Most of us are fortunate that, when we turn on the tap, clean, safe and high-quality water comes out.

But a senate inquiry into the presence of PFAS or “forever chemicals” is putting the safety of our drinking water back in the spotlight.

Lidia Thorpe, the independent senator leading the inquiry, says Elders in the Aboriginal community of Wreck Bay in New South Wales are “buying bottled water out of their aged care packages” due to concerns about the health impacts of PFAS in their drinking water.

So, how is water deemed safe to drink in Australia? And why does water quality differ in some areas?

Here’s what happens between a water catchment and your tap.

Human intervention in the water cycle

There is no “new” water on Earth. The water we drink can be up to 4.5 billion years old and is continuously recycled through the hydrological cycle. This transfers water from the ground to the atmosphere through evaporation and back again (for example, through rain).

Humans interfere with this natural cycle by trapping and redirecting water from various sources to use. A lot happens before it reaches your home.

The quality of the water when you turn on the tap depends on a range of factors, including the local geology, what kind of activities happen in catchment areas, and the different treatments used to process it.

How do we decide what’s safe?

The Australian Drinking Water Guidelines define what is considered safe, good-quality drinking water.

The guidelines set acceptable water quality values for more than 250 physical, chemical and bacterial contaminants. They take into account any potential health impact of drinking the contaminant over a lifetime as well as aesthetics – the taste and colour of the water.

The guidelines are not mandatory but provide the basis for determining if the quality of water to be supplied to consumers in all parts of Australia is safe to drink. The guidelines undergo rolling revision to ensure they represent the latest scientific evidence.

From water catchment to tap

Australians’ drinking water mainly comes from natural catchments. Sources include surface water, groundwater and seawater (via desalination).

Public access to these areas is typically limited to preserve optimal water quality.

Filtration and purification of water occurs naturally in catchments as it passes through soil, sediments, rocks and vegetation.

But catchment water is subject to further treatment via standard processes that typically focus on:

• removing particulates (for example, soil and sediment)
• filtration (to remove particles and their contaminants)
• disinfection (for example, using chlorine and chloramine to kill bacteria and viruses)
• adding fluoride to prevent tooth decay
• adjusting pH to balance the chemistry of the water and to aid filtration.

This water is delivered to our taps via a reticulated system – a network of underground reservoirs, pipes, pumps and fittings.

In areas where there is no reticulated system, drinking water can also be sourced from rainwater tanks. This means the quality of drinking water can vary.

Sources of contamination can come from roof catchments feeding rainwater tanks as well from the tap due to lead in plumbing fittings and materials.

So, does all water meet these standards?

Some rural and remote areas, especially First Nations communities, rely on poor-quality surface water and groundwater for their drinking water.

Rural and regional water can exceed recommended guidelines for salt, microbial contaminants and trace elements, such as lead, manganese and arsenic.

The federal government and other agencies are trying to address this.

There are many impacts of poor regional water quality. These include its implication in elevated rates of tooth decay in First Nations people. This occurs when access to chilled, sugary drinks is cheaper and easier than access to good quality water.

What about PFAS?

There is also renewed concern about the presence of PFAS or “forever” chemicals in drinking water.

Recent research examining the toxicity of PFAS chemicals along with their presence in some drinking water catchments in Australia and overseas has prompted a recent assessment of water source contamination.

A review by the National Health and Medical Research Council (NHMRC) proposed lowering the limits for four PFAS chemicals in drinking water: PFOA, PFOS, PFHxS and PFBS.

The review used publicly available data and found most drinking water supplies are currently below the proposed new guideline values for PFAS.

However, “hotspots” of PFAS remain where drinking water catchments or other sources (for example, groundwater) have been impacted by activities where PFAS has been used in industrial applications. And some communities have voiced concerns about an association between elevated PFAS levels in their communities and cancer clusters.

While some PFAS has been identified as carcinogenic, it’s not certain that PFAS causes cancer. The link is still being debated.

Importantly, assessment of exposure levels from all sources in the population shows PFAS levels are falling meaning any exposure risk has also reduced over time.

How about removing PFAS from water?

Most sources of drinking water are not associated with industrial contaminants like PFAS. So water sources are generally not subject to expensive treatment processes, like reverse osmosis, that can remove most waterborne pollutants, including PFAS. These treatments are energy-intensive and expensive and based on recent water quality assessments by the NHMRC will not be needed.

While contaminants are everywhere, it is the dose that makes the poison. Ultra-low concentrations of chemicals including PFAS, while not desirable, may not be harmful and total removal is not warranted.

