PFAS have been studied for decades, and the scientific consensus is increasingly clear: chronic exposure causes measurable harm to human health across multiple organ systems. Here are seven of the most well-documented effects — with what the research actually says, not the watered-down version.
A note on this research: The studies cited throughout this article are from peer-reviewed scientific journals, the EPA, the National Toxicology Program, and the Agency for Toxic Substances and Disease Registry (ATSDR). This is not fringe science — it is the mainstream scientific consensus that led the EPA to set new PFAS drinking water standards in April 2024.
1. Cancer
PFAS exposure has been linked to multiple cancer types in occupational studies (workers at PFAS manufacturing facilities) and general population studies. The cancers with the strongest evidence include:
- Kidney cancer — the most well-established link; PFAS workers show significantly elevated kidney cancer rates
- Testicular cancer — found in multiple studies of communities near PFAS-contaminated water supplies
- Bladder cancer — linked to PFAS exposure in multiple epidemiological studies
- Breast cancer — emerging evidence, particularly for PFOA exposure
- Non-Hodgkin's lymphoma — linked in several occupational exposure studies
The EPA classifies PFOA as a "likely human carcinogen" and PFOS as having "suggestive evidence of carcinogenic potential." The National Toxicology Program's 2024 report elevated the cancer classification for several PFAS compounds.
2. Thyroid Disease
The thyroid gland is exquisitely sensitive to chemical disruption. PFAS are structurally similar to thyroid hormones and compete with them in the body's signaling pathways. Research consistently finds that higher PFAS blood levels are associated with:
- Hypothyroidism (underactive thyroid) — fatigue, weight gain, brain fog, depression
- Hyperthyroidism (overactive thyroid)
- Thyroid cancer
- Disrupted thyroid hormone levels even in the "normal" range
This matters especially for women, who are 5–8 times more likely than men to develop thyroid disorders. The connection between PFAS and the thyroid epidemic is an active area of research.
3. Immune System Suppression
Some of the most alarming PFAS research concerns the immune system. The Faroe Islands birth cohort — a decades-long study of children with PFAS exposure — found that higher blood PFAS levels in children predicted significantly lower antibody concentrations after routine childhood vaccination. Some children showed up to 50% reduction in vaccine effectiveness.
This means that PFAS-exposed children aren't just at greater risk from environmental chemicals — they're at greater risk from every disease their vaccines were supposed to prevent. In a post-COVID world, this finding deserves serious attention.
4. Developmental Harm in Children and Fetuses
PFAS cross the placental barrier freely. Prenatal exposure — from a mother drinking contaminated water during pregnancy — is associated with:
- Lower birth weight
- Reduced head circumference
- Delayed developmental milestones
- Lower IQ scores in childhood
- Behavioral problems including ADHD symptoms
- Disrupted pubertal timing (earlier puberty in girls, delayed puberty in boys)
The mechanism appears to involve disruption of hormone signaling during critical developmental windows. Because PFAS also concentrate in breast milk, exposure can continue postnatally.
5. Metabolic and Liver Effects
PFAS accumulate in the liver — the organ responsible for detoxifying the body — and disrupt its function in multiple ways. Research links PFAS exposure to:
- Non-alcoholic fatty liver disease (NAFLD)
- Elevated cholesterol and triglycerides
- Disrupted blood glucose regulation (type 2 diabetes risk)
- Obesity, particularly in children — likely via hormonal disruption
The liver finding is significant because it creates a compounding health burden: PFAS both accumulate in the liver and impair the liver's ability to process other toxins.
6. Reproductive and Fertility Effects
PFAS exposure has been linked to reproductive harm in both men and women:
- Women: Reduced fertility (longer time to conception), PCOS, endometriosis, pregnancy-induced hypertension
- Men: Lower sperm count and quality, reduced testosterone levels
- Both: Pregnancy-induced preeclampsia, gestational diabetes
Several studies have found that women with higher PFAS blood levels take longer to become pregnant, even when controlling for other reproductive factors.
7. Cardiovascular Disease
More recently, research has linked PFAS exposure to elevated cardiovascular disease risk — specifically elevated LDL ("bad") cholesterol, increased blood pressure, and higher rates of heart disease in exposed populations. The mechanism appears to involve PFAS disruption of lipid metabolism — the way the body processes and manages fats in the bloodstream.
A 2023 study in the journal Environmental Health Perspectives found that individuals with higher PFAS blood levels showed significantly greater cardiovascular disease incidence over a 20-year follow-up period.
⚠️ The Accumulation Problem
Unlike many environmental toxins, PFAS don't leave the body quickly. Depending on the specific compound, the half-life of PFAS in the human body ranges from 3 to 8+ years. This means that every year of exposure adds to the total body burden. The effects listed above are associated with chronic, cumulative exposure — which is exactly what years of unfiltered tap water in a city like Durham represents.
The Bottom Line
PFAS health effects are not theoretical. They are documented across multiple organ systems, in multiple population studies, on multiple continents, over multiple decades. The science reached critical mass in 2024, when the EPA set enforceable MCLs for six PFAS compounds — a regulatory action that only happens when the evidence is overwhelming.
Durham's water contains PFAS. The city's fix is scheduled for 2029. In the meantime, the only protection available to Durham families is filtration at the point of use — an under-sink RO or whole-home filter certified for PFAS removal.