"fresh~horses" <[email hidden]> wrote in message
news:[email hidden]...
Quoted message said:http://www.whp-apsf.ca/en/documents/pharmWater.html
Tests on water in North America have found trace amounts of
antibiotics, painkillers, anti-inflammatories, hormones,
tranquilizers, chemotherapy drugs and drugs used to treat epilepsy and
blood cholesterol. A family of chemicals called phthalates, found in
many cosmetics, perfumes and hair products, has also been detected.
Some of the substances (e.g., anti-epileptic drugs) persist in the
environment; others are "pseudo-persistent" -- they break down but are
continually replaced because of widespread use.
Let's be more clear on what is being talked about here. Those sorts of test
results apply to surface water sources, and only those surface water sources
into which sewage discharge occurs. One man's sewage can become another
man's drinking water. Look what happens to the Colorado River, for example.
Every community most certainly brings in drinking water upstream of their
own sewage outflow pipe, but what about the next community downstream?
By water, are they saying drinking water? Or, is this a unnecessarily
unspecific reference to water, meant to incite an overly emotional response?
Receiving waters just downstream of a sewage outfall (where many such
samples are taken (I'm an environmental toxicologist. I have done such
analyses.)) ought not to be confabulated with treated drinking water.
Of far more concern are other man-made chemicals that make their way into
surface waters (and, in some cases groundwater), particularly agricultural
chemicals. The only reason we're discovering that pharmaceuticals are
entering the environment in any appreciable amount is because analytical
technology has become so advanced over the last two decades. It's not like
they're suddenly appearing only recently. They've always been there, one
must assume.
The article makes reference to some very low concentrations, down to 1 ppt
(part per trillion). Do you have any real comprehension just how dilute that
is? Let me give you an example. For a liquid dissolved in water, part per
trillion is best represented by a single drop of the substance diluted in
the contents of 880 rail tank cars (a train six and a half miles long). Or
that same drop in the contents of three Olympic size swimming pools.
By any chance, has your post been inspired by the publication of an article
in the Guardian (UK), which claimed to have found Prozac in drinking water?
The report was fabricated. Did you know that? In any case, consider the
inference of the massive dilution.
1 ppt is defined in units such as ng per litre. A ng is 10^-9 of a gram, and
a litre of water is, by definition, one kilogram of water, or 10^3 grams.
There is thus a ratio of 10^-12, analyte to water. To preserve that ratio,
whatever we do to one side of the ratio (mathematically), we must also do to
the other. If Prozac was in the water at 1 ppt, to obtain 20 mg of Prozac
(the basic pharmaceutical dose), you would have to multiply the 1 ng/litre
by some factor, so that the mass on the left became 20 mg. That factor is
20,000,000 (There are 1,000,000 nanograms in a miligram, and we want 20
mg.). Therefore, there are 20 mg Prozac in 20,000,000 litres of water. To
visually represent that mass of water, let us consider the volume of 1,000
litres of water. By definition, that volume of water occupies a space of 1
metre cubed, and weighs one metric tonne. To visualize that mass of water,
you would need to look at 20,000 of such metre cubed volumes. Stacked on
end, that would be column of water one metre by one metre square, with a
height of 20,000 metres, or 20 km high (about 2 1/2 times the height of Mt.
Everest), having a mass of 20,000 tonnes. I'd like to see anybody drink that
much water, let alone the kidneys that could retain the drug from that
volume.
The U.K.'s Drinking Water Inspectorate has been quietly monitoring all
drinking water under their perview for many years. Because agricultural
chemicals had been shown (twenty years ago) to be making their way into
drinking water, all drinking water is now pre-treated by solid-phase
extraction, to remove pesticides, herbicides, and the like. Any
pharmaceuticals (except perhaps ibuprofen, I'm not sure) are removed along
with those other contaminants.
There was actually a research report upon which the Guardian "based" their
article, but they completed falsified what it found. The report was prepared
for the *Environment Agency*, and was an analysis of riverine waters just
downstream of sewage outfalls. Indeed, it has for years been the policy of
that agency to understand the impact of pharmaceutical drugs entering the
environment. The subject report is not specific to Prozac, or to even
antidepressants as a class. Prozac was not even an analyte in the study, as
it breaks down both before it is excreted, and after excretion, under
microbial influence. Here's a link to the original report. Take a gander at
how much ibuprofen is getting into the environment.
http://www.environment-agency.gov.uk/commondata/105385/p601206trv2_578719.pdf
That might be an issue. Also, consider that report in the context of the
following policy statement:
http://www.environment-agency.gov.uk/aboutus/512398/289428/698017/?version=1&lang=_e
As you can see, governments are taking proactive stands with respect to
these contaminants, as soon as they are known to be in the water.
Once pharmaceuticals are released into the environment from sewage outfalls,
very complex physio-chemical influences come into play. Dr. MacKay developed
mathematical modelling of these influences, generalized under the term
fugacity (the ability of a substance to flee, or to move through the
environment, and where it will end up). It's a far cry from saying that we
found something making it through an STP undegraded, and concluding that it
also in drinking water.
For the individual consumer, prudence would indicate that all drinking water
be subject to some form of chemical purification. Most water treatment
plants (world-wide) are there to remove suspended particles, organic
material, and pathogenic organisms, but not dissolved chemicals (although
that is changins all the time). Water is known as "the universal solvent".
(Of course, it doesn't dissolve everything.) The simplest treatment to
remove pesticides, pharmaceuticals, and the like, is solid phase extraction.
Brita makes such filters, but so do many others. Some (but not all) bottled
waters are purified. Simple prudence, not abject fear. As long as man has
been a polluter, water has carried pollutants. What a pollutant, or
combinations thereof, will do to organisms at very low concentrations is an
open question, but filtering your water may render the question moot in your
own case.
Lar
