Nanoplastics from biodegradable plastics can cross the placenta and accumulate in foetal organs
PLA plastic breakdown product Oligomeric nanoplastics can penetrate the placental barrier and reach the foetus. Image credit: Dr Jia Lv (CC-BY 4.0)
When the “eco-friendly” bioplastic, polylactic acid (PLA), biodegrades, the resulting nanoplastics can accumulate in the foetuses of pregnant mice and interfere with foetal growth. Yichao Huang and De-Xiang Xu of Anhui Medical University, China, and Mingliang Fang of Fudan University, China, report these findings in a new study published March 26thin the open-access journal PLOS Biology.
PLA, which is made from corn starch and sugarcane, came onto the market as a biodegradable alternative to conventional plastics around two decades ago and has since become one of the most widely used bioplastics. Due to exponential growth in the production of PLA for packaging and medical applications, humans are increasingly exposed to its main breakdown product, oligomeric lactic acid (OLA) nanoplastics, which have recently been shown to have negative health effects.
In the new study, researchers exposed pregnant mice to OLA at doses proportional to what a human typically consumes and looked for impacts on the mouse pups. They demonstrated that OLA crosses the placenta and accumulates in various organs in the fetus. Furthermore, they showed that OLA interferes with a signaling pathway that controls the development of blood vessels in the placenta, which leads to slower growth of the fetus. This is a concern, because in humans, low birth weight is associated with an increased risk of stillbirth, as well as a higher risk of developing multiple other health problems later in life.
This work is the first animal study to evaluate the developmental health effects from the breakdown products of a supposedly eco-friendly plastic in pregnant mammals. The researchers propose that future work should focus on evaluating the exposure levels and health risks associated with eco-friendly plastics in humans, and a rethinking of our approach to plastic alternatives.
The authors add, “One of our co-authors Dr Mengjing Wang had previously discovered that the widely merchandised PLA microplastics undergo gut enzyme–mediated hydrolysis into oligomeric products that are toxic to the intestinal tract and can trigger enteritis.”
“To follow up on this work, as toxicologists, we went on to ask an additional question: do these oligomeric products, aka OLA, pose developmental threat particularly during the susceptible stage in utero?”
“What we have found was quite astonishing to us. Even under realistic exposure dose scenario during pregnancy, OLA nanoplastics can penetrate the placenta and even reach the foetus, in a mouse model. Such exposure would then cause placental vascular dysplasia and further lead to compromised foetal development.”
“While biodegradable plastics present a viable path to mitigate traditional plastic pollution, their potential health hazards necessitate a recognition in responsibility toward informed consumer intentions and conscientious usage.”
Humans evolved in an atmosphere containing roughly 200–300 parts per million (ppm) of carbon dioxide (CO₂). Today, that figure sits above 420 ppm, higher than at any point in the history of our species.
We know this extra CO₂ is contributing to climate change, but could it also be changing the chemistry of our bodies?
In our recently published research we looked at two decades of information from one of the biggest health datasets in the world to start answering this question. We found some concerning trends.
What we found
We analysed blood chemistry data from the US National Health and Nutrition Examination Survey (NHANES), which collected samples from about 7000 Americans every two years between 1999 and 2020. We looked at three markers: CO₂, calcium and phosphorus.
When CO₂ enters the blood, it is converted to bicarbonate. This process largely occurs inside red blood cells, and also produces hydrogen ions.
During short-term exposure to increased CO₂, this can make blood more acidic, and result in a modest increase in bicarbonate levels in the blood (to reduce acidity).
If the exposure continues for a long time the kidneys reduce the amount of bicarbonate lost in urine and also produce more bicarbonate. This has the net effect of higher bicarbonate levels in the blood, to counteract the persistent acidity.
Levels of calcium and phosphorus in the blood may also be affected, as they too play a role in regulating acidity in the blood. These processes are completely normal.
Over the 21 years from 1999 to 2020, we found that average blood bicarbonate levels rose by about 7%. Over the same period, atmospheric CO₂ concentrations rose by a similar proportion.
