health issues for this particular individual is not the arsenic in the wine,” said Dr. Carl K. Winter, a specialist in the cooperative extension of the University of California, Davis, Department of Food Science and Technology.

Winter is an expert on toxic substances or organisms found in foods and beverages and provided context on the purported risks posed by arsenic and the herbicide glyphosate in the keynote speech of the national conference of the American Society for Enology and Viticulture held June 27-30 in Monterey.

His comments come after a class-action lawsuit against major producers and retailers of wine in California was recently dismissed, and the advocacy group Moms Across America attempted to raise concerns about glyphosate in wine.

Both received coverage by national media, with most of the headlines focused on the arsenic scare. The lawsuit had been based on a study of 1,300 wines, of which more than a quarter had levels of total arsenic higher than 10 ppb, or what is allowed by the U.S. Food and Drug Administration in drinking water and apple juice. Total arsenic is the level of both organic and the toxic inorganic arsenic.

Winter said the Environmental Protection Agency’s (EPA) reference limit on acceptable exposure for an adult is 0.3 micrograms per kilogram of body weight per day. For an average American eating grains and legumes, fish, poultry, red meat and beverages, the typical exposure is just 0.05 micrograms per kilogram per day. Beverages account for only about 5% of a typical adult’s exposure to arsenic.

Using that typical exposure rate as a starting point, Winter then calculated how much wine containing 18 ppb of total arsenic one would have to consume to reach the EPA’s limit, and that’s how he arrived at five glasses per day.

Concerns about glyphosate, which is used for weed control, cropped up soon after the arsenic case had been dismissed. Winter said as the substance is an herbicide, its toxicity to mammals is relatively low, and there’s an ongoing debate in the international community about whether or not it’s carcinogenic for humans.

The EPA reference on glyphosate is 0.1 mg/kg per day, and to reach that level of exposure, the same hypothetical male would have to drink 2,500 glasses of wine per day for 70 years.

Winter used a quotation from the 16th century Swiss physician Paraclesus to remind the audience that any substance can be a poison as “it’s the dose that differentiates a poison and remedy.”

In addition to his academic research and teaching, Winter has also gained a reputation as the “Elvis of E. Coli” and the “Sinatra of Salmonella” for writing lyrics to well-known tunes concerning food safety. He wrapped up his keynote speech with a recording of “I Sprayed it on the Grapevine,” which is about vineyard pest control and set to the music of Marvin Gaye’s “I Heard It Through the Grapevine.” Winter didn’t have much luck getting the audience to join him in singing the chorus, but he did receive a resounding round of applause for the music. 

Using water wisely

The ASEV’s 67th annual conference began with a full-day symposium about managing water in California that featured experts from academia and the industry discussing tools, techniques and research on irrigation, soil salinity and managing drought conditions.

Luis Sanchez, principal research scientist at E. & J. Gallo Winery, described that company’s development of a variable-rate drip-irrigation system to adjust for the different characteristics of a vineyard.

Gallo is seeking to develop such a system to manage field variability as well as maximize grape yield and quality while reducing the environmental impact. Sanchez said the company developed a prototype system at a 31-acre vineyard near Wilton, Calif.

The vineyard was divided into a grid of 15- by 15-meter squares (or pixels, as Sanchez referred to them), and each square was irrigated separately. He said the grid was comprised of 140 squares and required more than 700 solenoid valves and miles of control wires. Water flow was controlled by a two-hose system with computer-controlled solenoids and check valves at each square.

The trial lasted from 2011 to 2015 and was compared to a control vineyard irrigated with a traditional drip system. Irrigation was adjusted with data from Landsat normalized difference vegetation index (NDVI) images for better uniformity, and the variable drip-irrigated system provided an average of 10% more yields with 17% more water efficiency than the control.

Sanchez said Gallo is currently working with the Israeli irrigation specialist Netafim on a next-generation system that may feature larger (30-meter by 30-meter) irrigation squares and could even be used for nutrient additions. All of the valves and control boxes would also be located outside of the vineyard rows.

Dr. David Block, chair of the viticulture and enology department at University of California, Davis, described a project conducted at the school’s research vineyard in Oakville, Calif., to develop a precision irrigation system for each individual vine. The project began in 2014 and involved five vineyard blocks of Cabernet Sauvignon vines, with three trial blocks and two control blocks.

He said the system involved control boxes containing flowmeter, distributor, valves and tubing to individual valves. Each box contained four racks and controlled water applications to 32 vines. Referring to a photo of the boxes in his presentation, Block admitted they had a bit of a DIY appearance because the project had been conducted with no outside funding. “If it looks like this stuff can be purchased at Home Depot, it’s because almost all of it can be, and the rest we bought on Amazon,” he said.

The system used 11 miles of irrigation tubing that was first laid on the ground and then tied up to the trellis. The research team used donated NDVI scans to manage variation during the first growing season and then cutting weights for the second. Irrigation rates varied from 0 to 10 gallons per vine per application. When compared to the control blocks, the results on managing variation were mixed, but Block said the rudimentary system proved that vine specific precision irrigation is possible.

That was further demonstrated with the investment of $208,000 by Cypress Semiconductor to UC Davis and the University of Michigan to develop the next generation of the system. Block said a prototype was deployed that week in the research vineyard that includes a 3 cm cubed sensor that is attached to the vineyard guide wire and controls a valve for each vine.

Block said the first-generation system, without any sensor capability, cost $75 to $100 per vine, and the current prototype would cost $30 to $40 per vine with per-vine costs approaching $10 by 2017. When asked what the sensor would measure, Block said the team is analyzing all possible inputs such as soil moisture, NDVI, weather data and more.

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