kukor lect 1_what is enviro toxicol
TRANSCRIPT
-
7/31/2019 Kukor Lect 1_What is Enviro Toxicol
1/21
What is environmental toxicology ?
ecotoxicology
Definition: study of impacts of pollutants on the
structure and function of ecosystems
manmade poisonous chemicals and their effect on theenvironment
does not include the study of naturally occurring toxins, forexample cholera toxin, or brevitoxin
-
7/31/2019 Kukor Lect 1_What is Enviro Toxicol
2/21
Environmental toxicology is a new discipline that grew out ofstudies on the environmental fate and transport of pesticides inthe 1940s and 1950s
The discipline toxicology is as old as medicine many toxic
plant chemicals are used as therapeutic agents in medicine.
The term ecotoxicology appeared in the literature in 1969
Field was pioneered by Rachel Carson
-
7/31/2019 Kukor Lect 1_What is Enviro Toxicol
3/21
Environmental toxicology is highly interdisciplinary field
-
7/31/2019 Kukor Lect 1_What is Enviro Toxicol
4/21
Rachel Carson
1907-1964 Marine Biologist from Pennsylvania
MA from Johns Hopkins U.
Author of Silent Spring
Received much attention, because she wrote
and presented scientific facts well
She was disturbed by the widespread and indiscriminate use ofpesticides
Many of these pesticides were known to affect wildlife e.g. kill birds
She lobbied very hard to control and ban certain highly toxicchemicals
Testified before congress in 1963 and called for new policies withrespect to human health and the environment
-
7/31/2019 Kukor Lect 1_What is Enviro Toxicol
5/21
-
7/31/2019 Kukor Lect 1_What is Enviro Toxicol
6/21
Environmental toxicology is driven by legislation
National Environmental Policy Act
Clean Air Act
Federal Environmental Pesticide Control Act
Federal Water Pollution Control Act
Safe Drinking Water Act
Toxic Substances Control Act
Resource Conservation and Recovery Act
Comprehensive Environmental Response, Compensation and Liabilities Act
Clean Water Act
-
7/31/2019 Kukor Lect 1_What is Enviro Toxicol
7/21
First piece of environmental legislation was the NationalEnvironmental Policy Act 1970
Created the EPA Initially 5000 employees (1970)
Budget of 1.3 B
In 1995 there were >18,000 employees, budget of 7.2 B
USA is divided into 10 management regions
Clean Air Act Also in 1970
Required the EPA to set standards
EPA in charge of controlling mobile and stationary emissionssources
EPA controls hazardous pollutants
Amended in 1977 to set compliance standards
Amended again in 1990 to regulate acid rain and CFC emissions
-
7/31/2019 Kukor Lect 1_What is Enviro Toxicol
8/21
Federal Environmental Pesticide Control Act 1972
amended to FIFRA Federal Insecticide, Fungicide, and
Rodendicide Act Required manufactures to provide PMNs (Pre Manufacture
Notice) with toxicological information to register a pesticide
Sets up system of tiered toxicity testing mechanism, mesocosmexperiment, field test
Federal Water Pollution and Control Act 1972
Provided sewage treatment plant grants for many municipalities
Set effluent limits based on technology standards
Toxicity testing is used to set maximum allowable concentrationsof toxicants in discharges and receiving waters
Goal was to have all water fishable and swimable by 1983
Established goal to eliminate pollution discharges by 1985
-
7/31/2019 Kukor Lect 1_What is Enviro Toxicol
9/21
Safe Drinking Water Act 1974
Set mandatory drinking water standards
Controlled underground injection of wastes (aquifer protection) Amended in 1984 to set a schedule for establishing drinking
water standards for 80 chemicals (provides notice to consumers)
Toxic Substances Control Act 1976
Regulated the use of chemicals in manufacturing and production
Goal was to characterize the human health and environmentalimpact of EVERY chemical manufactured in the USA
EPA has only 90 days to review the PMN to evaluate data
Because there are thousands of chemicals produced in the USAevery year, QSAR models or rapid throughput assays are usuallyused
-
7/31/2019 Kukor Lect 1_What is Enviro Toxicol
10/21
Resource Conservation and Recovery Act 1976
Controlled the disposal of solid waste
Set new hazardous waste regulations
Comprehensive Environmental Response, Compensationand Liabilities Act
Also known as SUPERFUND 1980
Provided funding mechanisms to clean up abandoned wastesites
Amended in 1984 to ban land disposal of hazardous waste
Amended in 1986 to include requirements for communityemergency plans and publication of corporate Toxic ReleaseInventories
Established the SBRP program to develop innovative approachesfor cleanup and assessment of hazards
-
7/31/2019 Kukor Lect 1_What is Enviro Toxicol
11/21
Clean Water Act
1987
sets national water quality standards
Toxicological (animal) testing of xenobiotics is federallymandated by
Federal Insecticide, Fungicide, and Rodendicide Act (FIFRA)
Federal Environmental Pesticide Control Act
Federal Water Pollution Control Act
Safe Drinking water act
Toxic Substances control Act
-
7/31/2019 Kukor Lect 1_What is Enviro Toxicol
12/21
Definition : XENOBIOTIC
a chemical that is foreign to the biosphere i.e. is not produced by anatural biological or abiotic source
Also called anthropogenic, man-made, synthetic, pollutant,contaminant, recalcitrant, persistent, and toxicant
Distinguishes between quantity and scale Gordon Gribble e.g.studied the natural occurrence of organohallogens (chlorbenzoatesin fungi) this is different from large scale chemical processes forthe production of PCBs
BTEX is an acronym for benzene, toluene, ethylbenzene, andxzylene natural ??