Meanwhile, blood calcium levels dropped by about 2% and phosphorus by around 7%.
If these trends continue, blood bicarbonate levels may exceed healthy levels in around 50 years. Calcium and phosphorus levels may fall below healthy levels, too, by the end of the century.
Our hypothesis is that rising CO₂ exposure could be contributing to these trends.
What’s causing the changes?
It’s important to be clear about what this study does and doesn’t show. It identifies population-level trends in blood chemistry that parallel rising atmospheric CO₂.
But correlation is not causation. The study does not adjust for factors such as diet, kidney function, diuretic use or obesity, which can influence the measurements and should be considered in future analyses.
There are other plausible contributors. One important consideration is indoor air.
Participants in the NHANES study likely spend most of their time indoors, where CO₂ concentrations often exceed 1000 ppm in poorly ventilated spaces. Other studies show time spent indoors has increased over the past two decades.
The NHANES dataset doesn’t capture this parameter, so we can’t directly assess this contribution. However, if more time indoors is contributing, it means total CO₂ exposure is rising even faster than atmospheric trends suggest. This arguably reinforces rather than alleviates the concern.
Other factors, such as shifting dietary patterns, changing rates of obesity, differences in physical activity and even variations in sample collection or processing across survey cycles, could also be important.
Can our bodies cope?
Some critics have argued that, based on what we know about how our bodies manage blood chemistry, we should have no trouble compensating for future increases in atmospheric CO₂, even under worst-case climate scenarios. For example, the lungs can increase ventilation and the kidneys can adjust to produce more bicarbonate.
For most healthy individuals, small long-term increases in outdoor CO₂ are not expected to meaningfully change the levels of bicarbonate, calcium or phosphorus in the blood.
This makes the population-level trends we observed puzzling. They could reflect a confounding rather than a direct CO₂ effect, but they do highlight how little data we have on long-term, real-world exposure.
A lack of long-term data
The argument that we can cope easily with higher CO₂ is based on short-term responses. Whether the same reasoning applies when CO₂ levels are higher across a person’s entire life remains largely untested.
There is, however, a growing body of evidence across many species which shows that even modest, environmentally relevant increases in CO₂ can produce subtle but measurable physiological effects.
In humans, short-term exposure at concentrations commonly found indoors (1000–2500 ppm) has been linked to reduced cognitive performance and changes in brain activity, though the mechanisms aren’t fully understood.
These new findings highlight a gap in evidence about long-term, real-world CO₂ exposure and human physiology. Unfortunately, there simply aren’t any studies assessing the physiological effects of breathing slightly elevated CO₂ over a lifetime.
This is particularly important for children, who will experience the longest cumulative exposure. And that’s why it’s vital to investigate this area further.
What this means
Our findings are not suggesting people will become suddenly unwell when atmospheric CO₂ reaches a certain level. What the data show is a signal that warrants attention.
If rising atmospheric CO₂ is contributing to gradual shifts in blood chemistry at a population level, then the composition of the atmosphere should be monitored alongside traditional climate indicators as a potential factor in long-term public health.
Reducing CO₂ emissions remains crucial for limiting global warming. Our findings suggest it may also be important for safeguarding aspects of human health that we’re only just beginning to understand.
Cohort study finds people with stroke may be extra susceptible to air pollution’s impact on the brain
Photo by Kouji Tsuru on Pexels
People with greater exposure to air pollution face a higher risk of developing Alzheimer’s disease, according to a new study by Yanling Deng of Emory University, U.S.A., and colleagues, published February 17th in the open-access journal PLOS Medicine.
Alzheimer’s disease is the most common form of dementia, affecting about 57 million people worldwide. Exposure to air pollution is a known risk factor for Alzheimer’s disease, and for several common chronic health conditions, such as hypertension, stroke and depression. These chronic conditions are also linked to Alzheimer’s disease, but previously it was unclear whether air pollution causes these chronic conditions, which then lead to dementia, or if these conditions might amplify the effects of air pollution on brain health.
