Water fluoridation is proven safe for brain function

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study that followed 26,820 U.S. adolescents since the 1980s has concluded that water fluoridation does not negatively affect cognitive function.

A team led by Professor John Warren at the University of Minnesota published statistical analysis results in the international journal Science Advances, finding no link between water fluoridation and adolescent cognitive decline.

Water fluoridation began in some U.S. states in 1945. The cavity-prevention effect of water fluoridation is regarded as a major public health achievement of the 20th century.

Subsequently, controversy arose over water fluoridation after some studies suggested it could cause side effects, including cognitive decline in childhood and an increase in Attention-Deficit/Hyperactivity Disorder (ADHD).

Warren’s team tracked participants from 1,020 U.S. high schools from 1980 to 2021. The study compared the participants’ high school test data—in reading comprehension, mathematical ability, and vocabulary—with subsequent cognitive function assessments of those who grew up with exposure to fluoridated water.

The team determined the correlation between fluoride exposure and cognitive function by analyzing data up to 2021, when most participants had reached their 60s, including the implementation of water fluoridation and tap water fluoride concentrations in their residential areas.

The results showed that adolescents exposed to fluoride experienced a slight improvement in cognitive function, an association that nearly disappeared as the participants approached their 60s. No correlation with a decline in cognitive function from tap water was found.

The study was published in JAMA Pediatrics.

Discovering the oldest ice in history

A team of scientists from several U.S. institutions, including the University of Minnesota, discovered 6-million-year-old ice in Antarctica, the oldest dated ice on the planet.

The NSF COLDEX team recovered the ice in the Allan Hills region of Antarctica during the 2019-20 and 2022-23 austral summer science seasons, supported by the United States Antarctic Program. Ice cores drilled in Antarctica and the air bubbles they contain provide insights into earth’s climate history.

The NSF COLDEX researchers found:

• The 6-million-year-old ice preserved in Antarctica more than doubled the next oldest ice samples found at the same site. It’s nearly six times older than the current oldest continuous ice core record, which extends back 800,000 years.
• Isotopic measurements that estimate temperature show progressive cooling at the Antarctic site through the Pliocene—the geologic time period between 5.3 and 2.6 million years ago—with even warmer temperature signatures before that.
• This ancient ice archive allows for study of these times when earth was warmer and sea level was higher—independent of the human-caused warming and sea level rise observed today.

“Future research on these ice cores may provide insights into the history and stability of the Antarctic ice sheet and its relationship to atmospheric greenhouse gases and average ocean temperature, and could have direct implications for future projections of ice sheet sensitivity, sea-level rise, and global temperature,” says coauthor Peter Neff, assistant professor in the College of Food, Agricultural and Natural Resource Sciences at the University of Minnesota and codirector for knowledge transfer for NSF COLDEX. Neff leads the University of Minnesota Neff Ice and Climate Exploration Lab, which has collected new ice in Canada and Antarctica.

Published in Proceedings of the National Academy of Sciences in the Nov. 4, 2025, edition.

Identifying genetic factors in childhood leukemia

A study led by researchers from the University of Minnesota Medical School has identified genetic factors that may help explain why African American children are less likely to develop acute lymphoblastic leukemia (ALL) but face worse outcomes when they do.

ALL is a blood cancer that begins in the bone marrow. It’s the most common type of cancer in children.

The study showed that genetic variants linked to ALL in other ancestries were also present in African American children, although less common, which may explain their lower overall risk. The research team uncovered several new variants unique to African ancestry. Children in this study with ALL who carried one of these new risk variants had a 2.6-fold greater risk of death.

“We plan to evaluate these new, African-specific genetic variants to understand how they influence survival from leukemia,” says Logan Spector, a professor at the University of Minnesota Medical School.

The findings were published in Nature Communications.

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