RA— Reasonable Alternative;
Regulatory Alternatives; Regulatory Analysis;
Remedial Action; Resource Allocation; Risk
Analysis; Risk Assessment
RAATS— RCRA Administrate Action Tracking
RAC— Radiation Advisory Committee. Raw
Agricultural Commodity; Regional Asbestos
Coordinator. Response Action Coordinator
RACM— Reasonably Available Control Measures
RACT— Reasonably Available Control Technology
RAD— Radiation Adsorbed Dose (unit of
measurement of radiation absorbed by humans)
RADM— Random Walk Advection and Dispersion
Model; Regional Acid Deposition Model
RAM— Urban Air Quality Model for Point
and Area Source in EPA UNAMAP Series
RAMP— Rural Abandoned Mine Program
RAMS— Regional Air Monitoring System
RAP— Radon Action Program; Registration
Assessment Panel; Remedial Accomplishment
Plan; Response Action Plan
RAPS— Regional Air Pollution Study
RARG— Regulatory Analysis Review Group
RAS— Routine Analytical Service
RAT— Relative Accuracy Test
RB— Request for Bid
RBAC— Re-use Business Assistance Center
RBC— Red Blood Cell
RC— Responsibility Center
RCC— Radiation Coordinating Council
RCDO— Regional Case Development Officer
RCO— Regional Compliance Officer
RCP— Research Centers Program
RCRA— Resource Conservation and Recovery
RCRIS— Resource Conservation and Recovery
RD/RA— Remedial Design/ Remedial Action
R&D— Research and Development
RD&D— Research, Development and
RDF— Refuse-Derived Fuel
RDNA— Recombinant DNA
RDU— Regional Decision Units
RDV— Reference Dose Values
RE— Reasonable Efforts; Reportable Event
REAP— Regional Enforcement Activities
REE— Rare Earth Elements
REEP— Review of Environmental Effects
RECLAIM— Regional Clean Air Initiatives
RED— Reregistration Eligibility Decision
REDA— Recycling Economic Development
ReFIT— Reinvention for Innovative Technologies
REI— Restricted Entry Interval
REM— (Roentgen Equivalent Man)
REM/FIT— Remedial/Field Investigation
REMS— RCRA Enforcement Management System
REP— Reasonable Efforts Program
REPS— Regional Emissions Projection
RESOLVE— Center for Environmental Conflict
RF— Response Factor
RFA— Regulatory Flexibility Act
RFB— Request for Bid
RfC— Reference Concentration
RFD— Reference Dose Values
RFI— Remedial Field Investigation
RFP— Reasonable Further Programs. Request
RHRS— Revised Hazard Ranking System
RI— Reconnaissance Inspection
RI— Remedial Investigation
RIA— Regulatory Impact Analysis; Regulatory
RIC— Radon Information Center
RICC— Retirement Information and Counseling
RICO— Racketeer Influenced and Corrupt
RI/FS— Remedial Investigation/ Feasibility
RIM— Regulatory Interpretation Memorandum
RIN— Regulatory Identifier Number
RIP— RCRA Implementation Plan
RISC— Regulatory Information Service
RJE— Remote Job Entry
RLL— Rapid and Large Leakage (Rate)
RMCL— Recommended Maximum Contaminant
Level (this phrase being discontinued in favor
RMDHS— Regional Model Data Handling
RMIS— Resources Management Information
RNA— Ribonucleic Acid
ROADCHEM— Roadway Version that Includes
Chemical Reactions of BI, NO2, and O3
ROADWAY— A Model to Predict Pollutant
Concentrations Near a Roadway
ROC— Record Of Communication
RODS— Records Of Decision System
ROG— Reactive Organic Gases
ROLLBACK— A Proportional Reduction Model
ROM— Regional Oxidant Model
ROMCOE— Rocky Mountain Center on Environment
ROP— Rate of Progress; Regional Oversight
ROPA— Record Of Procurement Action
ROSA— Regional Ozone Study Area
RP— Radon Progeny Integrated Sampling.
Respirable Particulates. Responsible Party
RPAR— Rebuttable Presumption Against
RPM— Reactive Plume Model. Remedial
RQ— Reportable Quantities
RRC— Regional Response Center
RRT— Regional Response Team; Requisite
RS— Registration Standard
RSCC— Regional Sample Control Center
RSD— Risk-Specific Dose
RSE— Removal Site Evaluation
RTCM— Reasonable Transportation Control
RTDF— Remediation Technologies Development
RTDM— Rough Terrain Diffusion Model
RTECS— Registry of Toxic Effects of
RTM— Regional Transport Model
RTP— Research Triangle Park
RUP— Restricted Use Pesticide
RVP— Reid Vapor Pressure
RWC— Residential Wood Combustion
of energy though space or any medium. Also
known as radiant energy.
