The word "hormones" is one that readily catches the attention of all of us in the transvestite and transsexual community. For some it means the start of the process of change to more closely match their body to their mental understanding of who they are. For others it means a dream of femininity and for still others it is the reason why their wife or girlfriend finds the simplest of things aggravating at certain times of the month.

So when the subject of hormones became headline news a year or two ago I think almost all the readers of Cross Talk will have sat up and taken notice. In an earlier piece in this most august publication (Issue 29) I attempted to give an outline of the concerns over the discovery of feminised fish in rivers in the UK and elsewhere. These fish were believed to have been feminised by the presence of Oestrogen’s (female hormones) in the water. Since that piece appeared the story has moved out of the headlines and back to the scientific journals, because a great deal of research and monitoring work has been going on in Europe and in North America.

The first thing that has happened is that the names have been changed. The term used now is ‘Endocrine Modulating Substances’. In the bodies of animals there are glands that secrete hormones that act on their cells and tissues to create and maintain effects and the characteristics of the animal. Amongst these are glands that secrete oestrogens and androgens (male hormones) as well as non-sexually differentiated compounds like adrenalin. These glands collectively form the endocrine system. An ‘Endocrine Modulating Substance’ is one that in some way changes the natural balance of hormones in an animal, and the reason for the change in terminology is that research has shown that there are substances in the aquatic environment that are not oestrogenic but are anti-androgenic, that is they tend to suppress the effect of androgens in the body.

Now this sort of substance sounds quite appealing to us doesn’t it? A compound that would suppress the androgens that generate the secondary sexual characteristic of the male seems like the average TV’s dream. No more of that irritating body and facial hair, a glad goodbye to shaving, without the potentially embarrassing feminisation that prolonged use of oestrogen brings about. (I know for some that that is just what they do want!) Sadly it is not like that in the real world. The sort of man-made compounds that have been identified as having such activity are orders of magnitude less efficient in their activity than natural ones. If you were to take them, the amounts needed to have any noticeable anti-androgenic effect would be so toxic that you would poison yourself. Oh well, another great idea bites the dust.

There are genuine concerns about the effects of EMSs on the environment. Whereas in man and other mammals the determination of the sex of any individual is due to their chromosomes (hormones only generate the secondary sexual characteristics), in lower species such as the fish hormones have a far greater part in determining sex. In fact several species of fish change sex during their life span, generally from male to female as they get older. Clearly, the presence of chemicals in lakes, rivers and the sea that may alter the balance of the sexes in fish populations, has major implications for the environment.

Researchers have now tested 150 important chemicals and found that 80 or 90 of them have some endocrine effect on fish. So far all those that show activity are very much less potent than natural compounds, such as oestrones and oestradiol used in products used by women, that pass through sewage treatment. To give an example, if Ethinyl oestradiol has an oestrogenic potency of 1.0, Nonyl phenol has an oestrogenic potency of 0.000009. Ethinyl oestradiol is used in Hormone Replacement Therapies for post-menopausal women. Nonyl phenol is a compound that arises from the partial breakdown of some industrial detergents.

Other chemicals that cause concern include a compound known as ‘Bisphenol A’, which is a common component of the coatings that are applied to the insides of food and beverage cans. Foods such as tomatoes and drinks such as Colas are sufficiently acid to leach small amounts of this compound out of the coating into the liquid in the can. Only very small amounts are lost in this way but some people do seem to drink an awful lot of Cola!

In addition to these types of substance, there is evidence of endocrine modulating activity in several chemicals that might be termed the ‘usual suspects’, by which I mean things that are already known to have other environmental effects. Those included are many pesticides, the anti-fouling compound TBT and some phthalates, the plasticisers added to PVC and other plastics to make them pliable.

The studies conducted in British European and North American waters have shown that there are traces of some or all of these chemicals in most watercourses. However with a few exceptions, concentrations are low and as we have seen most of them have only very slight levels of endocrine modulating activity.

Research is now under way to try and understand the mechanisms by which chemicals have their modulating effect and to look at the possibility of synergism between two or more chemicals. Put simply, it is possible that the interaction of chemicals may lead to greater effects than simple addition would suggest.

Another area of study is in the differences between species of fish; the effects on the Carp family appear at different levels from those on Trout. There are definitely more puzzles than answers at present.

There are a lot of scientists who see this area of study as a very promising source of research funds (it has been so far!). If you are a scientist who happens also to be a TV it undoubtedly adds a little extra edge to your study in this field.

So where is all this activity leading us, what do we actually know that we did not know before? First, we know that there is a real problem in the environment and that there are a number of compounds that have sub-lethal effects on animal physiology and reproductive systems. So there is now an additional type of pollutant to add to those that are toxic persistent and bio-accumulative in the environment. It probably means that all new chemicals that are brought to the market will need additional testing to see whether they are endocrine disrupters. It will also mean that many other existing substances will need some testing.

Secondly, there are perhaps fewer immediate effects on humans, particularly males, than we first thought. You will probably remember that the early tabloid fuss was about the reduced level of sperm production in men. Researchers in the USA (led by Dr Harry Fisch) looked at samples of sperm from donor clinics in different parts of the country and found very large regional variations in sperm counts. For example the average count in New York city was twice that in Los Angeles. Even with all those California Girls around.

Other studies have shown that high levels of exercise or running cause a lowering of sperm count, and that a change from wearing tight briefs to boxer shorts can rapidly lead to doubling or even trebling sperm counts.

It is pleasing that the subject of ‘Endocrine Modulating Substances’ has returned to the scientific arena from the shock horror territory. There is a real problem to be investigated, quantified and hopefully solved. All of us, as concerned citizens, should follow the story. But the real story does not have that special edge that the word HORMONES brings to a member of the Northern Concord.