Ecology: Theory & Practice

Ecology: Theory & Practice Course Lecture Notes Site Map

WeeK

Week 8: Toxic Materials in the Environment
The Nature of Toxicity

Concentration, dose levels, chronic vs. acute exposure, LD-50's
Type of toxicant (chemical/biological; carcinogens, mutagens, teratogens, radioactive compounds, pathogens)
Synthetic versus biodegradable chemicals
Risk Assessment techniques (estimating risk before exposure)
Communication between toxicologists, physicians, ecologists, chemists, etc. (IRM Model)
Pathways of dispersal in the environment (biogeochemical cycles)

Pollutants, Pathways & Impacts

Biomagnification of toxic chemicals in food chains (e.g., mercury, DDT, radionuclides)
Waterborne pollutants (e.g., dioxins, chlorinated HCNs, metals, Gonyaulax, Pfeisteria)
Soil contaminants (e.g., petroleum byproducts, mining byproducts, industrial chemicals, pesticides, organic solvents, radioisotopes)
Degree & duration of exposure (lethal compounds; debilitating compounds; larval sensitivity; dosage to body size, e.g. children vs. adults)
Threshold and non-threshold toxicants
Naturally occurring toxics that circulate through ecosystems (e.g., arsenic, radon, oil seeps, biologic agents)

Managing Toxics in the U.S. (Essential for survival of all life forms, including humans)

Environmental Outrage in the 1970s (led to passage of powerful U.S. laws)
Resource Conservation and Recovery Act - RCRA

Regulates waste disposal of all types, including landfills, incineration, recycling, etc.
Characterized by its "cradle to grave" tracking of toxic wastes and
Emphsizes proper management of solid wastes (source reduction; recycling)

Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)

Also known as the Superfund Act
Elaborate law designed to oversee cleanup of past contamination
Funded by fines collected from polluters or "responsible parties," along with taxes on industrial corporations
Based on the assumption that the "polluter must pay" and pay more when not cooperative with EPA
The worst sites are rated on the "National Priority List" or NPL
Early stages of cleanup are a remediation investigation and feasibility study (RIFS)
Many critics see the law as too cumbersome or too slow in cleaning up sites

Other Laws that Regulate Toxics

Clean Water Act (regulates sewage wastes; grants NPDES permits regulating release of pollutants into public waterways)
Safe Drinking Water Act (regulates groundwater wells, aquifers and reservoirs)
Oil Spill Protection Act (regulates cleanup of oil spills; sets liabibility and penalties)
Pesticide control laws

Federal and State Agencies which Implement these Laws

U.S. Environmental Protection Agency (USEPA) - broad oversight powers
State Environmental Protection Agencies (e.g., R.I. Department of Environmental Management - RIDEM)
U.S. Department of Energy - DOE (oversight of energy industries)
Nuclear Regulatory Agency - NRC (oversight of the nuclear energy industry)
U.S. Department of the Interior (regulates leases of public lands, including mining and forestry sites)

Key terms we use to describe the effects of toxics

Toxicity	PCBs	Waste Manifest
Threshhold	Radionuclides	NPDES Permit
Carcinogen	Radon	Treble Damages
Mutagen	Hormone Disrupters	NPL
Teratogen	LD-50	USEPA
Risk Assessment	Methyl Mercury	RIFS
IRM Model	RCRA	RIDEM
Dioxins	CERCLA	Chernobyl
Pesticides	Cradle to Grave Tracking	Thyroid Cancer
Childhood Leukemia	Acute vs. Chronic Exposure	Sulfur Dioxide
Nitrogen oxides	Carbon Dioxide	PANs
Methane	CFCs	Greenhouse Gases
Stratospheric OzoneDepletion	NAAQS	SIPs
NRC	Three Mile Island Accident	Bhopal Chemical Accident

Focus Questions for Week 8
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copyright Gaytha A. Langlois, Ph.D., 1999 Bryant College, Smithfield, RI 02917 E-mail: langlois@bryant.edu Last Updated: August 2000