Radiation Standards— Regulations
that set maximum exposure limits for protection
of the public from radioactive materials.
Radioactive Decay— Spontaneous
change in an atom by emission of of charged
particles and/or gamma rays; also known as
radioactive disintegration and radioactivity.
Substances that emit ionizing radiation.
variants of radioactive elements with potentially
oncogenic, teratogenic, and mutagenic effects
on the human body.
particle, man-made (anthropogenic) or natural,
with a distinct atomic weight number. Can
have a long life as soil or water pollutant.
Radius of Vulnerability Zone—
The maximum distance from the point of release
of a hazardous substance in which the airborne
concentration could reach the level of concern
under specified weather conditions.
Radius of Influence—
1. The radial distance from the center of
a wellbore to the point where there is no
lowering of the water table or potentiometric
surface (the edge of the cone of depression);
2. the radial distance from an extraction
well that has adequate air flow for effective
removal of contaminants when a vacuum is applied
to the extraction well.
Radon— A colorless naturally
occurring, radioactive, inert gas formed by
radioactive decay of radium atoms in soil
Radon Daughters/Radon Progeny—
Short-lived radioactive decay products of
radon that decay into longer-lived lead isotopes
that can attach themselves to airborne dust
and other particles and, if inhaled, damage
the linings of the lungs.
Radon Decay Products—
A term used to refer collectively to the immediate
products of the radon decay chain. These include
Po-218, Pb-214, Bi-214, and Po-214, which
have an average combined half-life of about
Rainbow Report— Comprehensive
document giving the status of all pesticides
now or ever in registration or special reviews.
Known as the “rainbow report”
because chapters are printed on different
colors of paper.
Rasp— A machine that
grinds waste into a manageable material and
helps prevent odor.
Raw Agricultural Commodity—
An unprocessed human food or animal feed crop
(e.g., raw carrots, apples, corn, or eggs.)
Raw Sewage— Untreated
wastewater and its contents.
Raw Water— Intake water
prior to any treatment or use.
Re-entry— (In indoor
air program) Refers to air exhausted from
a building that is immediately brought back
into the system through the air intake and
of air into the lower layers of a reservoir.
As the air bubbles form and rise through the
water, the oxygen dissolves into the water
and replenishes the dissolved oxygen. The
rising bubbles also cause the lower waters
to rise to the surface where they take on
oxygen from the atmosphere.
Monitoring and measuring environmental developments
with technology and communications systems
that provide time-relevant information to
the public in an easily understood format
people can use in day-to-day decision-making
about their health and the environment.
Reasonable Further Progress—
Annual incremental reductions in air pollutant
emissions as reflected in a State Implementation
Plan that EPA deems sufficient to provide
for the attainment of the applicable national
ambient air quality standards by the statutory
Reasonable Maximum Exposure—
The maximum exposure reasonably expected to
occur in a population.
Reasonable Worst Case—
An estimate of the individual dose, exposure,
or risk level received by an individual in
a defined population that is greater than
the 90th percentile but less than that received
by anyone in the 98th percentile in the same
Reasonably Available Control
Measures (RACM)— A broadly defined term
referring to technological and other measures
for pollution control.
Reasonably Available Control
Technology (RACT)— Control technology
that is reasonably available, and both technologically
and economically feasible. Usually applied
to existing sources in nonattainment areas;
in most cases is less stringent than new source
in which carbon dioxide is bubbled into water
being treated to lower the pH.
Receiving Waters— A river,
lake, ocean, stream or other watercourse into
which wastewater or treated effluent is discharged.
entity exposed to a stressor.
Recharge— The process
by which water is added to a zone of saturation,
usually by percolation from the soil surface;
e.g., the recharge of an aquifer.
Recharge Area— A land
area in which water reaches the zone of saturation
from surface infiltration, e.g., where rainwater
soaks through the earth to reach an aquifer.
Recharge Rate— The quantity
of water per unit of time that replenishes
or refills an aquifer.
Reclamation— (In recycling)
Restoration of materials found in the waste
stream to a beneficial use which may be for
purposes other than the original use.
A microorganism whose genetic makeup has been
altered by deliberate introduction of new
genetic elements. The offspring of these altered
bacteria also contain these new genetic elements;
i.e. they “breed true.”
