BIOLOGY 403:
PRINCIPLES OF ECOLOGY
(Toxics AND Pollution)
POLLUTION & TOXIC SUBSTANCES
• Pollution
an undesirable change in the physical, chemical or
biological characteristics of our air, land and water
that may or will harmfully affect human life or that
of desirable species, our industrial processes, living
conditions, and cultural assets; or that may or will
waste or deteriorate our raw material resources (OR
any addition to the ecosystem that threatens the
health, survival, or activities of humans or other
organisms)
• Virtually anything can be a pollutant.
• Is POLLUTION “in the eye of the beholder” ?
“HARMFUL” CHEMICALS
• What does ‘harmful’ mean? What can be
‘harmful’?
• Hazardous
any chemical that can cause damage to an organism,
structure, etc. (flammable, explosive, irritating,
allergic reactions, asphyxiant, toxic, etc.)
• Poisonous
TECHNICALLY: any chemical which 50
milligrams (or less) per kilogram of body weight
produces LD50
Toxic vs. Toxin
• Toxic
any chemical on or in an organism that can
negatively affect the metabolic functioning of
that organism
• Toxin
any chemical produced metabolically by an
organism which can negatively affect the
functioning of an organism
HOW DO TOXICS WORK
• block, slow down, or speed up essential
functions or the formation of important
metabolites
• interact with the DNA / chromosomes causing
mutations (replication mistakes, missing
pieces, extra pieces, broken chromosomes,
etc.)
WHAT EFFECTS CAN TOXICS
HAVE ON ORGANISMS?
• Mutagenic / Carcinogenic
- Mutagens and Promutagens
- Carcinogens and Procarcinogens
• Teratogenic
- Teratogens and Proteratogens
• Affect Fertility / Reproduction
• Altered Everyday Metabolism / Functioning
RESPONSES TO TOXICS:
• Acute
immediate or rapid reaction, often to small
amounts; effects usually go away rather
rapidly when the toxic is removed
• Chronic
usually takes considerable exposure and long
time period before it shows itself; once the
effects are seen they usually take a while to go
away or sometimes the effects are permanent
Threshold / Distribution
• Some substances will not show ANY effect until a
certain amount (the THRESHOLD) is present.
Once they reach this level they begin to have an
effect.
• Other substances have no threshold.
(a little will have a small effect, a bit more has more
effect, etc.)
It is important when discussing any toxic to know if
it is generally distributed around the body or if it is
localized (concentrated) in a particular part of the
body.
SOME GROUPS OF TOXICS
• Toxins:
Some (?) Antibiotics (Penicillin, Tetracycline,
Streptomycin, Aureomycin, etc.); Pyrethrins;
Rotenone; Alkaloids (nicotine, strychnine,
atropine, digoxine, etc.)
• Radioactive Isotopes
• Synthetic Organic Toxics (concentrating on
pesticides)
• Inorganic Toxics
WHY IS RADIATION HARMFUL?
• Referring here specifically to IONIZING
RADIATION
• can cause burns
• can cause metabolic disturbances
• can induce mutations
not all mutations are harmful
some mutations can lead to cancer
some mutations can be passed on
SOURCES OF IONIZING
RADIATION
• BACKGROUND
• cosmic rays, X-rays, etc. from space and from
materials occurring on the earth
• ANTHROPOGENIC
• Medical (X-rays & other nuclear diagnostic
techniques); Nuclear Power Plants; Nuclear
Fallout; Consumer Products (color TV,
smoke alarms)
IONIZING RADIATION IN mREM
for an average U.S. person at sea level
• BACKGROUND
Cosmic Rays --- 26
Internal --- 39
Soil, water, etc. --- 226
TOTAL: 291
• ANTHROPOGENIC
Medical --- 50
Nuclear Industry --- 1
Nuclear Fallout --- 1
Consumer Products --- 10
TOTAL: 62
• Suggested maximum over the background:
Nuclear Industry Workers --- 5 REM / year
Average Person --- 170 mREM / year
HALF-LIFE OF RADIOACTIVE
MATERIALS (II)
•
•
•
•
•
•
•
•
•
Pu239 ----- 24,000 years
U235 ------ 710 million years
U238 ------ 4.5 billion years
Sr90 ------ 28 years
Ce137 ----- 30 years
I131 ------- 8.1 days*
Co60 ----- 5.27 years*
C14 ------ 5,370 years
Ra226 ---- 1,600 years
*used in medical tests and treatments
RADIOACTIVE SUBSTANCES I
Strontium 90
• common component of nuclear fallout and
nuclear wastes
• half-life of 28 years
• similar to calcium
• more readily taken up by plants than other
fallout materials
• concentrated in bones when taken up by
higher animals
• can cause leukemia
RADIOACTIVE SUBSTANCES II
Cesium 137
•
•
•
•
•
•
•
has a half-life of about 30 years
common component of nuclear fallout
similar to potassium
caused problems in arctic and subarctic areas
greatly concentrated by lichens
lichens are main winter food of reindeer & caribou
wolves and native human populations existed
largely on reindeer and caribou
• problem has been decreasing since the 1970’s
• WHY?
