Vocabulary - 2009
1.toxicology - The study of poisons.
- dose - The actual amount (concentration) of a poison causing toxicity.
- exposure - The magnitude, duration, and frequency with which an organism interacts with biologically available toxicants.
- ecotoxicology - Study of the impact of toxicants on ecological systems.
- toxicity test - Test used to measure the degree of negative response produced by exposure of organisms or biological material to a specific level of stimulus (or concentration of a chemical, or percentage of an effluent), for a specified time period.
- bioassay - Test used to evaluate the relative potency of a chemical by measuring its effect (positive or negative) on living organisms. Bioassays are frequently used by the pharmaceutical industry to evaluate the potency of vitamins and drugs.
7.whole effluent toxicity (WET) - The aggregate toxic effect of an effluent measured directly by an aquatic toxicity test.
8.ambient toxicity - toxicity measured by a toxicity test on water taken directly from a water body.
- in situ toxicity - toxicity measured by placing organisms (often caged) directly in a water body
10.pore water/interstitial water – water that occupies the spaces between particles in sediments.
11.acute - Having a sudden onset, lasting a short time. A stimulus severe enough to induce a response rapidly. The duration of an acute aquatic toxicity test is generally 4 days if the organisms tested are fish 2 days if the organisms tested are invertebrates. The response most often measured in acute toxicity tests is death.
12.effect - Power to bring about a result, to cause to come into being, to bring about.
13. application factor - In toxicological literature a term that has been applied to acute toxicity data to estimate an expected no-effect concentration under chronic exposure conditions.
14.acute-to-chronic ratio - (ACR) is the ratio of the acute toxicity of an effluent or a toxicant to its chronic toxicity. It is used as a factor for estimating chronic toxicity on the basis of acute data, or for estimating acute toxicity on the basis of chronic data.
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15.chronic - Involving a stimulus that is lingering or continues for a long time; often signifies periods from several weeks to years, depending on the reproductive life cycle of the test species. The responses measured include mortality, but more importantly growth, reproduction, physiological responses, etc.
16.Water effects ratio (WER) – ratio of the acute toxicity of a chemical in water taken from above a discharge to the acute toxicity of the same chemical in laboratory water. If the ratio is greater than 1 it means that the receiving water has had an effect on the toxicity of that chemical and that ratio can be used to modify a water quality criterion.
17.sub-lethal - Below the concentration that directly causes death. Exposure to sub-lethal concentrations of a material may produce less obvious effects on behavior, biochemical and/or physiological function, and histology of organisms.
18.short-term chronic test - Term used to describe tests that evaluate chronic endpoints that are performed over a relatively short time period when compared to traditional chronic tests.
19.threshold - Term used to describe the concentration at which an effect either just begins or just quits. For example, the threshold concentration may be the concentration at which acute toxicity ceases and chronic toxicity begins.
20.biomonitoring - The use of living organisms as sensors in water quality surveillance to detect changes in an effluent or water and to indicate whether aquatic life may be endangered.
21.biological assessment - is an evaluation of the biological condition of a water body using biological surveys and other direct measurements of resident biota.
22.biological criteria or biocriteria - are narrative expressions or numeric values of the biological characteristics of aquatic communities based on appropriate reference conditions. Biological criteria serve as an index of aquatic community health.
23.LC50 - Lethal concentration 50. Concentration causing death to 50% of the exposed test organisms in a specified time period.
24.EC50 - Effect concentration 50. Concentration causing measurable effects to 50% of the exposed organisms in a specified time period.
25.LD50 - Lethal dose 50. Dose causing death to 50% of the exposed organisms in a specified time period.
26.IC50 - Inhibition concentration 50. Concentration inhibiting growth of exposed organisms by 50% in a specified time period, generally used to describe effects on algal or bacterial population growth.
27.TLm - Median tolerance limits; term used in early aquatic toxicology literature as the concentration that killed 50% of an exposed population of test organisms in some period of time. Term currently used to mean the same thing is LC50.
