Reducing arsenic in drinking water cuts risk of death, even after years of chronic exposure: 20-year study

Arsenic is among the most common chemical pollutants of ground water.

Arsenic is a naturally occurring element that accumulates in groundwater, and because it has no taste or odor, people can unknowingly drink contaminated water for years.

A 20-year study of nearly 11,000 adults in Bangladesh found that lowering arsenic levels in drinking water was associated with up to a 50% lower risk of death from heart disease, cancer and other chronic illnesses, compared with continued exposure.

The study provides the first long-term, individual-level evidence that reducing arsenic exposure may lower mortality, even among people exposed to the toxic contaminant for years.

The landmark analysis by researchers is important for public health because groundwater contamination from naturally occurring arsenic remains a serious issue worldwide.

The study shows what happens when people who are chronically exposed to arsenic are no longer exposed. You're not just preventing deaths from future exposure, but also from past exposure.

The results provide the clearest evidence to date of the link between arsenic reduction and lower mortality.

For two decades, the research team followed each participant's health and repeatedly collected urine samples to track exposure, which they say strengthened the accuracy of their findings.

People whose urinary arsenic levels dropped from high to low had mortality rates identical to those who had consistently low exposure throughout the duration of the study. The larger the drop in arsenic levels, the greater the decrease in mortality risk. By contrast, individuals who continued drinking high-arsenic water saw no reduction in their risk of death from chronic disease.

 Arsenic Exposure Reduction and Chronic Disease Mortality, JAMA (2025). jamanetwork.com/journals/jama/ … 1001/jama.2025.19161

Lethal dose of plastics for ocean wildlife: Surprisingly small amounts can kill seabirds, sea turtles and marine mammals

By studying more than 10,000 necropsies, researchers now know how much plastic it takes to kill seabirds, sea turtles, and marine mammals, and the lethal dose is much smaller than you might think. Their new study titled "A quantitative risk assessment framework for mortality due to macroplastic ingestion in seabirds, marine mammals, and sea turtles" is published in the Proceedings of the National Academy of Sciences.

Nearly half (47%) of all sea turtles; a third (35%) of seabirds; and 12% of marine mammals in the dataset had plastics in their digestive tracts at their time of death. Overall, one in five (21.5%) of the animals recorded had ingested plastics, often of varying types. Additional findings included:
Seabirds
Of seabirds that ate plastic, 92% ate hard plastics, 9% ate soft plastics, 8% ate fishing debris, 6% ate rubber, and 5% ate foams, with many individuals eating multiple plastic types.
Seabirds are especially vulnerable to synthetic rubber: just six pieces, each smaller than a pea, are 90% likely to cause death.
Sea turtles
Of sea turtles that ate plastic, 69% ate soft plastics, 58% ate fishing debris, 42% ate hard plastics, 7% ate foam, 4% ate synthetic rubbers, and 1% ate synthetic cloth.
Sea turtles, which on average weigh several hundred pounds, are especially vulnerable to soft plastics, like plastic bags: just 342 pieces, each about the size of a pea, would be lethal with 90% certainty.
Mammals
Of marine mammals that ate plastic, 72% ate fishing debris, 10% ate soft plastics, 5% ate rubber, 3% ate hard plastics, 2% ate foam, and 0.7% ate synthetic cloth.
Marine mammals are especially vulnerable to fishing debris: 28 pieces, each smaller than a tennis ball, are enough to kill a sperm whale in 90% of cases.
Threatened species and broader impacts
The study also found that nearly half of the individual animals who had ingested plastics are red-listed as threatened—that is, near-threatened, vulnerable, endangered or critically endangered—by the IUCN. Notably, the study only analyzed the impacts of ingesting large plastics (greater than 5 millimeters) on these species, and did not account for all plastic impacts and interactions. For example, they excluded entanglement, sublethal impacts of ingestion that can impact overall animal health, and microplastics consumed.

This research really drives home how ocean plastics are an existential threat to the diversity of life on our planet.

 Murphy, Erin L., A quantitative risk assessment framework for mortality due to macroplastic ingestion in seabirds, marine mammals, and sea turtles, Proceedings of the National Academy of Sciences (2025). DOI: 10.1073/pnas.2415492122. doi.org/10.1073/pnas.2415492122

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