Hormones… the menace in our water

They’re not visible to the human eye, but unseen pollutants in the form of female sex hormones are frighteningly common in our waterways… and that is bad news for people and wildlife alike. Vicky Ellis investigates.

We have something sinister wreaking havoc in our waterways that we can’t see or smell and that has a direct effect on our physiology: female sex hormones – natural oestrogens and synthetic chemicals that imitate oestrogens. This invisible pollutant is penetrating all our natural waterways and entering our drinking water supply chain.

Research by Brunel University and the University of Exeter has found these pollutants are entering the water via our sewage systems, leading to reduced fish-breeding and feminising of fish and other aquatic organisms. Other studies have found a causational link between hormones in water and an increase in human male infertility, low sperm counts and testicular dysgenesis syndrome (a male reproduction disorder).

What are hormones?
Hormones are signalling molecules, otherwise known as chemical messengers, that are present in all multicellular organisms from humans through to fungi. In humans and other animals, hormones are produced in the endocrine gland and carried around the body via the vascular system to all organs and tissues to regulate physiology and behaviour such as development and growth, metabolism, sexual function and reproduction, cognitive function, mood and much more.

Hormones influence who we are as people.

So, apart from in nature, where else are hormones used?
Humans also use hormones to manipulate nature, such as in animal agriculture to muscle up cattle; in the gym for bodybuilders to bulk up, where they are referred to more commonly as steroids; for contraception; and to help with symptoms of the menopause, along with other pharmaceutical uses.

Animal agriculture
Animal agricultures use a synthetic hormone version of oestrogen, testosterone or progesterone, which are utilised to increase growth speed, thus using less feed and saving money. However, in the UK, using hormones for dairy cattle has been banned since 1990 due to animal welfare implications. The UK also has a ban on importing all hormone-treated beef and other meats. However, this may be under review since leaving the EU.

Oral contraception
The UK’s first oral contraceptives, using synthetic hormones, became available in 1961 and since then their popularity has grown considerably. From 1962 to 1969 the number of women taking ‘the pill’ grew from an estimated 50,000 to one million, and in 2000 the numbers had risen to more than three million, making the birth-control pill the most popular form of contraception in the UK.

Synthetic hormones
Synthetic hormones lack a chemical structure that matches a woman’s biological hormone structure. They are produced by synthesis – oestrogen and progesterone are synthesised from other sources such as pregnant mares (a highly controversial source of extraction).

Synthetic hormones have several uses, from the contraceptive pill through to cancer treatments. Diethylstilbestrol is a synthetic oestrogen first synthesised in 1938 and prescribed to many women between 1940 and 1971 for the prevention of miscarriage in the first trimester. Due to unforeseen side-effects, it is no longer prescribed.

All the metabolites from this hormone and others are then released into the environment via urine and faeces from users. According to the Daily Mail article ‘Fertility timebomb found in drinking water’, synthetic oestrogens are 50-100 times more potent than natural oestrogens.
Hormones are in such wide use now that they pose a serious threat to the natural environment, from soil to water resources, and biological organisms such as fish and humans.

However, this is not new news: in 2010 Susanne Goldenberg wrote a report detailing that “more than 80% of the male bass fish in Washington’s major river are exhibiting female traits such as egg production because of a ‘toxic stew’ of pollutants”, while in 2012 The Observer reported on how “Britain faced a £30bn bill to clean up rivers, streams and drinking water supplies contaminated by synthetic hormones from contraceptive pills”. In 2014, the BBC produced an article entitled ‘How drugs are entering UK water systems through urine’ and in 2016 The National Geographic wrote an article with the headline ‘Why are these male fish growing eggs?’. Hormone pollution is not just a UK-wide issue but a global one.

Oestrogen in water courses and how they got there
Back in 1999, the Environment Agency produced a report entitled ‘Fate and behaviour of steroid oestrogens in rivers: A scoping study’. This was a 94-page research report focusing exclusively on three oestrogen compounds: two natural oestrogens – oestrone and 17β oestradiol – and one synthetic hormone, ethynyl-oestradiol. This research, financed by Defra and the Natural Environment Research Council, concluded that half of all male fish in our rivers were changing sex because of pollution by these three hormones.

Natural hormones are generally inactive, or if active only at high doses due to the body’s ability to metabolise them rapidly. Synthetic hormones are more stable and remain within the body long enough to be utilised as contraceptives. This increased stability results in up to 80 per cent being excreted in conjugated form.

