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Conversion factors
Organism Group Refers to broad categories of plants or animals with similar characteristics. Organism groups included in the Ecotox database are:
Average Group Toxicity The acute toxicity of a particular chemical to Organism Groups (amphibians, fishes, zooplankton, etc.). Narrative descriptions of acute toxicity to aquatic species were assigned based on LC50, according to the guidelines in M. A. Kamrin, Pesticide Profiles: Toxicity, Environmental Impact, and Fate, Lewis Publishers (Boca Raton, FL, 1997), p. 8 (see table below). Aquatic Species: Fish, Crustaceans, Mollusks, Amphibians
Acute toxicity for honeybees is assigned based on a ranking scheme developed at the University of California and discussed in detail by the University of Florida, Protecting Honeybees from Pesticides. Honeybees (Apis mellifera)
Since any single summary rating will inherently not be representative of the extremes of the sensitivity of organisms to chemical exposure, we also provided the Toxicity Range for species within the Organism Group, as well as the raw data for the individual studies, so the analyst can evaluate the studies and make his or her own decision about toxicity to a particular species. The technique used to determine these ratings is explained in more detail in the Methodology section. The range of acute toxicity of a pesticide to species within a particular Organism Group. The toxicity range assigned to each Organism Group was based on the most sensitive and least sensitive members of the group, including outlier species. Chronic toxicity data for bees is available for some chemicals. Population-level effects on bees may occur even if a pesticide has low acute toxicity. For example, certain pesticides interfere with bee reproduction, ability to navigate, or temperature regulation, any of which can have an effect on long-term survival of bee colonies. The neonicotinoids, pyrethroids and keto-enol pesticides are some types of pesticides causing one or more of these effects. Because no dose-equivalent scale has been set for chronic toxicity for bees, the Chronic Bee Toxicity ranking is a "Yes" when studies have shown adverse effects on honeybee colonies on exposure to the pesticide in question. These emerging data are from the peer-reviewed literature, US EPA, and/or the European Union reports on pesticides toxic to bees. As this data set is fleshed out and chronic effects are more fully documented through research, specific references for pesticides having chronic toxicity to bees will be provided. General References:
The different types of observed effects of a particular pesticide on aquatic organisms. Effects include mortality (used to define the acute toxicity rating), behavorial, bioaccumulation, biochemical, developmental, enzymatic, feeding behavior, genetic, growth, histological, intoxication, morphological, mobility, physiological, population, and reproductive. The name commonly used to describe an organism, e.g. rainbow trout. Scientific Name The Latin name that gives the genus and species of an organism, e.g. Oncorhynchus mykiss for rainbow trout. Average Species LC50 The average LC50 value calculated for each chemical/species combination by adding the LC50 values for each study and dividing by the number of studies. The LC50 is the concentration of toxicant that is lethal to 50% of the test organisms. Studies with results more than two standard deviations away from the average of all studies for a species were marked as outliers and a new average was calculated excluding the outliers. For more detail, see Methodology section. The standard deviation for the LC50 value was calculated for each chemical/species combination. The standard deviation provides a measure of how close the individual study results are to each other, with a small standard deviation indicating that most studies produced similar LC50 values. A population formula was used to calculate this statistic (N, not N-1). Number of Studies The number of studies averaged together to determine the Average Species LC50 for a particular chemical/species combination. Average Species Rating The average toxicity of a chemical to a particular species. Narrative descriptions of toxicity were assigned based on Average Species LC50, according to the guidelines in M. A. Kamrin, Pesticide Profiles: Toxicity, Environmental Impact, and Fate, Lewis Publishers (Boca Raton, FL, 1997), p. 8 (see table).
The technique used to determine these ratings is explained in more detail in the Methodology section. Outlier Result for Organism Group? Any LC50 value for a particular chemical/species combination that was more than two standard deviations from the average value for that Organism Group was flagged as an outlier, and a new average was calculated excluding outliers to give the average organism group LC50. This procedure eliminated particularly sensitive or particularly insensitive species from the data used to generate the Average Group Toxicity; however, the summary data for all species are presented in the Species Summary page and include outlier status. The measurement used to determine the extent of the effect of a particular pesticide on aquatic organisms. For example, if behavioral changes were being observed, one measurement is avoidance of the pesticide. The measurements vary considerably among the studies. For complete details, it is necessary to go to the original reference. Life Stage The age of the plant or animal used in the toxicity study. Terms used include: juvenile (juv), seedling, early life (erlylf), adult, gravid, sperm, embryo, larval, worker (for bees), or not reported (N.R.). Other terms used are self-explanatory. Age is also given by reporting the average mass of the test organisms. Study Time The length of time organisms are exposed to the given dose of pesticide. Abbreviations used are: MI = minutes; H = hours; D = days, WK = weeks, and NR = not reported. If different studies are being compared, it is important to use only toxicity tests conducted with the same study time. The toxicity endpoint of an ecotoxicity study is the observable effect of a toxin on the test organism. Typical endpoints are death, genetic effects, behavioral effects, and growth inhibition, but many others are also used. The toxicity endpoint of a particular study is somewhat arbitrary; however, several standards have emerged as the most commonly used endpoints in toxicity testing. These standards are the LD50, LD25, LC50, LC25, NOEL, LOEL, NOEC, LOEC, and MATC. The LD50 is the dose of the pesticide in milligram (mg), microgram (ug), or nanogram (ng) of pesticide per kilogram (kg) of body weight that is lethal to 50% of the test organisms within the stated study time. Units used are: ppm (mg/kg), ppb (ug/kg), and ppt (ng/kg). For bees, the dose is given in microgram per bee (see definition of conversion factors between one unit and another). The LC50 is defined as the amount of pesticide present per liter of aqueous solution that is lethal to 50% of the test organisms within the stated study time. Units used are mg or