Two recent studies have confirmed that per- and polyfluoroalkyl substances (PFAS), commonly known as “forever chemicals,” become significantly more toxic when mixed with other chemicals compared to when they are present individually.
Study #1: PFAS Mixtures
A study led by researchers at the University at Buffalo and published in Environmental Science & Technology revealed that PFAS are significantly more toxic when present in mixtures.
The researchers tested the effects of PFAS mixtures on human blood serum and surface water samples, creating scenarios that mimicked real-world exposure to these chemicals.
The study found that the combined effects of PFAS were much more harmful compared to the effects of individual PFAS. Here are a few of their main findings:
- Cytotoxicity: The mixture’s overall cytotoxicity (cell toxicity) increased when multiple PFAS were combined. Perfluorooctanoic acid (PFOA), one of the most studied PFAS, was responsible for 42% of the total cytotoxicity, even when its concentration in the mixture was relatively low.
- Neurotoxicity: Similar results were found for neurotoxicity, with both PFOA and perfluorooctane sulfonic acid (PFOS) contributing equally to the overall neurotoxic effects, even though they were present in low concentrations.
The study demonstrated that these PFAS mixtures act in a “concentration-additive” manner, meaning that when PFAS chemicals are mixed together, their harmful effects add up.
This indicates that even low concentrations of PFAS, when combined, can result in significant toxicity.
Lead author Diana Aga emphasized the importance of regulating PFAS mixtures rather than individual chemicals: “Mixtures pose more of a risk than individual PFAS. As they act and occur in mixtures, they ought to be regulated as mixtures”.
Study #2: PFAS and Microplastics
Another new study conducted by researchers at the University of Birmingham took a different approach, focusing on the combined effects of PFAS and microplastics in aquatic environments.
Microplastics are small plastic particles that also persist in the environment and are often found together with PFAS in water systems.
Using water fleas (Daphnia magna) as test subjects, the researchers demonstrated that the combination of microplastics and PFAS caused more harm to aquatic life than either pollutant did alone.
Here are a couple of their key findings:
- Reproductive and Developmental Issues: The water fleas exposed to PFAS and microplastics showed stunted growth, delayed sexual maturity, and developmental failures, such as aborted eggs and reduced offspring.
- Historical Exposure: The study found that organisms previously exposed to chemical pollutants were less tolerant to these chemical mixtures, suggesting that historical pollution weakens their ability to withstand new pollutants.
Interestingly, the study found that 59% of the combined effects of PFAS and microplastics were additive, while 41% were synergistic. This means that in those 41% of cases, the two pollutants together were more harmful than each pollutant added together.
Dr. Luisa Orsini, who co-led the research, highlighted the need for better regulation: “Current regulatory frameworks focus on testing the toxicity of individual chemicals… It is imperative that we investigate the combined impacts of pollutants on wildlife throughout their lifecycle to get a better understanding of the risk posed by these pollutants under real-life conditions”.
“Additive” vs. “Synergistic” Mixtures
Both studies emphasize that PFAS are rarely found in isolation in the environment or in the human body.
Instead, they often exist as part of complex chemical mixtures, interacting with other pollutants such as microplastics.
When chemicals have an additive effect, it means their combined harm is just the total of each one’s individual harm. For example, if one chemical is harmful and another is also harmful, the total harm is like adding them together.
A synergistic effect is different. This happens when the combined harm is much worse than just adding up the individual effects. It’s like the chemicals work together to create a stronger, more dangerous result than expected.
Here is a simplified way of looking at it:
- Additive: 2+2=4
- Synergistic: 2+2=10
Why This Matters for the Real World (& Why “Low Dose” Does Not Always Mean “Safe”)
While many people claim that certain chemicals are “safe at low doses,” the concept of synergy challenges this idea.
In the real world, chemicals don’t exist in isolation.
Instead, they often mix with other substances, and when that happens, their combined effects can be far more harmful than expected. Even if a chemical seems safe by itself at a low dose, it can interact with other chemicals in ways that make the mixture more dangerous.
For example, a chemical that appears harmless alone might become toxic when mixed with others, creating a synergistic effect—where the harm is much greater than the sum of its parts. This means that what’s considered “safe” in a controlled lab setting doesn’t always reflect what happens in real-world environments, where people are exposed to many chemicals at once.
So, relying on the claim that a chemical is safe at low doses ignores the risk that these mixtures pose.
All of this has significant implications for public health and environmental regulation. For example, the U.S. Environmental Protection Agency (EPA) has recently introduced drinking water standards for six types of PFAS, but thousands more PFAS are present in the environment, and few are currently regulated. These studies suggest that focusing on individual PFAS may not be enough to protect public health. Regulators need to account for the cumulative and combined effects of these chemicals.
There’s A Lot You Can Do To Reduce Your Exposure
Although this type of information can be stressful, there is a lot you can do to decrease your exposure not just to PFAS but also to microplastics, endocrine-disrupting chemicals, carcinogens, and environmental toxins as a whole.
Here at The Filtery, we have hundreds of shopping guides and other articles that help you to steadily decrease the toxic chemicals in your home in a mentally and financially sustainable way.
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