BS EN ISO 15952:2018 pdf download – Soil quality – Effects of pollutants on juvenile land snails (Helicidae) – Determination of the effects on growth by soil contamination 4 Principle Juvenile land snails (usually Helix aspersa aspersa Müller) are exposed during a period of 28 d to test mixtures containing the test substance, preparation or matrix at different concentrations. The test mixtures are freshly prepared and renewed every 7 d. According to the objectives of the study, the test mixtures may be prepared with artificial soil (see 6.3.2) or with a suitable natural soil (see 6.3.3). The snails are fed during the test with uncontaminated food. The effects on growth (biomass and shell diameter) and on survival are measured after 28 d of exposure (optionally, effects could be measured every 7 days during 28 d). The results obtained during testing are compared with those of a control to determine the NOEC or LOEC and to allow the estimation of the concentration which reduces the growth of the snails by 50 % within 28 d with respect to the fresh mass [EC 50,m (28 d)] and to the shell diameter [EC 50,d (28 days)] or other values of EC x . If the concentrations selected result in lethal effects, the results obtained during testing are compared with those of a control and used for estimating the concentration which causes the death of 50 % of the snails [LC 50 (28 d)]. For particular applications, various parameters (EC x , NOEC, LOEC, LC 50 ) can be determined (optional) after exposure periods lower than 28 d (7 d, 14 d or 21 d). The test is conducted in two stages: — a preliminary test intended to indicate both the non-observed effect concentration, NOEC, and the complete growth inhibition. The resulting dose-response relationship is important for the proper design of the definitive test; — a definitive test specifying the concentrations which cause between 10 % and 90 % of growth inhibition. It is not necessary to perform a final test where the preliminary test has not revealed any inhibitory effects at the maximum concentration tested. 5 Test environment The test shall be carried out at a temperature of (20 ± 2) °C under a day-night photoperiod of 18 h to 6 h. The illumination intensity (artificial light of daylight type), without any natural light in the test containers shall be 50 to 100...
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