A team at Emory University studied more than 27.8 million U.S. Medicare recipients aged 65 years and older from 2000 to 2018. The researchers looked at individuals’ air pollution exposure level and whether they developed Alzheimer’s disease, while emphasizing the role of other chronic conditions. They found that greater exposure to air pollution was associated with an increased risk of Alzheimer’s disease, and that association was slightly stronger in individuals who had experienced a stroke. Hypertension and depression, however, had little additional impact.
Overall, the findings suggest that air pollution contributes to Alzheimer’s disease mostly through direct pathways rather than through other chronic health conditions. However, people with a history of stroke may be especially susceptible to the harmful effects of air pollution on brain health. The study indicates that improving air quality could be an important way to prevent dementia and protect older adults.
The authors add, “In this large national study of older adults, we found that long-term exposure to fine particulate air pollution was associated with a higher risk of Alzheimer’s disease, largely through direct effects on the brain rather than through common chronic conditions such as hypertension, stroke, or depression.”
“Our findings suggest that individuals with a history of stroke may be particularly vulnerable to the harmful effects of air pollution on brain health, highlighting an important intersection between environmental and vascular risk factors.”
McGill researchers studying printed stickers on packaged food find some chemicals now used instead of bisphenol A can disrupt human ovarian cell function, and warn that ‘BPA-free’ does not necessarily mean safe
Chemicals used to replace bisphenol A (BPA) in food packaging can trigger potentially harmful effects in human ovarian cells, according to McGill University researchers.
A new study examined several chemicals commonly used in price stickers on packaged meat, fish, cheese and produce found early signs of potential toxicity.
The findings, published in the journal Toxicological Sciences, raise concerns about the safety of BPA-free packaging and whether current regulations go far enough to protect consumers.
BPA substitutes disrupt gene expression
The research began with the 2023 discovery by Stéphane Bayen, Associate Professor in McGill’s Department of Food Science and Agricultural Chemistry, that label-printing chemicals like bisphenol S (BPS), a BPA replacement, were leaching through plastic wrap into the food. He teamed up with colleagues in reproductive toxicology to investigate what these substances could be doing inside the body.
Lab-grown human ovarian cells were exposed to four commonly used BPA substitutes: TGSA, D-8, PF-201 and BPS. Several of the chemicals, particularly TGSA and D-8, caused a buildup of fat droplets in the cells and changed the activity of genes that help cells grow and repair their DNA.
“These are major cellular functions,” said Bernard Robaire, co-senior author of the study and James McGill Professor in McGill’s Departments of Pharmacology & Therapeutics and Obstetrics & Gynecology. “Disrupting them doesn’t prove harm in humans, but it gives us a strong signal that these chemicals should be further investigated.”
Unregulated replacements under the radar
BPA is a chemical that can interfere with the body’s hormones, and has been linked to problems with fertility, early development and metabolism. Because of these risks, it has been banned in baby bottles and restricted in some products in Canada.
Many of the chemicals used to replace BPA are not regulated or routinely tested, the researchers explained.
“‘BPA-free’ is an incredibly misleading label,” said Robaire. “It usually means one bisphenol has been swapped for another, and there are more than 200 of them. Some may be just as harmful, or even worse. We need to test these compounds before they’re widely adopted, not after.”
Health Canada has now added all four substances to a list of chemicals requiring further investigation.
For consumers looking to err on the side of caution, Robaire suggests removing labels and plastic wrap from fresh foods before storing. He also recommends choosing items from the top of store display piles rather than the bottom, where pressure from stacking may push chemicals more deeply into the packaging and food.
South Africa’s water quality monitoring gap explained
By Robert Erasmus, Managing Director at Sanitech
Source: Unsplash CC0
Access to safe and clean water remains a critical concern in South Africa. Recent incidents, including a highly contaminated water sample from Secunda that showed extreme levels of E. coli, have highlighted the urgent need for faster and more reliable water quality monitoring across the country. Public health depends on the safety of the water flowing through our rivers, dams and municipal systems, yet current monitoring processes often struggle to detect contamination before it reaches communities. Improving these systems will require a combination of practical testing methods, independent oversight and community involvement.