RADIOACTIVE SUBSTANCES III
Iodine
• short half-life (8.1 days)
• was a localized problem in the south Pacific in
the 1950’s to the 1970’s
• WHY?
|
• caused thyroid tumors, especially in children
SYNTHETIC ORGANIC TOXICS
(concentrating on pesticides)
• designed to kill / inhibit a large number of
organisms (plants, algae, fungi, bacteria,
insects, rodents, etc.)
• a very large number of compounds
• for convenience we can ‘lump’ these
chemicals into ‘chemical families’
• two families will be studied as examples of
synthetic organic toxics
ORGANOPHOSPHATE COMPOUNDS
• Examples include: malathion, parathion, chlorthion
and phosdrin
• derivatives of a WWII nerve gas, TABUN
• inhibitors of the enzyme CHOLINESTERASE
• results in hyperactivity of the nervous system
• ‘BAD NEWS’ - some are very deadly, even to humans
• ‘GOOD NEWS’ - have very short half-lives, therefore
T.L. concentration usually is not a consideration
ORGANOCHLORINE COMPOUNDS
(also called chlorinated hydrocarbons)
• Examples include: DDT (dichlorodiphenyltrichlorethane)
(DDD & DDE), toxaphene, aldrin, chlordane, dieldrin,
lindane, endrin, heptachlor, kepone, 2,4-D & 2,4,5-T
• most of these have a fairly high toxicity to a wide
range of organisms
• most of these are chemically stable and have relatively
long half-lives (a few years to several decades)
• some form breakdown products which are also toxic
• concentrated in food chains because they are lipid
soluble (and have a long half-life)
HOW TIMES CHANGE
DDT CONCENTRATION IN THE
FATTY TISSUES OF ORGANISMS
‘PROBLEMS’ WITH
ORGANOCHLORINES (I)
• Spraying at Clear Lake (north Of San Francisco)
• midge problem
• DDD applied in 1949, 1954 and 1957 at 0.025 ppm
• 1st and 2nd applications produced 99% kill
• 3rd application had limited and brief ‘success’
• midges evolved resistance
• pesticides accumulated in all aquatic life in the lake
• most fish exceeded the 7 ppm limit set by FDA
‘PROBLEMS’ WITH
ORGANOCHLORINES (II)
• colony of 1,000 Western Grebes breeding at the lake
died out (body fat had 1,600 ppm DDD - a 64,000x
increase in concentration over the water
• extensive mortality in other Grebes visiting and
feeding at the lake
---------------------------------------------------------------------• numerous problems associated with organochlorine
use soon showed up worldwide
• Silent Spring by Rachel Carson (1962) alerted us to
T.L. concentration of these compounds and their
effects on non-target organisms
‘PROBLEMS’ WITH
ORGANOCHLORINES (III)
• World-wide contamination of food webs
• mortality in Robins and other songbirds, high
mortality in Bald Eagles, Pelicans and other predatory
birds
• decrease in fertility in many bird species
• decrease in rates of photosynthesis in aquatic algae
• decrease in ability of gills to take up oxygen in fish
• use of Agent Orange - a mixture of 2,4-D and 2,4,5-T
(contaminated with dioxins)
• PCB’s
62,000,000x T.L.
