Low-level pesticide exposure linked to autism-like brain changes

An NIEHS-funded study in mice sheds light on how maternal exposure to low levels of common pesticide, deltamethrin, impaired brain activity and induced autism-like behaviors in offspring. These neurodevelopmental effects occurred in male mice only.

The researchers exposed female mice to a low level of deltamethrin from the time of mating until their pups were weaned. They followed the offspring into adulthood and then tested their sociability. Electrical activity and imaging techniques were used to examine brains in exposed mice compared to mice that were not exposed, called controls. Specifically, they assessed signaling of a neurotransmitter called GABA that regulates neural activity, and the activity of parvalbumin neurons that inhibit or stimulate activity in the brain. They also looked at long-term potentiation (LTP) — a process that strengthens connections between neurons over time and is a key part of learning and memory. Finally, they used chemogenetic approaches, which combine genetically altered receptors and specialized small molecule drugs, to further pinpoint the effects on parvalbumin neurons.

Male mice exposed to deltamethrin in early life had decreased GABA signaling, reduced parvalbumin neuron activity, and LTP loss in the hippocampus compared to unexposed mice. They also had social memory deficits, a key feature of autism spectrum disorder. Restoring parvalbumin activity with chemogenetic approaches restored LTP and rescued social memory in deltamethrin-exposed mice.

According to the authors, these results provide a mechanistic link at the cellular, circuit, and behavioral levels, and suggest that exposure to deltamethrin in early life at levels considered safe may contribute to autism development. The findings also pave the way for targeted interventions to better protect against neurodevelopment effects, they wrote.

Citation: Di Re J, Koff L, Avchalumov Y, Singh AK, Baumgartner TJ, Marosi M, Matz LM, Hallberg LM, Ameredes BT, Seeley EH, Buffington SA, Green TA, Laezza F. 2025. Environmental exposure to common pesticide induces synaptic deficit and social memory impairment driven by neurodevelopmental vulnerability of hippocampal parvalbumin interneurons. J Hazard Mater 485:136893.

Study reveals how microplastics accumulate in the body

The concentration of micro- and nanoplastics increased markedly in human bodies over an eight-year period, according to an NIEHS-funded study. Researchers also revealed important information about which parts of the body tend to accumulate specific types of plastics.

The team used a new technique that combines mass spectrometry with visualization methods to measure the amount and distribution of micro- and nanoplastics in human postmortem liver, kidney, and brain samples donated from 2016 to 2024.They also looked at the proportion of specific types of plastics, including polyethylene, polypropylene, polyvinyl chloride, and styrene-butadiene rubber, in each organ. Finally, they compared plastic distribution and composition in individuals with and without a diagnosis of dementia at the time of their death.

Overall, plastic concentrations tended to increase from 2016 to 2024 in both the liver and the brain, with polyethylene contributing the most. Brain tissues accumulated more plastics, and polyethylene in particular, than the other two organs. More plastics were found in the brains of individuals with a dementia diagnosis at the time of their death compared to those without that diagnosis.

According to the authors, as micro- and nanoplastic exposures are increasing, more research is needed to understand whether these exposures contribute to neurological disorders or other human health effects.

Citation: Nihart AJ, Garcia MA, El Hayek E, Liu R, Olewine M, Kingston JD, Castillo EF, Gullapalli RR, Howard T, Bleske B, Scott J, Gonzalez-Estrella J, Gross JM, Spilde M, Adolphi NL, Gallego DF, Jarrell HS, Dvorscak G, Zuluaga-Ruiz ME, West AB, Campen MJ. 2025. Bioaccumulation of microplastics in decedent human brains. Nat Med; doi: 10.1038/s41591-024-03453-1. [Online ahead of print Feb 3]

Innovative sensor detects low levels of cancer-causing chemical in water

Researchers funded by NIEHS developed and evaluated a novel sensor for detecting a cancer-causing chemical, N-nitrosodimethylamine (NDMA), in water. The new approach allows for one of the lowest detection limits reported to date.

NDMA and related nitrosamines, found in drinking water, food, and pharmaceuticals, have been linked to cancer and liver toxicity. Standard detection approaches require sophisticated and expensive laboratory equipment, which can be a barrier to rapid environmental monitoring. To overcome these limitations the researchers created a reversible electrochemical sensor for NDMA. This new sensor expands on recent innovations in molecularly imprinted polymers (MIP), which have cavities that bind to specific molecules.

The scientists selected two separate molecules, called monomers, to create the MIP. One monomer was selected based on its strong interactions with NDMA and ability to create recognition sites. The second monomer produces the structural polymer matrix, contributing to the overall stability and durability of the sensor. According to the team, this strategic combination of monomers is critical for enhancing both the sensitivity and the selectivity of the MIP layer. The researchers then tested the sensor’s sensitivity and selectivity for NDMA, reversibility, and performance in realistic conditions.

The sensor achieved a low limit of detection for NDMA of 1.16 parts per billion, which the authors stated significantly exceeded that of existing detection methods. They further reported high selectivity of the sensor to NDMA compared to five similar molecules. In addition, electrochemical conditioning effectively reversed the NDMA-treated sensor to its background state to be reused. When tested in NDMA-treated river water, tap water, and electrolyte solution, the sensor performed similarly to NDMA-treated deionized laboratory water.

According to the authors, this sensor offers a practical and cost-effective approach to detecting cancer-causing nitrosamines and better protecting public health.

Citation: Guo Z, Feng H, Swager TM. 2025. Reversible electrochemical sensor for NDMA: Leveraging molecularly imprinted polymers for enhanced sensitivity and selectivity. ACS Sens 10(2):881-885.

Prenatal PFAS exposure may increase risk of childhood obesity

Exposure to PFAS early in life was associated with a higher risk of overweight or obesity in childhood and adolescence, according to an NIEHS-funded study. Children who are overweight or obese have a higher risk of developing hypertension, type-2 diabetes, musculoskeletal disorders, cardiovascular disease, and cancer in adulthood.

The study included 1,189 mother-child pairs from the Boston Birth Cohort. Researchers assessed the association between eight PFAS measured in maternal plasma samples collected 24 to 72 hours after delivery, and children’s BMI Z-scores from 2 to 18 years old. They also considered maternal pre-pregnancy overweight or obesity status, child age, sex, and race as factors that may influence the relationship.

Maternal plasma PFHpS and PFHxS were associated with higher child BMI Z-scores at all ages. These associations were stronger in children aged 6 to 12-years and 13 to 18 years compared to children aged 2 to 5 years. They also found significant associations for the PFAS mixture with child BMI Z-score, but only among children whose mothers were not overweight or obese prior to pregnancy. In children aged 13 to 18 years, a combination of high maternal plasma PFDeA, PFNA, and PFOA concentrations and maternal pre-pregnancy overweight or obesity resulted in the highest risks of childhood overweight or obesity compared to children with only one of those factors.

According to the authors, these findings underscore the complexity of how prenatal exposure to PFAS may affect obesity in childhood and adolescence, and they can be used to inform future research and comparisons across studies.

Citation: Li Z, Wang G, Braun JM, Hong X, Choi G, O'Leary SP, Yu CH, Pearson C, Adams WG, Fan ZT, Buckley JP, Wang X. 2025. Associations of early life per- and polyfluoroalkyl substances (PFAS) exposure with body mass index and risk of overweight or obesity at age 2-18 years: Mixture analysis in the prospective Boston Birth Cohort. Environ Int 195:109206.