Protecting U'K' wildlife from chemicals: the harsh realities

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Protecting U.K. wildlife from chemicals the
harsh realities

• John Sumpter
• Brunel University

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The task Protecting U.K. Biodiversity
An enormous task!
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From what?

• There are about 70,000 man-made chemicals in
  everyday use.
• Many, perhaps most, will reach the aquatic
  environment.
• Some are persistent, others are not.
• Some, possibly most, will degrade into other
  (sometimes unknown) chemicals.
• Exposure is nearly always to highly complex,
  ill-defined mixtures of these chemicals and their
  degradation products.

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What about natural chemicals?

• There are a very large number of these but that
  number is unknown.
• We know even less about the effects of these
  natural chemicals (and their degradation
  products?) on wildlife.
• But, animals have probably co-existed with these
  natural chemicals for a very long period.
• So, our wildlife are likely to be well adapted to
  living in a soup of natural chemicals.
• Therefore, these chemicals tend to be of less
  concern.

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• But are we scaremongering?
• Is there really a problem with chemicals
  affecting our wildlife?

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Two, very different, examples of chemicals
adversely affecting wildlife made us realize that
releasing chemicals into the environment might
sometimes lead to undesirable consequences

• Tributyltin (TBT) causing imposex
  (intersexuality) in molluscs
• DDT causing eggshell thinning in predatory birds

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TBT and Imposex in Molluscs

• TBT was, for decades, the active ingredient of
  antifouling paints used on ships
• It degrades only very slowly in the environment
• It causes irreversible intersexuality in all
  species of molluscs (it masculinizes females)
• This had led to local extinctions of mollusc
  populations

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The wider consequences of TBT contamination of
the aquatic environment

• Mollusc populations crash
• Grazing on algae and macrophytes is reduced
• Plant communities explode, and choke waterways
• Fish populations decline
• Thus, the entire aquatic ecosystem is
  dramatically degraded.

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DDT and Eggshell Thinning in Predatory Birds

• DDT was very widely used for over 30 years
• It bioconcentrated in predators
• In predatory birds (e.g. peregrine falcon) it
  caused eggshell thinning
• This caused most eggs to break before hatching
• Populations of some predatory birds fell
  dramatically
• They have risen since, after the ban on DDT

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Numbers of breeding pairs of peregrine falcons in
the U.K.

• 1968-1972
• (average) 616
• 1988-1991
• (average) 1,338
• 2005 1,258

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Both of these are old examples

• Surely we have learnt from them, and we no longer
  contaminate the environment with chemicals that
  adversely affect our wildlife?

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A more recent example of chemicals unexpectedly
affecting wildlife feminisation of fish
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We have conducted extensive field studies of
endocrine disruption in the roach (Rutilis
rutilis)
We have found many intersex fish
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INTERSEX GONAD (MILDLY AFFECTED FISH)
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RESULTS OF A BREEDING TRIAL IN WHICH THE EFFECT
OF DIFFERENT DEGREES OF INTERSEXUALITY WERE
INVESTIGATED

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The cause of intersexuality in fish?

• The male fish are being feminized by
  oestrogenic chemicals.
• Many chemicals with oestrogenic activity are
  present in STW effluent and are therefore
  released into our rivers.
• Steroid oestrogens, both natural (e.g.
  oestradiol, oestrone) and synthetic (e.g. ethinyl
  oestradiol) appear to be the primary causative
  chemicals.

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KEY LESSONS

• Chemicals released into the environment can have
  unexpected, adverse effects on wildlife.
• In all these cases, the problem was first
  detected after the chemical was used and
  released.
• The adverse effects were noticed first, and then
  began the long, and difficult, task of trying to
  discover what was causing the effects.
• Chemicals were only one possibility.

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The scale of the problem!
Obviously we cannot study 1.75 billion
combinations of chemicals potentially affecting
each and every species of plant and animal.
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But perhaps the problem of determining which
chemicals will affect what wildlife can be
reduced to something manageable.Let us take a
look at the situation with fish as an example.
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Protecting fish from man-made chemicals
But, if all fish species respond in the same
manner to a chemical, the problem becomes
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Can we simplify the problem of such a large
number of chemicals?

• Perhaps there are only a limited
• number of chemicals
• e.g. Surfactants,
• Metals,
• Pesticides,
• Oestrogens,
• Pharmaceuticals
• And therefore the number of chemicals
• may not be 70,000, but instead 100, or 1000.

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Protecting fish from chemicals reality

• Assume
• 6 species of fish are representative of all
  native species
• 100 chemicals are representative of the entire
  milieu of chemicals
• This produces only 600 combinations, or
  experiments needing to be carried out.

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Could we do the necessary tests, to protect all
our fish from chemicals?

• Currently, there are about 50 scientists in the
  U.K. capable of doing the necessary tests.
• A large budget (very many millions) would be
  required.
• Would the results be useful in protecting fish
  from mixtures of chemicals?

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What we do nowWe assess the possible effect of a
new chemical on

• One species of fish
• One species of invertebrate
• One species of plant

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Does this approach work?

• In many cases, probably yes
• - very toxic chemicals, especially those that
  inhibit growth or cause death, are detected
• But sometimes, no
• - the example of ethinyl oestradiol demonstrates
  that some chemicals harmful to wildlife still get
  released into the environment

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Could a better system of assessing the effects of
chemicals on wildlife be developed?

• It needs to be
• Practical
• a highly complex system will not work
• Not too expensive
• it already costs about 100,000 to do the
  minimum testing required
• Ethical
• using more laboratory animals will not be
  acceptable

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A more intelligent system of assessing the impact
of chemicals on wildlife is required.We need to
better utilise all the knowledge we have gained
about how chemicals reach the environment, how
they behave once there, and the mechanisms
underlying the effects they have.
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An example Ethinyl oestradiolExisting Knowledge

• An extremely potent oestrogen
• Very persistent (i.e. does not degrade easily)
• The active ingredient of the contraceptive Pill
• Excreted by users of The Pill
• Will enter rivers in STW effluent
• Fish (like women) produce oestrogens, which are
  necessary for reproduction
• Oestrogens known to be able to feminize fish for
  last 50 years

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Conclusions

• It should have been obvious that ethinyl
  oestradiol would be present in rivers.
• It should also have been obvious that it was
  possible that the chemical would feminize fish.
• We must do better, if we are to protect our
  wildlife from chemicals.

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BUT!

• We know very little about much of our wildlife!
• How would we know if a chemical was adversely
  affecting a beetle, a spider, or a unicellular
  plant?
• Would we even notice their demise?

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Conclusions

• Many biologically active chemicals are present in
  the environment.
• Most originate from humans, so tend to enter the
  aquatic environment in effluents of STWs.
• Some definitely cause effects on wildlife, with
  effects on fish being the most studied.

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Conclusions

• However, for the vast majority of biologically
  active chemicals, we have no idea whether or not
  they cause effects to wildlife.
• It is likely that other examples of chemicals
  affecting wildlife will be uncovered.
• But, we are learning from past experiences, and
  reducing the amount of chemicals we release into
  the environment.

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Finally!

• It is very difficult to rank threats to wildlife
• Even if some chemicals are causing effects to
  some wildlife, are other threats (e.g. new
  diseases, introduced predators, climate change,
  etc) more serious. If they are, would it not be
  wiser to focus on these, and not chemicals!

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THANK YOU FOR LISTENING