Roughly one in six people are affected by infertility worldwide and with more than half the world’s population now living in urban areas, researchers are interested in whether living in noisy and polluted cities could be to blame.

A new study in Denmark has used nationwide data to explore infertility.

It found long-term exposure to air pollution and traffic noise may be associated with higher infertility – but these factors affect men and women differently.

What do pollution and noise do to the body?

We know traffic pollution has undeniable impacts on the environment. Its negative effects on human health are also well established, with links to cancers and heart disease.

Inhaled chemicals from polluted air may also travel to the reproductive tract via the blood. They can reduce fertility by either disrupting hormones or causing direct damage to eggs and sperm.

The effects of traffic noise on health are less clear, but some research suggests this affects stress hormones, which could alter fertility.

What did they look at?

This new study was conducted in Denmark, which collects data about every resident into multiple national databases over their lifetime, using a unique identification number.

Nationwide data allows researchers to investigate links between a person’s health and factors such as where they live, their job, education history and family. This method is called “data linkage”.

The study aimed to capture people who were likely to be trying to get pregnant, and therefore at risk of receiving an infertility diagnosis.

Over 2 million men and women were identified as being of reproductive age. The study looked at those who were:

• aged 30 – 45
• living together or married
• with less than two children
• living in Denmark between January 1 2000 and December 31 2017.

It excluded anyone who was diagnosed with infertility before age 30, lived alone or in a registered same-sex partnership. People with incomplete information (like a missing address) were also excluded.

There were 377,850 women and 526,056 men who fit these criteria.

The study did not survey them. Instead, over a five-year period it cross-checked detailed information about where they lived and whether they received an infertility diagnosis, collected from the Danish National Patient Register.

Researchers also estimated how much each residential address was exposed to road traffic noise (measured in decibels) and air pollution, or how much fine particulate matter (called PM2.5) is in the air.

What did they find?

Infertility was diagnosed in 16,172 men (out of 526,056) and 22,672 women (out of 377,850).

The study found the risk of infertility was 24% greater for men exposed to PM2.5 levels 1.6 times higher than recommended by the World Health Organization.

For women, exposure to traffic noise at 10.2 decibels higher than average (55-60 decibels) was associated with 14% increased infertility risk for those over 35.

Risks were similar based on residing in urban or rural areas, and when accounting for education and income.

What does it suggest?

The study highlights how environmental exposure can have immediate and long-term effects, and may affect male and female reproduction differently.

After puberty, men constantly produce sperm – up to 300 million a day. The impact of environmental changes on male fertility – such as exposure to toxic pollutants — tends to show up more quickly than in females, affecting sperm number and quality.

In contrast, women are born with all their eggs, and cannot produce new ones. Eggs have some “damage control” mechanisms to protect them from environmental hazards across a lifetime.

This doesn’t mean eggs are not sensitive to damage. However it may take longer than the five years of exposure this study looked at for the impact on women to become clear.

It is possible even longer-term studies could reveal a similar impact for pollution on women.

Is data linkage a good way to look at fertility?

Data linkage can be a powerful tool to uncover links between environmental exposures and health. This allows assessments in large numbers of people, over long periods of time, like this recent Danish study.

But there are inherent limitations to these types of studies. Without surveying individuals or looking at biological factors – like hormone levels and body mass — the research relies on some assumptions.

For example, this study involved some major assumptions about whether or not couples were actually trying to conceive.

It also calculated people’s exposure to noise and air pollution according to their address, assuming they were at home.

A more precise picture could be painted if information was gathered from individuals about their exposure and experiences, including with fertility.

For example, surveys could include factors like sleep disturbance and stress, which can alter hormone responses and impact fertility. Exposure to chemicals that disrupt hormones is also found at home, in everyday household and in personal care products.

In its scale, this study is unprecedented and a useful step in exploring the potential link between air pollution, traffic noise and infertility. However more controlled studies – involving actual measures of exposure instead of estimations – would be needed to deepen our understanding of how these factors affect men and women.

Amy L. Winship, Group Leader and Senior Research Fellow, Anatomy and Developmental Biology, Monash University and Mark Green, Merck Serono Senior Lecturer in Reproductive Biology, The University of Melbourne

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

Personal care products (PCP) like face washes and shower gels in India contain a significant amount of harmful microplastics, new research has revealed.

According to a study published in the Emerging Contaminants journal and led by Riya K. Alex, a third-year Ph.D Scholar at the Cochin University of Science and Technology, polyethylene (or polythene, PE) is the dominant polymer noted in microplastic emissions from PCPs.

What are microplastics?

Microplastics are defined as particles of plastic that are under 5mm in range — in terms of microbeads, under 5mm in diameter and mainly in the range of 1-1,000 micrometres.

Findings of the new research

The research analysed 45 samples of PCP across four categories — face wash, face scrub, shower gel, and body scrub available in Indian market and manufactured in the year 2022. The study especially used products marketed as “eco-friendly”, “natural”, and “organic” to scrutinise the legitimacy of these claims. Around 23.33% of products contained cellulose microbeads, and their biodegradability is unclear. Most of these microbeads were coloured white, followed by blue, pink, yellow, red, and green. According to the researchers, the white colour of microbeads could be intended to hide them from easy identification.

