|Rosin, CAS No. 8050-09-7Alga, Growth Inhibition Test(72 h, EL50)|
Rosin, CAS No. 8050-09-7Alga, Growth Inhibition Test(72 h, EL50)
This study was designed to determine the median effective loading (EL50) of Rosin, CAS No. 8050-09-7, by exposing alga (Selenastrum capriconutum) to solutions prepared as Water Accommodated Fractions (WAF) at different loading rates. This study was performed based on procedures in OECD (1984) Guideline 201 for Testing of Chemicals and following procedures in OECD (2000) Guidance Document No. 23 on Testing Difficult Substances. The test met all validity criteria. Rosin, an amber crystalline solid, is a poorly soluble complex mixture. The method of preparation was selected to maximise the solubility of the test item under specific test exposure conditions, but reduce exposure of the test organism to insoluble fractions. The effects of both filtering and adjusting pH were investigated in the range finding test. For both the range finding and definitive-limit tests, the test item was prepared and tested at a temperature appropriate to the test organism as WAF, up to a maximum loading rate of 1000 mg.l 1. WAF were prepared in 2 litre capacity glass vessels with sidearm, with 2 litres of ISO freshwater algal medium. The vessels were placed on a magnetic stirrer and a stir bar added. The appropriate weight of the test item was added to the stirring medium and the vessels were sealed to avoid loss of volatile fractions. The stirring speed was adjusted to give a stirring vortex 5 - 10 % of the water column. After a stirring period of ca 48 h the test solutions were allowed to settle for ca 1 h. The WAF was then removed via the sidearm taking care not to remove any undissolved material at the top or bottom of the water column. The test organisms were exposed to the WAF. Following the results of the range finding test a definitive-limit test was conducted at a maximum loading rate of 1000 mg.l 1, with an untreated control. As no effects or inhibition of growth was observed the 72 h EL50 for Area Under the Curve (AUC) and Average Specific Growth Rate (0-72 h) was > 1000 mg.l 1, the highest loading rate. Both the Average Specific Growth Rate and the AUC in the test treatments were greater than in the control group for 0 to 72 h. Hence the No Observed Effect Loading Rate (NOELr) for Average Specific Growth Rate and AUC was 1000 mg.l 1, under the conditions of the test. During the definitive-limit test, pH and temperature ranges were recorded as follows, pH: 7.6 9.31 (Table 4) and temperature: 24 - 26 ?C. The light intensities were 9450 lux (range finding test) and 8830 lux (definitive-limit test).
Author: Kelly C R ~ Clayton M A - Provided by: Walter Jones - ID: 100.IR.20681 - Date: 6/12/2002
Providing Organization: Pine Chemicals Association
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