Category: Environmental Effects

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Eczema and Asthma in Children: How Household Fuels are Harming Health in Poor South African Homes

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Mandla Bhuda, University of South Africa; Janine Wichmann, University of Pretoria, and Joyce Shirinde, University of Pretoria

In many households in Mabopane and Soshanguve – townships on the northern outskirts of South Africa’s City of Tshwane that are marked by high poverty, unemployment and informal economic activity – evenings follow a familiar pattern.

When electricity cuts occur or power becomes unaffordable, families turn to gas stoves, paraffin heaters, or wood and coal fires to cook meals and keep warm. These energy sources contribute to air pollution, but the most harmful exposure often happens indoors, where children spend much of their time. These choices, though often unavoidable, put young children’s health at risk.

Children are particularly vulnerable to air pollution. Their lungs are still developing, their airways are narrower, and they breathe faster than adults.

In 2021, exposure to air pollution was linked to more than 700 000 deaths of children under five years old globally.

They are exposed by inhaling polluted air, swallowing contaminated dust or food, and through skin contact. Household fuel combustion releases tiny particles and harmful gases that irritate the lungs and airways. These pollutants can also damage the skin, triggering immune responses that worsen allergic conditions such as eczema and asthma.

As public health specialists, we examined the association between household air pollution and eczema and severe asthma symptoms among children aged seven years and younger in Mabopane and Soshanguve. We found that the use of polluting household fuels and gas was associated with an increased likelihood of eczema, followed by severe asthma symptoms.

Eczema and its impact

Eczema, or atopic dermatitis, is a chronic skin condition that causes itching, redness and inflammation.

It can significantly affect a child’s life by disrupting sleep and increasing the risk of skin infections. It also raises the likelihood of developing asthma, hay fever, or food allergies later. Visible rashes can equally affect confidence, social interactions and participation in school or play. Exposure to cigarette smoke inside the home further increases the risk of developing or worsening eczema, especially when mothers or female caregivers smoke.

Severe asthma and its impact

Asthma is a long-term condition affecting the lungs and airways, making breathing difficult. Symptoms include wheezing, coughing, chest tightness and shortness of breath. Global asthma prevalence ranges from 9.1% to 9.5% for children.

Severe asthma refers to frequent, hard-to-control, and sometimes life-threatening symptoms. Children with severe asthma may struggle to speak during attacks and are far more likely to need emergency care or hospitalisation. Young children are particularly vulnerable because their lungs, skin barrier and immune systems are still developing. Exposure to indoor air pollution during these early years increases the risk of long-term health problems.

Our study

To understand how household environments affect children’s health, we studied preschool-aged children in Mabopane and Soshanguve, in South Africa’s largely urban Gauteng province, between January 2022 and March 2023.

We randomly selected 42 preschools and collected health and household information from caregivers of 1840 children, including details on eczema, asthma symptoms, household fuel use, and exposure to cigarette smoke inside the home.

What we found

About one in eight children had experienced eczema at some point, and a similar proportion were currently experiencing symptoms. We also found that children from households using electricity for cooking and with no tobacco smoke exposure were less likely to have eczema than those who were exposed.

Children living in homes using open fires – such as paraffin, wood, or coal – for cooking or heating were more likely to have eczema. Exposure to cigarette smoke inside the home further increased this risk, particularly when mothers or female caregivers smoked.

Severe asthma symptoms were also common, affecting about one in six children. The use of gas for cooking or heating was strongly linked to severe asthma symptoms, even though gas is often viewed as a cleaner alternative during power cuts. Poor ventilation can increase indoor pollution, making these energy sources harmful to children.

The use of combined building materials in homes increased the likelihood of having eczema and corrugated iron significantly increased the likelihood of developing its symptoms. The frequency of trucks passing near the preschool children’s residences on weekdays was found to be associated with eczema and current symptoms. There was a significant association observed when trucks passed the children’s residences almost all day on weekdays. Children who walked to preschool had an increased risk of severe asthma symptoms compared with those using other modes of transport.

Why this matters

Although nearly 89% of residents in the study area have access to electricity, many households cannot rely on it consistently. Rising electricity costs and scheduled power cuts force families to use alternative fuels. These coping strategies, while understandable, increase children’s exposure to indoor air pollution during the most vulnerable stage of their development.

Eczema and severe asthma are not just medical issues but also social and environmental ones.

Our study confirmed that children in poorer communities face higher health risks due to their living environments, not just genetics. Susceptible groups, such as children, should be prioritised to reduce the adverse health effects of both outdoor and indoor air pollution.