Why traditional testing cannot keep up South Africa’s public water testing framework is accurate but slow. When contamination is suspected, samples must be collected, couriered to an accredited laboratory and cultured to detect biological threats such as E. coli. While potential of Hydrogen (pH) and chlorine levels can be measured quickly on site, biological tests take one to two weeks because the organisms must be grown before results can be confirmed. This delay leaves a dangerous gap in which water quality could deteriorate without immediate detection.
The process is also costly. A single accredited test, including logistics, can cost around R5 000, which makes frequent testing inaccessible for households and many community organisations. As a result, many people rely on the assumption that water from the tap is safe. When contamination does occur, individuals may fall ill without realising the cause because there is no real time feedback on water quality.
How in-house testing can speed up detection Although accredited labs are still required for official reporting, new approaches are emerging that can help organisations identify risks earlier. Some companies are now investing in equipment that allows them to carry out basic testing in house. These tests are not accredited but they give fast, useful readings that act as early warning indicators. If an organisation detects abnormal results, it can immediately escalate the matter to an accredited lab instead of waiting for contamination to spread.
Routine pH and chlorine monitoring also plays a valuable role. These tests are inexpensive, easy to perform and can be carried out continuously within businesses or local facilities. While they cannot detect biological contamination, they help ensure that the chemical balance of the water stays within safe limits. When combined with monthly or cyclical biological testing, this creates a more proactive monitoring system.
This approach recently proved critical in Secunda, where a business conducting its own branch-level testing discovered that municipal water entering the site was contaminated with sewage. The in-house test flagged the issue quickly, prompting further investigation. Without this internal programme, the problem might have gone unnoticed for far longer.
Why collaboration improves water safety A stronger water monitoring system cannot rely on public authorities alone. Partnerships between municipalities, private companies and communities can help improve both the speed and reliability of responses. Independent testing at business level introduces greater transparency and can highlight water quality issues that may otherwise go unreported. When patterns of poor quality emerge, communities gain evidence to push for corrective action.
Transparency also drives accountability. If businesses in a region consistently report poor water quality, it becomes more difficult for the problem to remain hidden. Public pressure increases and municipalities have a clearer picture of where urgent interventions are needed. This type of shared visibility is essential for strengthening trust and promoting faster action.
Communities have an important role as well. Residents are often the first to notice discolouration, odour or unusual cloudiness in their tap water. Reporting these signs to employers or organisations with the means to test can lead to early detection. Raising issues solely through political channels may not always lead to immediate investigation, but involving local businesses can create quicker pathways to testing and response.
A path toward safer and more reliable water A safer water future for South Africa will depend on strengthening both formal and informal monitoring systems. Accredited labs remain vital for official results, yet in house testing, routine checks and community reporting can highlight risks long before formal samples are processed. When contamination is confirmed, solutions like filtration, Ultraviolet (UV) treatment or proper chlorination can be deployed quickly to restore safety.
What this shows is simple: the safety of tap water cannot be taken at face value. Consistent monitoring and transparent reporting are key to safeguarding public health. With better coordination between public bodies, private organisations and communities, South Africa can build a water monitoring system that identifies problems early and protects every household.
Microplastics could be fuelling neurodegenerative diseases like Alzheimer’s and Parkinson’s, with a new study highlighting five ways microplastics can trigger inflammation and damage in the brain.
More than 57 million people live with dementia, and cases of Alzheimer’s and Parkinson’s are projected to rise sharply. The possibility that microplastics could aggravate or accelerate these brain diseases is a major public health concern.
Pharmaceutical scientist Associate Professor Kamal Dua, from the University of Technology Sydney, said it is estimated that adults are consuming 250 grams of microplastics every year – enough to cover a dinner plate.
“We ingest microplastics from a wide range of sources including contaminated seafood, salt, processed foods, tea bags, plastic chopping boards, drinks in plastic bottles and food grown in contaminated soil, as well as plastic fibres from carpets, dust and synthetic clothing.”