In PCPs, microbeads are widely used for exfoliation, as well as delivery of active ingredients and improved aesthetics, among other uses.

Microbeads in PCP are made of materials like polyethylene, polypropylene, and polyester, with polyethylene being the most dominant polymer identified in more than half the microbeads studied.

On average, 1.34% of the total product of each analysed sample was microbeads. This ranged from 0.04% at the lowest to 5.04% at the highest. In 30 grams of each kind of product, the average quantities of microbeads were noted to be 0.26g, 0.90g,1.24g and 1.74g for face washes, face scrubs, body scrubs, and shower gels respectively. The highest quantities obtained were 2.30g, 1.73g, 1.75g and 4.87g, respectively, whereas the lowest quantities extracted were 0.01g, 0.13g, 0.55g and 0.13g, respectively.

The average sizes of microbeads in samples under study were 640.74 μm, 452.45 μm, 556.66 μm and 606.30 μm for face washes, face scrubs, body scrubs, and shower gels respectively. Shower gels contained the largest microbeads, followed by body scrubs, face scrubs, and face washes.

The study also shows that most microbeads were not spherical but instead irregularly shaped. This is worse for the environment, as irregular shapes provide more surface area for adsorption of other environmental pollutants, and sharper edges can potentially cause cuts and injuries to organisms who ingest them.

The research also found polycaprolactone, a type of bioplastic, in two of the tested samples. Although polycaprolactone is gaining attention as an efficient carrier for drugs, and for its anti-ageing and antibacterial constituents, it has been known to cause embryonic developmental delays and other malformations in aquatic biota.

Findings of the report also indicate greenwashing in the Indian PCP market, especially with labels like “organic”, “natural”, and” eco-friendly.” Brands rely on consumers to not scan the ingredient lists in detail, and the blends of natural and plastic in the same product poses challenges in recognising the presence of plastic.

Why are microbeads bad?

Like most other plastic pollution, microbeads are terrible for the environment. They accumulate in food chains, reach wastewater treatment facilities and eventually end up in oceans causing aquatic pollution.

Many countries, like the U.S., U.K., Canada, France, and New Zealand have banned the production and sale of products with microbeads, but it remains an ambiguous issue in developing countries like India. In 2023, India rose to the fourth position in terms of revenue in global beauty and personal care markets, behind the U.S., China, and Japan.

The 2030 microbead emission forecast for India is “alarmingly high,” researchers say. The trend can go up as well due to an evolving retail landscape, cosmetic trials, and enhanced purchasing power in the coming years.

Are microplastics everywhere?

Yes, microplastics are almost everywhere. A recent study by Toxics Link, a non-government organisation working in the field of environmental research and advocacy, found microplastics ranging from 6.71 to 89.15 pieces per kg of dry weight, and between 0.1 mm to 5 mm in size in several varieties of salt and sugar.

Microplastics have also been found in the human brain, blood, lungs, colon, placenta, testicles, and stool.

The study advocates for better policies to control microplastic pollution in India, and suggests coffee, apricots, walnut, kiwi seeds, and soluble cellulose beads, etc. as some natural and sustainable alternatives to microbeads in PCPs.

New Delhi:

More than seven percent of all deaths in 10 of India’s biggest cities are linked to air pollution, a large study said Thursday, leading researchers to call for action to save tens of thousands of lives a year.

Smog-filled Indian cities including the capital Delhi suffer from some of the world’s worst air pollution, choking the lungs of residents and posing a rising threat to health still being revealed by researchers.

For the new study, an Indian-led team looked at the levels of cancer-causing microparticles known as PM2.5 pollutants in the cities of Ahmedabad, Bengaluru, Chennai, Delhi, Hyderabad, Kolkata, Mumbai, Pune, Shimla and Varanasi.

From 2008 to 2019, more than 33,000 deaths a year could be attributed to PM2.5 exposure above the World Health Organization’s recommendation of 15 micrograms per cubic metre, the study said.

That represents 7.2 percent of the recorded deaths in those cities during that period, according to the study in The Lancet Planetary Health journal.

India’s capital Delhi was the worst offender, with 12,000 annual deaths linked to air pollution — or 11.5 percent of the total.

But even cities where air pollution is not thought to be as bad — such as Mumbai, Kolkata and Chennai — had high death rates, the researchers emphasised.

They called for India’s air quality standards to be toughened.

The country’s current recommendation is 60 micrograms of PM2.5 per cubic metre, which is four times higher than the WHO’s guidelines.

Lowering and enforcing the limit “will save tens of thousands of lives per year,” study co-author Joel Schwartz of Harvard University said.

“Methods for controlling pollution exist and are used elsewhere. They urgently need to be applied in India,” he said in a statement.

The WHO says that almost everyone on Earth breathes in more than the recommended amount of air pollution, which can trigger strokes, heart disease, lung cancer and other respiratory diseases.

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)