From the newsrooms of the Sydney Morning Herald and The Age.

This is the morning edition.

I'm Samantha Sellinger Morris.

It's Tuesday, November 4th.

Is sperm mageddon coming?

Well, the results of a new study on men's fertility and testosterone levels has left experts concerned as male sperm counts plunge.

Many experts suspect the drop is driven by a cocktail of air pollution, microplastics and other hormone disrupting toxins, including so-called forever chemicals in the environment.

Today, science reporter Angus Dalton on this new Australian study and whether male fertility is at serious risk.

Hey, Angus.

Welcome.

Thanks, Sam.

You know how obsessed I am with your science stories in general, and particularly with this one.

I've got a shout out one sentence before we begin.

And you're talking about sperm.

And you say, for a cell so crucial to human existence, we know precious little about it.

Are you shocked?

I was super shocked after a lot of experts were telling me that.

I just thought, here's this cell that is very, you know, important to male fertility, male health.

And there seems to be no shortage of attention on male health in particular.

And also it is kind of one of the only two things that we need to bring life into this world.

Seems like a kind of important thing.

And yet there's all this mystery around it.

So that is definitely something that surprised me when I was researching this story.

Because you've just spoken with a professor and male fertility expert at the University of Newcastle, this is Brett Nixon, and he has conducted a new study about sperm production and testosterone.

There's some worrying findings.

I think it'd be safe to say.

So.

What did he find?

Yeah.

So his study was looking at PFAS and specifically its effect on mouse fertility and sperm production in mice.

PFAS, often referred to as forever chemicals.

Toxic forever chemicals known as PFAS.

Cancer linked chemicals were discovered in the city's water.

Per and polyfluoroalkyl substances known as python.

After the forever chemicals, PFAS contaminated their land and their waterways, leaving them in limbo.

This umbrella term for a whole raft of man made substances that have been used since the 1950s on everything from firefighting foam to nonstick pans.

So they are now very pervasive in the environment.

And the reason that scientists are particularly concerned about them is that they don't break down.

They bioaccumulate, including in human bodies.

So that's why they've started to investigate health issues.

What was really interesting about this study, in particular, is that it used environmentally relevant concentrations of PFAS.

Like a lot of the time, when you're looking at these sort of endocrine disrupting chemicals in the environment, which are these chemicals can affect human hormones?

You might be pumping a little mouse with a lot more than a human might typically be exposed to, but for this study, they actually based the concentration of PFAS they were exposing mice to to groundwater near Williamtown, which is that town near Newcastle in New South Wales, which is famed for its PFAS contamination.

So this is levels of PFAS that theoretically a lot of people have been exposed to for many decades now from groundwater.

And they fed mice these concentrations of PFAS through their drinking water over a period of 12 weeks, and then observed what happened to the mouse's sperm health.

And essentially, what they observed was lower daily sperm production in these mice and lower production of key hormones involved in sperm production, including testosterone.

So this was kind of one of the first studies that looked at an environmentally relevant concentration of one of these chemicals that were a bit suspicious of and linked it to a direct effect on sperm count, at least within mice.

And also within the mice, I think there was some impact on the embryos that the mice then produced.

Is that right?

That is right.

That's the interesting thing.

So we're in this particular study, they found that the mice exposed to high levels of PFAS, their sperm quality wasn't necessarily impacted like the sperm on the whole looked normal.

They had normal what's called motility, which is another measure of sperm health, which is essentially how well they swim.

And so, yeah, they were swimming fine.

They looked fine.

There were less of them.

But yeah, they were more than capable of going on to fertilize an egg and create an embryo, which seems like a good thing.

But the issue there is that any changes within the sperm caused by the PFAS could then theoretically be passed on to the embryo.

So they sort of looked in the latter stages of the study at what sort of changes might be happening.

And there did seem to be some changes passing on to the embryo that affected how it developed, and in particular, what size the embryo was.

So the concerning part there is that these chemicals can have an effect on what's called the sperm's epigenome, which is the raft of molecules that basically decides which genes get turned on and which ones get turned off.

