Per- and polyfluoroalkyl substances (PFAS) are a large family of manufactured chemicals that do not naturally occur in the environment. These synthetic compounds have been used in various industrial and consumer products since the 1940s due to their unique properties, such as resistance to heat, oil, stains, grease, and water. PFAS are frequently referred to as “forever chemicals” because they are exceptionally resistant to degradation, meaning they do not break down easily in the environment or the human body. Their widespread presence and persistent nature raise significant concerns regarding their potential impact on human health.
How Humans Encounter PFAS
Humans encounter PFAS through multiple pathways, leading to widespread exposure across the population. A significant source is contaminated drinking water, where PFAS can leach into water supplies from industrial sites, military bases, firefighting foams, and landfills. These chemicals are highly mobile in water, allowing them to migrate into groundwater and surface water sources.
Exposure also occurs through food consumption. This includes eating contaminated fish from polluted waters, as PFAS accumulate in animals. Additionally, food packaging, particularly paper and cardboard wrappers for fast food and bakery goods, can contain PFAS that transfer to food.
Consumer products also contribute to exposure. Non-stick cookware, stain-resistant furniture and carpets, water-repellent clothing, and some personal care products like cosmetics often incorporate PFAS. Occupational exposure is another pathway for individuals working in industries that manufacture or extensively use PFAS, such as chemical production or firefighting.
How PFAS Accumulate and Persist in the Body
Once PFAS enter the human body, they are not easily broken down or excreted, leading to bioaccumulation. This means the chemicals build up over time, primarily in the blood and various organs. The persistence of PFAS stems from their chemical structure, specifically the strong carbon-fluorine bonds, which resist degradation.
Different PFAS compounds have varying half-lives in the human body. While some short-chain PFAS may have half-lives of days to weeks, long-chain PFAS can persist for years, or even decades. For instance, PFOA has an estimated half-life of 1.5 to 5.1 years, and PFOS can remain in the body for 3.4 to 5.7 years. This prolonged retention contributes to their potential for long-term health effects.
Documented Health Outcomes
Exposure to PFAS has been linked to a range of adverse health outcomes in humans, with ongoing research investigating the full spectrum of effects.
One area of concern is the immune system, where PFAS exposure has been associated with reduced antibody response to vaccines, potentially weakening the body’s ability to fight infections.
PFAS exposure is also linked to metabolic changes, including increased cholesterol levels and an increased risk of obesity. Studies have shown an association between PFAS and alterations in liver enzymes, suggesting liver damage. The chemicals may also interfere with the body’s natural hormones, leading to disruption of thyroid hormone levels and an increased risk of thyroid disease.
Regarding cancer risk, studies indicate an increased risk of certain cancers, particularly kidney and testicular cancers. Some research also suggests a possible association with breast cancer.
Reproductive and developmental effects are another area of concern. PFAS exposure has been associated with decreased fertility and an increased risk of high blood pressure during pregnancy (gestational hypertension and preeclampsia). For children, exposure can lead to developmental delays, including low birth weight, accelerated puberty, and bone variations.
Why Individual Responses Vary
The impact of PFAS exposure on an individual’s health can vary significantly, influenced by several factors. The level and duration of exposure play a considerable role, with higher and more prolonged exposure correlating with a greater risk of adverse health outcomes. Communities with contaminated drinking water, for example, often exhibit higher PFAS levels in their blood.
Genetic predisposition can also influence an individual’s susceptibility to PFAS. Some individuals may be genetically more vulnerable to the effects of these chemicals.
Age at exposure is another determinant, as exposure during developmental windows can have more profound effects. Infants and young children may be more sensitive to the harmful effects of PFAS because their bodies are still developing, and they consume more water and food per pound of body weight. Additionally, exposure can occur prenatally or through breast milk, meaning babies can be born with PFAS already in their system.
An individual’s overall health status, including pre-existing conditions or a compromised immune system, also influences their susceptibility to PFAS-related health problems. While it is challenging to completely avoid PFAS exposure due to their widespread presence, limiting exposure can help reduce the levels of these chemicals in the body over time.