BIOLOGY 157: LIFE SCIENCE: AN

ENVIRONMENTAL APPROACH (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

• Hazardous

any chemical that can cause harm (flammable, explosive, irritating, allergic reactions, asphyxiants, disease, etc.)

• Poisonous

TECHNICALLY: any chemical which 50 milligrams (or less) per kilogram of body weight produces LD50

Toxic vs. Toxin

• Toxic

any chemical that can negatively affect the metabolism of an organism

• Toxin

any chemical produced metabolically by an organism which can negatively affect the metabolism 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 US?

• 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 vs. Non-threshold

• Some substances will not show ANY effect until a certain amount is present. Once they reach this amount they begin to have an effect. They must exceed a certain THRESHOLD.

• Other substances have no threshold. A little will have a small effect, a bit more has more effect, etc.

Whole Body vs. Localized Concentrations

It is important when discussing any toxic to know whether or not is is generally distributed around the body or whether it is localized (concentrated) in a particular part of the body.

SOME GROUPS OF TOXICS

• Toxins

• Radioactive Substances

• Synthetic Organic Toxics (concentrating on pesticides)

• Inorganic Toxics

TOXINS

• Some Antibiotics Penicillin, Tetracycline, Streptomycin,

Aureomycin, etc.

• Pyrethrins

• Rotenone

• Alkaloids (nicotine, strychnine, atropine, digoxine, etc.)

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 the earth materials themselves

• ANTHROPOGENIC

• Medical (X-rays & other nuclear diagnostic techniques); Nuclear Power Plants; Nuclear Fallout; Consumer Products (color TV, smoke alarms)

IONIZING RADIATION IN mREMfor an average U.S. person

• BACKGROUNDCosmic Rays --- 30Internal --- 30 TOTAL: 170Soil, water, etc. --- 110

• ANTHROPOGENICMedical --- 55Nuclear Industry --- 1Nuclear Fallout --- 4 TOTAL: 70Consumer Products --- 10

• Suggested maximum over the background:Nuclear Industry Workers --- 5 REM / yearAverage Person --- 170 mREM / year

HALF-LIFE OF RADIOACTIVE MATERIALS (I)

HALF-LIFE OF RADIOACTIVE MATERIALS (II)

• Pu239 ----- 240,000 years

• U235 ----- 710 million years

• U238 ----- 4.5 billion years

• Sr90 ----- 28 years

• Ce137 ----- 15 years

• I131 ----- 8.04 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 IICesium 137

• has a half-life of about 15 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 IIIIodine

• short half-life (8 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

• problems related to 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)

SOME QUESTIONS FROM CHAPTER 8

• How much risk is acceptable for environmental hazards?

• We did not discuss diseases. Below are some things that involve “diseases”.

• What is a Pathogen?

• What is an Emergent Disease?

• What is an Ecological Disease?