Recombinant DNA— The
new DNA that is formed by combining pieces
of DNA from different organisms or cells.
Recommended Maximum Contaminant
Level (RMCL)— The maximum level of a
contaminant in drinking water at which no
known or anticipated adverse effect on human
health would occur, and that includes an adequate
margin of safety. Recommended levels are nonenforceable
Facility in which components are replaced
to such an extent that the fixed capital cost
of the new components exceeds 50 percent of
the capital cost of constructing a comparable
brand-new facility. New-source performance
standards may be applied to sources reconstructed
after the proposal of the standard if it is
technologically and economically feasible
to meet the standards.
Reconstruction of Dose—
Estimating exposure after it has occurred
by using evidence within an organism such
as chemical levels in tissue or fluids.
Record of Decision (ROD)—
A public document that explains which cleanup
alternative(s) will be used at National Priorities
List sites where, under CERCLA, Trust Funds
pay for the cleanup.
Recovery Rate— Percentage
of usable recycled materials that have been
removed from the total amount of municipal
solid waste generated in a specific area or
by a specific business.
waste generation by recovering and reprocessing
usable products that might otherwise become
waste (.i.e. recycling of aluminum cans, paper,
and bottles, etc.).
Recycling and Reuse Business
Assistance Centers— Located in state
solid-waste or economic-development agencies,
these centers provide recycling businesses
with customized and targeted assistance.
Recycling Economic Development
Advocates— Individuals hired by state
or tribal economic development offices to
focus financial, marketing, and permitting
resources on creating recycling businesses.
Recycling Mill— Facility
where recovered materials are remanufactured
into new products.
Recycling Technical Assistance
Partnership National Network— A national
information-sharing resource designed to help
businesses and manufacturers increase their
use of recovered materials.
Red Border— An EPA document
undergoing review before being submitted for
final management decision-making.
Red Tide— A proliferation
of a marine plankton toxic and often fatal
to fish, perhaps stimulated by the addition
of nutrients. A tide can be red, green, or
brown, depending on the coloration of the
Redemption Program— Program
in which consumers are monetarily compensated
for the collection of recyclable materials,
generally through prepaid deposits or taxes
on beverage containers. In some states or
localities legislation has enacted redemption
programs to help prevent roadside litter.
Reduction— The addition
of hydrogen, removal of oxygen, or addition
of electrons to an element or compound.
Reentry Interval— The
period of time immediately following the application
of a pesticide during which unprotected workers
should not enter a field.
Reference Dose (RfD)—
The RfD is a numerical estimate of a daily
oral exposure to the human population, including
sensitive subgroups such as children, that
is not likely to cause harmful effects during
a lifetime. RfDs are generally used for health
effects that are thought to have a threshold
or low dose limit for producing effects.
Gasoline with a different composition from
conventional gasoline (e.g., lower aromatics
content) that cuts air pollutants.
Emissions released during vehicle re-fueling.
Refuse Reclamation— Conversion
of solid waste into useful products; e.g.,
composting organic wastes to make soil conditioners
or separating aluminum and other metals for
of cells to cause them to develop into whole
Regional Response Team (RRT)—
Representatives of federal, local, and state
agencies who may assist in coordination of
activities at the request of the On-Scene
Coordinator before and during a significant
pollution incident such as an oil spill, major
chemical release, or Superfund response.
Registrant— Any manufacturer
or formulator who obtains registration for
a pesticide active ingredient or product.
listing with EPA of a new pesticide before
it can be sold or distributed. Under the Federal
Insecticide, Fungicide, and Rodenticide Act,
EPA is responsible for registration (pre-market
licensing) of pesticides on the basis of data
demonstrating no unreasonable adverse effects
on human health or the environment when applied
according to approved label directions.
Published documents which include summary
reviews of the data available on a pesticide’s
active ingredient, data gaps, and the Agency’s
existing regulatory position on the pesticide.
Material (RACM)— Friable asbestos material
or nonfriable ACM that will be or has been
subjected to sanding, grinding, cutting, or
abrading or has crumbled, or been pulverized
or reduced to powder in the course of demolition
or renovation operations.
Regulated Medical Waste—
Under the Medical Waste Tracking Act of 1988,
any solid waste generated in the diagnosis,
treatment, or immunization of human beings
or animals, in research pertaining thereto,
or in the production or testing of biologicals.
Included are cultures and stocks of infectious
agents; human blood and blood products; human
pathological body wastes from surgery and
autopsy; contaminated animal carcasses from
medical research; waste from patients with
communicable diseases; and all used sharp
implements, such as needles and scalpels,
and certain unused sharps.
