Glossary of Water Quality and Pesticide Terms

walkway with flowersAs you read about pesticides, water quality, and use the decision-making toolbox and data portal, it is important that you understand the terms and acronyms referred to throughout the website. The following list will aid you in your understanding terms and acronyms commonly used in the environmental decision-making process in the Low Country, throughout the U.S., and at the international level.


  1. Ecology - The study of the relationships between all living organisms and the environment, especially the totality or pattern of interactions; a view that includes all plant and animal species and their unique contributions to a particular habitat.
  2. Ecosystem - The interacting synergism of all living organisms in a particular environment; every plant, insect, aquatic animal, bird, or land species that forms a complex web of interdependency. An action taken at any level in the food chain, use of a pesticide for example, has a potential domino effect on every other occupant of that system.
  3. Raw water - Intake water prior to any treatment or use
  4. Effluent - Wastewater discharged from a point source, such as a pipe.
  5. Receiving Waters - A river, lake, ocean, stream, or other body of water into which wastewater or treated effluent is discharged.
  6. Surface Water - All water naturally open to the atmosphere (rivers, lakes, reservoirs, ponds, streams, seas, estuaries) and all springs, wells, or other collectors directly influenced by surface water.
  7. Ground Water - Water found below the surface of the land, usually in porous rock formations. Ground water is the source of water found in wells and springs and is used frequently for drinking.
  8. Pollution - Any substances in water, soil, or air that degrade the natural quality of the environment, offend the senses of sight, taste, or smell, or cause a health hazard. The usefulness of the natural resource is usually impaired by the presence of pollutants and contaminants.
  9. Point Source Pollution - A stationary location or fixed facility such as an industry or municipality that discharges pollutants into air or surface water through pipes, ditches, lagoons, wells, or stacks; a single identifiable source such as a ship or a mine.
  10. Nonpoint Source Pollution - Any source of pollution not associated with a distinct discharge point. Includes sources such as rainwater, runoff from agricultural lands, industrial sites, parking lots, and timber operations, as well as escaping gases from pipes and fittings.
  11. Sediment - Topsoil, sand, and minerals washed from the land into water, usually after rain or snow melt. Sediments collecting in rivers, reservoirs, and harbors can destroy fish and wildlife habitat and cloud the water so that sunlight cannot reach aquatic plants. Loss of topsoil from farming, mining, or building activities can be prevented through a variety of erosion-control techniques.
  12. Floodplain - Mostly level land along rivers and streams that may be submerged by floodwater. A 100-year floodplain is an area which can be expected to flood once in every 100 years.
  13. Fecal coliform Bacteria - Found in the intestinal tracts of mammals, this bacteria in water or sludge is an indicator of pollution and possible contamination by pathogens.
  14. Aquifer - A water-bearing layer of rock (including gravel and sand) that will yield water in usable quantity to a well or spring.
  15. Erosion - The wearing away of soil by wind or water, intensified by land-clearing practices related to farming, residential or industrial development, road building, or logging.
  16. Hydraulic gradient - The direction of ground water flow due to changes in the depth of the water table.
  17. National Pollutant Discharge Elimination System (NPDES) - The primary permitting program under the Clean Water Act which regulates all discharges to surface water.
  18. Zone of Saturation - The layer beneath the surface of the land in which all openings are filled with water.