CONCENTRATION OF PCB’s
INORGANIC TOXICS (I)
• Copper ----- main use is as an algacide
• Mercury ----- used as a seed treatment; found
in coal; used in silent switches, mercury
vapor lamps, thermometers, as an electrode in
chlorine production
- Mad Hatter
- Minimata Bay, Japan
- eating foods made with treated seed
INORGANIC TOXICS (II)
• Arsenic
- one of the original pesticides
- used in the extraction of gold
- makes for good murder mysteries
• Lead
- solder and lead based paints
- gasoline additive
- pewter and leaded crystal
- some poorly glazed pottery / dishes
- ancient Romans
- arctic expedition
? WHAT TO DO ABOUT TOXICS ?
(PARTICULARLY PESTICIDES)
• More rigidly controlled use (place and amount)
• replacement with less toxic materials / pesticides
• replacement with more rapidly degrading materials /
pesticides
• replacement with more specific pesticides
• breed crops which are resistant to pests (don’t need
pesticide or as much pesticide)
• eliminate / reduce crops which are pest prone and also
provide little of ‘real’ value
• use BIOLOGICAL CONTROL instead of pesticides
• use IPM practices in crop production
INTEGRATED PEST
MANAGEMENT (IPM)
• A high synergy management practice
• education to use a wide variety of pest control
practices
- crop rotation
- crop replacement
- Biological Control
- coordination of efforts (proper planting time,
work with others in the region)
- pesticides (if necessary) and then in the
proper way, amount, time, place, etc.
BIOLOGICAL CONTROL (I)
• DEFINITION
the use of predators, parasites, diseases or some
unique attribute of the pest species to control it
• Cottony Cushion Scale
1st biological control project
used Vedalia Ladybird Beetle to control this pest
in the citrus groves of southern California
• Prickly Pear Cactus
in Australia; controlled by an argentine cactus
moth
BIOLOGICAL CONTROL (II)
• stem tip and seed boring beetles on Puncture
Vine in western U.S.
• Gypsy Moth control in the U.S. with several
parasitic wasps and flies AND with BT
(Bacillus thuringiensis) against the caterpillar
stage; sex lures for the adult males
• Various Viruses and Bacteria on immature
stages of Codling Moth, Boll Weevil, Japanese
Beetle, Mosquitoes, and many more
• Sex and floral lures for Japanese Beetles
GYPSY MOTH
GYPSY MOTH
BIOLOGICAL CONTROL (III)
ATTEMPTS THAT FAILED
(AND MADE FOR ADDITIONAL PROBLEMS)
• Cane Field Toad in Australia failed to control the
cane borer.
• Mongoose introduced into Hawaii for rat control
didn’t work.
RISKS (I)
• EVERYTHING you do (or don’t do) poses
some risk!
• Risk Analysis --- What are the ‘costs’ vs.
what are the ‘benefits’ ???????????????
• What level of risk is acceptable for a
particular amount of benefit????????
RISKS (II)
RISKS (III)
AVERAGE YEARS OF LIFE LOST DUE
TO OCCUPATIONAL ACCIDENTS
• Civilian Airplane Crew ........................................... 2.0
• Commercial Fishing ................................................. 1.5
• Coal Miner ................................................................ 1.5
• Construction .............................................................. 1.5
• Manufacturing ........................................................... 0.3
• Nuclear (if 5,000 mREM / year) ............................ 0.6
• Nuclear (if 500 mREM / year) ............................. 0.06
RISKS (IV)
AVERAGE NUMBER OF DAYS OF LIFE
GIVEN UP FOR CERTAIN “BENEFITS”
• Living in a City (rather than in the country) ... 1,800
• Remaining Unmarried ............................................. 1,800
• Smoking (one pack / day) ........................................ 3,000
• 10 lbs. Overweight ....................................................... 500
• Automobiles .................................................................. 240
• “The Pill”........................................................................ 30
• Drowning Risk While Swimming .............................. 25
• 170 mREM / yr of Radiation....................................... 10
(average background levels)
RISKS (V)