env100 note 57.docx

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28 Mar 2012
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ENV100 Lecture Notes Mar 21, 2012
Northern Exposure: The Tools of CSI Applied to the Environment
Guest lecture: Professor Krull
Selection Criteria
Which chemicals are problems?
o Considerations:
Amounts produced, used, released
Chemical properties
Toxicological properties
Exposure potential
Presence/behaviour in ecosystem
Threat to ecosystem integrity Analytical Chemistry
Analytical Chemistry
Chemical science applied to situations where identification, speciation and quantity are
to be established.
Measurements:
o intrinsic Properties: mass, density, etc.
o chemical interactions: reactions
o effects of externally applied energy
electrochemical
thermal
electromagnetic
Detection & Measurement
ppm: 1 part in a million parts
o 1 g per 10^6 g
o 1 mg/kg
o 1 mg/L
ppb: 1 part in a billion parts
o 1 g per 10^9 g
1 ppt: 1 part in a trillion parts
o 1 g per 10^12 g
Detection & Measurement
A sensitive nose
o can detect the odour of fuel oil at ppb level
Highly sensitive, modern analytical techniques
o can detect and measure concentrations of some chemicals in water and other
media at even better than ppt level
Studies by the U.S.: Geological Survey
The “Toxic Substances Hydrology Program” has found a median of 7 and as many as 38
chemical contaminants in any given water sample. Among the chemicals most
commonly detected in this national survey are known and suspected endocrine
disruptors.
How to determine what is out there?
Improved analytical methods have revealed that trace amounts of pharmaceuticals,
including narcotics, birth control, antidepressants and other controlled substances, are
in the drinking water.
What do these very small concentrations actually mean?
How to detect, and quantify, specific compounds in a sample
there are many methods, and choice often depends on the detection level and sample
complexity
Problems of Detection & Identification
All real samples are complex.
Contain many molecular species and potential interferents.
Concentrations are often verysmall.
Issues of Concern for ecosystem, wildlife & human health
Acid rain
Air quality
Drinking water quality
Global warming
Ground-level ozone
Landfills
Stratospheric ozone depletion
Surface water quality
Hazardous waste
o Chronic vs. Acute Exposure!?
What Are Endocrine Disrupting Chemicals (EDCs)?
The Endocrine System is responsible for regulating many hormone functions in the
body. EDCs mimic natural hormones and interfere with the body’s ability to process
these hormones. This disruption can lead to an array of health problems:
o Growth and Development
o Tissue Functions
o Metabolism
o The Thyroid System
o Insulin
o Kidney Function
o Reproductive Functions
How do EDCs act?
EDCs can act in a number of ways in different parts of the body, they may:
o reduce the production of hormones in endocrine glands,
o affect the release of hormones from endocrine glands,
o copy or counteract the action of hormones at target tissues, or
o speed up the metabolism of hormones and so reduce their action.
What has been established mainly in the laboratory is:
exposure to EDCs during early development (e.g. in the womb, during childhood) may
cause permanent effects,
exposure to EDCs during adult life may not show any significant or visible effects,
exposure to EDCs may produce varying effects depending upon the stage of the life
cycle or even the season, and
unforeseen effects may occur in the target tissues due to endocrine interactions.
Do EDCs affect human health?
At the moment there is no firm evidence that environmental EDCs cause health
problems at low levels of exposure. However, the fact that high levels of chemicals can
impair human health through interferences with the endocrine system, raises concerns
about the possible harmful effects of mixtures of EDCs, even at low background-levels.
It has been suggested that in humans EDCs may be causing:
o reductions in male fertility,
o abnormalities in male reproductive organs,
o female reproductive diseases,
o earlier puberty, and
o declines in the numbers of males born.
Role of Technology
Analytical technologies
o Advanced techniques for detection at very low concentrations (ppt)
o Bioindicators
Chemical evaluation technologies
o Screening to determine transport & fate
o Assessing persistence, toxicity, bioaccumulative tendency
Control technologies
o To control emissions or discharge
Prevention technologies
o New processes, alternative methods
Water Treatment and Removal Efficiencies of EDCs
Coagulation
Lime softening
Biofiltration
Ozonatin and oxidization