  1. Pesticide - Any economically justifiable substance used for controlling, preventing, destroying, repelling, or mitigating any pest.
  2. Pesticide Usage - Refers to actual applications of pesticides, generally in terms of quantity applied or units treated.
  3. Active Ingredient (AI) - Chemicals in a product that are responsible for the pesticidal effect; in some cases brand name products will contain more than one AI as well as other ingredients termed inert ingredients that make up the majority of the formulation.
  4. Insecticide - A pesticide used to mitigate insect pests.
  5. Organochlorines (OCs) - Broad- spectrum insecticide that includes carbon, chlorine, and hydrogen (e.g., DDT, chlordane, endosulfan); OCs will be completely phased out of use by the end of 2012 in the US.
  6. Organophosphates (OPs) - Insecticides derived from phosphoric acid esters (e.g., chlorpyrifos, malathion); broad–spectrum insecticide eliciting neurological effects on target and non-target species via interference with the neurotransmitter acetylcholine.
  7. Pyrethrins - Pyrethrins are insecticide that are derived from the from the pyrethrum flower, Chrysanthemum cinerariaefolium. The six individual pyrethrins are pyrethrin 1, pyrethrin 2, cinerin 1, cinerin 2, jasmolin 1, and jasmolin 2.
  8. Pyrethroids - Insecticides that are adapted from the chemical structures of the pyrethrins and act in a similar manner to pyrethrins by altering nerve function, which causes paralysis in target insect pests, eventually resulting in death; these compounds are extremely toxic to invertebrates, but have a relatively low toxicity for mammals which is why many are registered for in home use when a pest control situations arises.
  9. Carbamates - Insecticide that effects the nervous system and are derived from carbamic acid (e.g., carbaryl, aldicarb); Carbamates, similar to OPs, are considered broad-spectrum insecticides meaning there insecticidal effects can control multiple insect pests.
  10. Insect Growth Regulators (IGRs) - Insecticides that work by disrupting the growth or development of an insect; these are commonly used to prevent mosquitoes (or fly species) from repopulating a treated area, as the IGRs will target the larvae. IGRs are in general considered safer than many insecticides, as they are more target-specific and potentially cause less collateral damage to non-target organisms.
  11. Herbicide - Pesticide used for mitigating nuisance plant species (e.g., atrazine). Often, many herbicides are considered pre-emergent (will inhibit the weed before it is above ground or post-emergent (will inhibit weed growth after the weed has produced foliage and is above ground).
  12. Algaecide - Pesticide used to control algae and aquatic weeds.
  13. Algae - unicellular or multicellular, threadlike green plants that can form dense coating over water and soil surfaces.
  14. Fumigant - A volatile material that forms vapors destroying insects, pathogens, or other pests predominantly in soils.
  15. FIFRA - Federal Insecticide, Fungicide, and Rodenticide Act; the federal law that regulates pesticides registration and use in the United States.
  16. FFDCA - The Federal Food, Drug, and Cosmetic Act was passed to cover food safety and tolerances for pesticides in food.
  17. FQPA - Passed in 1997, the Food Quality Protection Act (FQPA) amended both FIFRA and FFDCA; this act fundamentally changed the way tolerances for pesticide residues for food are determined. One of the more important amendments to FIFRA under the FQPA, was the reregistration of pesticides every 15 years.
  18. Best Management Practices (BMP) - Effective practices that emphasize proper mixing, loading and application of pesticides and also include methods that should be used before, during and after application.
  19. Synergists - Additives in pesticide mixtures that increase the efficacy of the product (e.g., PBO).
  20. Mixture - Two or more pesticides mixed together in formulation, that can together be more toxic, less toxic, or have an equivalent toxicity to the individual compounds alone.
  21. Restricted Use Pesticide (RUP) - Pesticide designation by the EPA indicating that the active ingredient can only be applied by certified applicators because of their inherent toxicity or potential hazard to the environment.
  22. Environment - In risk management, the EPA must consider the economic, social, and natural environmental in the risk benefit analysis for a pesticide.
  23. Personal Protective Equipment (PPE) - PPE consists of the personal safety equipment a pesticide applicator should be wearing while application is occurring.
  24. Integrated Pest Management (IPM) - Pest control that utilizes regular monitoring and record keeping to determine when treatments are needed, and utilizes biological, cultural, physical, mechanical, educational, and chemical methods to address pest problems.
  25. Turfgrass - Golf turf, sports fields, domestic and commercial lawns, cemeteries, parks, campsites, and recreational areas.
  26. Ornamentals - Plants or trees grown for aesthetic appeal. (Ex: roses)
  27. Estuary - A complex ecosystem between a river and near-shore ocean waters where fresh and salt water mix. These brackish areas include bays, mouths of rivers, salt marshes, wetlands, and lagoons and are influenced by tides and currents. Estuaries provide valuable habitat for marine animals, birds, and other wildlife.
  28. Arthropods - Animals that don't have a backbone or spinal cord. Examples are insects with hard shells and spiders.
  29. Biological Pesticide - A chemical which is derived from plants, fungi, bacteria, or other non-man-made synthesis and which can be used for pest control. Certain microorganisms, including bacteria, fungi, viruses, and protozoa that are effective in controlling target pests. These agents usually do not have toxic effects on animals and people and do not leave toxic or persistent chemical residues in the environment.
  30. Blights - Diseases that hurt and sometimes destroy plants. Blights will cause a plant to wither, stop growing, or cause all or parts of it to die.
  31. Organism - Any living being, whether plant, mammal, bird, insect, reptile, fish, crustacean, aquatic or estuarine animal, or bacterium.
  32. Non-target Organism - Any organism for which the pesticide was not intended to control.
  33. Surfactant - A detergent compound that promotes lathering.


