Forget gender-bending estrogenics or human waste leeching into the aquifers. European research has turned up something that could be a far more insidious threat in our water supply - drugs.
Swiss chemist Hans-Rudolf Buser, known in the past for his work on dioxins,
was analysing lake water for pesticides when he and his team at the Federal
Research Station in Wadneswil picked up a spurious result. They were getting
a signal that indicated the presence of the herbicide mecoprop (used to kill
broad-leaved weeds in cereal crops) but the spectra were not quite right -
they actually looked more like those of the pesticide lindane but lindane
was not present. When the researchers looked more closely at the analyses
they found clofibric acid - a widely used cholesterol-lowering drug at
concentrations of some 1 to 100 nanograms per litre of water. The
concentration was correlated with population density of the region.
Clofibric acid is not produced in Switzerland, so the scientists ruled out
an industrial source - spillage or effluent - immediately. They reached the
only conclusion they could see as possible - that the drug had come from
human waste - faeces and urine. Anything from half to almost all of a drug
taken by a patient can pass through their body without being absorbed or
metabolised and the original form of a drug can also be regenerated from
excreted metabolites. The findings are reported in more detail in the March
21st issue of Science News. Buser notes that the amounts of this particular
drug are very, very small so that they are unlikely to pose a health risk in
the short term- they are present at millions of times less than the usual
prescribed dose. The long-term effects or impact on the environment are not
yet known.
Other scientists too are detecting the presence of pharmaceuticals. Thomas
Heberer and Hans-Jürgen Stan of the Technical University of Berlin have also
found clofibric acid and other lipid-regulating drugs such as phenazone and
fenofibrate in groundwater below a German sewage treatment works. In
addition, they have detected painkillers such as ibuprofen and diclofenac in
the same place. This is perhaps more than a little worrying as the
groundwater is used as a source of drinking water. They will be publishing
their results in the Journal of Environmental Analytical Chemistry.
Thomas Ternes of the Institute for Water Research and Water Technology in
Wiesbaden, has also found startling results: anticholestaemics, painkillers,
antibiotics, beta-blockers, epilepsy drugs and contrast agents all present
in sewage and rivers. Many of the compounds were detected only at parts per
trillion but in small rivers where treated sewage water could form a large
proportion of the volume, numerous pharmaceuticals were found in higher
concentrations (up to 6 ppb). There are likely to be no short-term effects
but who can say what effects continued exposure to even just tiny amounts of
a chemotherapy agent, say, might have on healthy individuals?
Pharmaceuticals have not generally been considered as environmental
pollutants - with the possible exception of the contraceptive pill, which
has received much attention as one of the possible estrogenics allegedly
giving rise to sexless fish, hermaphroditic Florida alligators, and falling
human sperm quality. As such, the regulatory bodies concerned with the
environment have concentrated almost entirely on industrial waste,
pesticides, herbicides, and other agrochemicals and chlorinated organics.
However, as analytical techniques have improved so has the detectability of
even the tiniest traces of other compounds, such as the likes of clofibric
acid, cancer chemotherapy agents, and numerous other pharmaceuticals.
Although the amounts detected are very small, 4 ppb in the case of Buser's
analysis of clofibric acid, their presence raises several issues: Are they a
health risk to those drinking 'contaminated' water? What effect, if any are
they having on the environment? And, in the light of emergence of new
bacterial strains, how will the presence of antibiotic residues in water
affect the development of resistance?
The problem of resistance would obviously depend on the concentrations of
any antibiotics in a body of water. However, the levels of some can affect
bacteria such as Escherichia coli at only the parts per trillion level. US
researchers have found higher levels in effluent from hospitals while the
levels of pharmaceuticals in water being reported in Europe are a thousand
times higher than this limit.
Until July last year [1997], the FDA in the US asked pharmaceutical
manufacturers to estimate how likely it would be for a drug to enter the
environment via the human waste route. The companies did not produce figures
that warranted further investigations on most occasions (less than 1 ppb in
their estimates) and the FDA has dropped the scheme from its approval
process for new drugs.
The profile of individual drugs in terms of their effect on the environment
might, however, be useful in prescribing. If there is an alternative with
less potential environmental impact then why not use that in preference -
providing it is suitable for a patient. It could add yet one more factor to
the design and use of pharmaceuticals and without proof positive that the
effects are worth worrying about legislative pressure will not be brought to
bear and the manufacturers and doctors are unlikely to take note.
In March this year [1998], a US National Research Committee announced that
reclaimed waste water could be used to augment municipal drinking water
supplies. The NRC, is the principal operating agency of the National Academy
of Sciences and the National Academy of Engineering and provides scientific
advice under a congressional charter. The NRC report (Issues in Potable
Reuse: The Viability of Augmenting Drinking-Water Supplies with Reclaimed
Water) points out that waste water should only be used at times of most
extreme needs and then only after major processing criteria have been met.
The presence of industrial and agricultural chemicals would, of course,
preclude a supply from being potable.
The NRC report, however, mentions likely contaminants, and whether they
considered the presence of just small amounts of pharmaceuticals is not
clear.
Much of the European detective work has been carried out over the last few
years with results now being reported in full. It adds yet another factor to
the list of concerns for environmental agencies to contend with. It is
perhaps time pharmaceuticals were considered as potential pollutants
alongside the likes of pesticides, herbicides, fertilisers and organics.
Ever wondered what all those Rx and online prescription spams are about -
read our
Drugs on the Internet article