“Common plastics include polyethylene, polypropylene, polystyrene and polyethylene terephthalate or PET. The majority of these microplastics are cleared from our bodies, however studies show they do accumulate in our organs, including our brains.”
The systematic review, recently published in Molecular and Cellular Biochemistry, was an international collaboration led by researchers from the University of Technology Sydney and Auburn University in the US.
The researchers highlighted five main pathways through which microplastics can cause harm to the brain, including triggering immune cell activity, generating oxidative stress, disrupting the blood–brain barrier, impairing mitochondria and damaging neurons.
“Microplastics actually weaken the blood–brain barrier, making it leaky. Once that happens, immune cells and inflammatory molecules are activated, which then causes even more damage to the barrier’s cells,” said Associate Professor Dua.
“The body treats microplastics as foreign intruders, which prompts the brain’s immune cells to attack them. When the brain is stressed by factors like toxins or environmental pollutants this also causes oxidative stress,” he said.
Microplastics cause oxidative stress in two main ways: they increase the amount of “reactive oxygen species” or unstable molecules that can damage cells, and they weaken the body’s antioxidant systems, which normally help keep those molecules in check.
“Microplastics also interfere with the way mitochondria produce energy, reducing the supply of ATP, or adenosine triphosphate, which is the fuel cells need to function. This energy shortfall weakens neuron activity and can ultimately damage brain cells,” said Associate Professor Dua.
“All these pathways interact with each other to increase damage in the brain.”
The paper also explores specific ways in which microplastics could contribute to Alzheimer’s, including triggering increased buildup of beta-amyloid and tau; and in Parkinson’s through aggregation of α-Synuclein and damage to dopaminergic neurons.
First author UTS Master of Pharmacy student Alexander Chi Wang Siu is a currently working in the lab of Professor Murali Dhanasekaran at Auburn University, in collaboration with Associate Professor Dua, Dr Keshav Raj Paudel and Distinguished Professor Brian Oliver from UTS, to better understand how microplastics affect brain cell function.
Previous UTS research has examined how microplastics are inhaled and where they are deposited in the lungs. Dr Paudel, a visiting scholar in the UTS Faculty of Engineering, is also currently investigating the impact of microplastic inhalation on lung health.
While evidence suggests microplastics could worsen diseases like Alzheimer’s and Parkinson’s, the authors emphasise that more research is needed to prove a direct link. However, they recommend taking steps to reduce microplastic exposure.
“We need to change our habits and use less plastic. Steer clear of plastic containers and plastic cutting boards, don’t use the dryer, choose natural fibres instead of synthetic ones and eat less processed and packaged foods,” said Dr Paudel.
The researchers hope the current findings will help shape environmental policies to cut plastic production, improve waste management and reduce long-term public health risks posed by this ubiquitous environmental pollutant.
Children living near nuclear power stations in the UK are not at increased risk of childhood cancers, according to a new analysis.
The research was led by scientists at Imperial College London and University of Bristol and commissioned by the UK Committee on the Medical Aspects of Radiation in the Environment (COMARE). The results, published in International Journal of Epidemiology, found no evidence of increased risk of childhood cancers among children living near 28 nuclear installations between 1995 and 2016.
Researchers analysed cancer incidence data for nearly 50 000 cases of childhood leukaemia, non-Hodgkin’s lymphoma (LNHL), central nervous system (CNS) tumours, and other solid tumours in children aged 0–14 years.
They looked at data for communities living within 25 kilometres of installations, including those which have been linked to historical concerns about potential health impacts – such as Sellafield in Cumbria and Dounreay in northern Scotland.
The analysis found no evidence of increased risk of childhood cancers among children living near 28 nuclear installations between 1995 and 2016. (Credit: Davies, B. et al. Int J Epidemiol, 2025)
Using these data and advanced statistical modelling, they found no increased incidence of childhood cancers in these areas compared to national averages.[1] They also found no evidence that cancer risk increased the closer children lived to the nuclear sites.
