Springborn Publications
Springborn actively participates in industry technical meetings and conference. Several Springborn publications are available for download. You will need Adobe Acrobat Reader to view these files.
Three of our Study Directors from our Horn laboratory presented poster sessions at SETAC Europe in June.
Merve Anne Biester, The effect of coloured substances on algal growth
Abstract:
Algal testing of highly coloured substances is difficult due to their absorption of photosynthetically active light causing reduced algal growth. Hence it is important to distinguish between real toxicity and growth inhibition caused by light limitation. Several approaches (testing at different light intensities or using a light transmission filter) have been recommended, however, little information has been published. This study assessed the effect of a highly coloured substance on the growth of the freshwater green alga, Pseudokirchneriella subcapitata, using a liquid filter (double flask method). Two sets of treatment vessels, (Test 1 and Test 2) with different treatment levels and six control replicates were established. For the tests 250-mL Erlenmeyer flasks with 100 mL solution of 2cm depth were prepared. The solution volume in each vessel placed above the test vessels (light filter) also had a solution depth of 2 cm. Test 1 vessels contained untreated medium and algae, and the overhead vessels (light filter) contained test solution. Test 2 vessels contained the test solutions and algae and the overhead vessels contained untreated medium. Control vessels contained untreated medium and algae and the overhead vessels (light filter) contained untreated medium. At test termination (72 hrs) control algae showed a good performance. Test 1 showed similar results compared to the controls thus no effects were induced by light absorption. Test 2 showed a well defined concentration-dependent reduction on yield. Thus the observed effect was a genuine toxic effect and the light absorbance imparted by the substance had no significant impact. This study showed that this method can be applied to confirm a lack of effects of light absorption in algal testing.
Marc Hamitou, The Double Mixing Chamber System - an approach for difficult to test substances
Abstract:
Many substances are difficult to test in aqueous solutions because of their physico-chemical behaviour. Considering the ratification and implementation of the REACH and EMEA regulations, testing of such substances is likely to gain in importance. Difficulties were encountered during a fish early life stage (ELS) study, with a pharmaceutical agent (fungicide) which was sparingly water soluble, not stable in aqueous solutions and very adsorptive. In order to compensate for these characteristics, the conventional diluter system was modified to include double mixing chambers. The modified delivery system consisted of dual 250 mL Erlenmeyer mixing chambers, equipped with overflow drains. Each exposure concentration was maintained with continuous delivery of the test item into a primary mixing flask positioned above a magnetic stirrer. The solution from the primary mixing flask flowed to a second identical mixing vessel that continued to mix the solution with a magnetic stirrer plate in order to insure a homogenous exposure solution. The modification of different parameters (number, position and flow rate of the mixing chambers) in combination with the Mixing Chamber System enabled a large improvement in the consistency of substance recovery rendering a flow-through study with this difficult compound possible. This study showed a possibility to modify the diluter design of a flow-through study to obtain homogeneous test solutions and to achieve stable and consistent recoveries of a difficult substance in the test solutions throughout a chronic study (ELS). The findings of this study are applicable for other difficult substances which need to be tested in a flow-through design.
Sebastian Hoffmann, Influence of vessel dimensions and light conditions on the outcome of toxicity tests with larvae of Poecilus cupreus (L.) (Coleoptera: Carabidae)
Abstract:
Poecilus cupreus (L.) (Coleoptera: Carabidae) play an important role as predators in agricultural fields and ecotoxicological tests on adults or larvae may be requested in the context of the registration of plant protection products in Europe ( Directive 91/414/EEC).
A previous study based on the ringtest protocol (2002) as well as Heimbach et al (1998, 2002) and Heise et al (2004) carried out in this laboratory suggested that light conditions and vessel size may influence the outcome of toxicity studies. Therefore a laboratory study which aimed to investigate the potential influence of these parameters on the test results was carried out.
Based on the standard protocols described above, a dose response laboratory study exposing carabid larvae to the insecticide Perfekthion over 41 days in natural Lufa 2.1 soil (temp. 20 ± 2, humidity 70 ± 20%) was carried out, varying test vessel size and light conditions as outlined below:
- no light, glass tubes with a capacity of 35 mL containing 25 g dry soil
- 16h/8h light/dark rhythm, glass tubes with a capacity of 35 mL containing 25 g dry soil
- 16h/8h light/dark rhythm, glass container, with a capacity of 1000 mL containing 530 g dry soil
The endpoints were mortality and adult weight. LC50 values differed depending on test vessel size but were independent of light regime.
For more information about these topics, contact us.
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