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28.LL50 - Lethal level 50. Term used to describe the level of an environmental factor such as pH (in standard units) or temperature, etc. which kills 50% of an exposed group of organisms in a specified time period.
29.LOEL - Lowest observable effects level. The lowest level (pH, in standard units, temperature) in a chronic toxicity test that causes a statistically significant difference from the control for the end-point being measured.
30.NOEL - No observable effects level. The highest level (pH in standard units, temperature) in a chronic toxicity test that is not statistically significantly different from the control for the end-point being measured.
31.LOEC - Lowest observable effects concentration. The lowest concentration in a chronic toxicity test that causes a statistically significant difference from the control for the end-point being measured.
32.NOEC - No observable effects concentration. The highest concentration of a toxicant in a chronic toxicity test that is not statistically significantly different from the control for the end-point being measured.
33.GM-MATC - Geometric mean maximum acceptable toxicant concentration. Calculated as:
GM-MATC = the antilog of the natural log of NOEC + natural log LOEC
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34.NOAEL - No observable adverse effects level. The highest level (pH in standard units, temperature) in a chronic toxicity test that is not statistically significantly different from the control for the end-point being measured.
35.LOAEL - Lowest observable adverse effects level. The lowest level (pH in standard units, temperature) in a chronic toxicity test that is statistically significantly different from the control for the end-point being measured.
36.NOAEC - No observable adverse effects concentration. The highest concentration of a toxicant in a chronic toxicity test that is not statistically significantly different from the control for the end-point being measured.
37.LOAEC - Lowest observable adverse effects concentration. The lowest concentration of a toxicant in a chronic toxicity test that is statistically significantly different from the control for the end-point being measured.
38.7Q2 (7Q10) - Lowest recorded flow for seven consecutive days over either a two (7Q2), or ten (7Q10) year time period.
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39.Receiving Water Concentration (RWC) - The concentration of a toxicant or the parameter being measured in the receiving water after mixing (formerly known as instream waste concentration (IWC).
40.absolute toxicity - The toxicity of an effluent without considering dilution (100% effluent).
41.static - Term used to describe aquatic toxicity tests in which the solutions in which the organisms are exposed is not flowing or continuously replaced.
42.continuous flow - Type of toxicity tests in which the medium is continuously replaced.
43.renewal - Term used to describe aquatic toxicity tests in which the medium is replaced during the tests at a frequency less than that found in continuous flow tests, but greater than that in non-renewal static tests.
44.diluter - A device that is used in continuous flow tests to deliver various concentrations of toxicants.
45.tiered testing - A type of testing which generally, but not necessarily, proceeds from the less to more sophisticated tests (also generally less to more expensive tests) as one evaluates the potential impact of chemicals or mixtures or chemicals or mixtures of chemicals in the environment.
46.persistent - Refers to materials released into the environment that retain their original form or state. For example, metals (copper, zinc, lead, etc.) are not degraded or very slowly degraded to a simpler form in the environment.
47.non-persistent - Refers to materials released into the environment that can be degraded to simpler forms i.e., many organic materials are degraded by bacteria into simpler forms different from their original state.
48.bioaccumulation - General term describing a process by which chemicals are taken up by aquatic organisms from water directly, or through consumption of food containing the chemicals.
49.bioconcentration - A process by which there is a net accumulation of a chemical directly from water into aquatic organisms (e.g., by gill, epithelial tissue or through cell walls).
50.biomagnification - A process by which there is a net accumulation of a chemical as the chemical passes up through two or more trophic levels. The term implies an efficient transfer of chemical from food to consumer, so that residue concentrations increase systematically from one trophic level to the next.
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51.bioaccumulation factor (BAF) - Is the ratio of a substance’s concentration in tissue versus its concentration in ambient water, in situations where the organism and the food chain are exposed.
52.bioconcentration factor (BCF) - Is the ratio of a substance’s concentration in tissue versus its concentration in ambient water in situations in which the food chain is not exposed or contaminated.
53.bioavailable - Term used to describe the availability of toxicants or materials to living organisms. Measurement of the total concentrations of chemicals in water or sediments does not necessarily indicate that the chemical measured is in a form that can be taken up by organisms.
