Dr. Rhonda Patrick appeared on the Triggernometry podcast to discuss a mounting environmental health concern that affects nearly every aspect of modern life.
During the conversation, she stated that microplastics accumulate in the brain at levels 10 to 20 times higher than other organs, with people who have Alzheimer’s disease showing 10 times more microplastics in their brains postmortem compared to those without the condition.
Dr. Patrick explained that we are constantly exposed to endocrine-disrupting chemicals (EDCs) from plastics, primarily bisphenol A (BPA), bisphenol S (BPS), and phthalates. These chemicals appear in plastic water bottles, reusable bottles, aluminum cans, canned food linings, and to-go coffee cups.
“These chemicals leech into the beverage. In the case of heating them, it’s even worse,” Dr. Patrick said. “There have been studies that have shown if you add boiling water to this BPA chemical it increases the leeching by 55-fold into the water.”
BPA and BPS act as xenoestrogens, meaning they mimic estrogen in the body. They bind to estrogen receptors and androgen receptors, confusing the body’s hormone regulation.
“Your body thinks, ‘Oh, I have enough testosterone around. I don’t need to make more.’ When really it wasn’t testosterone binding to that androgen receptor, it was the BPA,” Dr. Patrick explained.
Studies show these effects across all life stages. In healthy adolescents, for every log increase in BPA, there was almost a 50% reduction in testosterone. Adult men with higher BPA levels also show significantly lower testosterone.
Animal studies confirm causation. When male rodents receive high levels of BPA, their testosterone decreases, and sperm quality and quantity decline.
Phthalates are found in PVC piping, food packaging, and personal hygiene products including shampoos, shaving cream, lotion, makeup, and hair products. They hide under the labels “perfume” or “fragrance.”
“Phthalates disrupt testosterone on multiple levels,” Dr. Patrick said. “They are directly disrupting testosterone production in the testes and they’re affecting the hypothalamic pituitary gonadal axis, this is the axis that’s regulating our hormone production.”
Pregnant women with high phthalate levels face serious risks for their sons. Dr. Patrick listed the consequences: undescended testicles, hypospadias (where the urethral opening is positioned further back on the penis), and smaller anogenital distance.
“Undescended testicles, the biggest factor that plays a role in testicular cancer,” she noted. “That’s more likely to happen.”
The effects continue throughout life. Large nutritional and health surveys in the United States involving hundreds of thousands of participants show men with higher phthalate levels have much lower testosterone.
Dr. Patrick presented compelling evidence connecting plastic chemicals to autism spectrum disorder.
“Pregnant women that have the highest levels of BPA in their urine, they’re six times more likely to have a child diagnosed with autism by the age of 11,” she said.
Multiple studies confirm this correlation. Animal evidence supports it as well. Pregnant mice exposed to BPA are more likely to have pups displaying autistic-like behavior.
The mechanism involves the aromatase enzyme and brain development. “It’s counterintuitive because BPA is inhibiting that aromatase enzyme. That aromatase enzyme is important for increasing estrogen, particularly during very specific moments of brain development,” Dr. Patrick explained.
Estrogen plays a role in masculinizing the male brain during development. When BPA blocks aromatase, estrogen surges do not occur at critical moments. “The connectivity of the brain, the wiring of the brain, the structure of the brain isn’t quite right,” she said.
Genetic evidence strengthens the case. Boys with dysfunctional aromatase enzymes are much more likely to be diagnosed with autism, especially when combined with environmental exposure to BPA.
Children with autism show 15 times higher BPA levels than non-autistic children, suggesting a dysfunctional excretion mechanism. Clinical trials using sulforaphane, a compound from broccoli sprouts that helps excrete BPA, showed improvement in autism symptoms in two separate placebo-controlled studies.
BPA and BPS are associated with ADHD at every life stage. Dr. Patrick acknowledged overdiagnosis is a factor, noting that boys born in July and August are three to four times more likely to be diagnosed with ADHD simply because they are the youngest in their class.
“There’s nothing about being born in July or August that makes you have ADHD. You’re just the younger boy and so you’re moving around more,” she said.
However, environmental chemicals play a real role. “The genetics is like the template. It sets you up for the environmental insults that we’re all exposed to now that make those individuals more vulnerable,” Dr. Patrick explained.
Dr. Patrick highlighted a study from Sao Paulo, Brazil, that examined microplastics in various organs. The findings were alarming: microplastics accumulated in the brain 10 to 20 times more than other organs.
“That’s astounding considering we have something called the blood-brain barrier that’s supposed to not let stuff get into the brain like microplastics,” she said.
Two pathways allow microplastics into the brain. The smaller nanoplastics can cross the blood-brain barrier. Additionally, inhaled microplastics can enter through olfactory neurons in the nose, which have fibers extending into the brain.
“You breathe in the microplastics and they can get into the brain through the olfactory fibers and then get transported to other parts of the brain,” Dr. Patrick explained.
Dr. Patrick identified the primary routes of exposure. “The major source is ingestion,” she said, but added, “The other major source of microplastics is actually from the air we breathe.”
Airborne microplastics come from tire friction (tires contain plastic polymers), synthetic clothing fibers released during washing and drying, and shoes. “It’s in the air. And so when we breathe in the microplastics they get into our lungs which plays a role in respiratory disease,” Dr. Patrick said.
Patrick called it a public health crisis. “It’s totally a public health crisis. Oh my god. It’s like time to wake up. The problem is we can’t see these chemicals. We don’t really smell them. They’re just insidious. They’re there. They’re in our water. They’re in our drinking water. They’re in our food that we’re eating. They’re in our personal hygiene products. Every day we’re being exposed to them.”
