Uranium buildup in kidneys is detected using urine biomarker

Biological markers found in urine may indicate uranium accumulation in kidneys, according to an NIEHS-supported study in mice.

Uranium is a heavy metal found in rocks, soil, and water. Most community water systems in the U.S. contain uranium but at levels below the maximum contaminant level set by the U.S. Environmental Protection Agency. Even low-dose exposure to the metal can cause kidney damage, but no existing test can measure how uranium ingestion affects different parts of the human body.

Natural uranium exists primarily as two isotopes, uranium 238 and uranium 235, which have different numbers of neutrons but the same number of protons. The researchers examined whether changes in the ratio of uranium 238 to uranium 235 could be used as a biomarker to assess uranium accumulation in the body. They detected changes in the composition of uranium isotopes in mice exposed to uranium through drinking water for 7-14 days. In particular, the kidneys and bones were enriched in uranium 235, whereas urine was enriched in uranium 238.

The results suggest that uranium 238 in urine could serve as an accurate, noninvasive biomarker for uranium accumulation in the kidneys. According to the authors, the findings could help improve early detection of kidney problems linked to chronic uranium exposure.

Citation: Lucey CM, Pearson BL, DeSantis K, Goldsmith J, Halliday AN, Navas-Acien A, Schilling K, Basu A. 2025. Isotopic fractionation of natural uranium in mice as a potential biomarker of renal accumulation. Environ Sci Technol 59(28):14279-89.

Living near trees may boost the heart health of women during midlife

Visible greenspace may improve cardiovascular health among middle-aged women, according to an NIEHS-supported study.

Many women develop cardiovascular health problems during midlife. Past research has shown that greenspace may help lower disease risk by reducing exposure to air pollution and promoting physical activity. However, most studies have relied on satellite-based evidence rather than street-level measures, which more accurately capture what people see on a daily basis and differentiate between various types of vegetation.

In this study, the researchers tested how street-view greenspace affected the cardiovascular health of 767 women. They quantified greenspace by applying models to Google Street View images, measuring the percentage of trees, grass, and other plants visible within 500 meters of participants’ homes, when participants were an average age of 46 years. Approximately five years later, participants completed questionnaires and research measurements, and the team calculated health scores.

Women living near more trees, but not more grass, had better overall cardiovascular health. Higher tree exposure was also linked to improved diet, physical activity, sleep, body weight, blood pressure, blood glucose, and smoking avoidance.

The findings suggest that planting and preserving trees in residential areas may help reduce the cardiovascular health problems that many women experience during midlife

Citation: Rifas-Shiman SL, Yi L, Aris IM, Lin PD, Hivert MF, Chavarro JE, Suel E, James P, Oken E. 2025. Associations of street-view greenspace exposure with cardiovascular health (Life's Essential 8) among women in midlife. Biol Sex Differ 16(1):45.

Alligators may serve as sentinels for human exposure to PFAS

Alligators in North Carolina carry high levels of per- and polyfluoroalkyl substances (PFAS), according to researchers supported in part by NIEHS.

PFAS are chemicals known for their toxicity and persistence in humans and the environment. However, the health effects of most PFAS are unclear, and detecting unknown PFAS is a top research priority. Toxicants bioaccumulate in alligators — due to their long lifespans and position near the top of the food chain — making them valuable animals for understanding how human health might be affected by known and novel PFAS.

In the new study, the researchers collected PFAS data from alligators in the lower Cape Fear River in North Carolina. The river is a primary source of drinking water known to contain elevated PFAS levels. For comparison purposes, they also examined data collected from other sites in North Carolina and in Florida.

Using nontargeted analysis, the team detected 46 PFAS in alligator blood. They characterized the structures of 12 PFAS, including two previously unknown compounds. In addition, the researchers observed high concentrations of 21 of the 34 known PFAS. Alligators in North Carolina showed more PFAS than those in Florida, where no novel PFAS were observed.

According to the authors, future work should monitor these compounds and assess their toxicity and potential to bioaccumulate.

Citation: Boatman AK, Kudzin GP, Rock KD, Guillette MP, Robb F, Belcher SM, Baker ES. 2025. Novel PFAS in alligator blood discovered with non-targeted ion mobility spectrometry-mass spectrometry. Sci Total Environ 985:179760.

Arsenic exposure disrupts human metabolism

Arsenic exposure has wide-ranging effects on human metabolism, which may explain its link to multiple diseases, according to researchers supported in part by NIEHS.

Long-term exposure to arsenic in drinking water is associated with cardiovascular disease, metabolic syndrome, neurological impairments, and cancer. However, the full scope of arsenic’s metabolic effects is not fully understood. Previous studies have demonstrated that treatment with the B vitamin folic acid increases the methylation of arsenic, which facilitates urinary arsenic elimination. However, the downstream metabolic effects of these methylation changes remain unclear.

To address these questions, the researchers analyzed the metabolic profiles of 598 Bangladeshi adults who were exposed to moderate to high arsenic levels, and they tested whether taking folic acid supplements for 12 weeks changed the adults’ metabolism in a randomized clinical trial. The team identified 74 arsenic-associated metabolites — small molecules that are produced or used during metabolism — and four metabolites linked to folic acid induced arsenic methylation changes.

Many of these metabolites are related to the production of amino acids, such as phenylalanine, tyrosine, and tryptophan, which play a key role in generating neurotransmitters — chemicals that allow neurons to communicate. The findings suggest a biological basis for arsenic’s role in increasing the risk of neurological impairments, cancer, melanosis, and cardiovascular disease.

According to the authors, these findings shed light on the mechanisms behind arsenic toxicity and could inform prevention and treatment strategies. Furthermore, the findings suggest that some arsenic-induced metabolic disruptions could be improved with folic acid supplementation.

Citation: Li W, Wu H, Goldsmith J, Glabonjat RA, Ilievski V, Balac O, Slavkovich V, et al. 2025. Metabolic signature of arsenic exposure and metabolism: The Folic Acid and Creatine Trial. Environ Sci Technol 59(29):14905-16.