Birth control is always a hot topic. The Government’s latest campaign – ‘Contraception: Worth Talking About’ - encourages 18-24 year old women to choose hormonal contraception as the best way of avoiding unwanted pregnancies and abortions.
But the thickening soup of oestrogens in our water should mean that this advice is not doled out without caution.
For over 15 years, researchers in UK and North America have been watching the feminisation of male fish. After leaving the human body, oestrogen hormones - natural and synthetic - as well as oestrogen-like chemicals and hormone disruptors in the environment - also referred to as endocrine disrupting chemicals (EDCs) - are discharged into rivers through sewage effluent and cause disruption to the reproductive behaviours of fish.
Scientists observing the effects of oestrogen in wildlife have now begun to fear the worst: that those effects may also appear in humans.
Of course, fish are not humans. But the similarities between the hormone systems, especially the sex hormones, of fish, birds, mammals and humans is why scientists argue that our bodies might behave similarly if exposed to comparable concentrations of hormones.
'We just don’t know what can happen in the long run,' says Charles Tyler, Professor of Ecotoxicology at the University of Exeter.
Persistent and traceable
Our hormones are the chemical messengers released by glands to regulate almost every cell, and function in the body - from metabolism, digestion and reproduction to moods, emotions and behaviour. This endocrine system is a finely tuned network that guides development in a similar way in both animals and humans.
Among the myriad compounds in fresh water, ethinylestrodial - the main component of the contraceptive pill - is traceable and persistent even at very low concentrations. This is because bacteria chew off the excreted hormone residues, which brings the compound back to life.
'In fact, almost as soon as the hormone hits the water in your toilet it can become active again,' says Tyler.
The two big studies that Tyler and colleagues have undertaken with the UK Environment Agency involved sampling thousands of fish from 42 sites around the country. They established a definitive link between exposure to these chemicals [oestrogens] and the effects on the fish. 'Ethinylestrodial is present in relatively low concentrations but it is extremely potent. I have little reservation that it is a player in feminising our fish,' says Tyler.
The latest research by Tyler and his team with colleagues at Brunel University (to be published later this year) goes a step further. It shows this sexual disruption can reduce capability of fish to breed. Removing males from the breeding population reduces genetic variation, lessens the ability of a population to adapt to changes in the environment, and may eventually cause its collapse.
Since the early 1990s, scientists have been warning us of damage to aquatic life. John Sumpter and Susie Jobling, Professors at Brunel University, made the early observations that male fish are producing female egg proteins and developing immature eggs in response to waterborne oestrogen residues. Their work was followed by Professor Karen Kidd at the University of New Brunswick in Canada, who discovered similar contaminants in Canadian rivers.
The additive effect
For many years, the phenomenon of falling male sperm count and rising incidences of testicular disease has been the focus of scrutiny for both Danish-based endocrinologist Niels Skakkebaek and Richard Sharpe from the Medical Research Council in Edinburgh. In the 1990s, they found synthetic oestrogens commonly used in livestock farming and numerous chemicals used in everyday products with oestrogenic properties.
Bisphenol A (used in some plastic drinks bottles and the inner coatings of drink and food cans), phthalates (used in food wrapping and other plastics) and nonylphenols (a group of surfactants found in detergents) are just a few of the chemicals that mimic the effects of oestrogen. They received a lot of media attention during the 1990s - Our Stolen Future by Theo Colborn, Dianne Dumanoski and John Peterson Myers was a bestseller, highlighting the true nature of these chemicals on wildlife and humans. But scientists are still uncertain whether they are to blame for reproductive disorders in the breast, prostate, ovary and uterus.
No single culprit
It is widely believed that around 100,000 chemicals or more are discharged into the environment each year and we are yet to screen them all for oestrogenic properties, so the culprits could still be out there. Sharpe admits, 'it’s unlikely to be a single oestrogen compound that causes testicular disorders, but they could play a role as part of complex mixture effects'.
Sharpe also points to persistent contaminants such as dioxins - a group of compounds that are by-products of pesticide production, waste incineration and the paper manufacturing industry. They are also fat-soluble and can be ingested through meat and dairy products. It is the unknown cumulative effect when these chemicals combine that raises alarm bells, not the effects of any single one of them. Adding further to the complexity of the problem, lifestyle factors including changing diets and increased obesity are also likely to contribute to an increase in reproductive disorders.
Saving our waters
The Environment Agency for England & Wales is fully aware that steroid oestrogens and other EDCs are entering rivers, and the water industry has invested heavily in cleaning up domestic wastewater. In addition, a national ‘Endocrine Disruption Demonstration Programme’ (undertaken by the water industry and the Environment Agency) has been assessing how effective sewage treatment processes are in removing steroid oestrogens. Sewage works vary in size and level of treatment but low concentrations of steroid oestrogens are present in all sewage effluents.
In terms of drinking water, the Drinking Water Inspectorate (DWI) for England and Wales is keen to highlight that whilst EDCs may lead to abnormal sexual development in aquatic life there is no current evidence of human risk through drinking water. According to a spokesperson, the environmental concerns are quite separate from, and should not be related to, our drinking water supplies. The DWI continues to monitor the ongoing research in this field.
Alongside the ecological downsides to hormone-overload, what about the effect on women’s health? Should we ignore the subtle but potentially substantial changes to hormones, cycles, emotion and behaviour?
Infertility experts Jane Bennett and Alexandra Pope say no. They brought the side-effects of hormonal contraception - from mood swings, headaches and depression to more serious risks such as thrombosis and breast cancer - to the attention of women last year with their book, The Pill: Are you sure it’s for you?. They argue that fundamentally altering the endocrine system’s delicate orchestration is detrimental for all sorts of reasons.
'The Pill induces a permanent state of infertility, and its impact isn’t just limited to ovaries, uterus and cervix but alters at least 150 bodily functions and affects all of the organs,' say Pope and Bennett.
The synthetic oestrogen and progesterone dose in the Combined Oral Contraceptive (COC) Pill is approximately four times greater than the body’s normal levels (at the peak of a normal cycle) and flattens the natural ebb and flow of hormones. This includes the rise in oestrogen around ovulation that makes a woman feel sexy. Not surprisingly, a lack of sex drive among Pill-users is a common complaint.
Once on the Pill, it’s not always plain sailing. The liver has to work hard to break down the extra compounds, the byproducts of which have been suggested as the reason behind unwanted effects such as depression, nausea and moodiness. Women at risk of blood clots, smokers over the age of 35 and those at risk of breast or other cancers are advised to avoid it and a large study published in Neurology in 2006 concluded that headaches, particularly migraines, are more likely among women taking oral contraception containing oestrogen (the mini-Pill and IUD coil are progesterone-only).
Too much oestrogen is potentially carcinogenic, and the fact the COC Pill has been classified as 'carcinogenic to humans' by the International Agency for Research of Cancer is rarely discussed by the medical profession (although studies have also shown that the COC Pill can protect against certain other types of cancer, notably ovarian cancer).
For most of the four million women in the UK who take oral contraception, the benefits of birth control outweigh the potential health risks; for others it’s a form of internal (and external) pollution and they will seek non-hormonal alternatives. In any case, women, especially teenagers, should be fully informed of all the risks.
EU regulations are now in place to ensure companies screen their chemicals for oestrogenic properties before discharging them into rivers – a move Tyler says is long overdue.
'We need to be savvier and more informed about how abnormalities in wildlife and humans relate to the plethora of chemicals in our environment,' he says.
Yanar Alkayat is a freelance journalist
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