Dr Bethan Davies, from Imperial’s School of Public Health and lead author of the study, said: “For many years there have been public concerns about the potential health impacts of living near nuclear installations. Our analysis suggests that children living near these sites today are not at increased risk.”
The latest study builds on decades of research following reports in the 1980s of clusters of cancer cases near nuclear facilities in England, Scotland and Germany[2] – following which, the UK Government set up COMARE to advise on the health effects of radiation.
Early investigations confirmed clusters of cases of some cancers near nuclear installations, particularly LNHL.
However, subsequent studies failed to show any direct link between these cases and radiation exposure from nuclear facilities.
In 2016, a COMARE report[3] suggested other potential explanations for these case clusters, including infections introduced due to population mixing in the areas.
The new findings come at a time of renewed interest in nuclear energy as part of the UK’s strategy to meet net-zero carbon targets and the government committing £14.2bn to build a new nuclear power station in Suffolk and develop small modular reactors.
The researchers say that while their study offers reassurance, they support COMARE’s recommendations for ongoing surveillance of cancer incidence near nuclear sites.
The authors acknowledge a number of limitations with their study, including the use of residential address at diagnosis as a proxy for exposure.
They were also unable to account for individual-level risk factors – such as genetic or medical conditions. However, they emphasise that the study’s design and comprehensive data make it one of the most detailed assessments to date.
Dr Davies added: “As the UK government announces a multibillion-pound investment for new nuclear energy infrastructure, our findings should provide reassurance that the historical clusters of childhood cancers reported near sites such as Sellafield and Dounreay are no longer evident.”
Professor Mireille Toledano, Mohn Chair in Population Child Health in Imperial’s School of Public Health, said: “These findings are both timely and important. As the UK and other countries expand their nuclear energy capacity, it’s vital that public health remains a central consideration. It’s reassuring that our study found that the historic case clusters have resolved, but it remains important we continue to monitor public health data around such sites across the UK for any emerging trends of concern.”
The full study, published today in the International Journal of Epidemiology, was supported by funding from the National Institute for Health and Care Research (NIHR), Health Data Research UK (HDRUK) and the UK Medical Research Council (UK Research and Innovation (UKRI)).
The work was also supported by the NIHR Imperial Biomedical Research Centre, a translational research partnership between Imperial College Healthcare NHS Trust and Imperial College London.
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[1] Researchers obtained national incident cases of cancer diagnosed between 1995 and 2016 in children under 15 years of age from NHS England (formerly Public Health England), Welsh Cancer Intelligence and Surveillance Unit and Health Protection Scotland.
[2] A cluster of cases of leukaemia in children living close to the Sellafield nuclear plant was reported in 1983. An Independent Advisory Group confirmed the cluster and the UK government established COMARE to advise on the health effects of radiation. Subsequent studies identified increased risks of cancers in children and young adults living near Sellafield, Dounreay (Scotland), and Hamburg (Germany) nuclear installations.
[3] Committee on Medical Aspects of Radiation in the Environment (COMARE) – Seventh report (2016) https://assets.publishing.service.gov.uk/media/5a7f70ed40f0b6230268f83c/COMARE_17th_Report.pdf
The indiscriminate use of non-sterile gloves in hospitals and clinics is significantly adding to environmental pollution, with little evidence to prove that there are substantial benefits.
New research from Edith Cowan University (ECU) has highlighted the lack of evidenced-based guidelines in the use of non-sterile gloves in healthcare nursing and other medical fields, which could be impacting patient outcomes, healthcare costs, and environmental sustainability in healthcare.
Lead author Dr Natasya Raja Azlan noted while non-sterile gloves are necessary when there is a risk of touching body fluids that could carry viruses or bacteria or hazardous medications, there is no evidence to support the use of gloves for activities like moving patients, feeding, or basic washing or preparing many medications.
In fact, unnecessary glove use can be harmful. Staff are less likely to wash their hands, even though handwashing remains the best way to stop infections spreading. The result can be increased spread of harmful disease between vulnerable patients as well as healthcare staff.
