Plastics scramble your brain
.webp)
Using data from nearly 900 U.S. adults with an average age
of 69, researchers found that combined exposure to phenols, parabens,
and especially phthalates was linked to lower scores on standard
tests of brain function, particularly among men.
The more chemicals in participants’ bodies, the worse they
performed on tests that measure cognition, such as memory, learning,
problem-solving, and attention. But even low levels, as detected in urine
samples, were associated with signs of cognitive decline, the researchers say.
Key findings include:
- Men
with higher levels of these chemicals in their bodies were nearly 1.8
times more likely to show cognitive difficulties, especially in immediate
word recall and processing speed. That means a task that typically takes 5
minutes took 9.
- Phthalates
(PAEs), particularly MECP and MEHP, showed the strongest link to impaired
brain function, mainly in men.
- The
harmful effects were significantly more pronounced in men, possibly due to
biological differences.
Most chemical safety standards still evaluate substances
individually, even though people are exposed to mixtures every day. The study
warns that these combined exposures may accumulate and interact in the
body.
This could have stronger, more harmful effects on brain
health than single chemicals alone—especially in older adults at a time when
aging-related Alzheimer’s and Parkinson’s diseases
are common neurodegenerative disorders. According to a 2022 study, nearly one in 10 U.S. adults ages 65 and older has
dementia, while another 22% have mild cognitive impairment.
“Chronic exposure to harmful elements can disrupt neural processes, damaging the brain and causing memory loss,” the researchers say. “Given that older adults are a vulnerable group in terms of health, cognitive decline can severely impact their quality of life and independence.”
Combined chemicals linked to lower cognitive test scores
Phthalates, parabens, and phenols—common in consumer
products like plastic containers and shampoos—are known endocrine disruptors.
These chemicals interfere with hormone function and have been associated with
reproductive issues, developmental delays, obesity, asthma,
metabolic dysfunction, cancer, and other severe health
problems. Most recently, new evidence emerged that plastic polymers and their
chemical additives contribute to cardiovascular disease.
In 2018, more than 356,238 deaths worldwide were attributed to exposure to DEHP, the most widely used plasticizer or plastic “softener,” representing about 13% of all cardiovascular deaths among individuals aged 55–64. Of these, the vast majority (349,113) were attributed to the use of plastics, according to a study [April 2025] published in the journal eBioMedicine.
The researchers analyzed data from 856 people (417 men and
439 women) who participated in the National
Health and Nutrition Examination Survey (NHANES) between 2011 and
2014. Urine samples were analyzed for nine chemicals:
- Bisphenol A (BPA), used in plastics and resins for
items such as food storage containers and the lining of canned foods
- Triclosan (TCS), an antibacterial used in products
including body washes, cosmetics, detergents, clothing, and kitchenware
(the FDA in 2016 banned its use in consumer antiseptic wash products)
- Methylparaben
(MPB) and ethylparaben (EPB), used as preservatives in food and personal
care products, including shampoos and cosmetics
- Chemical
byproducts, formed when the body breaks down phthalates:
- mono(2-ethylhexyl)
phthalate (MEHP)
- mono-isobutyl
phthalate (MiBP)
- mono-benzyl
phthalate (MBzP)
- Industrial
chemicals methylcyclopentadienyl (MeCP) and methanol (methyl alcohol, or
MeOH), used to make products like metal coatings, paint, and windshield
washer fluid
Participants also completed four cognitive tests assessing
memory, attention, and processing speed:
- Immediate
Recall Test (IRT): recalling 10 unrelated words at a time right
after hearing them
- Animal
Fluency Test (AFT): naming as many animals as possible in one
minute
- Digit
Symbol Substitution Test (DSST): matching numbers and symbols
within two minutes
- Delayed
Recall Test: recalling words from the earlier IRT after a delay
Researchers then used three types of statistical models to
examine the relationship between chemical exposures and cognitive performance.
All showed that combined chemical exposures were significantly associated with
lower test scores, with the strongest and most consistent declines seen in men.
Of all the chemicals, the phthalate MEHP—a breakdown product
of DEHP—had the greatest negative association with cognitive scores, though it
may interact with other factors. MEHP is more toxic than DEHP and more easily
absorbed by the body, the researchers say.
Prior studies suggest MEHP may contribute to inflammation, a
known factor in cognitive decline, and have toxic effects on organs like the
liver, testes, pituitary gland, and heart, the researchers say. Prenatal
exposure to phthalates may be associated with slower information-processing and
lower recognition memory ability in infants, one study shows.
MPB, which is commonly used to prolong shelf life in
preserved foods like jams and beverages, showed the highest exposure levels
among participants. Higher levels of both MPB and EPB were associated with
a lower risk of cognitive problems on certain tests. But these
results were inconsistent, the researchers note, and may reflect more complex
interactions between chemicals, overall health, and brain function.
The authors also suggest that biological differences may
help explain why older men were more affected by environmental chemicals than
women. A prior study showed boys exposed to phthalates before birth
scored lower on language tests, while an animal study linked phthalates to anxiety-like
behaviors and brain changes in male mice. Gender differences in the brain also
make males developmentally vulnerable to neurological disorders, according to
another study.
More studies needed on mixed chemical impacts on the
brain
Earlier research with 835 NHANES participants indicated that
mixed exposure phthalates may be a risk factor for cognitive decline.
The authors of this study caution that it also does not
definitively prove these chemicals directly cause cognitive problems—only that
a strong association exists. More research, particularly long-term and focused
on men, is needed to confirm these findings and clarify how chemical mixtures
affect the brain.
Among other limitations, the study did not adjust for
multiple statistical comparisons, which raises the chance of false-positive
results, the authors say. It also used data from only two NHANES cycles, which
may limit how broadly the findings apply. In addition, health conditions like
stroke or smoking history were also self-reported, which can introduce errors,
they say.
Reference
Du H, Wang Q, Chen Y, Wu X, Jiang J, Zhao Y. Association
between mixed exposure of phenols, parabens, phthalates and cognitive function
in US elders. J Affect Disord. Published online April 19, 2025.
doi:10.1016/j.jad.2025.04.079