  1. Ecological Risk Assessment - A process that evaluates the likelihood that adverse ecological effects may occur as a result of exposure to a stressor. It is a tool for evaluating information, assumptions, and uncertainties in order to understand the relationships between stressors (e.g., pesticides) and ecological effects; the ultimate goal is inform environmental decision making.
  2. Hazard Identification - The first of three fundamental components of ecological risk assessment; Identification of chemical hazards to ecological species reliant upon a battery of standard acute and chronic bioassays in ecologically relevant species (including both plants and animals).
  3. Exposure Assessment - The second of three fundamental components of ecological risk assessment; Exposure assessments are based on measured or modeled concentrations of a chemical hazard in different environmental media (e.g., soil, water, etc.).
  4. Risk Characterization - The third of three fundamental components of ecological risk assessment taking data gathered from both the hazard identification step and the exposure assessment; Estimates risk to the ecosystem based on the chemical hazards measured in surrogate species with predicted doses or concentrations based on the exposure scenarios.
  5. Ten-to-the-Minus-Sixth (10^-6) - Used in risk assessments to refer to the probability of risk. Literally means a chance of one in a million. Similarly, ten-to-the-minus-fifth means a probability of one in 100,000, and so on.
  6. Risk Quotient (RQ) - EPA uses a deterministic approach or the quotient method to compare toxicity to environmental exposure. In the deterministic approach, a RQ is calculated by dividing a point estimate of exposure by a point estimate of effects. This ratio is a simple, screening-level estimate that identifies high- or low-risk situations. RQs are based upon ecological effects data, pesticide use data, fate and transport data, and estimates of exposure to the pesticide. In this method, the estimated environmental concentration (EEC) is compared to an effect level, such as an LC50. RQ = EXPOSURE / TOXICITY
  7. Level of Concern (LOC) - Threshold level (concentration) set for adverse effects occurring in the population set based on toxicological testing. If the RQ exceeds this set value (generally ranging from 0.1 to 1 depending on the toxicity test), then the product is either not registered or the label is modified to mitigate use patterns.
  8. Tolerance - Permissible residue level for pesticides in raw agricultural produce and processed foods. Whenever a pesticide is registered for use on a food or feed crop, a tolerance must be established. EPA establishes the tolerance levels, which are enforced by the Food and Drug Administration and the Department of Agriculture. The maximum amount of a pesticide allowable in a food or feed product before it is considered adulterated, usually specified in parts per million. 1)The ability of a living thing to withstand adverse conditions, such as pest attacks, weather extremes, or pesticides. 2) The amount of pesticide that may safely remain in or on raw farm products at time of sale.
  9. Trade Secret - Any confidential formula, pattern, process, device, information, or set of data that is used in a business to give the owner a competitive advantage. Such information may be excluded from public review.
  10. Cumulative Risk - The risk of a common toxic effect associated with concurrent exposure by all relevant pathways and routes of exposure to a group of chemicals that share a common mechanism of toxicity.