54.lipophilic - a high affinity for lipids (fats).
55.hydrophobic - a low affinity for water.
56. biotic ligand model (BLM) – a model that predicts the toxicity of metal based on characteristics of water beyond hardness. Includes Ca2+, H+, OH-, CO32-, Cl-, and dissolved organic matter.
57.sensitivity - Term used by toxicologists to rate or rank the degree to which a chemical or condition influences different organisms.
58.statistically significant effects - Terms used to describe whether the probability of observed responses is greater than those observed due to chance alone. Not all statistically significant differences are biologically or ecologically important. Statistically insignificant differences are not always biologically or ecologically insignificant.
59.ecologically significant effects - Terms used to describe whether observed effects are ecologically important. Not all effects are necessarily ecologically important.
60.environmentally acceptable effects - Society ultimately determines whether an effect is acceptable. They do this in a variety of ways but generally it is ultimately expressed through laws enacted by their elected representatives.
61.parametric - Type of statistical tests that have underlying assumptions concerning independence, normality, and homogeneity of variance.
62.non-parametric - Type of statistical tests that do not require that the assumptions of normality and homogeneity of variance be met.
63.homogeneous variances - Variances that are equal within certain probabilistic limits. An important pre-condition in many parametric statistical tests.
64.heterogeneous variances - Variances that are not equal within certain probabilistic limits. Homogeneity of variance is a prerequisite for many parametric analyses.
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65.Minimum Significant Difference (MSD) and Percent Minimum Significant Difference (PMSD) – the MSD is the minimum significant difference in original units (weight, survival, neonate production, etc.) that could have been detected as statistically significantly different. The PMSD is the MSD expressed as a percent difference.
66.log normal - Distribution, generally assumed to underlie dose-response relationships. This distribution can be transformed into a normal distribution by taking the log of the concentration axis.
67.probit - A transformation used in pharmacology and toxicology to straighten certain types of sigmoid dose response curves.
68.moving average - A transformation used in toxicology to straighten certain types of dose response curves.
69.additivity - The toxicity of a mixture of chemicals that is approximately equivalent to that expected from a simple summation of the known toxicities of the individual chemicals present in the mixture. If 1 unit of chemical A kills 50% of a group of test organisms (LC50 = 1 unit); and if 1 unit of chemical B kills 50% of a group of test organisms (LC50 = 1 unit); then 0.5 units of chemical 1 plus 0.5 units of chemical 2 should kill 50% of a group of the same species of test organisms if the chemicals behave additively.
70.synergistic - The toxicity of a mixture of chemicals is greater than that which would be expected from a simple summation of the toxicities of the individual chemicals present in the mixture. If 1 unit of chemical A kills 50% of a group of test organisms (LC50 = 1 unit); and if 1 unit of chemical B kills 50% of a group of test organisms (LC50 = 1 unit); then when 0.5 units of each chemical are mixed together the mixture should kill more than 50% of a group of test organisms if the chemicals behave synergistically.
71.antagonistic - The toxicity of a mixture of chemicals that is less than that expected from a simple summation of the known toxicities of the individual chemicals present in the mixture. If 1 unit of a chemical A kills 50% of a group of test organisms (LC50 = 1 unit); and if 1 unit of chemical B kills 50% of a group of test organisms (LC50 = 1 unit); then 0.5 units of each chemical mixed together should kill less than 50% of a group of test organisms if the chemicals behave antagonistically.
72.structure of aquatic communities - One goal of water quality legislation is the maintenance of the structure and function of aquatic communities. The structure of aquatic communities is often measured through a variety of indices based in part on the following parameters; number of species, number of individuals of the various species, the distribution of individuals amongst the various species, habitat, etc. The premise of the maintenance of the structure of aquatic communities is that the structure below an outfall from an industry or municipality should look like the structure above the outfall from an industry or municipality, or non-point source of pollution.
