Pollution

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Unit 4 Environmental Science Revision Lecture
1 Pollution and Health Monday October
14th Melbourne University
Peter Hamilton Sandringham College
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Pollution and Environmental Health

• Pollutants,
• environmental human health,
• health of the environment,
• environmental hazards.
• point and diffuse sources of pollution,
• pollutant sinks.
• Transport mechanisms of pollutants, including
• persistence,
• mobility,
• bioaccumulation.

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Pollution and Health

• Exposure,
• dosage,
• chronic and acute toxicity,
• allergies,
• specificity,
• synergistic action.
• Pollutants in emerging issues in human health,
  for example endocrine disruptors, particles in
  the atmosphere.
• Factors that reduce the risk of pollutants
  affecting human health and the environment
  through strategies such as environmental risk
  assessment and management, Australian Design
  Rules for motor vehicles.

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For Any Pollutant

• The important factors to identify include the
  following

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• Properties
• Solid /liquid gas
• Melting / Boiling Points
• Flammability
• Solubility

• Fate
• Persistence
• Elimination

• Mobility
• Transport mechanisms

• Impact
• Effects on Organisms and Environment

Source

• Exposure
• Dosage
• Toxicity

Strategies to mitigate effects
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Pollution

• Contamination of air,water, or soil with
  undesirable amounts of materials or energy.

• An undesirable change in the physical, chemical
  or biological characteristics of air, water,soil
  or food that can adversely affect the health,
  survival or activities of humans or other living
  organisms.

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Environmental Health
Ecological integrity the ability of the
environment to retain its complexity and capacity
for self-organization (its health) and sufficient
diversity, within its structures and functions,
to maintain the ecosystem's self-organizing
complexity through time.
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Environmental hazard

• The potential for a substance or situation to
  cause harm or to create adverse impacts on
  persons, the environment, and/or property.

• Lead is a hazardous substance with the potential
  to cause harm if inhaled over a period of time.

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Risk

• The probability of a substance or situation to
  cause harm or to create adverse impacts upon
  persons, the environment and/or property.

• The risk of lead causing harm is increased by its
  presence in leaded petrol burnt in combustion
  engines.

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A risk is a combination of the Hazard and also
the Probability that the hazard will happen.
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Source of Pollutants
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Point-Source Pollution

• Pollutants released from specific points that may
  be collected, treated or controlled.
• eg
• domestic waste water
• industrial wastes
• sewage treatment effluent

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Non-point / Diffuse sources of Pollution

• a diffuse source of pollution that cannot be
  attributed to a clearly identifiable, specific
  physical location or a defined discharge channel.
• eg
• general runoff of sediments
• pesticide spraying
• fertilisers from farms an urban areas

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• Non-point Source Pollution
• includes the nutrients that runoff the ground
  from any land use - croplands, feedlots, lawns,
  parking lots, streets, forests, etc. - and enter
  waterways.
• also includes nutrients that enter through air
  pollution, through the groundwater, or from
  septic systems.

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• Non-point Source Pollution
• Can be caused by rainfall or snowmelt moving
  over and through the ground.
• As the runoff moves, it picks up and carries
  away natural and human-made pollutants, finally
  depositing them into lakes, rivers, wetlands,
  coastal waters, and even our underground sources
  of drinking water.

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Point / Non Point source Pollution

• No clear cut distinction
• eg a number of individual point source
  discharges can result in diffuse source pollution
  on a local /regional scale.
• Eg air pollution from cars
• Fugitive emissions emissions which escape from
  a number of points around a building.
• eg the smell of a cheese factory
• Difficult to control.

• Mobile emissions from mobile sources.
• eg cars.
• Can be controlled by installation
• of pollution control devices

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The Pathways of Pollutants

• Risk to organisms and the environment depends
  upon how the pollutant is transported through the
  environment.
• Particles or compounds that can be dispersed by
  air / wind currents are likely to be inhaled,
  absorbed through dermal contact and ingested.
• Compounds that dissolve in and are dispersed by
  water are likely to be ingested, absorbed through
  dermal contact but are less likely to be inhaled
  by terrestrial organisms.
• Compounds that are fat soluble are likely to
  biomagnify and therefore pass through the food
  web and be ingested.

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Exposure How much of a pollutant an organism
is exposed to over a specific period of time.
Dosage the amount of a chemical absorbed per
unit body weight.
Toxicity a measure of the harm a substance can
cause an organism.
Ingestion Inhalation Dermal absorption

• Respiration rate
• Hazard concentration
• Frequency of exposure
• Length of exposure
• Properties of the chemical
• Body size
• Allergies

Impact
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Health Effects of Chemical Pollutants

• Toxic Substances
• Hazardous substances
• Carcinogens
• Mutagens
• Teratogens

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Toxicity

• Acute toxicity
• the adverse health effects from a single dose or
  exposure to a toxic chemical or substance.

• Chronic toxicity
• the adverse health effects of repeated doses or
  exposure to a chemical or substance over a
  relatively prolonged period.

• Threshold
• the level of the exposure below which there is no
  adverse effect and above which there is a
  significant toxicological effect.