Relative Ecological Sustainability—
Ability of an ecosystem to maintain relative
ecological integrity indefinitely.
The permeability of a rock to gas, NAIL, or
water, when any two or more are present.
Relative Risk Assessment—
Estimating the risks associated with different
stressors or management actions.
Release— Any spilling,
leaking, pumping, pouring, emitting, emptying,
discharging, injecting, escaping, leaching,
dumping, or disposing into the environment
of a hazardous or toxic chemical or extremely
Remedial Action (RA)—
The actual construction or implementation
phase of a Superfund site cleanup that follows
Remedial Design— A phase
of remedial action that follows the remedial
investigation/feasibility study and includes
development of engineering drawings and specifications
for a site cleanup.
An in-depth study designed to gather data
needed to determine the nature and extent
of contamination at a Superfund site; establish
site cleanup criteria; identify preliminary
alternatives for remedial action; and support
technical and cost analyses of alternatives.
The remedial investigation is usually done
with the feasibility study. Together they
are usually referred to as the “RI/FS”.
Remedial Project Manager (RPM)—
The EPA or state official responsible for
overseeing on-site remedial action.
Remedial Response— Long-term
action that stops or substantially reduces
a release or threat of a release of hazardous
substances that is serious but not an immediate
threat to public health.
Remediation— 1. Cleanup
or other methods used to remove or contain
a toxic spill or hazardous materials from
a Superfund site; 2. for the Asbestos Hazard
Emergency Response program, abatement methods
including evaluation, repair, enclosure, encapsulation,
or removal of greater than 3 linear feet or
square feet of asbestos-containing materials
from a building.
Remote Sensing— The collection
and interpretation of information about an
object without physical contact with the object;
e.g., satellite imaging, aerial photography,
and open path measurements.
Removal Action— Short-term
immediate actions taken to address releases
of hazardous substances that require expedited
Renewable Energy Production
Incentive (REPI)— Incentive established
by the Energy Policy Act available to renewable
energy power projects owned by a state or
local government or nonprofit electric cooperative.
Repeat Compliance Period—
Any subsequent compliance period after the
Reportable Quantity (RQ)—
Quantity of a hazardous substance that triggers
reports under CERCLA. If a substance exceeds
its RQ, the release must be reported to the
National Response Center, the SERC, and community
emergency coordinators for areas likely to
and replacing major components of a power
plant instead of building a new one.
A portion of material or water that is as
nearly identical in content and consistency
as possible to that in the larger body of
material or water being sampled.
Reregistration— The reevaluation
and relicensing of existing pesticides originally
registered prior to current scientific and
regulatory standards. EPA reregisters pesticides
through its Registration Standards Program.
Reserve Capacity— Extra
treatment capacity built into solid waste
and wastewater treatment plants and interceptor
sewers to accommodate flow increases due to
future population growth.
Reservoir— Any natural
or artificial holding area used to store,
regulate, or control water.
Residential Use— Pesticide
application in and around houses, office buildings,
apartment buildings, motels, and other living
or working areas.
Residential Waste— Waste
generated in single and multi-family homes,
including newspapers, clothing, disposable
tableware, food packaging, cans, bottles,
food scraps, and yard trimmings other than
those that are diverted to backyard composting.
Residual— Amount of a
pollutant remaining in the environment after
a natural or technological process has taken
place; e.g., the sludge remaining after initial
wastewater treatment, or particulates remaining
in air after it passes through a scrubbing
or other process.
Residual Risk— The extent
of health risk from air pollutants remaining
after application of the Maximum Achievable
Control Technology (MACT).
Saturation level below which fluid drainage
will not occur.
Residue— The dry solids
remaining after the evaporation of a sample
of water or sludge.
Resistance— For plants
and animals, the ability to withstand poor
environmental conditions or attacks by chemicals
or disease. May be inborn or acquired.
Resource Recovery— The
process of obtaining matter or energy from
materials formerly discarded.
Response Action— 1. Generic
term for actions taken in response to actual
or potential health-threatening environmental
events such as spills, sudden releases, and
asbestos abatement/management problems. 2.
A CERCLA-authorized action involving either
a short-term removal action or a long-term
removal response. This may include but is
not limited to— removing hazardous materials
from a site to an EPA-approved hazardous waste
facility for treatment, containment or treating
the waste on-site, identifying and removing
the sources of ground-water contamination
and halting further migration of contaminants.