Dr Raja Azlan
Co-author Dr Lesley Andrew added that the abundant use of non-sterile gloves was also contributing to the cost of healthcare, pointing out that one New South Wales hospital’s decision to cut-back on the use of these gloves had saved $155 000 in a single year and reduced medical waste by 8 tonnes.
“The disposal of healthcare products represents 7% of Australia’s national total carbon emissions, only slightly less than the 10% attributed to all road vehicles. Manufacturing these gloves consumes fossil fuels, water, and energy, while their disposal if through incineration can degrade air quality and release harmful chemicals. If sent to landfill, they may leach microparticles and heavy metals into soil and water systems, posing risks to both human health and the environment,” she added.
Dr Raja Azlan noted that, despite non-sterile glove use being a common and routinely taught practice during intravenous antimicrobial preparation and administration, there are currently no evidence-based guidelines or protocols in place to support or standardise this aspect of nursing care.
This lack of evidence-based protocols has resulted in co-author Dr Carol Crevacore calling for a review into this practice.
There is no question that the moon has a significant influence on Earth. Its gravitational pull affects the planet and moves water masses in the daily rhythm of ebb and flow (tides) – this point is undisputed. More difficult to answer is the question of whether the same gravitational force also affects life on Earth, especially the human organism. And the discussion becomes even more complicated when it comes to how the fluctuating brightness of the Earth’s satellite between full and new moon affects humans.
A research team led by Julius-Maximilians-Universität Würzburg (JMU) has now presented new findings on this topic. Its conclusion: “We show that synchronisation with the moon has decreased significantly since the introduction of LEDs and the increasing use of smartphones and screens of all kinds,” explains Charlotte Förster. The Würzburg chronobiologist recently headed the Department of Neurobiology and Genetics; she now conducts research there as a senior professor.
Comparing Records from two Centuries
For their study, now published in the journal Science Advances, Förster and her team analysed long-term menstrual records of women from the past 50 years. “The results showed that the menstrual cycles of women whose records were made before the introduction of light-emitting diodes in 2010 and the widespread use of smartphones were significantly synchronised with the cycle of the full and new moon,” says Förster, describing the key finding. After 2010, the cycles were mostly only synchronized in January, when the gravitational forces between the moon, sun, and Earth are at their highest.
The scientists therefore hypothesize that humans have an internal moon clock that can be synchronised to the lunar cycle by natural night light and gravitational forces. However, the coupling of the moon clock to the lunar cycle in humans is impaired by increasing nighttime illumination from artificial light.
Other Studies Support the Moon Clock Hypothesis
“Moon clocks are widespread in marine organisms, but have not yet been proven in humans,” explains Charlotte Förster. In fact, many species synchronize their reproductive behaviour with a specific phase of the lunar cycle in order to increase reproductive success. The human menstrual cycle also has a similar duration to the lunar cycle, at approximately 29.5 days, and recent studies also suggest at least temporary synchronicity between the menstrual and lunar cycles.
The influence of the moon on the female cycle remains controversial. “It is completely unclear how such a lunar clock can be synchronised by the small cyclical changes in gravity between the Earth and the moon,” says Förster. The findings now published are consistent with results from sleep research and psychiatry.
For example, studies by two chronobiologists, Basel researcher Christian Cajochen and Washington biologist Horacio de la Iglesia, show that people sleep significantly less around the full and new moon than at other times. “Interestingly, this also applies to city dwellers, where nighttime city lighting is much brighter than the light of the full moon,” says the chronobiologist. And US psychiatrist Thomas Wehr has concluded that people with bipolar disorder are more likely to switch between mania and depression around the full and new moon.
Artificial Light Disrupts Synchronisation
Taken together, these findings suggest that humans can respond not only to moonlight, but also to the gravitational cycles caused by the moon, according to the Würzburg research team. “However, our study shows that increased exposure to artificial light severely impairs the synchrony between the menstrual cycle and the lunar cycle,” explains Charlotte Förster.