What needs to change

Protecting children’s health requires more than asking parents to make better choices, as many families do not have safe, affordable alternatives.

Public health education on the dangers of cigarette smoke is crucial. Education campaigns, smoking cessation support and community-level interventions can help reduce children’s exposure to environmental tobacco smoke.

Stronger action on indoor and household air pollution is urgently needed. Evidence from this study can support the South African government in fast-tracking regulations and enforcing ambient air quality laws. It can also help in promoting safer household energy options.

Cleaner air inside homes is not a luxury. For South Africa’s children, it is a public health necessity.

Mandla Bhuda, Senior Lecturer: Public Health, University of South Africa; Janine Wichmann, Professor, University of Pretoria, and Joyce Shirinde, Associate Professor, University of Pretoria

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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HEPA Air Purifiers May Boost Brain Power in Adults Over 40 – New Research

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Photo by Mari Lezhava on Unsplash

Nicholas Pellegrino, University of Connecticut; Doug Brugge, University of Connecticut, and Misha Eliasziw, Tufts University

Using an in-home HEPA purifier for one month spurs a small but significant improvement in brain function in adults age 40 and older. That’s the result of a new study we co-authored in the journal Scientific Reports.

HEPA purifiers – HEPA stands for high efficiency particulate air – remove particulate matter from the air. Exposure to particulate matter has been connected to respiratory and cardiovascular illnesses as well as neurological diseases such as Alzheimer’s and Parkinson’s. Environmental health researchers increasingly recommend that people use HEPA air purifiers in their homes to lower their exposure to particulate matter, but few studies have examined whether using them boosts mental function.

We analysed data from a study of 119 people ages 30 to 74 living in Somerville, Massachusetts. Somerville sits along Interstate 93 and Route 28, two major highways, resulting in relatively high levels of traffic-related air pollution. This makes it an especially good location for testing the health effects of air purifiers.

We randomly assigned participants to one of two groups. One used a HEPA air purifier for one month and then a sham air purifier – which looked and acted like the real thing but did not contain the air-cleaning filter – for one month, with a monthlong break in between. The second group used the real and sham purifiers in reverse order.

After each month, participants took a test that measured different aspects of their mental capacity. The test probed people’s visual memory and motor speed skills by measuring how quickly they could draw lines between sequential numbers, and it tested executive function and mental flexibility by asking them to draw lines between alternating sequential numbers and letters.

We found that participants 40 years and older – about 42% of our sample – on average completed the section testing for mental flexibility and executive function 12% faster after using the HEPA purifier than after using the sham purifier. That was true even when we accounted for factors like differences in the amount of time participants spent indoors, with either filter, as well as how stressful they found the test.

This improvement may seem small, but it is similar to the cognitive benefits that people experience from increasing their daily exercise. While you may not experience a sudden increase in clarity from a 12% boost, preventing cognitive decline is vital for long-term well-being. Even small decreases in cognitive functioning may be associated with a higher risk of death.

Studies increasingly show that air pollution can be detrimental to brain health.

Why it matters

Air pollution can negatively affect mental function after just a few hours of exposure. Studies show that air purifiers are effective at reducing particulates, but it’s unclear whether these reductions can prevent cognitive harm from ongoing pollution sources like traffic. Research has been especially lacking in people living near major sources of air pollution, such as highways.

People living near highways or major roadways are exposed to more air pollution and also experience higher rates of air pollution-related diseases. These risks aren’t encountered by all Americans equally: People of color and low-income people are more likely to live near highways or areas with heavy traffic.

Our study shows that HEPA air purifiers may offer meaningful health benefits under these circumstances.

What still isn’t known

Research shows that air pollution begins to affect cognitive function especially strongly around age 40. These effects may become increasingly prominent as people age.

HEPA air purifiers may therefore be especially beneficial for older adults. Our study did not explore this possibility, as fewer than 10 of our 119 participants were over the age of 60.

Also, our participants only used a HEPA air purifier for one month. It’s possible that longer durations of air purification may sustain or even increase the improvement in cognitive function we observed in our study.

Finally, it is unclear exactly how air purifiers improve cognition. Some studies suggest that exposure to particulate matter reduces the amount of the brain’s white matter, which helps brain cells conduct electrical signals and maintains connections between brain regions. The brain regions most harmed by air pollution are the ones that control mental flexibility and executive function, the same domains in which we saw improvements in our study.

