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Google Image Result for http://www.longwood.edu/cleanva/Images/cigbuttsl.jpg 3/10/08 2:17 AM the Data Cards as a separate item in 1990. Because of the vast inflow of cigarette butts into the environment, experiments were conducted to determine if cigarette butts as litter present an environmental problem beyond aesthetics and have a measurable toxic effect when they enter the aquatic environment. A series of bioassays (tests which use the response of a living organism to determine the effective level of a chemical in the environment) were conducted. One of the organisms most studied in aquatic bioassays is the planktonic animal Daphnia magna, often called a water flea. Static acute toxicity tests using D. magna have been widely used for decades to estimate the acute toxicity of chemicals to aquatic invertebrates. In aquatic ecosystems, water fleas occupy a critical position as they transfer energy and organic matter from primary producers (algae) to higher consumers such as fishes. Water fleas are small transparent crustaceans, have one central black compound eye, and swim in jerky motions. They feed by rhythmically beating their legs, collecting algae or bacteria on the filter-like bristles on their thoracic legs, and passing the food toward their mouths. The Experiments The large number of chemicals in used cigarette filters precluded toxicity testing of each chemical. Thus, a test that can estimate aquatic toxicity from the composite of chemicals and compounds found in cigarette butts was used. Using the US, Environmental Protection Agency's 1996 "Aquatic invertebrate acute toxicity test for freshwater daphnids" standardized toxicology protocols and procedures, water fleas were introduced to petri dishes filled with dilution water and the test solution. For these experiments, the test solution was made by soaking the components of cigarette butts (remnant tobacco or the cellulose-acetate filters) in distilled, de!onized water, and allowing the chemicals in the butts to leach into the water. Water fleas in the petri dishes were observed at 24 and 48 hours. In addition to death, any abnormal behavior or appearance was also recorded. The transparent crustacean Daphnia (often called a water flea) are planktonic animals which occupy a critical position in aquatic ecosystems, as they transfer energy and organic matter from algae to Y higher consumers. Tests using Daphnia have been widely used for ¢ decades to estimate acute toxicity. 1 Daphnia Illustration O by Chris Register Do Not Copy or Reproduce Without Permission from Clean Virginia Waterways! Click here to learn more about water fleas. Data collected during the experiments were used to develop dose-response curves. Data were also used to determine the experimentally derived toxicant concentration producing death to 50% of the test population during continuous exposure over a specified period of time. This is referred to as the "Lethal Concentrations 50" values (LC50). LCO means no animals died, and LC100 means they all died. Lethal Concentrations provide a quantifiable measure and precise expression of toxicity. http://Images.google.com/imgres?imgurl-http://www.longwood.edu/cl...%3DClgarette%28Lltter%2Bon%2BBeaches%26um%3D3%26h%3Den%26sa%3DX Page 4 of 8