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Recent study shows most water filters do not remove cancer-linked PFAS chemicals from drinking water

FALLBROOK – PFAS chemicals have been in the news for the past few years because of their link to cancer, thyroid disease, reproductive and immune disorders and other health problems. They're found on nonstick pans, waterproof fabrics and furniture, food packaging and some foods. They're most widely used in fire-fighting foam and products to resist heat, oil stains, grease and water. They have also been found in drinking water supplies across the country.

Scientists call this group of Perfluorooctanesulfonates "forever chemicals" because they accumulate in the environment and in the body without breaking down. So each exposure adds more to the body.

Many people use filtered water believing these point-of-use filters, such as those on refrigerators and water pitchers, protect them from harmful chemicals such as PFAS. But a study released in early February 2020 by Duke University disproved that notion.

According to the Duke University study, "Most carbon filters in pitchers, refrigerators and whole house filtering systems do not remove PFAS and some even make them worse."

Heather Stapleton, professor of environmental health who oversaw Duke's testing, said, "The under-sink reverse osmosis filter is the most efficient system for removing contaminants. All of the under-sink reverse osmosis and two-stage filters achieved near-complete removal of the PFAS chemicals we were testing for. In contrast, the effectiveness of activated-carbon filters used in many pitcher, countertop, refrigerator and faucet-mounted styles was inconsistent and unpredictable. The whole-house systems were also widely variable and, in some cases, actually increased PFAS levels in the water."

PFAS chemicals have been found in rainwater

Martin Shafer, principal researcher with the National Atmospheric Deposition Program, and his team collected and analyzed 37 rainwater samples in 2019 and found "each sample contained at least one of the 36 different PFAS compounds currently being studied." He said he suspects they are getting into rainwater because of industrial emissions and evaporation from PFAS in firefighting foam.

Some people might wonder why tap water isn't already purified of PFAS contaminates. The short answer is that during the past 50 years, literally thousands of different types of PFAS chemicals have been used in products and let loose in the environment. Yet only a tiny fraction of those thousands have scientific tests to accurately measure the level of PFAS contamination in drinking water.

7,800 PFAS chemical variants – scientific tests available for only 45 of them

According to the Metropolitan Water District of Southern California, which supplies most of the water for Fallbrook, Bonsall, Vista and Oceanside, "there are more than 7,800 PFAS."

And even though the Metropolitan District and each cities' water district regularly tests for PFAS at supply sources as well as treated water, "current science only allows for detection of 45 different kinds of PFAS."

"As testing methods are refined, Metropolitan will expand the number of PFAS it tests for," according to the Metropolitan's website.

So the bottom line is researchers really don't know how many of more than 7,000 types of PFAS that cannot yet be tested for remain in tap water because there are no scientific tests to measure them.

When asked why PFAS measurements – the ones that can be tested for – were not included in Fallbrook Public Utility District's yearly Consumer Confidence Report, Noëlle Denke, public affairs representative for the district, said that "If the results come back as None Detected, it is not a requirement to include them in the report. Fallbrook PUD sampled for PFOS and PFOA during the Unregulated Contaminant Monitoring Rule, as required by the Environmental Protection Agency. At that time, no results were detected for us during this test period."

PFOS and PFOA chemicals are the most studied of the 7,800 types of PFAS chemicals and the ones which can be scientifically tested for in water supplies.

Denke said, "Along with the growing concerns with PFAS, we foresee more testing being required by the EPA and the division of drinking water here in California in the near future. We support this and will be doing testing required as our top priority is our commitment to a safe water supply."

The only publicly available data for Fallbrook and surrounding cities' testing of PFAS chemicals is on the California Water Board's website. The California Water Board required all public water utilities with over 10,000 customers to monitor PFASs levels from 2013 through 2015 and to notify their customers of the presence of levels over 70 parts per trillion of combined PFAS chemicals. At that time, 18 of the estimated 7,800 PFAS chemical variants could be tested for, including PFOA and PFOS. The Water Board's report showed at the time of those 2013-2015 measurements that Fallbrook, Bonsall, Vista and Oceanside all measured 0.02 ppt for PFOA and 0.04 ppt for PFOS.