We plan to study whether reducing particulate matter by using air purifiers is indeed protecting the brain’s white matter, and whether it could reverse some cognitive decline. We will explore that possibility by studying how levels of molecules called metabolites, which cells produce as they do their jobs, change in response to breathing polluted air and air cleaned by a HEPA filter.

The Research Brief is a short take on interesting academic work.

Nicholas Pellegrino, Research Associate in Public Health Sciences, University of Connecticut; Doug Brugge, Professor of Public Health Science and Community Medicine, University of Connecticut, and Misha Eliasziw, Associate Professor of Biostatistics, Public Health and Community Medicine, Tufts University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Fluoride in Drinking Water Does Not Harm Children’s IQ

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Fluoride is a naturally occurring mineral that has been shown to strengthen teeth and reduce cavities. Many municipalities add fluoride to their drinking water – called community water fluoridation – as a public health measure to support dental health. In recent years, however, some have claimed that ingesting fluoride can harm children’s IQ.

Researchers at the University of Minnesota led a team that investigated the connection between fluoride in drinking water and children’s IQ to see if these claims had merit. The study, published in PNAS, examined Wisconsin state testing records, archival information about when Wisconsin cities began to fluoridate their water, and data from the Wisconsin Longitudinal Study, which has followed a random sample of 10,317 high school seniors from 1957 through 2026. Key findings include:

  • There is no evidence supporting a connection between community water fluoridation and children’s IQ.
  • There is also no evidence supporting a connection between community water fluoridation and cognitive functioning at various points later in life.
  • Findings confirm evidence published in previous research which also used a national sample, but considered school achievement test scores instead of actual IQ scores.

“Utah, Florida and many municipalities have chosen to remove fluoride from drinking water based on flawed studies that considered the IQ effects of exposure to massive doses of fluoride,” said lead researcher John Robert Warren, a professor in the College of Liberal Arts. “Because levels of fluoride added to municipal drinking water in the U.S. are so much lower, almost all prior evidence from those international studies is not relevant to U.S. public policy debates.”

Future research will continue examining the benefits and harms of adding fluoride to community drinking water.

Study co-author Gina Rumore, co-director of the Demography and Economics of Aging Coordinating Center at the University of Minnesota, noted that these findings “provide no support for the claim that community water fluoridation has any harmful effect on children’s IQ or on adult cognition.”

Source: University of Minnesota

Categories : Environmental Effects Obstetrics & GynaecologyTags :

Plastic Additives Tied to Millions of Preterm Births Worldwide

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Exposure to a chemical commonly used to make plastic more flexible may have contributed to about 1.97 million preterm births in 2018 alone, or more than 8 percent of the world’s total, a new analysis of population surveys shows. The chemical was also linked to the deaths of 74 000 newborns, the researchers further estimate.

The toxin, di-2-ethylhexylphthalate (DEHP), is part of a group of chemicals called phthalates, which appear in cosmetics, detergents, bug repellents, and other household products. Experts have found that these substances can break down into microscopic particles and enter the body through food, air, and dust.

Led by NYU Langone Health researchers, the new study focused on preterm birth, which is a major risk factor for lasting learning and developmental issues and is a leading cause of infant death, according to the World Health Organization.

The new analysis provides the first global estimate of preterm births connected to exposure to DEHP and explores which parts of the world are most affected, according to the authors. A report on the findings published online March 31 in the journal eClinicalMedicine.

“By estimating how much phthalate exposure may contribute to preterm birth worldwide, our findings highlight that reducing exposure, especially in vulnerable regions, could help prevent early births and the health problems that often follow,” said study lead author Sara Hyman, MS.

Past studies have linked DEHP exposure to cancer, heart disease, and infertility, among many other health concerns, added Hyman, an associate research scientist at NYU Grossman School of Medicine. There is also a large body of research connecting the chemical to preterm birth.

According to the new work, DEHP exposure may have contributed to 1.2 million years lived with disability, a measure of all the years that people have lived or will live with illnesses, injuries, and other health issues caused by being born prematurely.

Hyman said that while the phthalate is in widespread use, certain regions are estimated to bear a much larger share of the health impacts than others, with the Middle East and South Asia representing 54 percent of estimated illness from preterm birth. These areas have rapidly growing plastics industries and high levels of global plastic waste.

Africa, which accounted for 26 percent of health problems from DEHP-linked preterm birth, has a disproportionate share of deaths compared with its share of overall premature cases. The researchers said this reflects the region’s higher underlying death toll from preterm birth.

For the study, the research team estimated DEHP exposure in 2018 across 200 countries and territories by pulling data from large national surveys in the United States, Europe, and Canada. They also used estimates from earlier investigations to fill in regions that did not have their own data.