According to this, artificial light at night not only “outshines” the natural moonlight cycles, but also shortens the length of the menstrual cycle. However, since continuous synchronization is only possible if the length of the cycle is close to the lunar cycle, this shortening in turn reduces the likelihood of synchronization.
A High Proportion of Blue Light Increases the Effect
Anyone wondering why the introduction of LEDs and the increasing use of smartphones have this effect – after all, artificial lighting has been around for a long time, from gas lanterns to incandescent light bulbs – will find an explanation in Charlotte Förster’s words: “LEDs have much higher energy than gas lanterns and light bulbs. In addition, they have a high proportion of blue light, to which our photoreceptors in the eye are particularly sensitive.” That is why LED light has a much stronger effect on humans than previous light sources.
And even though Charlotte Förster and her team were able to clearly demonstrate that the synchronization of the female menstrual cycle with the moon is weakened by LEDs, smartphones, and screens of all kinds, there is one small caveat when interpreting these results: “Our findings show a correlation between these two phenomena. We were unable to establish a causal link,” says the scientist.
In principle, the study now published is basic research. Nevertheless, a potential benefit emerges from the evaluation of the data: “Since period length appears to be a possible age-dependent marker for female fertility, our findings could be relevant not only for human physiology and behaviour, but also for fertility and contraception,” says Charlotte Förster.
Scientists at The University of Manchester are calling for the creation of a global network of air monitoring stations to track the movement of airborne plastic pollution, which may be travelling further and faster around the planet than previously thought.
In a new review, published in the journal Current Pollution Reports, the researchers have examined the current scientific research on how tiny plastic fragments – called micro and nanoplastics – enter the air, where they come from, and the mechanisms that transport them across vast distances.
The study reveals significant gaps in knowledge and understanding of airborne plastic pollution, driven by inconsistent measurement techniques, limited data, oversimplified simulations, and gaps in understanding atmospheric cycling mechanisms.
One key uncertainty is the scale of plastic entering the atmosphere. Current estimates vary wildly – from less than 800 tonnes to nearly 9 million tonnes per year – making it difficult to assess the true global impact. It also remains unclear whether the dominant contributors are land-based, such as road traffic, or marine based, such as sea spray.
Such large uncertainties raise the concern that airborne plastics, which pose potential risks to human and environmental health, may have a more extensive presence and influence than previously captured by current monitoring and simulation systems.
“The scale of uncertainty around how much plastic is entering our atmosphere is alarming. Plastic pollution can have serious consequences for human health and ecosystems, so in order to assess the risks, we need to better understand how these particles behave in the atmosphere. If we want to protect people and the planet, we need better data, better models, and global coordination.”
Lead author Zhonghua Zheng, Co-Lead for Environmental Data Science & AI at Manchester Environmental Research Institute (MERI) and Lecturer in Data Science & Environmental Analytics at The University of Manchester
Each year, the world produces over 400 million tonnes of plastic, with a significant proportion ending up as waste. Over time, these plastics breaks down into microscopic particles called microplastics (less than 5mm) and nanoplastics (smaller than 1 micron), which are increasingly being found in the air we breath, oceans and soil. These particles can move thousands of miles within days and have even remote regions like polar ice zones, desserts and remote mountain peaks.
While our understanding of the problem has grown rapidly, limited real-world data, inconsistent sampling methods, and computer models that oversimplify how plastic behaves in the air, means that key questions remain unanswered.
To address these concerns, the authors are calling for future research efforts to focus on three critical areas:
Expanding and standardising global observation networks
Improving and refining atmospheric modelling
Harnessing the power of artificial intelligence (AI)
They say this integrated approach could transform how we understand and manage the plastic pollution crisis.
“By adopting this integrated approach, we can fundamentally transform how we understand and manage this emerging threat. AI can play a powerful role in analysing data and simulating plastic movement, it can help make sense of fragmented datasets, detect hidden patterns, and integrate information from multiple sources – but it needs good quality data to work with. All of these areas must work hand in hand to manage this emerging threat and shape effective global pollution strategies.”
Fei Jiang, PhD researcher at The University of Manchester
