Update, July 18, 2017:

More than 25 years after the state determined that 1,2,3-TCP causes cancer, the State Water Resources Control Board voted to approve a standard for the chemical in drinking water. They set the limit at 5 parts per trillion, a level supported by clean water and pesticide reform advocates. The state will now start water systems to test all of their wells every month starting in January. 

Board chair Felicia Marcus called the vote, “a very important day for public health.”

“It’s a very serious public health threat,” agreed board Vice-Chair Steven Moore. “California officially determined that this is a carcinogen. And when you look at the science and the experiments and all that was done to show it, it is disquieting how serious and insidious this chemical is.” 

Update, June 20, 2017:

The state water board has proposed a standard for 1,2,3-TCP and held a hearing to receive public comment. The state is proposing that the maximum contamination for 1,2,3-TCP in drinking water be set at 5 parts per trillion. The nonprofit Community Water Center, which advocates for safe, clean drinking water in the San Joaquin Valley, testified in support of the proposed standard.

State water officials have not yet formally implemented the standard, but they have issued an updated map showing contaminated wells.

The Fresno City Council has authorized a study to find out how to remove 12,3-TCP from the city’s water supply. 

Update, January 2, 2017:

In January, The State Water Resources Control Board is expected to roll out the draft of a first-ever enforceable standard for 1,2,3-TCP in California drinking water.

In December, the city of Clovis, in Fresno County, won a $22 million court judgment against Shell Oil Co., for TCP contamination in wells. More than 40 other cases remain open.

Original Story, March 7, 2016:

I have to admit, after the water crisis in Flint, Michigan, I’m a little freaked out about what’s in my tap water. So when I opened my water bill from the city of Fresno recently, I decided to actually read the “consumer confidence report” for drinking water. And I found this footnote in tiny print:

Wait…what? I have two little kids, and my family drinks the tap water. And it might cause cancer? I decided to fork out $200 to get mine tested. And to start digging into how 1,2,3-TCP got into the water.

Turns out, it’s not just Fresno. According to the State Water Resources Control Board, 1,2,3-TCP has been found in about a hundred public water systems across California, mostly in the Central Valley but also in counties like Santa Cruz, Monterey, Sacramento, and Los Angeles.

But many Californians don’t know whether this stuff is in their water, because neither the state nor the federal EPA regulates 1,2,3-TCP in drinking water. So that means public utilities don’t have to test for it, filter it out, or advise their customers if it’s in the water.


Water systems where significant levels of contaminant 123-TCP have been detected.


That’s even though the state determined it was a carcinogen back in 1992. And the California Office of Environmental Health Hazard Assessment (OEHHA) set a very low public health goal for 1,2,3-TCP in 2009.

“There is no absolutely no question that is a genotoxic carcinogen,” says Robert Howd, a toxicologist who led the scientific review for OEHHA.

There have been no studies of 1,2,3-TCP’s effect on humans, but animal studies showed multiple tumors at multiple sites in both rats and mice.

“The data are very clear,” Howd says. “Virtually nobody is disputing that. There’s just no controversy about this being a DNA reactive carcinogen.”

Howd’s team set the public health goal at .7 parts per trillion (.0007 parts per billion) The only carcinogen with a lower state public health goal for drinking water is dioxin.

How Did It Get Into the Water?

“This whole story begins in the 1930s, the dawn of the age of chemical agriculture” says San Francisco attorney Todd Robins. He represents about 30 communities around the state who are suing over 1,2,3-TCP contamination, and he’s spent the last decade trying to track how it leached into groundwater.

“Somebody at the Pineapple Research Institute in Honolulu got ahold of this sample of what was essentially hazardous waste from a chemical production process at Shell,” he says, “and he used it in some experiments.”

The experiments, Robins says, were to figure out how to control nematodes, tiny microscopic worms in the soil that attack a plant’s roots.

“Shell saw a huge opportunity to take a hazardous waste stream from their chemical plants … and start putting it in barrels, and selling it to farmers,” says Robins. “Then Dow soon followed suit.”

The companies sold the product to farmers as a fumigant, which is injected into the soil.

Robins has compiled a huge stack of documents that show neither Dow Chemical nor Shell listed 1,2,3-TCP on their product labels, even though it was one of several ingredients. One of Dow’s own scientists admitted that the compound had served no function killing nematodes.

Robins shows me a 1974 memo where Dow describes some of the fumigant components as “garbage.”

Ralph Gutierrez says Shell and Dow should pay to clean 1,2,3-TCP out of Woodville's water.
Ralph Gutierrez says Shell and Dow should pay to clean 1,2,3-TCP out of Woodville’s water. (Sasha Khokha)

“Some of the most startling information is how clearly the companies understood from a scientific perspective the amount of garbage they were putting into these products,” says Robins, “and knowingly having farmers essentially dispose of their hazardous waste for them on farm fields throughout our state.”

In a few cases, Dow and Shell have paid to clean up groundwater with 1,2,3-TCP. But in the more than 3 dozen cases filed against the companies over the contamination, they’ve never admitted any wrongdoing.