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LD50 test - Acute toxicity

• LD50 Lethal Dose 50
• the dose of a substance that will kill half the
  test animals.
• usually expressed as mg/kg.
• eg
• if it took 400 milligrams of a test substance to
  kill half the rabbits weighing 4 kilograms, then
  the LD50 is 100mg/kg.
• Oral LD50(rat) - 100mg/kg

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Synergistic action
2 2 8

• The phenomenon in which two factors acting
  together have a much greater effect than would
  indicated by the sum of their effects separately.
• eg the impact of a low dose of toxin A and B
  administered together has a far greater effect
  than the sum of the toxins administered
  individually.

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Persistence and Fate

• The fate of pollutants depends on
• Chemical Stability
• Photo-degradabilty
• Bio-degradability
• Metabolism
• Bioaccumulation
• Accumulation in specific tissues
• eg liver, brain etc
• Mobility
• Dispersal

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Fate of oil spilled at sea showing the main
weathering processes
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Fate Pollutant sinks

• Sink a process or place that removes, stores or
  absorbs a pollutant.
• eg1 Carbon dioxide sequestration
• by dissolving water.
• in plants, by photosynthesis.
• eg2 Phosphates
• adhering to particulate matter which settles out
  in bottom sediments.
• in organisms.

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Physical / Chemical Properties

• Affect the entry/ uptake, the transport and the
  storage/fate of the toxicant.
• Melting pt
• Boiling Point
• Density
• Flammability
• Solubility in water
• Solubility in other solvents eg fats

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• Uptake
• the entrance of a chemical into an organism such
  as by breathing, swallowing, or absorbing it
  through the skin without regard to its subsequent
  storage, metabolism, or excretion by that
  organism.
• Storage
• the temporary deposit of a chemical in body
  tissue or in an organ.

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Uptake

• Bioaccumulation begins when a chemical passes
  from the environment into an organism's cells.
• Chemicals tend to move, or diffuse, passively
  from a place of higher concentration to one of
  lower concentration it works to move a chemical
  from outside to inside an organism.

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Bioaccumulation

• an increase in the concentration of a chemical
  over time in a biological organism compared to
  the chemical's concentration in the environment.
• Compounds accumulate in living things any time
  they are taken up and stored faster than they are
  broken down (metabolised) or excreted.
• is the net result of the interaction of
• uptake
• storage
• elimination of a chemical

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Bioconcentration

• the specific bioaccumulation process by which the
  concentration of a chemical in an organism
  becomes higher than its concentration in the air
  or water around the organism.
• usually refers to chemicals foreign to the
  organism.

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Biomagnification

• a process that results in the accumulation of a
  chemical in an organism at higher levels than are
  found in its own food.
• occurs when a chemical becomes more and more
  concentrated as it moves up through a food chain.

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Biomagnification
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Uptake and Storage

• factors may increase the chemical potential of
  certain substances.
• solubility in water compared to fats and oils
• substances more soluble in lipids ( fats and
  oils) will tend to move out of water into cells.

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Water soluble compounds

• Compounds that are highly water soluble have a
  low potential to bioaccumulate and do not readily
  enter the cells of an organism.
• Once inside the organism, they are easily removed
  unless the cells have a specific mechanism for
  retaining them.

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• Heavy metals like mercury and certain other
  water-soluble chemicals are the exceptions,
  because they bind tightly to specific sites
  within the body.
• When binding occurs, even highly water-soluble
  chemicals can accumulate.

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Elimination

• Another factor affecting bioaccumulation
• is whether an organism can break down and/or
  excrete a chemical.
• The biological breakdown of chemicals is called
  metabolism. This ability varies among individual
  organisms and species and also depends on the
  chemical's characteristics.
• Chemicals that dissolve readily in fat but not in
  water tend to be more slowly eliminated by the
  body and thus have a greater potential to
  accumulate.

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Emerging Environmental Health Issues
Lead
GM
Endocrine Disruptors
Asbestosis
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• The endocrine system works in parallel with the
  nervous system to control growth and maturation
  along with homeostasis.

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Endocrine disruptors

• Synthetic or naturally occurring chemicals that
  affect the Endocrine or hormonal system of
  animals
• May either
• Mimic hormones causing inappropriate responses or
  over response to a stimulus.
• Block hormone activities thus preventing a
  response.
• May directly stimulate or inhibit the endocrine
  system resulting in either overproduction or
  under production of a hormone.

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Major Sources

• Synthetic origin
• eg DES diethylstilbestrol originally prescribed
  for preventing miscarriage 1948-1972.
• Natural Origin phyto-oestrogens include
  soybeans, apples, cherries, wheat and peas.
• Environmental endocrine disruptors (EEDs)
  incudes environmental pollutants such as
  organochlorides eg PCB's

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Effects of Endocrine Disruptors

• At high doses, can affect an animal's endocrine
  system, especially during critical developmental
  stages.
• May cause reproductive and developmental
  problems.

Abnormal gonads in a male Xenopus frog, the
result of exposure to the herbicide atrazine.
Male juvenile alligators became feminized, had
smaller than normal penises, abnormal testes and
had higher estrogen levels and lower testosterone
levels.