-
7/31/2019 Kukor Lect 1_What is Enviro Toxicol
13/21
Environmental toxicology depends on
Lab work Effects of toxicants on biochemistry and physiology
Field work Field observations of reproduction and survival in polluted vs.
non-polluted sites
Modeling of fate and transport of toxicants in theenvironment i.e. exposure and risk assessment
Static models : short term modeling of ecosystems
Strategic models : model of a specific aspect of a
system
Testable models : model makes predictions that can
be tested in the field or laboratory
-
7/31/2019 Kukor Lect 1_What is Enviro Toxicol
14/21
Purpose/function of environmental toxicology is to
Identify the mode / site of action of a xenobiotic
FATE and TRANSPORT / interaction of a xenobiotic with thebiosphere (including specific organisms) after it is released /pollution occurs
identify the effect the xenoboitic has on an ecosystems / higherlevel organisation e.g. loss of fertility of Alligators in Lake Apopca
Introduction ofxenobiotic
Ecosystemeffect
site ofaction
biotransformation
physiologybehavior
communityparameters
biochemistry population
dynamics
-
7/31/2019 Kukor Lect 1_What is Enviro Toxicol
15/21
Introduction ofxenobiotic
Ecosystemeffect
DNARNA
ReceptorsKey enzymes
Biochemical integrity
enzyme inductionGlutathione S TransferaseMixed Functional Oxidases
HydrolasesDNA repair mechanisms
Physiology, BehaviorChromosome damage
Lesions, NecrosisTumors
Teratogenic effectsBehavior, Mortality
Community structure
DiversityEnergy transfer
StabilitySuccession
Chemical parameters
Stress proteins
Metabolic indicatorsAcetylcholinesterase inhibition
Adenyl energy chargeMetallothionen production
Immuno suppression
Population densityProductivityMating success
FecundityGenetic alterations
Competitive alterations
Parameters of xenobiotic interaction with the ecosystem
-
7/31/2019 Kukor Lect 1_What is Enviro Toxicol
16/21
How do we measure these effect ?
Physio-chemical characteristics:
QSAR (quantitative structure activity relationship)
CH2
NH
CH
O
CH
N
O
S
CH3
CH3
COOH
CH2
O
HN
CH CH
N
O
S
HC
N
S
CH3
CH3
COOH
CH3
CH3
COOH
Estimate the contribution of portions of the molecule to physio-chemical characteristics
Ionic interactions
Hydrophobic interactions
Van der Vaals forces
Hydrogen bonding
-
7/31/2019 Kukor Lect 1_What is Enviro Toxicol
17/21
Abiotic environmental fate
Partitioning
Adsorption Transport/advection
PCB vs. Benzene
-
7/31/2019 Kukor Lect 1_What is Enviro Toxicol
18/21
Biotic environmental fate
The interaction of a xenobiotic at the site of action in an organism is oftenmolecular happenstance i.e. xenobiotic mimic compounds which are naturally
found in species that they affect hormone mimics
Bioaccumulation
The storage of a compound in fatty tissue of an animal
Result of food chain / trophic levels
Biotransformation
Metabolic processes, mainly by environmental bacteria, that alter the
structure and toxicity of a compound
Biodegradation
Breakdown of a xenobiotic to CO2 and water
-
7/31/2019 Kukor Lect 1_What is Enviro Toxicol
19/21
Biotic mode of action (Receptors)
Chemicals that interfere with biochemical receptor sites
Signaling
proteins in membranes
Replication
Protein synthesis
Chemicals that damage biochemical or molecular targets
DNA damage
Strange breakage
Chromosome abnormalities
Cancer
Non-genotoxic effects such as immunosuppression
-
7/31/2019 Kukor Lect 1_What is Enviro Toxicol
20/21
Physiological and behavioral effects
Standard tool for assessing toxicological effects on populations Tissue lesions
Tumors
Reproductive success
Population success
Population age structure xenobiotics often exert a strongereffect on juveniles => a shift in age structure might indicate that apopulation is not doing well, because it is affected by a
xenobiotic Shift in bacterial communities contamination reduces bacterial
diversity; bacterial numbers often increase because thecontaminant is food for some while it is toxic for others
-
7/31/2019 Kukor Lect 1_What is Enviro Toxicol
21/21
Community effects
Species diversity
Abundance Distribution
Ecosystem effects
Productivity Trophic level structure Stability