Thursday, August 03, 2006

Environmental Estrogens

Queensland opposition leader, Lawrence Springborg, raised the issue of ‘environmental estrogens’ this week. Predictably, various newspapers and blogs were jammed with arguments about whether chemicals in sewage can change the sex of fish and whether they could turn a male human into a female. Seriously, they were. So let’s get a few facts straight.

A one-paragraph biology lesson: Human sexuality is determined by DNA chromosomes. Most of us have two chromosomes, either XX or XY (yes, I know there are other possibilities, but lets keep this simple). You got one of these from your father (an X or a Y) and one from your mother (an X). If you scored XX, you are genetically female. If you scored XY, you are genetically male. No amount of exposure to chemicals (such as hormones) in the environment can change this. You can not change a man to a woman or a woman to a man. Yes, I accept that people may identify as “male” or “female” regardless of chromosomes...I don’t mean to offend anyone...I simply want to deal with this complex topic in a single paragraph…woah…a can of worms that I really didn’t mean to open...Move on!

But fish and reptiles are different to mammals. Changing sex is natural for many species and it is common to do this in response to chemical signals.

Researchers have found that if they paint a turtle's egg with estrogen, the turtle inside can change from male to female. Strangely enough, the same thing can be achieved using industrial chemicals called polychlorinated biphenyls (PCBs). These (artificial) PCBs have some chemical similarities to (natural) estrogen, which causes them to interact with the estrogen-receptors. In other words, the PCBs ‘mimic’ the action of estrogen.

Male frogs’ eggs or embryos exposed in the lab to the widely used pesticide, atrazine, develop ovaries and are infertile. In fact, not only do the males (which normally only have testes) develop ovaries, they develop multiple ovaries, sometimes six or seven. Unlike the PCBs, atrazine does not mimic estrogen. Instead, it enhances the conversion of testosterone to estrogen.

Even mammals can be affected by these chemical ‘endocrine disruptions’ (although they don’t change sex). For example, sheep that graze on clover ingest natural plant estrogens (phytoestrogens) which can make them infertile.

Recently, researchers at the Cincinnati Zoo were trying to work out why some cheetahs were not breeding. It turned out that phytoestrogens in soy-based materials included in their diet was acting as a contraceptive. When the cheetahs were given a diet without soy several quickly gave birth to kittens.

There are lots of compounds that can act like estrogen. From the above examples, we know that they include natural estrogens, industrial compounds, pesticides and natural phytoestrogens (plant estrogens). Many of these compounds can wind up in sewage, so it is no surprise that poorly treated sewage can also have these sorts of effects.

For example, there are reports of fish in the Potomac River (USA) being “feminised” by water-borne pollutants. This was identified by an increase in the production of the protein that is involved in egg-production, by male fish. This protein, called ‘vitellogenin’ is not usually made by male fish unless they are treated with estrogen. It turns out that some detergents in the water are likely to be responsible for tricking male fish into producing vitellogenin. These detergents can be major constituents of municipal sewage. Human estrogens (excreted in urine) and synthetic steroids such as the contraceptive pill can have the same effect.

So what does all of this have to do with recycled water? Well that depends on how we define ‘recycled water’. If we are talking about advanced water treatment (processes such as reverse osmosis, granular activated carbon, advanced oxidation), then the answer is 'absolutely nothing'.

The concentrations of estrogenic substances in advanced treated recycled water are miniscule (or unmeasurable). We know this both by chemical analysis (measuring the concentrations of chemicals) and by estrogenic activity (running assays to measure the effect of any estrogens or estrogen mimics that may be present).

However, if we are talking about conventionally-treated (or poorly-treated) sewage, then yes, discharging poorly-treated sewage into creeks and rivers can be expected to disrupt the sexuality of some species including fish. All the more reason why we should pay better attention to treating water to a higher level than what we generally get away with today.

If you've come this far, leave a comment...tell me what you reckon.

9 comments:

Alexandra Golab said...

What happens if the membrane gets clogged? Could estrogens then get through?

Jaun said...

If Di Thorley never put in a application for funding for recycled sewerage, none of this would be happening, so why is it now, because Toowoomba voted no?

I'm seeing this as an excuse to push recycled water through because the public are now highly aware of the water shortage. The councils and governments are in panic mode and are looking for the cheapest and down right un-righteous decisions to calm the public.

RO technology is just that, a technology that has not been tested for such extreme use. As with all technology it will fail in some cases destroying the water supply of a city. This is just like our current water purifiers, they fail and the city ends up with dirty water until it's fixed.

I do not care about backups or how many fail safes are in places, it’s too big of risk to pump recycled effluent in drinking supplies.

As our Mayor said, I'd gladly go to WAR over this. STOP THE DAMS they say, I say STOP THE SHIT, which is safer? (and don't say recycled water Stuart, you know it's not.)

