Pick your poison: Professor O’Shea discusses arsenic in California wine

Brooklyn Dippo | News Editor


O’Shea researches arsenic in abandoned gold mines with graduate student Elizabeth Johnston.

O’Shea researches arsenic in abandoned gold mines with graduate student Elizabeth Johnston.

While many college students are recruited to go on international mission trips to build wells and help impoverished communities get access to clean drinking water, they might want to shift the focus of their efforts in their own backyards. Traces of toxic elements in drinking water in the United States, including California, are a cause for concern.

In California a growing reliance on groundwater is raising questions about arsenic poisoning. Professor Beth O’Shea, who teaches in the Environmental and Ocean Sciences department at USD, explained the concern for arsenic in California wine as a part of her talk, “Pick Your Poison” which was the first talk of the College of Arts and Sciences Illume Series.

O’Shea is also an arsenic geochemist. She explained in her talk that arsenic gets into the groundwater when rocks break down so she tests rocks for arsenic levels. She highlighted extensive research she conducted in Maine testing arsenic in well water.

Arsenic is a naturally occurring element that is lethal if contracted in large doses or cause cancer, keratosis, or neurotoxicity if you are exposed to small doses over a long period of time. People most often ingest arsenic in their food and drinks but can also inhale it from dust or soil.

Californians who get their water from wells should be testing it annually for arsenic levels. People who drink public water are safe for now.

“Public drinking water is regulated so your tap water is probably safe,” O’Shea said. “I drink tap water. I don’t use filters, I don’t use bottled water. Bottled water incidentally when it first became a popular item wasn’t regulated and so they weren’t required to test for arsenic. But it’s a rip off.”

People should, however, be conscious of where their water supply comes from. While a majority of San Diego’s water supply comes from the Colorado River those percentages can fluctuate.

O’Shea explained that in a normal year, groundwater supplies 40 percent of California’s water but in drought years that number can rise up to 65 percent, and that can have an effect on arsenic levels.

“Be aware of how much arsenic might be in your water,” O’Shea said. “The things that I do watch online and in the media are updates by the FDA. I’m not going to worry about what I see on blogs. I’m focused on the FDA results.”

Though drinking water is regulated for arsenic levels, other beverages and food are not. Arsenic rich groundwater is used to irrigate crops in California and is in some cases absorbed by the plants. In the case of grapes, all California wines are testing for arsenic levels 4-5 times higher than the limit for drinking water which is 10 ppb.

Unless you are drinking as much wine as you do water, the higher arsenic levels shouldn’t affect you. In fact, more arsenic is found in rice and rice products than wine.

O’Shea said the average person is exposed to arsenic more from food than from beverages and water combined so the best strategy is to balance.

“It is more about balancing, knowing where the arsenic is coming from and balancing,” O’Shea said.

Senior Claudio Trespalacios has taken classes with O’Shea and attended her talk. He hopes that all of this conversation will move towards getting food labels that include arsenic content.

“I think like she said, it’s not going to affect my drinking habits,” Trespalacios said. “I’m just going to be more conscious of what I eat and how I eat it. I’ve taken classes with Dr. O’Shea for over four years now so I have been hearing about [arsenic] a lot. It’s just nice to know that someone is thinking about it and doing something about it. It will be interesting to see in the future how labels will change hopefully for the benefit of us all.”

It’s not always obvious that foods or beverages contain high amounts of toxic chemicals. You cannot see, smell, or taste arsenic or lead that is dissolved in water, so source awareness is the key to keeping safe.

The biggest concern about public water is that the source often changes. And when problems arise, the government has a recent record of not being transparent with their constituents.

The city of Flint, MI is enduring a crisis after many residents contracted lead poisoning from drinking the tap water. In an effort to cut spending, the city stopped sourcing water from Detroit and started getting it from the Flint River. They didn’t use any corrosion control to prevent lead from the pipes from seeping into the water and that mistake is costing more than money.

Flint used to be a thriving city with several car manufacturers, but when the bulk of them moved, so did the money. The government decided to switch water sources to save the city nearly $1 million dollars a year. Faucets no longer flowed with the clear water of Lake Huron, they spattered out yellowish and often E. Coli polluted water that residents were advised to boil in order to remove toxins.

City officials continued to deny any problems with the water until researchers from Virginia Tech came in to test water around the city. The Environmental Protection Agency defines safe drinking water as having lead levels below 15 parts per billion; some samples at Flint measured lead at 13,200 ppb which is over twice the criteria needed to be classified as toxic waste.

The damage that lead poisoning does is irreversible. Children are the most vulnerable and can suffer developmental delays, behavioral problems, and seizures along with recurring headaches, abdominal pain, and a slew of other problems. The city has declared a state of emergency and was given $70 million by the state of Michigan with $165 million requested to follow this year.

The work of scientists and especially geologists has the potential to prevent public health crisis and save governments millions of dollars in damages. O’Shea continues her field work and arsenic research in the San Diego area with the help of graduate students.

She is currently examining arsenic levels in old gold mines in Black Mountain Open Space Park along with graduate student Elizabeth Johnston. The popular hiking spot is located just west of Poway and the arsenic levels they found are so high that they now wear full hazmat suits with respirators when they are taking rock samples. The arsenic levels are safe on the public hiking trails but hikers who go off the path exploring are vulnerable.

Johnston believes the research they are doing could open up the door to more research opportunities including those in the public health sector.

“It’s been pretty interesting since no one has really studied [these mines] before,” Johnston said. “So there are other known abandoned mines in the area, so potentially there is more research to be done in San Diego, maybe in similar tectonic settings. So we are hoping that this study will lead to other ones in the future. Not just in finding the sources of arsenic, the natural sources, but also moving on to figure out the health implications and maybe to pinpoint other areas that would be at risk.”

After O’Shea and Johnston  complete the research they will take their findings to the city to determine what to do about the mines. Most likely the mines will be cemented off to keep curious hikers from unknowingly exposing themselves to arsenic.

Despite the scare, USD students can prevent health complications by being aware of the elements around them.


Professor Bethany O’Shea wrote to the USD Vista with the following comments: 

‘In the case of grapes, all California wines are testing for arsenic levels 4-5 times higher than the limit for drinking water which is 10 ppb’, should read ‘In the case of grapes, all California wines presented in one study tested arsenic levels 4-5 times higher.’

‘She is currently examining arsenic levels in old gold mines in Black Mountain Open Space Park’ is an incorrect statement. The mines being examined in Black Mountain were old arsenic mines, not gold.