1. 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 the environment
does not include the study of naturally occurring toxins, for example cholera toxin, or brevitoxin

2. Environmental toxicology is a new discipline that grew out of studies on the environmental fate and transport of pesticides in the 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

3. Environmental toxicology is highly interdisciplinary field

4. 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 of pesticides
Many of these pesticides were known to affect wildlife e.g. kill birds
She lobbied very hard to control and ban certain highly toxic chemicals
Testified before congress in 1963 and called for new policies with respect to human health and the environment

6. 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. First piece of environmental legislation was the National Environmental 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 emissions sources
EPA controls hazardous pollutants
Amended in 1977 to set compliance standards
Amended again in 1990 to regulate acid rain and CFC emissions

8. 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, mesocosm experiment, field test
Federal Water Pollution and Control Act
Provided sewage treatment plant grants for many municipalities
Set effluent limits based on technology standards
Toxicity testing is used to set maximum allowable concentrations of 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

9. 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 environmental impact 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 USA every year, QSAR models or rapid throughput assays are usually used

10. Resource Conservation and Recovery Act
1976
Controlled the disposal of solid waste
Set new hazardous waste regulations
Comprehensive Environmental Response, Compensation and Liabilities Act
Also known as SUPERFUND
1980
Provided funding mechanisms to clean up abandoned waste sites
Amended in 1984 to ban ‘land disposal of hazardous waste
Amended in 1986 to include requirements for community emergency plans and publication of corporate Toxic Release Inventories
Established the SBRP program to develop innovative approaches for cleanup and assessment of hazards

11. Clean Water Act
1987
sets national water quality standards
Toxicological (animal) testing of ‘xenobiotics’ is federally mandated 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

12. Definition : XENOBIOTIC
a chemical that is foreign to the biosphere i.e. is not produced by a natural 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 (chlorbenzoates in fungi) – this is different from large scale chemical processes for the production of PCBs
BTEX is an acronym for benzene, toluene, ethylbenzene, and xzylene – natural ??

13. 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 the environment 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

14. Purpose/function of environmental toxicology is to
Identify the mode / site of action of a xenobiotic
FATE and TRANSPORT / interaction of a xenobiotic with the biosphere (including specific organisms) after it is released / pollution occurs
identify the effect the xenoboitic has on an ecosystems / higher level organisation e.g. loss of fertility of Alligators in Lake Apopca
Introduction of
xenobiotic
Ecosystem
effect
site of
action
biotransformation
physiology
behavior
community
parameters
biochemistry
population
dynamics

15. Parameters of xenobiotic interaction with the ecosystem
Physiology, Behavior
Chromosome damage
Lesions, Necrosis
Tumors
Teratogenic effects
Behavior, Mortality
Community structure
Diversity
Energy transfer
Stability
Succession
Chemical parameters
DNA
RNA
Receptors
Key enzymes
Biochemical integrity
Introduction of
xenobiotic
Ecosystem
effect
Stress proteins
Metabolic indicators
Acetylcholinesterase inhibition
Adenyl energy charge
Metallothionen production
Immuno suppression
enzyme induction
Glutathione S Transferase
Mixed Functional Oxidases
Hydrolases
DNA repair mechanisms
Population density
Productivity
Mating success
Fecundity
Genetic alterations
Competitive alterations

16. How do we measure these effect ?
Physio-chemical characteristics:
QSAR (quantitative structure activity relationship)
Estimate the contribution of portions of the molecule to physio-chemical characteristics
Ionic interactions
Hydrophobic interactions
Van der Vaals forces
Hydrogen bonding

17. Abiotic environmental fate
Partitioning
Adsorption
Transport/advection
PCB vs. Benzene …

18. Biotic environmental fate
The interaction of a xenobiotic at the site of action in an organism is often ‘molecular 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

19. 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

20. 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 stronger effect on juveniles => a shift in age structure might indicate that a population is not doing well, because it is affected by a xenobiotic
Shift in bacterial communities – contamination reduces bacterial diversity; bacterial numbers often increase because the contaminant is food for some while it is toxic for others

21. Community effects Ecosystem effects Species diversity Abundance
Distribution
Ecosystem effects
Productivity
Trophic level structure
Stability