3. Any of the following actions taken in school
buildings in response to AHERA to reduce the
risk of exposure to asbestos— removal,
encapsulation, enclosure, repair, and operations
A summary of oral and/or written public comments
received by EPA during a comment period on
key EPA documents, and EPA’s response
to those comments.
taken to return a site to pre-violation conditions.
Restricted Entry Interval—
The time after a pesticide application during
which entry into the treated area is restricted.
Restricted Use— A pesticide
may be classified (under FIFRA regulations)
for restricted use if it requires special
handling because of its toxicity, and, if
so, it may be applied only by trained, certified
applicators or those under their direct supervision.
Enzymes that recognize specific regions of
a long DNA molecule and cut it at those points.
Retrofit— Addition of
a pollution control device on an existing
facility without making major changes to the
generating plant. Also called backfit.
Reuse— Using a product
or component of municipal solid waste in its
original form more than once; e.g., refilling
a glass bottle that has been returned or using
a coffee can to hold nuts and bolts.
Reverse Osmosis— A treatment
process used in water systems by adding pressure
to force water through a semi-permeable membrane.
Reverse osmosis removes most drinking water
contaminants. Also used in wastewater treatment.
Large-scale reverse osmosis plants are being
Reversible Effect— An
effect which is not permanent; especially
adverse effects which diminish when exposure
to a toxic chemical stops.
Ribonucleic Acid (RNA)—
A molecule that carries the genetic message
from DNA to a cellular protein-producing mechanism.
Rill— A small channel
eroded into the soil by surface runoff; can
be easily smoothed out or obliterated by normal
Ringlemann Chart— A series
of shaded illustrations used to measure the
opacity of air pollution emissions, ranging
from light grey through black; used to set
and enforce emissions standards.
Riparian Habitat— Areas
adjacent to rivers and streams with a differing
density, diversity, and productivity of plant
and animal species relative to nearby uplands.
Riparian Rights— Entitlement
of a land owner to certain uses of water on
or bordering the property, including the right
to prevent diversion or misuse of upstream
waters. Generally a matter of state law.
Risk— A measure of the
probability that damage to life, health, property,
and/or the environment will occur as a result
of a given hazard.
Risk (Adverse) for Endangered
Species— Risk to aquatic species if
anticipated pesticide residue levels equal
one-fifth of LD10 or one-tenth of LC50; risk
to terrestrial species if anticipated pesticide
residue levels equal one-fifth of LC10 or
one-tenth of LC50.
Risk Assessment— Qualitative
and quantitative evaluation of the risk posed
to human health and/or the environment by
the actual or potential presence and/or use
of specific pollutants.
The last phase of the risk assessment process
that estimates the potential for adverse health
or ecological effects to occur from exposure
to a stressor and evaluates the uncertainty
Risk Communication— The
exchange of information about health or environmental
risks among risk assessors and managers, the
general public, news media, interest groups,
Risk Estimate— A description
of the probability that organisms exposed
to a specific dose of a chemical or other
pollutant will develop an adverse response,
Risk Factor— Characteristics
(e.g., race, sex, age, obesity) or variables
(e.g., smoking, occupational exposure level)
associated with increased probability of a
Risk for Non-Endangered Species—
Risk to species if anticipated pesticide residue
levels are equal to or greater than LC50.
Risk Management— The
process of evaluating and selecting alternative
regulatory and non-regulatory responses to
risk. The selection process necessarily requires
the consideration of legal, economic, and
The direction of resources to those areas
that have been identified as having the highest
potential or actual adverse effect on human
health and/or the environment.
Risk-Specific Dose— The
dose associated with a specified risk level.
River Basin— The land
area drained by a river and its tributaries.
Rodenticide— A chemical
or agent used to destroy rats or other rodent
pests, or to prevent them from damaging food,
Rotary Kiln Incinerator—
An incinerator with a rotating combustion
chamber that keeps waste moving, thereby allowing
it to vaporize for easier burning.
Rough Fish— Fish not
prized for sport or eating, such as gar and
suckers. Most are more tolerant of changing
environmental conditions than are game or
Route of Exposure— The
avenue by which a chemical comes into contact
with an organism, e.g., inhalation, ingestion,
dermal contact, injection.
Rubbish— Solid waste,
excluding food waste and ashes, from homes,
institutions, and workplaces. Run-Off—
That part of precipitation, snow melt, or
irrigation water that runs off the land into
streams or other surface-water. It can carry
pollutants from the air and land into receiving
Running Losses— Evaporation
of motor vehicle fuel from the fuel tank while
the vehicle is in use.