Stuart Khan said...

Hello Alexandra,

Membranes do eventually get ‘clogged’ as you suggest. This is caused by dissolved salts precipitating onto the membrane (known as ‘scaling’) or simply by the gradual build-up of organics. There are two main results of this:

1. There are less working ‘pores’ for water to permeate through. This makes the process less efficient and means that increasing pressure is required to maintain the same flow-rate through the membrane. Eventually the membrane needs to be replaced.

2. There can be a microscopic layer of organics formed on the feed-side of the membrane. This is known as the fouling-layer. The effect of the fouling layer is actually to improve the retention of small non-ionic compounds.

Neither of these effects can lead to estrogens getting through the membrane. Estrogens are relatively large and easily excluded from a tight RO membrane by size-exclusion. Since they are weakly acidic, many have the additional advantage of electrostatic repulsion away from the membrane.

Stuart Khan said...

Jaun,

You are correct. Australians tend to become very ‘water-aware’ during drought periods, but we also have very short memories and are less-inclined to make tough decisions when it’s wet. So yes, I am sure that it is true that governments see a need to act now while people are tuned in to the urgency of the problem.

You’ve made it clear that I cannot convince you that water recycling can be managed extremely safely...so I wont waste time trying!

Stuart.

mick said...

you can't blame jaun for being upset about it thou stuart. I'm 22 years old and i am starting too think i am going too have too put up with this crap when i am 50!! I know what you are trying too do. you are trying too give the facts out about recycling water. which i think you are doing a good job of. but as we both know education is the key! informing communties and talking throu with communities is the best way too go about this issue. Toowoomba has been damaged by this issue. I really hope that every other major city will not be as divied as toowoomba was (and still is) I personally think the scare campain is in gear now! driven by the media and our polliticans you can see it! there is no denying!! you just have too watch the news and read the papers! They wanted us too vote yes but we didn't wan't too! so now they'll winge about it untill another refurendum comes and if that town/city votes no then they'll get winged at too. maybe people aren't ready for the idea of directly pumping recycle sewage back into their own dams for drinking? I do however thing that the water should be reused for other purposes other then drinking. the amount of drinking water that could be freed up!! everyone will be happy!!! the drought will go! look at history drought come and go! there have been drought just as sevre if not worse then this one! I personally belive that the way the media is going on is going too be the death of recycling

Jaun said...

Just don't put the crap in our drinking water, and we'll all live happliy ever after. No need to for debats, no need for referendums, no need to scare people, no need to deny facts!

I'll be dropping this issue until someone can provide documented studies for recycled effluent on the environment, dams and human consumption, which no one can seem to produce and just avoid the issue.

That is all!

Stuart Khan said...

I have permanently deleted a comment that was posted here this morning. The comment was (by any standards) personally abusive and defamatory towards a third party. While some (anonymously authored) blogs have been willing to retain similar comments, there is absolutely no place for them here.

I am keen to allow dissenting views to be expressed and if the author would like to post a suitably modified comment, I would be happy to retain it. I trust that we can get back to “an unemotional and rational discussion of the facts...”.

Stuart

mick said...

just wondering stuart if you know any info about south australias drinking supplies? I have been told by someone that south australia drink recycled effulent. but all i have been able too find is alot of info about it being used for industral and agricultual purposes etc. any info would be great. or is it like the rest of country where treated effulent is realesed into the waterways etc etc. as i think this is where the confusion is with the recycling issue is. any info would be great

cheers

Stuart Khan said...

Thanks for the question Mick,

Most of the statements that you have heard regarding South Australians drinking recycled effluent would be in regard to ‘unplanned’ potable recycling. South Australian cities such as Adelaide source their water (in part) from the lower reaches of the Murray-Darling river system. As you would appreciate, many towns and cities in NSW and QLD discharge their treated effluent into the upper-reaches of the same river system. Toowoomba is one of these cities (via Gowrie creek and the Condamine River), but there are many more smaller towns and cities along the way. Poor-quality discharged effluent leads (no-doubt) to compromised water quality in Adelaide and blue-green algal growth can be a significant problem resulting from elevated nutrient concentrations. Agricultural run-off also has a major impact, particularly in regard to nutrients and salinity. These factors mean that drinking-water treatment can be a particular challenge in Adelaide.

Adelaide’s own treated effluent is also recycled (more so than any other large Australian city), but not for potable use. Recycled water from the city’s largest treatment plant (Bolivar) is delivered via the Virginia Pipeline to agricultural areas on the Northern Adelaide Plains and the Barossa Valley. The scheme supports one of Australia’s most valuable produce markets and provides an alternative source of water to the over-utilised local groundwaters in the region.

So yes, your assumption regarding 'where the confusion is' is quite correct.

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