PH24 Environmental Assessment, Environmental Toxicology
Exhibit Hall
8:00 AM - Thursday
(PH274) Proposal for an artificial soil substrate for toxicity tests in tropical regions.
Garcia, M.1, Roembke, J.2, Martius, C.3, 1 Embrapa Amazônia Ocidental, Manaus, Amazonas, Brazil2 ECT Oekotoxikologie GmbH, Floersheim, Hessia, Germany3 Center for Development Research - Bonn University, Bonn, Westfalia, Germany
ABSTRACT- Nowadays, the substrate to be used in ecotoxicological soil tests recommended by international agencies is artificial soil (OECD and ISO guidelines). However, in most tropical countries, international guidelines for the environmental assessment of chemicals in the soil are officially not in use. Besides the lack of legal requirements, the main limitation to use OECD artificial soil in tropical regions is the unavailability of the organic matter (i.e., Sphagnum peat moss) described in the guidelines. To allow the use of OECD artificial soil in other regions of the world where this component is not readily available, a new source of organic matter had to be identified in order to get a Tropical Artificial Soil (TAS). In this study, three sources of organic matter, available in Brazil, potentially suitable as a replacement for peat moss were investigated: Xaxim (tree fern roots), Coir dust (coconut peals ground and composted) and Sphagnum plants (instead of Sphagnum peat). Toxicity tests with Eisenia fetida for Carbendazim (fungicide) and Lambda-cyhalothrin (insecticide) were performed in artificial soils consisted of these alternative organic matter sources. The parameters mortality, body weight change and avoidance behavior were used to compare the suitability of the three substrates. The artificial soil with Xaxim showed to be a feasible substrate for the earthworms. However, the use of Xaxim is restricted by law in Brazil, since this species was included in the list of endangered species due to its overuse. The Sphagnum plant was found to be not suitable as a substrate in earthworm tests, probably because Sphagnum is not a decomposed organic material. In addition, the earthworms showed an avoidance behavior when exposed in this substrate. The Coir dust seems to be the most suitable alternative to Sphagnum peat for the composition of an artificial soil modified for tropical regions. It can be easily obtained in many tropical countries and recently became commercially available in garden stores for soil amending. However, the new formulation of tropical artificial soil proposed here, should be proven in a ring-test using the same substances in different laboratories in tropical countries before this modified test substrate can be included in international test guidelines.
Key words: terrestrial ecotoxicology, laboratory tests, earthworms, OECD/ISO guidelines