According to the report, all three hormones are excreted in a relatively stable and inactive form, so an adverse effect on the watercourses would seem unlikely. Therefore, something must occur to destabilise these hormones in the sewage treatment works. It was discovered that large quantities of active, unconjugated oestrogens were indeed present in treated sewage.

The same principle would apply to animal agriculture. Only the animal excretes on to the ground and the hormones then seep into water courses and may even be spread during muck-spreading.

The effects on fish and other organisms
Vitellogenin (a protein found in the blood stream synthesised by female fish to produce egg yolk) is used as a biomarker and has been observed to be produced by both male and juvenile females, with increased levels in mature females along polluted stretches of rivers, with some fish being reported as hermaphrodites. The danger with steroids, in comparison with other pollutants, is that the nature of sex hormones is such that even at low levels they can still have a profound effect on an organism’s physical development.

Synthetic oestrogen, found to be present in all lowland rivers in the UK, led to male fish developing female characteristics, with 50 per cent producing eggs in their testes; one in 10 were sterile and a quarter had damaged sperm, according to the company Pure Water People.

The Independent reported that all rivers, including the Lea in Hertfordshire, which supplies London with drinking water, and the Avon in Bristol, had male fish that had become feminised.
According to Adeel et al, as well as disrupting fish physiology, polluting oestrogens also negatively affect the development in both domestic animals and wildlife, and treatment of oestrogen was found to have affected root and shoot development, flowering and germination in flora.

Lab rats and mice when exposed to oestrogen, were found to be adversely affected by increased sexual behaviour, greater weight of the placenta, increased litter numbers and size of pups for gestational age in mice, higher abortion rates and changes of maternal behaviour in rats and advanced puberty.

In humans, women in Spain exposed to exogenous oestrogens were found to have an increased risk of breast cancer. In China, urinary phytoestrogen levels were associated with idiopathic infertility in men. Obesity has also been cited as an adverse effect, so could drinking water be inadvertently contributing to obesity?

How many oestrogen pollutants are in our drinking water?
Pure Water People claims it is hard to quantify how much oestrogen is present in drinking water as it’s difficult to measure at low concentrations. The American Chemical Society says that the contraception pill accounts for less than 1 per cent of the oestrogens found in the nation’s drinking water, concluding that hormones enter drinking water from other sources. However, 1 per cent of a massive data set amounts to quite a considerable percentage; furthermore, oestrogen has been found to be harmful at even very low doses.

Solutions to a man-made pollutant problem
So now we have created this problem for us and the natural environment, how can we best solve it?

Researchers are looking to neutralise these oestrogens in several ways before they enter the environment. One such idea is to use activated carbons in much the same way as a domestic water filter works. The active carbon hoovers up the oestrogens, allowing pure water to flow through.

Another method being tested is the use of ozone gas as a means to treat wastewater. Ozone works by splitting the molecules into less active biproducts. However, the downside and consequence of this method is that ozone can create toxic by-products such as bromate, which is considered carcinogenic, so then a further treatment would be required to remove this carcinogen.

Both these methods work small-scale but would take some thinking to scale up for use in industrial-sized sewage plants. Some water treatment plants such as that at Bewl Water have the facilities for ozonisation followed by active carbon treatment.

Switzerland’s recently introduced regulations aim to lower hormones in the environment by upgrading sewage plants and it is using ozone and/or activated carbon. However, researchers estimate the costs of running the water treatment plants will increase, along with energy consumption.

Another viable alternative is peroxide. Researchers from Carnegie Mellon University and Brunel University have worked together and claim this method is “promising”. They used a concentrated type of hydrogen peroxide alongside bespoke catalysts that act similarly to enzymes to accelerate the chemical reaction and denature synthetic oestrogens in water, urine and wastewater. They also tested this cleaned water by placing feminised male fish in a tank and found the male fish made less vitellogenin.

The most recent paper on the subject, ‘Water treatment: Removing hormones with sunlight’, published in 2021 by the KIT institute, acknowledges the issues surrounding scalability with the other methods and has come up with the idea of utilising photocatalysis, transforming the hormones into benign oxidation products and consequently reducing the concentration of oestradiol by some 98 per cent by filtering 60-600 litres of water per square meter of membrane in one hour. This would make this method more easily scalable but is still not without its challenges.

So, you can rest assured there are scientists who recognise the seriousness of this invisible pollutant and are working hard on a solution to help not just us but the natural environment.
If hormones in our water teaches us one thing, it’s how intrinsically linked we are to the health of the natural environment around us and that how we treat this natural environment can directly impact on our own health. A lesson, perhaps, to take note.