And that can obviously affect greatly what offspring ends up looking like and the health of the offspring.

So while it might seem like a good thing that FAS didn't necessarily alter the quality of the sperm, the fact that it can go on to fertilize an embryo means that then any other kind of more subtle changes within, I guess, kind of the genomic health of the sperm or the epigenome of the sperm means that those changes, those unwanted chemical changes, could possibly then pass on to the next generation.

So we're going from just a father being affected by these chemicals to potentially also the offspring.

And so what does this mean.

For male infertility?

Does this finding have any bearing on human sperm production?

I mean, there's a couple of things to say here.

Professor Brett Nixon was very clear in saying that you cannot directly translate these findings onto human health for a number of different reasons, the main ones being that although we use mice as these proxies for human health, they are very different animals to us, very different anatomically.

They metabolize chemicals like PFAS in very different ways to us.

So it is useful, and it does add to a growing body of evidence that these kind of chemicals can affect things like sperm production.

But we are way too early to actually draw a direct link.

And I guess, you know, mirror this finding onto humans and presume the exact same thing happens in us.

We cannot say that based on this study, but like I said, it does add to this growing body of evidence that PFAS can affect things like sperm production.

The difficult thing is, is when you go to study this in humans, you can't run it through like the gold standard type of scientific inquiry, which is a randomized controlled trial where you would take a group of people and you would expose them to PFAS and see what happens.

And then you would have a control group of people where you didn't expose them to PFAS.

Obviously, ethically, we can't knowingly expose people to this chemical that may have a raft of health effects.

So you're never going to get that direct causal evidence necessarily from humans.

What we can do is do things like go to people who've already been exposed to PFAS, test their blood for what level of PFAS they might have in their system, and then see how their kind of sperm health is.

And we can draw inferences there.

The issue there is that there are so many other factors that could be impacting that in terms of, you know, do they smoke?

Are they overweight?

Do they drink?

What level of air pollution are they breathing in.

Being able to control for all of those factors is almost impossible.

So it's going to be really, really difficult to nail down the exact health effects of PFAS on humans.

But like I said, these animal studies are very useful because they can reveal, I guess, these more sort of subtle chemical interactions between PFAS and things like sperm production and just sort of narrow scientists view on what might be happening within people.

And hopefully that means that in further studies, we can start trying to build more evidence and see exactly what might be going on.

But this research is still very young.

We'll be right back.

But it is such an important part, even though perhaps it's still in its younger stages into this wider discussion about male infertility, about sperm count worldwide.

So tell us what Brett Nixon has told you about what's been happening to the sperm count worldwide and then further about unexplained male infertility.

So the backdrop to this is a hypothesis you might call the great sperm count decline, which is this idea that was sort of popularized by these two very influential meta analyses, 1 in 2017 and one more recently in 2023, which found that since the 1970s, male sperm counts have crashed by more than 50%, so that's a decline of about 1% per year.

And that trend, according to these scientists, seems to be accelerating.

So more like 2 to 2.5% every year since 2001 of the authors of these meta analyses, Doctor Shanna Swan, who is a US epidemiologist, she wrote a popular science book called countdown, sort of going further into this and got a lot of media attention.

She has very squarely pinned the blame on this hypothesis or this, you know, supposed great sperm count decline on chemicals like PFAS and other plastic associated chemicals like BPA and phthalates, which are sort of all around us.

So that's where this sort of idea comes from, that there is this sort of background pollution that is bleeding into, I guess, human bodies and affecting their sperm counts, but it is not a universally supported hypothesis.

Sam.

Okay.

Well, I want to get into that.

But first, I do want to just point out would have to be one of her biggest claims in this book, countdown that you've mentioned, which is that by 2045, men's sperm will be so lackluster that almost all couples will have to rely on IVF.

So, I mean, that is a ginormous claim, a very terrifying one, especially given how soon that is.

How much support is there for that claim, or is it really just her standing alone in the scientific community saying, wow, this is where we're at?

It is a big claim.