The team then drew on earlier research that assessed how phthalate exposure may affect preterm birth and combined those findings with their global exposure estimates. Finally, they combined this information with worldwide figures on preterm births and deaths to gauge what share of these outcomes might be linked to DEHP.

The scientists repeated these steps for another phthalate called diisononyl phthalate (DiNP), a common replacement for DEHP. According to the results, DiNP may pose a similar risk as DEHP, having contributed to about 1.88 million preterm births around the world. The financial costs associated with newborn deaths ranged from millions to hundreds of billions of dollars for both phthalates.

“Our analysis makes clear that regulating phthalates one at a time and swapping in poorly understood replacements is unlikely to solve the larger problem,” said study senior author Leonardo Trasande, MD, MPP, Professor of Pediatrics at NYU Grossman School of Medicine. “We are playing a dangerous game of Whac-A-Mole with hazardous chemicals, and these findings highlight the urgent need for stronger, class-wide oversight of plastic additives to avoid repeating the same mistakes.”

Dr Trasande, who is also a professor in the Department of Population Health and director of the Division of Environmental Pediatrics and the Center for the Investigation of Environmental Hazards, cautions that the investigation was not designed to establish that DEHP and DiNP directly or alone cause preterm birth, nor did it take into account other types of phthalates.

In addition, because there is some uncertainty in the data, the researchers looked at a range of possible values rather than just one estimate. This uncertainty range showed that the true impact of DEHP could be up to four times smaller than the main estimate or slightly higher. Even under the most conservative estimates, the results point to a substantial health burden, said Hyman.

Despite the limits of this kind of global modelling, added Hyman, the work lays important groundwork for future studies to confirm and refine these results and begins to fill a major gap in understanding the extent to which plastic chemicals affect preterm birth worldwide.

Source: NYU Langone Health

Categories : Environmental Effects Respiratory DiseasesTags :

High Prenatal Exposure to PFAS May Increase the Risk of Childhood Asthma

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City residents exposed to contaminated drinking water in Sweden had higher rates of asthma diagnoses

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Asthma can lead to childhood hospitalisations, missed school days, missed workdays for caregivers, and a lower quality of life for both children and their caregivers. The global prevalence of asthma has increased over the past fifty years. A study published April 9th in the open-access journal PLOS Medicine by Annelise Blomberg at Lund University, Lund, Sweden and colleagues suggests that high prenatal PFAS exposure is associated with a higher incidence of asthma in childhood.

PFAS (Perfluoroalkyl substances) are widespread synthetic chemicals that impact the immune system and may play a role in the development of asthma. Previous epidemiological studies of PFAS and asthma only investigated low exposure levels and had inconclusive results. Due to decades-long contamination of a municipal waterworks in Ronneby, Sweden, researchers were able to study the impacts of high PFAS exposure. They accessed a register-based open cohort of all children born in Blekinge County between 2006 and 2013, including Ronneby. The researchers then linked maternal addresses during the exposure period to water distribution records to estimate prenatal exposure, and used asthma diagnosis data from the National Patient Register to assess individual asthma outcomes and prenatal exposure levels.

The researchers found that very high prenatal PFAS exposure was associated with a higher incidence of asthma in childhood. Future studies are needed to better understand exposure-response relationships and to address potential confounding variables, such as exposure beyond the prenatal period into early-childhood, exposure to other environmental contaminants or smoking among household members.

According to the authors, “PFAS contamination is a major source of high environmental exposure globally, and evidence from Ronneby offers important insights into the potential health effects of such contamination in affected communities. These results point to a substantial and previously unrecognized public health consequence of PFAS contamination.”

Blomberg adds, “We found that children whose mothers were exposed to very high levels of PFAS during pregnancy had a substantially higher incidence of clinically diagnosed asthma. The association was not observed at lower exposure levels, which may help explain why previous studies in general populations have reported mixed results.”

“Most previous research has examined populations exposed only to background levels of PFAS. In Ronneby, drinking water contamination resulted in exposure levels hundreds of times higher than the general population. This allowed us to evaluate potential health effects across a much broader exposure range.”

“Communities around the world have been affected by PFAS contamination from aqueous film-forming foams and other industrial sources. Our findings suggest that very high prenatal exposure may have lasting consequences for children’s respiratory health. At the same time, replication in other highly exposed populations will be important to confirm these results.”

