Persistent environmental toxins accumulate in tissues already in the fetal stage

University of Oulu, Finland

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Persistent organic pollutants (POPs) begin to accumulate in the tissues of mammals already during the foetal stage, according to new research from the University of Oulu, Finland. The animal-model study found that environmental toxins had built up in the tissues of sheep raised in clean organic production, and that the same substances were transferred in notable amounts to the developing foetuses’ adipose tissue.

Persistent environmental toxins, such as PCBs and DDT, remain in nature for long periods without breaking down. They can accumulate in the fatty tissues of organisms and bioaccumulate through the food chain. These substances were previously used in industry and as insecticides, and although their use is now strictly regulated, they remain widespread in the environment.

The study analysed tissue samples from 15 organic ewes and their lambs shortly after birth, searching for the most common POPs. Almost all of the substances investigated were detected in both adult sheep and lamb tissues. All the compounds identified were able to cross the placenta, and the transfer was so effective that concentrations in the lambs’ tissues averaged 30–103 per cent of those measured in the mothers.

Previous research in humans has shown that environmental toxins present in maternal circulation can pass through the placenta. What this study newly demonstrates is that, in sheep, compounds accumulated in the mother’s adipose tissue are transferred to the developing foetus in almost the same proportion.

Because placental structure in sheep differs from that in humans, no direct conclusions can be drawn regarding human exposure. However, concentrations of POPs in adult human adipose tissue are on average higher than in sheep, underscoring the need for further research.

‘The results illustrate the widespread distribution of persistent environmental toxins and the ways in which they infiltrate every part of our surroundings. In epidemiological studies, POP concentrations measured from umbilical cord blood after birth have been linked to obesity, metabolic syndrome and lower IQ. What remains for future research to determine is the extent of the health effects that POPs accumulated in adipose tissue may have on the foetus and on the child’s later health,’ summarises doctoral researcher Ella Vuoti.

Original article: Ella Vuoti, Jerry Nguyen, Panu Rantakokko, Heikki Huhta, Panu Kiviranta, Juha Räsänen, Sanna Palosaari, Petri Lehenkari. Adipose tissue deposition and placental transfer of persistent organic pollutants in ewes. Environmental Research, Volume 287, 2025. 

Journal

Environmental Research

DOI

10.1016/j.envres.2025.123164 

Enantioselective maternal transfer of pesticide metabolite and its thyroid effects

KeAi Communications Co., Ltd.

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HOW THE TWO MIRROR-IMAGE FORMS OF O,P'-DDD DIFFER IN THEIR TRANSFER TO OFFSPRING AND THEIR EFFECTS ON THE THYROID SYSTEM IN ZEBRAFISH.

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Credit: Lili Niu, et al

A new study published in Environmental Chemistry and Ecotoxicology has revealed that two mirror-image forms of a persistent pesticide metabolite behave differently when they move from mother fish to their offspring — demonstrating their environmental risks. Chiralmolecules that are mirror images of each other, like left and right hands.

“We were motivated by a simple question,” says lead author Lili Niu. “Many pesticides exist in two mirror-image forms, but environmental assessments usually treat them as if they're the same. We wanted to know whether that assumption is actually safe, especially across generations.”

To answer this, the researchers fed adult zebrafish diets containing each form of o,p'-DDD for four weeks. They then measured how much of the chemical accumulated in the adults and how much was passed to their developing embryos, as well as tracked hatching success, deformities, survival, and changes in thyroid hormones, which are essential for healthy growth.

“We found that offspring consistently carried even higher chemical levels than their parents, showing that maternal transfer was highly efficient,” shares Niu. “The S-enantiomer accumulated 134-176% more in adults and over 100% more in their larvae than its mirror-image R-form. This led to more severe outcomes in the next generation, including increased mortality, malformations, and reduced hatching success in the S-DDD exposed groups.”