ug of pesticide per liter of solution. Units used are: ppm (mg/L) and ppb (ug/L) (see definition of conversion factors between one unit and another). The EC50 is the effective concentration of the pesticide in mg/L or ug/L that produces a specific measurable effect in 50% of the test organisms within the stated study time. The measurable effect is lethality for zooplankton and a reduction in photosynthetic activity by 50% for phytoplankton. (See definition of conversion factors between one unit and another). The NOEL (NOEC) is the "no observed effect level (concentration)," or the level below which, no adverse effects are observed. Note that this level depends strongly on the sensitivity of the techniques used to measure the effects. The LOEL (LOEC) is the "lowest observed effect level," or the lowest level (concentration) at which adverse effects are observed. Note that this level (concentration) depends strongly on the sensitivity of the techniques used to measure the effects. The MATC is the "maximum acceptable toxicant concentration" and is a hypothetical threshold concentration that is the geometric mean between the NOEC and LOEC concentration. Toxic Dose The number given in this column is the concentration or amount of the substance (product or active ingredient) that produced the observed effect. For example, if the toxic dose is given as 320 ug/L for an LC50 toxicity endpoint, 50% of the test organisms died at a pesticide concentration of 320 ug/L. Several different units are used to indicate the dose:
Concentration Units The concentration units from all studies were converted to micrograms per liter (ug/L) in the process of preparing the data for upload to the PesticideInfo site. The concentration type denotes whether the substance tested was a pure active ingredient (A) or a formulated product (F) with inert ingredients that may have toxicity effects as well. If not specified in the original study, EPA assumes the test is on the formulated product. Other designations include: dissolved (D), labile or free metal ion (L), total (T), unionized (U), not reported (NR), or not applicable (NA). The Toxic Dose given is for the substance described in the Concentration Type column. The U.S. EPA did not include studies on mixtures of active ingredients in the AQUIRE database, so there are none in this data collection. Describes the substance tested. The percent active ingredient (AI) is generally included in this column if a formulated product was tested. The U.S. EPA did not include studies on mixtures of active ingredients in the AQUIRE database, so there are none in this data collection. Experiment Type For aquatic organisms (fish, zooplankton, and phytoplankton), tests are carried out using either static (S) or flow through (F) methods. In the static method, the pesticide and test organisms are added to the test solution and kept there for the remainder of the study time. In the flow-through method, a freshly prepared, pesticide-spiked test solution flows through the test chamber continuously for the duration of the test. The flow-through method provides a higher continuous dose of the pesticide; however, the static method does not remove waste products and may accumulate toxic pesticide breakdown products. Neither method exactly mimics a natural system. Other exposure types are: R: Renewal: A renewal test is similar to a static test because it is conducted in still water, but the test solutions and control water are renewed periodically (usually 24-h intervals) by transferring the test organisms to chambers with freshly prepared material or by removing and replacing the material in the original containers (1) P: Pulse: Intermittent or fluctuating dosing B: Tidal C: Topical exposure O: Diet or Oral exposure (includes simultaneous diet and water exposure) E: Lentic (static outdoor water system without measurable flow rate, e.g., ponds, lakes, troughs) I: Injection L: Leaching (used for leachate and sediment exposures, if water concentration reported) Reference: G. M. Rand, ed. Fundamentals of Aquatic Toxicology, Taylor and Francis Publishing (Washington, D. C., 1995). Acute Toxicity Rating The toxicity of a chemical to a particular species. Studies were assigned a Toxicity Rating only if they met all of the following criteria:
Narrative descriptions of toxicity were assigned based on LC50 , the concentration of pesticide that is lethal to 50% of the test organisms, according to the guidelines in M. A. Kamrin, Pesticide Profiles: Toxicity, Environmental Impact, and Fate, Lewis Publishers (Boca Raton, FL, 1997), p. 8 (see table).
See the Methodology section for more detail. Outlier Result for Species? Any LC50 value for a particular chemical/species combination that was more than two standard deviations from the average value was flagged as an outlier. A new average was calculated excluding outliers to give the Average Species LC50. The raw data used to calculate this number (including outlier status) is always visible on the "View All Studies" page. See the Methodology section for more detail. Date The year in which the study results were published. Journal The name of the journal or publication in which the study was reported. Summary Acute Aquatic Toxicity The summary ranking for acute aquatic toxicity is found on the Product Information page and is used to describe the acute toxicity of the active ingredients to aquatic organisms. This descriptor shows the average group toxicity of the most sensitive organism group for that chemical. Narrative descriptions of acute toxicity were assigned based on LC50 (see table). Since any single summary rating will inherently not be representative of the extremes of the sensitivity of organisms to chemical exposure, the Toxicity Range is provided on the Chemical Information page, Ecotoxicity section. Data are provided for species within the Organism Group, as well as the raw data for the individual studies, so the analyst can evaluate the studies and make his or her own decision about toxicity to a particular species. To get to the Chemical Information page from the Product Information page, click on the chemical name. Summary Other Aquatic Toxicity The summary ranking for other aquatic toxicity is found on the Product Information page and is used to describe toxicity effects of the active ingredients to aquatic organisms beyond mortality. These other effects include: behavorial, bioaccumulation, biochemical, developmental, enzymatic, feeding behavior, genetic, growth, histological, intoxication, morphological, mobility, physiological, population, and reproductive. More detail on the effects noted for a particular chemical is provided on the Chemical Information page, Ecotoxicity section. Data are provided for species within the Organism Group, as well as the raw data for the individual studies, so the analyst can evaluate the studies and make his or her own decision about toxicity to a particular species. To get to the Chemical Information page from the Product Information page, click on the chemical name. Last updated April 4, 2011 .
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