It does kind of sort of call to mind that maxim that extraordinary claims require extraordinary evidence, and many people would argue that we do not have that extraordinary evidence.

But there are certainly a lot of scientists, including Professor Brett Nixon, that is a believer in this data.

A lot of people say that it's pretty methodologically, you know, robust and that we should really be heeding this warning.

Look, the claim that all couples will have to be on IVF by 2045, from my research and speaking to quite a few scientists on this, I would be very skeptical of.

The thing is that even if this idea is true, that we are losing like 1 to 2% sperm count as a global average each year, we are still well above the levels of sperm needed for men to be considered fertile.

Well, well well above.

So there would still have to be a pretty dramatic crash globally, and a pretty massive blow to men's health to get to a point in 2045 where very little men can conceive naturally.

There was one scientist I spoke to, Doctor Tim Moss from Healthy Male, which is a government supported mail health organization, and he is very skeptical of this sort of idea of crashing male sperm counts.

He says it's a bit of a case of what he said was shit in, shit out the shit in being kind of dodgy data from the 70s, perhaps.

You know, back then, uh, we didn't have as good sperm count analysis techniques.

A lot of scientists think that back then, we would have overestimated the amount of sperm in male sperm samples would maybe sort of, you know, created a bit of a false decline for now, because now we're better at counting sperm and maybe we're more accurate and it's just showing, you know, less sperm.

And then also, at least in the early meta analysis, some of the data used was missing really key information like the age of the donors.

And obviously a man's age has a lot of bearing over the amount of healthy sperm he produces.

And there was also really key information missing from a lot of that data, for example, like the year that that sample was collected.

So a lot of red flags there.

The authors did say that they sort of addressed a lot of those issues in the 2023 meta analysis.

That's seen as a little bit more robust, and it did sort of sort of support this idea of a great sperm count crash.

But just this year, in January, in 2025, another team of scientists did a very similar study where they went and looked at a whole bunch of past data and looked at trends for male sperm production since the 70s.

And they actually found kind of the complete opposite to what Doctor Shanna Swan and her colleagues found.

They found that sperm counts have actually sort of been on a pretty even keel for the last decades, and in some cases maybe have even ticked up.

So the consensus, if I could summarize, is that most scientists seem to agree that yes, in some areas there is enough evidence to say that perhaps we are seeing a decline in male sperm health and male sperm counts on the whole.

Globally, the data is too mixed for us to make an assessment like that.

And for the most part, people working in sort of the male fertility space are pretty skeptical of the claim that all men are going to be basically reliant on IVF by 2045.

Or as you so colorfully put it, you know, whether we are headed for an impending Armageddon or not.

Exactly.

I think I think we can confidently say that sperm mageddon is more than 20 years away, but, you know, more data might come out and then we can prepare for sperm mageddon then.

But I think sperm mageddon for the minute, I think is canceled.

Okay.

I love that news.

And I do want to highlight one other statistic that you had in your study, because it's very sobering, which is as hopeful as as some of what you just said might be.

You said that in couples undergoing IVF, at least partly due to male fertility problems, 77% of those male infertility cases cannot be explained.

That's extraordinary, right?

I mean, is that is that something that really worries people within the fertility space?

Yes.

So we've arrived at the place where no matter where scientists are on either side of the great sperm count debate, everyone agrees on this, that we really know precious little about male fertility.

We don't talk about it enough.

We don't research it enough.

You know, male fertility, I think, is the direct cause of between 20 and 30% of when couples go to get IVF for fertility support.

And it's at least a factor in half of those IVF presentations, as you would kind of expect.

But for the longest time, it's been the women who have been exhaustively sort of, you know, poked and prodded and investigated for fertility issues.

So what everyone agrees on is that we need way more focus on men's health and men's fertility, because a lot of the time fertility issues can be really, really quickly diagnosed.

Like for example, there's these new male fertility guidelines that have just come into effect last week.

And they recommend that for one, that when a couple presents for IVF treatment or fertility treatment, that the male and the female are both investigated at the same time.

It seems crazy that wasn't already happening, but this is what the guidelines stipulate.