Mark Patrick Taylor, Chief Environmental Scientist, EPA Victoria; Honorary Professor, School of Natural Sciences, Macquarie University; Antti Mikkonen, Principal Health Risk Advisor – Chemicals, EPA Victoria, and PhD graduate, School of Pharmacy and Medical Sciences, University of South Australia, and Minna Saaristo, Research Affiliate in the School of Biological Sciences, Monash University

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

A stroke happens when the blood supply to part of the brain is cut off, either because of a blockage (called an ischaemic stroke) or bleeding (a haemorrhagic stroke). Around 83% of strokes are ischaemic.

The main emergency treatment for ischaemic strokes is a “clot-busting” process called intravenous thrombolysis. But this only works if administered quickly – ideally within an hour of arriving to hospital, and no later than 4.5 hours after symptoms begin. The faster treatment is given, the better the person’s chance of survival and recovery.

However, not everyone gets an equal chance of receiving this treatment quickly. Notably, research has shown ambulance staff are significantly less likely to correctly identify a stroke in women compared to men.

In a recent study, we modelled the potential health gains and cost savings of closing this gap. And they’re substantial.

The sex gap in stroke diagnosis

In Australia, about three-quarters of people who experience stroke arrive at hospital by ambulance. If paramedics suspect a stroke, they can take patients directly to a hospital which specialises in stroke care, and alert the hospital team so scans and treatment can start immediately.

Research has shown women aged under 70 are 11% less likely than men to have their stroke recognised by paramedics before they arrive at the hospital.

While younger men and women experience stroke at a similar rate, the symptoms they present with may be different, with “typical” symptoms more common in men and “atypical” symptoms more common in women.

Research has shown women and men are equally likely to present with movement and speech problems when having a stroke. However, women are more likely to show vague symptoms, such as general weakness, changes in alertness, or confusion.

These “atypical” symptoms can be overlooked, leaving women more vulnerable to misdiagnosis, delayed treatment, and preventable harm.

What we did

In our study, published recently in the Medical Journal of Australia (MJA), we used ambulance and hospital data from a 2022 MJA study in New South Wales. This is the study we mentioned above that showed paramedics correctly identified stroke more often in men than women under 70.

From this dataset, we identified more than 5,500 women under 70 who had an ischaemic stroke between 2005 and 2018. Using this group, we built a model to compare two scenarios:

1. the status quo, where women’s strokes are identified at the current rate of accuracy; and
2. an improved scenario, where women’s strokes are identified at the same rate as men’s.

We then projected patients’ health over time, including their level of impairment, risk of another stroke, and immediate and long-term survival.

Closing the diagnosis gap would save lives and money

When women’s stroke diagnosis rate was improved to match men’s, each woman gained an average of 0.14 extra years of life (roughly 51 days) and 0.08 extra quality-adjusted life years (QALYs), meaning an additional 29 days in full health.

Scenario two also meant A$2,984 in health-care costs would be saved per woman.

Scaled to the national level based on the number of women under 70 hospitalised with ischaemic stroke each year, closing this gap would mean 252 extra years of life, 144 extra QALYs, and $5.4 million in cost savings annually.

Some limitations

We didn’t have sex-specific data for every aspect of the model, which is in itself a telling sign of the lack of recognition of sex as an important factor in understanding disease. Because of this, we used combined data from both men and women in some parts of our model, which may have affected the results.

Further, the NSW data we used for rates of treatment with intravenous thrombolysis were higher than the national average, so our national figures may be slightly over-estimated.

Beyond stroke – why all this matters

The disparity we found is one example of a broader, systemic issue in women’s health: sex-based differences in diagnosis and treatment that favour men.

Too often, women’s symptoms are misinterpreted or dismissed because they don’t match a “typical” pattern. This can lead to delays, missed opportunities for early treatment, and worse outcomes for women.

In stroke, faster and more accurate diagnosis means people are less likely to die or require long-term care, and more likely to recover better and get back to their daily lives sooner.

So what can we do to close the diagnosis gap?

Investing in better training for paramedics and other emergency responders, so they can recognise a wider range of stroke presentations, could pay off many times over. Public awareness campaigns that highlight atypical stroke symptoms could also help.

Technologies such as mobile stroke units and telemedicine support may be part of the solution, but they must be implemented with attention to sex-specific needs.

Lei Si, Associate Professor in Health Services Management, Western Sydney University; Laura Emily Downey, Senior Lecturer, Health Economics and Policy, George Institute for Global Health, and Thomas Gadsden, Research Fellow, Health Systems Science, George Institute for Global Health

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