To understand why, the team used computer-based modeling to simulate how each form of the chemical interacts with key proteins involved in producing and regulating thyroid hormones. “These simulations showed that S-DDD binds more strongly to several of these proteins, helping explain its greater biological impact,” says Niu. “What surprised us most was how consistently the S-form caused stronger effects at every level we tested.”

Notably, a small structural difference in the molecule led to very large differences in how much accumulated in the fish, how it affected their hormone system, and how their offspring developed.

The team emphasised that understanding enantiomer-specific effects will help improve ecological risk predictions for long-lasting pollutants and support the development of more accurate environmental standards.

“If we ignore these differences, we risk underestimating long-term harm to wildlife,” adds Niu. “Our work shows that even very low exposure in parents can create meaningful risks for the next generation.”

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Contact the author: Lili Niu, Interdisciplinary Research Academy (IRA), College of Biological and Environmental Engineering, Zhejiang Shuren University, China, niulili@zjsru.edu.cn

The publisher KeAi was established by Elsevier and China Science Publishing & Media Ltd to unfold quality research globally. In 2013, our focus shifted to open access publishing. We now proudly publish more than 200 world-class, open access, English language journals, spanning all scientific disciplines. Many of these are titles we publish in partnership with prestigious societies and academic institutions, such as the National Natural Science Foundation of China (NSFC).

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Journal

Environmental Chemistry and Ecotoxicology

DOI

10.1016/j.enceco.2025.10.021 

Method of Research

Experimental study

Subject of Research

Animals

Article Title

Enantioselective maternal transfer of chiral pesticide metabolite o,p’-DDD in zebrafish (Danio rerio): Implications for intergenerational thyroid disruption.

COI Statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper

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New Reichman University study finds: Babies begin forming expectations of their parents as early as the first year of life

Reichman University

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Dr. Tahli Frenkel, a clinical psychologist and senior lecturer at Reichman University’s Baruch Ivcher School of Psychology

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Credit: Gilad Kavalerchik

How does a baby learn to understand the world before they even learn to talk? A new study from Reichman University reveals that as early as the first year of life, infants develop expectations about how their parents will respond to crying or distress. A baby who consistently receives calm and comforting responses learns to expect help and develops a sense of security, whereas one who experiences inconsistent responses learns to be less reliant on others and develops a sense of uncertainty.

 

The study, led by Dr. Tahli Frenkel, a clinical psychologist and senior lecturer at Reichman University’s Baruch Ivcher School of Psychology, in collaboration with Dr. Shyly Aptaker Ben-Dori of the Ziama Arkin Infancy Institute of Reichman University and Prof. Naama Atzaba-Poria from the Duet Center at Ben-Gurion University, shows that an infant’s daily experiences with their parent shape how they perceive the world around them — whether as a safe and supportive place or as distant and unpredictable.

 

The study, published in the scientific journal Attachment & Human Development, followed 72 mothers and their infants, who were observed twice during the infants’ first year of life. When the babies were four months old, natural home interactions were recorded to examine how mothers responded to their infants’ cries — whether by being present and soothing, or by remaining distant. About six months later, when the infants reached ten months of age, they were shown a short puppet show depicting a caregiver teddy bear character responding to an infant's (“baby bear”) cry — once in a supportive and accessible manner, and once in a cold and unresponsive way. The researchers monitored the infants’ reactions, including gaze duration, level of interest, and play preferences, to determine whether they recognized the difference in the caregiver’s response and how it corresponded with their previous experiences at home.

 

When the infants’ responses in the laboratory were compared with the interactions recorded at home six months earlier, a clear pattern emerged. Infants whose mothers had been observed responding calmly and with emotional availability at home tended to expect the caregiver-bear figure in the experiment to behave similarly — to be responsive and supportive. In contrast, infants who had experienced less consistent or more distant responses at home showed lower expectations and, in some cases, even indifference toward the unresponsive caregiver figure.