And one of the other main mandatory recommendations of these guidelines is that men undergo a physical examination of their scrotum, because there's a lot of physical issues that can be very quickly diagnosed and quite easily treated.

One of those examples that the experts gave me was something like varicose veins in the testicles, which is pretty common.

And if you've got varicose veins in the testicle, that means there's more blood.

There's sperm production is better when it's cooler, which is why testicles are outside the body.

So if you've got a varicose vein in there, your testicles will be warmer.

And that can affect sperm count, but it's very easily treated condition.

And if you get it addressed often that solves the sort of overall fertility issue.

So that's just one of the things that can be very easily addressed, but on the most part, we are still in this situation where, like you say, Sam, between 60 and up to 77% of male infertility cannot be explained, which is super, super interesting and worrying.

And that's why all these experts like having this debate, because at least it shines the spotlight on the fact that for a lot of the time, we just don't know what's going on with sperm.

And that seems crazy.

And even though we are, of course, talking about the science of it, I can only imagine.

And in fact, I have done some research in this area by by speaking to men who have been impacted in this for features in times gone by, but so upsetting for the men and the couples involved, you know, when it's because of their own health that there's unexplained infertility and it can just be devastating, right?

That's right.

Sam, one of the professors I spoke to actually made this point that there are some issues that are genetic that can't be fixed, that aren't easily treated or untreated at all.

But even if men are experiencing something that can't be treated when it comes to their fertility.

This professor's point was that the medical world has an obligation to get to the bottom of it, to be able to say to someone, this is why you're having trouble conceiving, or this is why your sperm count is low or non-existent.

There is this need, this due diligence for the medical world to be able to tell people what's going on with their bodies.

And we're kind of at a stage at the moment where we can't necessarily do that for a lot of men.

Yeah, and arguably men have really been failed in this regard.

I would have thought so.

I guess just to wrap up, you know, what should men know now?

You know, is there anything that they can do in their own lives?

You know, anything they control that can help ensure that they have as healthy sperm as possible?

Absolutely.

That's such a good question.

What I would say to you, based on the conversations I had with a lot of men's fertility experts, was that yes, there are anxieties about things like PFAS and other chemicals and stuff like that.

Yes, there may be health issues there.

We're still looking at that.

We're not sure.

And it's important that we do that.

In the meantime.

There are so many things that we know can boost men's health and, by extension, boost their sperm health and their fertility.

And these are the things, these are the messages that everyone would have heard a million times.

But I'll say them again if you are interested in being healthier and having healthier sperm, do not smoke.

Do not drink to excess.

One of the professors that I spoke to was professor Rob McLaughlin.

He is also at this healthy male organization and he says that you should not be obese.

If you want to have healthy sperm, you should be exercising.

One of the specific points he made, which I thought was really interesting, was that you should be vaccinated, particularly against mumps, because he's seeing this sort of global backlash to vaccines.

And that really concerns him, because if you get something like mumps after puberty, that can lead to complete sterility.

So being overall healthy, being up to date with your vaccinations is a really important thing for your sperm health.

And what we are beginning to understand is that it's not only the health of a would be mother that's really important for the health of her baby.

We now know that the healthier the man is at the time of conception, the healthier that baby is.

So when you are thinking about, you know, having a baby.

Men should be sort of getting their act together up to a year or at least three months before they start to conceive.

That's what one doctor told me, because that will increase their chances of having a good, beautiful, bouncing, healthy baby.

Well, Angus, I'm so delighted to speak to you about this.

I think it's such an important topic.

I think male health can be so underrepresented in research and it can be so ignored.

And also, I think culturally, it can be so difficult for men to speak about these things and, and that we should be open and honest about it to help everyone involved.

So thanks, Angus.

Completely agree with you, Sam.

Thank you.

Today's episode of The Morning Edition was produced by myself and Kai Wong.

Our executive producer is Tammy Mills.

Our head of audio is Tom McKendrick.

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Notes.

I'm Samantha Selinger.

Morris.

This is the morning edition.

Thanks for listening.