The highest levels in California during the 2013-2015 testing were found in San Diego County in a U.S. Marine Corps Base Camp Pendleton well with 820 ppt for several different PFAS chemicals, subsequently causing the well to be shut down in 2017. Since PFOAs and PFOSs are in firefighting foam and widely used around airports and military bases, wells around Camp Pendleton would understandably be at risk.

Controversy over what constitutes "safe" level of PFAS in drinking water

According to the EPA, even very low doses of PFAS have been linked to cancers, thyroid disease immune function and other health disorders. Yet, the EPA's health advisory response level remains at 70 ppt.

The California Water Board updated its drinking water response level Feb. 6, to 10 ppt for PFOA and 40 ppt for PFOS.

According the Environmental Working Group, an independent, nonprofit environmental watch group, those levels are "hundreds or thousands of times too week." Instead, they endorsed 1 ppt which they said is the same as what is recommended by the best independent studies of PFAS.

In September 2019, the EWG analyzed the most recent data collected by the California State Water Board and the EPA. According to the EWG, 74 community water systems serving 7.5 million Californians were contaminated with highly toxic PFAS.

In late January 2020, the EWG issued an updated finding, stating "PFAS contamination of drinking water is far more prevalent than previously reported" in their September 2019 report.

The EWG's latest findings come from testing samples collected by the group's staff of scientists and volunteers between May and December 2019. They sent the samples to an accredited independent laboratory that tested them for 30 different PFAS chemicals. The EWG concluded, "The results confirm that the number of Americans exposed to PFAS from contaminated tap water has been dramatically underestimated by previous studies, both from the EPA and EWG's own research."

EWG scientists said they now believe PFAS is likely detectable in all major water supplies in the U.S., almost certainly in all that use surface water.

Fecal samples in dogs and cats Show PFAS doses above minimal risk level for humans

Another independent study published Feb. 5, in "Environmental Science & Technology" bolstered the concern for more PFAS contamination than previously believed.

It studied 13 varieties of PFAS in pet fecal samples and found between 21.6 and 474 ng/g of PFAS. They found that "The estimated daily fecal excretion suggested that both dogs and cats are exposed to some PFASs at doses above the provisional minimum risk level recommended for humans."

A Fallbrook resident's reasoning on the PFAS research and Duke University filter study

"Small pets are like canaries that used to be in coal mines," Fallbrook resident Jan Hooper said. "They're early warning systems."

Hooper, who compiled information for this article, explained her interest in the PFAS research.

"I've had three small dogs with Cushing's disease and one with Addison's disease," Hooper said. "According to a study done in the 70s, the estimates of either of these disorders in mixed-breed dogs was only one out of a thousand.

"When I realized how far out of the norm I am, I became more interested in contaminates in the environment. I've always given them the highest quality dog food. I'd previously even given them filtered water from my refrigerator's cold-water dispenser, thinking it would filter out chemicals that could damage their health.

"But after reading the Duke study showing that reverse osmosis was the only proven way to get rid of at least the dangerous chemicals we can test for, I've installed a reverse osmosis system under my kitchen sink. My house is literally less than half a mile from Camp Pendleton where they undoubtedly use those PFAS chemical foams whenever there are fires on base. I can't control that or other contaminates in the environment. But I can at least install a reverse osmosis system that has proven to reduce the most chemical contaminates in our drinking water," Hooper said.

Waterheaters Plus Plumbing and owner Dale Anderson has been installing water treatment systems including reverse osmosis for the past 30 years in Fallbrook and neighboring cities.

For more information on reverse osmosis systems, visit

Article courtesy of Dale Anderson, owner of Waterheaters Plus Plumbing.


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