Moreover, when the infants were offered to choose whether they preferred to play with either the responsive or the unresponsive caregiver-bear, prior experience of caregiving observed in the infant’s home six months earlier was predictive of the infant's preference. Those whose mothers had been observed responding in a calm and responsive manner preferred to play with the responsive caregiver-bear, whereas those whose mothers had been observed as more distant preferred to play with the unresponsive caregiver-bear.

 

Taken together, the findings support the notion that infants’ expectations and preferences for parent responsiveness may reflect their early experiences of maternal responsiveness, as experienced by the infant within daily mother–infant interactions during the first year of life.   

These findings provide preliminary empirical evidence that, already in the first year of life, infants create an internal representation of what to expect when they express distress. Dr. Frenkel adds: “The results carry an encouraging message for parents — the first year of life is a particularly significant period, during which daily interactions lay the foundations for a child’s emotional resilience. Consistent, attentive, and supportive responses shape the baby’s sense of security and fundamental trust in the world around them.”

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Journal

Attachment & Human Development

DOI

10.1080/14616734.2025.2562511 

Method of Research

Experimental study

Subject of Research

People

Article Title

Individual differences in infants’ expectations and preferences for responsive vs. unresponsive parent-puppets and their associations with early maternal behavior

 

What our meadows reveal about the future

Spatial data shows biodiversity loss with surprising precision

Bielefeld University

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Professor Lena Neuenkamp is the lead author of the study, which has now been published in the journal Nature Ecology & Evolution.

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Credit: Bielefeld University

Meadows once teeming with buzzing insects and colorful plants are quietly losing their diversity. But how fast is this change happening and can we detect it before species disappear? A German-Swiss research team led by Professor Dr Lena Neuenkamp of Bielefeld University has found an answer. Their study, published in the journal Nature Ecology & Evolution, shows that spatial data can remarkably well predict how biodiversity changes over time.

“Long-term observations often take many years. Spatial data, on the other hand, are available immediately and yet they speak a clear language,” says the study’s first author, Professor Neuenkamp. “Our results show that we can already identify where nature is under pressure.”

Unique data from 150 meadows
For the study, the team of Bern and several German universities used a unique dataset of the Biodiversity Exploratories, a large-scale project funded since 2006 by the German Research Foundation. On 150 grassland sites, plants and arthropods—such as insects and spiders—were surveyed annually over eleven years.

The researchers compared how biodiversity differs between locations and how it changes over the years. The result: when land is used more intensively—more fertilization, more frequent mowing, or denser grazing—biodiversity declines. This applies both to the number of species within a site (so-called α-diversity) and to the differences between sites (β-diversity).

A tool for faster conservation
Especially striking: patterns in spatial data and time series are highly similar. This means that spatial observations can serve as a “shortcut” when long-term datasets are lacking.

“This gives us a potential early-warning system for biodiversity loss,” says Professor Dr. Norbert Hölzel of the University of Münster, who has been working in the Biodiversity Exploratories for more than 15 years. “We can now better anticipate where ecosystems might tip and act sooner.”

The study also shows that changes in nature often occur with delays. Some species respond only years after land use intensifies. Long-term data therefore remain essential to understand these time lags.

The researchers emphasize: even if change begins quietly, it can be made visible. And that visibility is crucial for protecting biodiversity before it’s too late.

Long-term monitoring of vegetation in the DFG biodiversity exploration sites is assured for the next six years, with Bielefeld and Münster Universities taking responsibility for this as part of a recently successful collaborative project with the University of Bern.

The researchers investigated biodiversity in different meadows.

Credit

Neuenkamp

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Journal

Nature Ecology & Evolution

DOI

10.1038/s41559-025-02896-0 

Method of Research

Observational study

Subject of Research

Animals

Article Title

Congruent direction but different magnitude of biodiversity response to land use intensification in space and time

Article Publication Date

25-Nov-2025