Long-term pesticide exposure speeds up aging in fish
Long-term exposure to low levels of a common agricultural pesticide can accelerate physiological aging and shorten lifespan in fish, researchers report.
The finding from new research led by University of Notre Dame biologist Jason Rohr has potentially far-reaching implications for environmental regulations and human health.
The study, published in Science, shows that chronic exposure to the insecticide chlorpyrifos at concentrations too low to cause immediate toxicity causes fish to age faster at the cellular level.
The research began with field studies in China where collaborators examined thousands of fish collected over several years from lakes with differing levels of pesticide contamination. Rohr and colleagues observed that fish living in contaminated lakes lacked older individuals, while populations in relatively uncontaminated lakes included many older fish. This pattern suggested that fish were not failing to add to their populations, but rather were dying earlier in life.
“When we examined telomere length and deposition of lipofuscin in the livers of the fish, well-established biological markers of aging, we found that fish of the same chronological age were aging faster in the contaminated than clean lakes,” says Rohr, a professor and chair in the biology department.
Chemical analyses revealed that chlorpyrifos was the only compound found in the fish tissues that was consistently associated with signs of aging. These include shortened telomeres, which act like the plastic caps shoelaces and decrease fraying in chromosomes, and lipofuscin deposition, a build-up of “junk” like old proteins and metals within long-lived cells.
However, to determine whether chlorpyrifos was the direct cause, researchers needed to conduct controlled laboratory experiments with concentrations matching those measured in the wild, Rohr says.
In this laboratory experiment, chronic low-dose exposure to chlorpyrifos caused progressive telomere shortening, increased cellular aging and reduced survival, particularly in fish from the contaminated lakes that were already physiologically older.
“Although the laboratory results closely matched the field observations, it was possible that a missed high-dose exposure event in the field, rather than chronic low-dose exposures, caused the reduced lifespan,” says Rohr, who is affiliated with Notre Dame’s Berthiaume Institute for Precision Health, Environmental Change Initiative and Eck Institute for Global Health.
To rule out this driver, Rohr and colleagues conducted another laboratory experiment demonstrating that short-term exposure to much higher doses caused rapid toxicity and death but did not accelerate aging through shortened telomeres and increased lipofuscin. This demonstrated that long-term accumulation of exposure to extremely common low concentrations—not brief high-dose spikes—was responsible for the observed aging, Rohr says.
The loss of older individuals can have serious ecological consequences, as older fish often contribute disproportionately to reproduction, genetic diversity, and population stability, Rohr says.
“These findings also raise broader concerns because telomere biology and aging mechanisms are highly conserved across vertebrates, including humans,” Rohr says. Potential future research will explore how widespread the phenomenon may be across species and chemicals.
While the European Union has largely banned chlorpyrifos, it remains in use throughout China, parts of the United States, and in many other countries. However, the aging effects observed in this study occurred at concentrations below current US freshwater safety standards, Rohr says.
“Our results challenge the assumption that chemicals are safe if they do not cause immediate harm,” he says.
“Low-level exposures can silently accumulate damage over time by accelerating biological aging, highlighting that chemical safety assessments must move beyond short-term toxicity tests to adequately protect environmental and human health.”
The research was funded by the National Science Foundations in both the United States and China, the Illinois-Indiana Sea Grant and the Frontiers Research Foundation.
Source: University of Notre Dame
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2 moral actions shape first impressions more than others
New research reveals that fairness and respect for property shape our first impressions—and our willingness to trust—more than other moral behaviors
Every day, we quietly judge the people around us. Did that coworker split the credit fairly? Did a neighbor return a lost package? Did someone cut in line or respect the rules?
According to a new study in PLOS One from researchers at the University of Michigan and University of Illinois, not all moral actions are judged equally, and two types stand out: how fairly someone treats others and whether they respect what belongs to other people.
Across a series of studies, researchers found that acts involving equality and property powerfully shape how we see someone’s character, how much we trust them, and even whether we’re willing to cooperate with them in everyday life. These judgments happen quickly, consistently, and even when our attention is stretched thin.
“Fairness and respect for property may be the moral behaviors that matter most when it comes to social trust,” says study coauthor Savannah Adams, a doctoral candidate.
Researchers says the findings’ importance is that people see fairness and respect for property as key signs of character, and we judge these things efficiently. So what does this mean in real life?
“These quick judgments might actually pick up on something important—fairness and respect for property could really be good signs that someone is trustworthy,” says study coauthor Oscar Ybarra, emeritus psychology professor. “Still, because we make these decisions so fast and with little information, it’s always worth taking a closer look.”
Psychologists have long known that morality consists of different domains—such as helping family, returning favors, respecting authority, sharing with the community, treating people equally, and respecting others’ property. What hasn’t been clear is whether these different moral behaviors leave the same kind of impression on us.
The answer came from three studies involving hundreds of US adults, who saw short descriptions of everyday behaviors performed by fictional people. Some examples included helping/refusing to help a family member; following/breaking rules set by authority; and treating people equally or showing favoritism.
Participants were asked what kind of person it was, if the behavior involved their character or situation, and if they would trust them.
In the final study, participants did all this while juggling a mental distraction task—memorizing long strings of numbers—to see whether these judgments would fall apart under pressure. They didn’t.
Equality (fairness/equal treatment) and property (respecting what belongs to others) triggered the strongest reactions, both positive and negative, the study showed. When someone acted fairly or respected property:
They were seen as highly moral and principled
Their behavior was attributed to their true character
People were more willing to trust and cooperate with them
When someone violated these norms, they were judged harshly. In addition, their actions were seen as reflecting who they really are, and people were less willing to engage, share, or rely on them.
Ybarra says the research showed that other moral behaviors—such as bravery, loyalty to community, or deference to authority—mattered too, but not nearly as much in shaping first impressions.
Researchers found a surprising finding in the third study. Even when participants were mentally overloaded—trying to remember long number sequences while judging others—their reactions to fairness and property violations stayed strong.
“This suggests these judgments are automatic and intuitive, not the result of slow, careful thinking,” noted Ybarra, professor at the University of Illinois Urbana-Champaign.
In other words, your brain doesn’t need much time or attention to decide how it feels about someone who cheats, steals, or plays favorites.
Source: University of Michigan
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