What are the toxic chemicals found in groundwater around SLO airport?
Toxic chemicals have leached from San Luis Obispo County Regional Airport to dozens of area residents’ water wells, the Central Coast Regional Water Quality Control Board recently found.
The chemicals — per- and poly-fluoroalkyl substances, or, PFAS — likely came from a special fire suppressant foam used by Cal Fire on the airport’s property.
The local water board has issued a draft order to San Luis Obispo County and Cal Fire to clean up and replace the polluted water. The two entities are contesting their legal obligation to do so.
At the heart of the issue is the fact that the ground and groundwater beneath the airport and surrounding neighborhood contain unhealthy levels of PFAS, according to data from the water board.
What are PFAS? How toxic are they? Can they be cleaned up?
Here are answers to some common questions, with information gathered from agencies including the U.S. Environmental Protection Agency, Agency for Toxic Substances and Disease Registry and California State Water Resources Control Board.
What are PFAS?
There are thousands of chemicals that fall under the PFAS umbrella.
Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are two of the first PFAS discovered in human blood in the early 2000s and remain some of the most heavily studied to date.
PFAS made of long chains of carbon-fluorine bonds, such as PFOA and PFOS, typically accumulate in the bloodstreams of people and animals and the cells of plants. This has earned them the nickname “forever chemicals.”
There are newer PFAS made up of fewer carbon atoms that were developed to replace PFOA and PFOS.
Although the chemicals get flushed from the human body more quickly than PFOA and PFOS, they are still persistent in the environment.
What are the potential health impacts of PFAS?
Much is still unknown about PFAS, including how they directly relate to human health impacts.
A large number of studies have examined possible relationships between the presence PFAS in blood and harmful health effects on humans.
“However, not all of these studies involved the same groups of people, the same type of exposure or the same PFAS,” the federal Agency for Toxic Substances and Disease Registry says on its website. “These different studies therefore reported a variety of health outcomes.”
The research has suggested high levels of certain PFAS, particularly PFOA and PFOS, may lead to:
- Increased cholesterol levels,
- Changes in liver enzymes,1
- Small decreases in infant birth weights,
- Decreased vaccine response in children,
- Increased risk of high blood pressure or pre-eclampsia in pregnant women, and
- Increased risk of kidney or testicular cancer.
There is a lot of ongoing research to better figure out what health issues may be related to PFAS.
Are there any drinking water regulations for PFAS?
Because the harmful health effects of PFAS weren’t disclosed by the Environmental Protection Agency until recently, there are no enforceable drinking water standards in the United States for regulators.
In 2016, the EPA issued health advisories for PFOA and PFOS indicating the level of drinking water contamination below which adverse health effects are not expected to occur.
In the case of PFOA and PFOS, the agency said, that’s 70 parts per trillion in drinking water.
A part per trillion is equal to one drop of pollution in 500,000 barrels of water, or traveling 6 inches out of a 93 million-mile journey toward the sun, according to the U.S. Navy. In other words, it’s a tiny amount of contamination that can cause harm to the human body.
In 2022, the EPA updated its health advisories to reflect evolving research that has revealed PFAS are more harmful than previously thought.
The interim updated health advisory for PFOA is 0.004 parts per trillion in drinking water, and 0.02 parts per trillion of PFOS in drinking water.
In March, the EPA announced a proposed National Primary Drinking Water Regulation for six PFAS including PFOA and PFOS. It would set the drinking water maximum contaminant levels for PFOA and PFOS at 4 parts per trillion.
The regulation is expected to be finalized, and therefore enforceable, by the end of this year.
How do I get exposed to PFAS?
There are several ways humans are exposed to PFAS.
The chemicals are found in nearly every corner of the Earth.
The Agency for Toxic Substances and Disease Registry says humans are most commonly exposed to PFAS by:
- Drinking contaminated municipal water or private well water,
- Eating fish caught from water contaminated by PFAS (PFOS, in particular),
- Accidentally swallowing contaminated soil or dust,
- Eating food grown or raised near places that used or made PFAS,
- Eating food packaged in material that contains PFAS, or
- Using some consumer products such as stain-resistant carpeting and water-repellent clothing.
Research has suggested that human exposure to PFAS from consumer products is usually low, especially when compared to exposures from contaminated drinking water.
“Based on the available data, only a small amount of PFAS can get into your body from skin contacting PFAS-contaminated water,” the toxic substances agency says on its website. “Also, most PFAS do not evaporate into the air from water readily. Therefore, for most PFAS, showering, bathing, or washing dishes in water containing PFAS should not increase exposure.”
The agency also encourages breastfeeding mothers exposed to PFAS to continue breastfeeding, as the benefits associated with breastfeeding appear to outweigh the risks of PFAS exposure.
Can I treat my water to remove PFAS?
Residents living on private wells can install activated carbon, anion exchange and high-pressure membrane water treatment systems on their well heads to remove PFAS from their drinking water, according to the EPA.
These treatment options are also widely available for in-home use. For example, activated carbon filters can be installed under kitchen sinks or on showerheads.
Activated carbon is the most studied treatment for PFAS removal, and is commonly used to absorb organic compounds in drinking water treatment systems. However, granular activated carbon treatment systems may have to be replaced more often than usual to effectively filter out PFAS.
Anion exchange resins “are like tiny powerful magnets that attract and hold the contaminated materials from passing through the water system,” the EPA’s website says.
Like the activated carbon systems, anion exchange systems may have to be replaced more often than usual if filtering out PFAS.
High-pressure membranes, such as nanofiltration or reverse osmosis, are slightly less effective at removing PFAS from water than the other two methods, according to the EPA.
“This technology may be best suited as a point of-use technology for a homeowner, since the volume of water being treated is much smaller and the waste stream could be disposed of down the drain with less cause for concern,” the EPA says on its website.
Questions about PFAS?
If you have additional questions about PFAS, check out these resources:
U.S. Environmental Protection Agency’s Q&A page for PFAS: epa.gov/sdwa/questions-and-answers-drinking-water-health-advisories-pfoa-pfos-genx-chemicals-and-pfbs
U.S. Agency for Toxic Substances and Disease Registry PFAS page: atsdr.cdc.gov/pfas/index.html
California State Water Resources Control Board PFAS page: waterboards.ca.gov/drinking_water/certlic/drinkingwater/pfas.html
You can also send your question to Tribune reporter Mackenzie Shuman via the Google Form below for possible inclusion in this Q&A. (Can’t see the form? Click here.)
This story was originally published May 2, 2023 at 12:31 PM.
