Children who are continuously exposed to high levels of naturally occurring radon gas in their homes may experience changes in the way their brains develop important attention and problem-solving skills. A recent study published in NeuroImage found that young people with high levels of chronic radon exposure showed changes in their brain wave patterns when completing tasks that required high levels of concentration. These electrical changes also affect how accurately children perform behavioral tasks, suggesting that typical brain maturation may be disrupted by common environmental toxins.
Radon is a colorless and odorless gas produced by the natural decomposition of radioactive materials in the earth. Although it is well known as a leading cause of lung cancer, its potential effects on brain development are largely unknown. Because radon often enters the home and accumulates over time, children whose brains are still in critical developmental stages are especially susceptible.
Despite the prevalence of radon, public awareness of the risks of indoor radon remains relatively low. It is estimated that one in 15 homes in the United States has indoor radon levels that exceed the Environmental Protection Agency’s recommended mitigation standards. Many households do not test their homes for invisible gases.
The researchers wanted to understand whether chronic background radiation from radon affects a set of mental skills called cognitive control. These skills allow people to eliminate distractions, resolve conflicting information, and stay focused on specific goals. Cognitive control is essential in children’s daily lives to function in the classroom, complete homework, and manage emotional responses.
Hayley R. Pulliam, a researcher at Boys Town National Research Hospital, led a team investigating this question. Pulliam, along with Brittany K. Taylor and colleagues, sought to measure whether changes in indoor radon concentrations were related to brain activity that supports these higher-level mental processes.
The researchers recruited nearly 60 young participants between the ages of 6 and 14. To estimate the amount of radiation each child received at home, parents placed a short-term radon test kit in the most habitable level of the house for several days. The researchers then calculated an exposure index based on these test results and the number of years each child lived in that particular home.
To analyze brain function, the children completed a special computer game known as the Simon task while sitting inside a brain scanning device. The machine uses a technology called magnetoencephalography to harmlessly measure the tiny magnetic fields produced by the brain’s electrical activity. The technology can track rapid brain waves in milliseconds as participants respond to fast-paced tests.
During the task, three rows of numbers appeared on the screen. Children had to press a button that corresponded to one number that was different from the two surrounding numbers. To create a mental challenge, tests may place target numbers in spatial locations that do not match the correct button response.
Participants should fight the urge to respond based on the location of the number on the screen and instead focus solely on identifying the number. This requires the brain to resolve spatial conflicts and inhibit automatic physical responses. The scanner mapped how different brain regions communicated through rhythmic brain waves while the children tried to eliminate spatial interference.
The research team found a link between radon exposure and certain changes in brain activity in children. The nervous system communicates by firing electrical impulses in a synchronized rhythm. They are often categorized by their frequency. While performing intensive tasks, children with higher radon exposure showed abnormal patterns in the alpha, theta, and gamma frequency bands.
Electrical changes were spread across multiple networks. Several changes occurred in the occipital and motor areas of the brain. The occipital lobe handles visual processing, and the motor cortex plans physical movements. This suggests that continuous background radiation may influence how the brain interprets basic visual cues and translates them into physical movements to overcome spatial interference of examination.
Changes were also seen in the prefrontal cortex, which is responsible for high-level thinking and attention. In some of these frontal regions, young people with higher radon exposure had weaker EEG responses during difficult parts of the task. Conversely, a brief baseline portion of the test showed unusually strong brainwave activity.
The authors suggest that this brain wave pattern is similar to biological compensatory mechanisms common in older adults who experience age-related neurocognitive changes. Children’s brains were working harder just to process simple baseline tasks, so when the tests got tougher, fewer neural resources were available. In other words, their cognitive resources were depleted faster than children with less exposure history.
The data also revealed that radon exposure appears to alter the normal developmental curve of the brain’s attention network. In neurotypical youth, the brainwave responses used to resolve spatial conflicts become more sophisticated and efficient as children grow from childhood to adolescence.
However, among the children with the highest radon exposure in this sample, these developmental trajectories were flattened or reversed in several key brain regions. Brain regions that typically experience greater stress as children grow did not show the expected maturational changes in children raised in high-radon environments.
These changes in brain activity translate into observable behavioral outcomes. The researchers determined that changes in electrical activity acted as a bridge between exposure to environmental gases and participants’ reaction times. Younger children with higher exposure to radon performed relatively poorly compared to children with lower exposure, even though they relied more heavily on specific frontal brain regions during testing.
The authors noted that the study had several limitations in terms of how environmental toxins were measured. Commercially available test kits only provide a short snapshot of radon levels over a few days and can fluctuate depending on things like weather, opening and closing of doors, and building ventilation. The study also did not measure radiation levels at the children’s schools or previous residences.
Future studies should follow larger groups of children over longer periods of time. This longitudinal approach will help researchers observe how brain networks mature over many years under continuous radiation exposure. Additional research is also needed to determine whether these early neural differences are associated with lifelong developmental disorders such as attention-deficit/hyperactivity disorder.
The study, “Chronic radon exposure is associated with developmental changes in neural and behavioral indicators of cognitive control,” was authored by Haley R. Pulliam, Kristin M. Embury, Maggie P. Lempe, Hannah J. Okelberry, Daniel L. Rice, Anna T. Coutant, Ryan Gresinger, Tony W. Wilson, and Brittany K. Taylor.