Provided by PLOS

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How One ‘Forever Chemical’ Can Disrupt Foetal Facial Development

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Researchers discovered perfluorodecanoic acid is the most toxic during foetal craniofacial development

Credit: Chemical Research in Toxicology (2026). doi:10.1021/acs.chemrestox.5c00468

Researchers have long associated per- and polyfluoroalkyl substances (PFAS), commonly known as “forever chemicals,” to certain severe birth defects but exactly how these pollutants harm a developing foetus has remained mostly a mystery. New research now provides the first clear molecular explanation, showing how one PFAS, called perfluorodecanoic acid (PFDA), can trigger craniofacial abnormalities before birth.

The research was published in ACS Chemical Research in Toxicology.

“Most people are exposed to small amounts of PFAS in everyday life but higher exposure can occur through contaminated water, living near manufacturing sites or certain jobs like firefighting and ski waxing, which is why it’s so important to understand the chemicals better,” said the paper’s senior author Jed Lampe, PhD, associate professor at University of Colorado Anschutz Skaggs School of Pharmacy and Pharmaceutical Sciences. “We wanted to understand which PFAS compounds are truly harmful during foetus development, especially for people with higher exposure, and how they cause damage.”

There are approximately 15 000 PFAS used in consumer and industrial products but scientists are increasingly finding that only some pose serious health risks. In this study, Lampe worked with the paper’s first author Michaela Hvizdak and co-author Sylvie Kandel to test 13 commonly found PFAS and discovered PFDA as the most toxic during foetal craniofacial development.

They demonstrated a possible link between PFDA and the extensive facial changes observed in humans and laboratory animals, with some estimates indicating a 10% increased risk at extremely low exposure levels. 

“This finding moves us beyond association by providing a clear explanation for how PFDA can interfere with foetal development. It’s a critical step toward understanding a vast and complex class of environmental chemicals,” said Lampe.

The cause of underdeveloped eyes and an abnormal jaw

They found that PFAS disrupts retinoic acid, a molecule essential for shaping the face and head during early pregnancy. Retinoic acid regulates hundreds of genes and its levels must be controlled. Because a foetus cannot produce or safely eliminate excess retinoic acid, it relies entirely on the mother to maintain the homeostatic balance of the hormone.

The researchers discovered PFDA blocks CYP26A1, a key enzyme responsible for breaking down excess retinoic acid. When this enzyme is inhibited, retinoic acid levels can rise too high, disrupting normal facial development. PFDA also suppresses the genes that produce this enzyme through a separate biological pathway, delivering a “double hit” to the system that regulates early development.

“As a result, severe craniofacial abnormalities can develop, including underdeveloped eyes and abnormal jaw formation, which were the most common effects of PFDA exposure during foetal development,” said Lampe.

The researchers hope by providing a molecular explanation for this abnormality that the research and scientific community can work to develop targeted laboratory assays and computer‑based screening tools to quickly rank PFAS by risk. They say this could help regulators and manufacturers distinguish more dangerous compounds from safer alternatives and guide the design of less toxic chemicals in the future.

They also hope the research can open the door to practical interventions for people with higher exposure, such as firefighters and ski wax technicians. This could include looking into how to reduce exposure levels and whether strategies can be developed to lower PFDA during pregnancy to protect foetal development.

By Julia Milzer

Source: CU Anschutz Medical Campus

Categories : Environmental Effects Obstetrics & GynaecologyTags :

Breakdown Products from ‘Eco-friendly’ Plastics Impede Foetal Development in Mice

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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.”

Provided by PLOS

Categories : Environmental EffectsTags :

Rising CO₂ Levels are Reflected in Human Blood. Scientists Don’t Know What it Means

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Alexander Larcombe, The Kids Research Institute Australia; Curtin University and Philip Bierwirth, Australian National University

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.

CO₂ is mainly carried in blood in the form of bicarbonate (HCO₃⁻).

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.

Atmospheric CO₂ has risen, along with increases in levels of carbonate in the blood and decreases in calcium and phosphorus. Larcombe & Bierwirth / Air Quality, Atmosphere & Health, CC BY

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.

Alexander Larcombe, Associate Professor and Head of Respiratory Environmental Health, The Kids Research Institute Australia; Curtin University and Philip Bierwirth, Emeritus Research Associate, Australian National University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Categories : Environmental Effects Neurodegenerative DiseasesTags :

Air Pollution may Directly Contribute to Alzheimer’s Disease

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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.”

Provided by PLOS

Categories : Environmental EffectsTags :

Many BPA Replacements may be Even More Toxic

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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

Photo by Polina Tankilevitch

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.

Source: McGill University