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73.function of aquatic communities - One goal of water quality legislation is the maintenance of structure and function of aquatic communities in the face of an ever-increasing level of insult. The function of aquatic communities refers in part to such things as how the community processes material (energy flow, etc.).
74.criteria - The term used in reference to recommendations concerning how much of a material should be released into the environment. Regulatory agencies, or groups of professionals such as committees of the National Academy of Sciences generally make the recommendations.
75.standards - Standards are legal limits adopted by regulatory agencies of government (States, municipalities, etc.). Standards may be adopted directly from criteria, the main difference between the two being the force of law behind the standards.
76.parthenogenetic - A type of reproduction amongst some organisms including the Cladocera (Daphnia, Ceriodaphnia, etc) in which female organisms give rise to female offspring.
77.molt - To shed and develop anew the outer covering of the body, as the cuticle, exoskeleton, skin, hair, or feathers.
78.brood - Newly born or recently hatched, in reference to individuals of a brood.
79.neonate - Newly born or recently hatched, in reference to the young of Cladocera.
80.instar - The stage of development or the form assumed by an organism (insect, cladoceran) between successive molts.
81.Selenastrum capricornutum - green algae used by environmental scientists to measure the degree of and limitations to growth from nitrogen and phosphorus in lakes and reservoirs. Also used as a food for cladoceran culture and testing. This is the name you will find in all the EPA methods manuals although the classification was changed to Raphidocelis subcapitata and changed again to Pseudokirchneriella subcapitata.
82.Daphnia magna - A large cladoceran (water flea) used by toxicologists in testing chemicals. D. magna has a restricted range in North America.
83.Ceriodaphnia dubia - A cladoceran (water flea) used extensively by toxicologists in effluent monitoring and ambient toxicity testing.
84.Chironomus tentans - A midge larvae (dipteran) that has a common name of bloodworm. A major fish food organism in many aquatic environments. Also used as a toxicity test organism.
85.Lemna minor - A small floating vascular plant called Duckweed. This plant is being recommended for use in effluent biomonitoring.
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86.xenobiotic - Literally, foreign to life, a term used to describe chemicals made by man for whom life has had little evolutionary exposure.
87.carcinogenic - Causing cancer.
88.mutagenic - Causing mutations.
89.teratogenic - Causing birth defects.
90.density dependent regulation - A term used to describe the type of regulation a population undergoes in which the fecundity (number of offspring per female) decreases as the population density (number of female increase). Generally attributed to organisms referred to as K-strategists.
91.density independent regulation - A term used to describe the type of regulation a population undergoes in which the fecundity (number of offspring per female) is not influenced (in a regulatory sense) by the number of females in the population. Generally attributed to organisms referred to as r-strategists.
92.diversity - The number of different kinds and abundance of species in a defined area.
93.indigenous - Native, not introduced, growing naturally in an environment or country.
94.matrix effects - The influence of the matrix in which a chemical is found on its bioavailability to living material (or the manner in which a sample is treated to reduce the influence of the matrix on the ability of the analyst to determine its concentration).
95.fecundity - The number of young (offspring, eggs) produced by females of a population.
96.fate - A term used to define the disposition of a chemical in various environmental compartments (e.g., soil, or sediment, water, air, biota) as a result of transport, transformation, and degradation.
97.compensatory reserve - The excess production of reproductive products over that that survives to reach maturity.
98.technology based approached to toxics control - In the early days of EPA, the approach taken in an attempt to control toxics. This approach was referred to as the Best Available Technology (BAT) economically achievable.
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- water quality based approach to toxics control - After best available technology economically achievable was in place all toxicity was not removed from industrial and/or municipal effluents. To attempt further control of toxics a program referred to as the Water Quality Based approach to toxics control. In this approach biological and chemical methods are used to determine the presence of toxicity.
100.randomized block design - a type of statistical design used in Ceriodaphnia dubia, short-term chronic tests in which the young of females are distributed amongst treatments so that the origin (the mother) of each neonate is known.
101.reconstituted water - Deionized water to which chemicals are added to (reconstituted) to achieve water of known chemical characteristics (hardness, alkalinity, etc.).