Both Dow and Shell declined my request for a taped interview. They sent me emails saying they couldn’t comment on active litigation.

Dow spokesman Randy Fishback wrote that fumigants with 1,2,3-TCP were part of what he called “historical, highly beneficial agricultural products” that “controlled agricultural pests that otherwise would have caused millions of dollars in annual crop losses.” He added those products have been off the market for several decades, and that “TCP is also associated with certain industrial processes in which Dow had no involvement.”

Tiny Communities Can’t Afford Cleanup

Woodville is a small farming community in Tulare County, where the 1,2,3-TCP in the drinking water is ten times the state's public health goal.
Woodville is a small farming community in Tulare County, where the 1,2,3-TCP in the drinking water is ten times the state’s public health goal. (Sasha Khokha/KQED)

Some of the communities suing Dow and Shell have only a few hundred households, like Woodville in rural Tulare County. Ralph Gutierrez runs the water system here.

“I’m the meter reader, I’m the sewer line cleaner, I do the budget,” says Gutierrez, grinning in his cowboy boots and Dodger hat.

He unlocks the gate to show me one of the town’s two drinking water wells, surrounded by orchards and cow pastures. These wells serve a total of 467 households, and 1,2,3-TCP has been detected in the water at 7 parts per trillion, ten times the public health goal.

“Dow and Shell are the ones that put this into the system,” Gutierrez says. “Obviously, they have money to attack their problems, but when you come to communities like this, they’re all farmworkers.”

Gutierrez says there’s no way he can raise water rates high enough to pay for expensive carbon filtration to keep the carcinogen from reaching people’s taps.

“I wouldn’t want my kids drinking it,” he says. “Would Dow Chemical or Shell like their people to be drinking this water? I don’t think so.”

Results From My Tap

Turns out the sample from my kitchen tap comes in at 2.2 parts per trillion. That’s three times the state public health goal for 1,2,3-TCP.

OEHHA sets its goal to try to reduce the lifetime cancer risk to less than one in 1 million. So my risk is three in 1 million, over a lifetime drinking my tap water.

Of course, my overall risk of getting cancer from any source is much higher; it’s more like one in three. Truth is, I should probably be more worried about secondhand smoke, or Fresno’s notoriously dirty air.

But I’m not taking any chances with my kids. I’ve installed an undersink filter that says it takes out Volatile Organic Compounds (VOCs). But there’s no guarantee it takes out 1,2,3-TCP, because without a government standard, it’s not rated for that.

State Regulation On Its Way

Some water systems in the Central Valley have levels of 1,2,3-TCP that push the potential cancer risk to roughly one in 6,000. And a grassroots group called Community Water Center is pressuring the state to set a maximum contaminant level for the compound. That’s an enforceable standard, unlike the public health goal.

Nearly 25 years after California declared 1,2,3-TCP to be a carcinogen, drinking water regulators are planning to set that level by next spring.

“It’s been a high priority for us to develop regulations, but we have had so many other regulations with limited resources to work on, that we haven’t been able to get it over the finish line,” says Cindy Forbes, deputy director for the water board’s drinking water program. “There are a lot of pieces to setting a new maximum contaminant level.”

Like conducting their own peer-reviewed science, taking public comment, and evaluating the cost of detection and cleanup — not just the health risks.

“It’s our number one priority,” says Forbes. “It’s my priority, it’s the board’s priority.”

Sasha Khokha has since moved from Fresno to the Bay Area, where she hosts KQED’s weekly edition of The California Report.

California Finally Begins Regulating Cancer-Causing Chemical Found in Drinking Water 21 July,2017Sasha Khokha

  • Frog Lover

    Where can we purchase this test?
    How can it be filtered out or dissimilated?
    It’s not in Hetch Hetchy water because that is surface water, correct?

  • Monique Boyer

    I see that Solano county is listed as being impacted by this contaminate in the water. Is this found in all water in Solano? What about Benicia?

  • Suzy Hayes

    Poisoned H2O? Get used to it! “We” as a species have spent the past 200 years monitoring the population numbers of all other species sans the one species causing all the havoc & grief…..US! We have poured concrete over everything in the name of “progress” & “economic gain”. PLASTIC GARBAGE swirling in the Pacific Ocean now outweigh surface ZOOPLANKTON, 6 to 1. GMO’s are being created in labs to “feed the masses” & on & on & on! Our species is the ONLY species which TRULY defecates where we eat……..Poisoned H2O?? Get used to it!

    • waraji

      Yes it’s true, but still worthwhile to do everything we can.

      • Suzy Hayes

        ABSOLUTELY! Which is why I get up each a.m.@ 4:00, in preparation to wade into the historic creeks & rivers of my CA county to take H2O samples EACH & EVERY morning! I apologize if I sound bitter, BUT it has gotten worse, instead of better, over the years. Let’s meet back here in 15-20 years & I will let you know if my attitude has gotten any better!