  1. Toxicity - The capacity of a chemical to do harm to an organism by other than mechanical means.
  2. Environmental Toxicology - examines how environmental exposures to chemical pollutants may present risks to biological organisms, particularly animals, birds, and fish as well as mammals including man.
  3. Haber's Law - E= D x T, Where E= Effect, D= Dose, & T=Time; Haber's law explains that in order for anything (ex: chemical) to have an effect on an organism, the effect itself is dependent upon the length time of exposure to the substance (time) and the amount (dose) that the organism receives. All basic toxicological principles are based on this concept.
  4. LC50/LD50 - The median lethal concentration (if aqueous exposure) or dose (oral, dermal) expressed as mg/kg of body weight, which is lethal in 50% of the test organisms exposed.
  5. ED50/EC50 - Effective Dose or concentration where the effect is a sublethal end point other than death (ex: adverse effects on reproduction or development).
  6. Acute Toxicity - Adverse effects that result from a single dose or single exposure of a chemical; any poisonous effect produced within a short period of time, usually less than 96 hours. This term normally is used to describe effects in experimental animals.
  7. Chronic Toxicity - The effects of long term or repeated low level exposures to a toxic substance (cancer, liver damage, reproductive disorders, etc.).
  8. Carcinogen or Carcinogenic - Capable of causing cancer. A suspected carcinogen is a substance that may cause cancer in humans or animals but for which the evidence is not conclusive.
  9. Bioassay - A method of testing a material's effects on living organisms.
  10. Route of Exposure - The way a chemical enters an organism after contact (e.g., ingestion, inhalation, or dermal absorption).
  11. No Observable Adverse Effects Level (NOAEL) - An experimentally determined dose at which there was no statistically or biologically significant indication of the toxic effect of concern.
  12. Lowest Observable Adverse Effects Level (LOAEL) - The lowest experimentally determined dose at which adverse effects are seen in the test population.
  13. Metabolite - A breakdown product of a pesticide resulting from biological, chemical, or physical action on the pesticide with a living organism.
  14. Dose response - How an organism's response to a toxic substance changes as its overall exposure to the substance changes. For example, a small dose of carbon monoxide may cause drowsiness; a large dose can be fatal.
  15. Mechanisms of Toxicity - The biochemical method by which a chemical reacts in a living organism.
  16. Apoptosis - Occurs when a cell dies through activation of an internally controlled suicide program; this process occurs either for unwanted cells during embryogenesis or when cells are damaged beyond repair, especially if something damages the cell's nuclear DNA.
  17. Necrosis - A type of cell death that occurs following abnormal stress (ex: chemical injury); always pathologic.
  18. Morbidity - Rate of incidence of disease.
  19. Mortality - Death rate


Transport Terms

  1. Volatilization - Dissolved and sorbed contaminants move from water and soil into air, in the form of gas and vapors.
  2. Sorption - Dissolved contaminants become bound to solids by attractive chemical, physical, and electrostatic forces.
  3. Sedimentation - Small suspended solids in water grow large enough to settle out of water under gravity (coagulation leads to flocculation).

Environmental Chemical Reactions

  1. Photolysis - In molecules that absorb solar radiation, exposure to sunlight can break chemical bonds and initiate breakdown of a compound.
  2. Complexation and chelation - Charged dissolved contaminants bind to electron-donor ligands to form complex or coordination compounds.
  3. Acid-base Reaction - Protons (H+ ions) are transferred between two different chemicals
  4. Oxidation-reduction (redox) Reaction - Electrons are transferred between chemical species, changing the oxidation states and the chemical properties of the electron donor and the electron acceptor.
  5. Hydrolysis - A compound forms chemical bonds to water molecules or hydroxyl anions (OH-).
  6. Chemical Precipitation - Two or more dissolved species react to form an insoluble solid compound, or there is a change in pH, redox potential, or concentrations, resulting in the formation of a solid from dissolved compounds.

Measurement Parameters

  1. Log Octanol - Water Partition Coefficient (Log Kow) - Used to predict the bioaccumulation potential in aquatic and terrestrial organisms. This describes the tendency of a non ionized organic chemical to accumulate in lipid (fatty) tissue and to sorb onto soil particles or onto the surface of organisms or other particulate matter coated with organic material.
  2. Half-life - The amount of time it takes half the initial amount of AI to disintegrate; this value can be generated for both water and soil.