This International Standard specifies a semi-static method for determining the effects of contaminants on growth and survival of young snails, usually Helix aspersa aspersa Müller. The animals are exposed via the cutaneous and digestive route using a test substrate (artificial or natural soil according to the objective of the study) to which defined amounts of the following are added: ¾ðsubstances, mixtures or preparations; ¾ðsoils (contaminated or of unknown quality) or waste materials. This test takes into account the possible changes in the test substance, preparation, soil or waste material because the test mixtures are prepared and renewed every week during the 28-day test period. A static method may be implemented in addition to the semi-static method (optional). This method is described in Annex A. This method does not apply to substances for which the air/soil partition coefficient is greater than one, or to substances with vapour pressure exceeding 300 Pa, at 25°C.