  • katiang

    We have the same issue here in Moorestown NJ, just fought for months to get our town council to shut down a well with TCP contaminants and other VOC’s. Our state legislation passed the bill to limit the MCL but our dear governor Chris Christie vetoed it at time of passing the bill saying it gives too much power to the EPA and DEP–let’s see–aren’t they the experts–I’d love them to have the power as to how much of a volatile chemical should be in my water-not a politician!!!. We installed a house filtration system too–good luck to you all!

  • Waterlover

    1,2,3 TCP is just one of a 100+ unregulated “risky” chemicals and pathogenic microbes known to the EPA and published on their Contaminant Candidate List (check it out at http://www.epa.gov/ccl). Another one is PFOA, which is also carcinogenic and was recently in the news. All of these chemicals have serious health effects, and are present at varying levels across the nation. NONE ARE REGULATED.

    For those who want to be proactive about protecting themselves and their families, it is best to install a NSF-certified reverse osmosis filter under the kitchen sink for drinking and cooking water needs (look for a system certified for standards 42 & 53 at a minimum). This will remove or greatly reduce (typically >95%) practically all contaminants. However, this will also remove healthy minerals from the water, and therefore it is important to add essential minerals like calcium and magnesium back into the purified water, by using a product such as emdrops (electrolyte mineral drops). This is the most cost-effective solution for individuals and families at present, and it is a much better option than regularly buying bottled water, which has several issues of its own.

    Another option for obtaining even higher purity water is a distillation system combined with a VOC filter. Just remember to add healthy mineral electrolytes, because any water purification system or filter that broadly removes various contaminants will also remove the good minerals.

    Deteriorating water quality is probably one of the key reasons why at least 50% of American adults are suffering from at least one chronic disease. Many drive fancy cars that cost of $$$$$, and yet most do not want to spend a 20 or 30 bucks a month on purifying their drinking and cooking water. Wake up people! The government is not going to do it for you.

    • great suggestions … but useless without filtering one’s entire water system … as the skin is the largest organ in the body, and absorbs everything from the water

  • Jeanie_MV

    Please send me information on how I can get my tap water tested.

  • waraji

    Dow spokesman Randy Fishback : “TCP is also associated with certain industrial processes in which Dow had no involvement.”


  • waraji

    Dow spokesman Randy Fishback :

    “TCP is also associated with certain industrial processes in which Dow had no involvement.”


  • anysteph

    Fresno has more in common with Flint: the Dow factory on the Flint River polluted that water as well, since the early 1900s (along with General Motors in the same area).

  • KennethL

    Too bad the moronic lower 49% IQ citizenry has elected a narcissicistic infant for president who has put a guy in charge of EPA who will do absolutely nothing at all about any of this. He’s more interested in getting rid of the regulations we already have. So stop whining liberals. The EPA is not in a position to protect the citizenry until we dump this illigitimate administration.

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  • Eric Caligo

    I don’t normally comment on stuff like this, but this is quite sensationalized and I feel the need to. TCP is an impurity (0.17% roughly) in a number of pesticides and soil fumigants that were used extensively in CA prior to the 1990s. It was not some evil plot by Shell and Dow to sell off their chemical waste, as the article says. TCP will break down fairly quickly in air or through evaporation, but it will also over time leech from soil to groundwater, hence the presence in the Central Valley. A lot of the chemicals containing TCP were used in California, explaining the abundance of the chemical, but the levels cited in the article don’t match the numbers put out by the CDC and the EPA. According to the CDC, the max safe level for children is 0.6 parts per million over 7 years. The level cited in the article is 7 parts per trillion, or 0.000007 parts per million. If this wasn’t a typo, this article grossly misrepresents the gravity of the situation as judged by the EPA. Even the graph in the article shows that the detection in wells 2002-2010 were as high as 150 ppt, but that is still .00015 ppm, well below any EPA recommended maximum level for children that I could find. Finally, the article states that TCP is proven as a carcinogen. This is a direct conflict with statements by the CDC and Pubchem. It is a suspected/probable carcinogen based on results from lab animals but it does not seem to have any cited definitive results for human results listed on PubChem.gov. I apologize for the rant, but this article seems to be more about scaring the public under the guise of science than actual research.

    Sources: https://pubchem.ncbi.nlm.nih.gov/…/1_2_3…




Sasha Khokha

Sasha Khokha is the host of The California Report  weekly magazine program, which takes listeners on sound-rich radio excursions around the Golden State.

As The California Report's Central Valley Bureau Chief for nearly a dozen years, Sasha brought the lives and concerns of rural Californians to listeners around the state. Sasha's reporting helped exposed the hidden price immigrant women janitors and farmworkers may pay to keep their jobs: sexual assault at work -- and helped change California law with regard to sexual harassment of farmworkers.  She's won a national PRNDI award for investigative reporting, as well as multiple prizes from the Radio Television News Directors Association and the Society for Professional Journalists.

She began her radio career in waterproof overalls, filing stories about the salmon fishery at Raven Radio in Sitka, AK. She has produced and reported for several documentary films. Calcutta Calling, about children adopted from India to Swedish-Lutheran Minnesota, was nominated for an Emmy Award.

Sasha is  a graduate of the University of California at Berkeley Graduate School of Journalism and Brown University, and is the mother of two young children.

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