Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Fish

The 96-Hour LL50 based on nominal loading rates in the key study was 24 mg/l loading rate WAF with 95% confidence limits of 18 - 32 mg/l loading rate WAF. The No Observed Effect Loading rate was 3.2 mg/l loading rate WAF (OECD 203).

 

Short-term toxicity to aquatic invertebrates

The 48-hour EL50 (immobilisation) was calculated to be 91.4 mg/L (95% CI: 51.3 - >99.5mg/L). The maximum loading rate causing no immobilisation was 10.5 mg/L (OECD 202).

Long-term toxicity to aquatic invertebrates

The "No Observed Effect Loading rate" (NOEL) was considered to be 0.12 mg/l loading rate WAF on the basis that at this loading rate there were no significant mortalities (immobilisation) observed in the parental generation (P1) and that there were no significant differences (P ≥ 0.05) between the control and the 0.12 mg/l loading rate WAF test group in terms of numbers of live young produced per adult by Day 21 (OECD 211).

 

Algae

 Exposure of freshwater alga to the test material resulted in a96hour EC50 of 6.4 mg/L (95% confidence interval = 5.7 to 7.3 mg/L) when calculated using cells/ml, and 15 mg/L (95% confidence interval = 14 to 16 mg/L) when determined using the average specific growth rate. The96hour NOEC is 1.7 mg/L when determined using either the number of cells/ml and 3.3 mg/L using the average specific growth rate (OECD 201).

 

Microorganisms

 Given an average inhibition of 20.6% and assuming that the relationship between concentration and effect is linear, an extrapolated EC 50 value equals 2433 mg/L (OECD 209).

Additional information

Short-term toxicity to fish

A key study was performed to assess the acute toxicity of the test material to rainbow trout (Oncorhynchusmykiss).The method followed that described in the OECD Guidelines for Testing of Chemicals (1992) No 203, "Fish, Acute Toxicity Test" referenced as Method C.1 of Commission Directive 92/69/EEC (which constitutes Annex V of Council Directive 67/548/EEC), US CFR Title 40, Part 797, Section 1400 andUS EPADraft Ecological Effects Test Guideline OPPTS 850.1075. Following a preliminary range-finding study, fish were exposed, in groups of ten, to Water Accommodated Fractions (WAFS) of the test material, prepared using a method employing a single phase separation over a range of nominal loading rates of 3.2, 5.6, 10, 18 and 32 mg/l for a period of 96 hours under static test conditions. The number of mortalities and any sub-lethal effects of exposure in each test and control vessel were determined 3 and 6 hours after the start of exposure and then daily throughout the study until termination after 96 hours. The 96-Hour LL50 based on nominal loading rates was 24 mg/l loading rate WAF with 95% confidence limits of 18 - 32 mg/l loading rate WAF. The No Observed Effect Loading rate was 3.2 mg/l loading rate WAF.

 

A supporting study was performed to assess the effect of the test substance on the Fathead Minnow/Pimephales promelasover a 96 h period following the method described in OECD 203. Following a preliminary range-finding study, fish was exposed to the test substance at nominal concentrations of 0, 6.0, 10, 17, 28 and 47 mg/L for a total of 96 hours under static conditions. The number of mortalities in each test and control vessel was determined until 96 h after initiation of the test. The following results were obtained: the 96-h LC50 value was 8.5 mg/L WAF (95% confidence interval of 6.0–10 mg/L). NOEL value was 6.0 mg/L WAF.

 

A second supporting study was performed to assess the effect of the test substance on the Fathead Minnow/Pimephales promelas over a 96 h period following the method described in OECD 203. Fish was exposed to the test substance at nominal concentrations of 0, 2.6, 4.3, 7.2, 12 and 20 mg/L for a total of 96 hours under static-renewal conditions. The number of mortalities in each test and control vessel was determined until 96 h after initiation of the test. The following results were obtained: the 96-Hour LC50 was 19 mg/L WAF with a 95% confidence interval of 16-26 mg/L WAF. The NOEL was 7.2 mg/L WAF.

 

Long-term toxicity to fish

In short-term tests, the water flea demonstrated equivalent sensitivity to the test substance as compared to the fish. Given that the chronic water flea study covers the complete life cycle of the organism it, along with the chronic algae results, was deemed sufficient to characterize the long-term effects for aquatic organisms.

 

Short-term toxicity to aquatic invertebrates

In a key study, the acute aquatic toxicity potential of the test substance was evaluated in a 48-hour static Daphnia magna test. The GLP test was conducted largely in accordance with OECD Test Guideline 202. Due to the nature of the test substance, test solutions were prepared as Water Accomodated Fractions (WAFs). Based on the results of a preliminary limit test in which a nominal loading rate of 100 mg/L resulted in no mortality at 24 hours, but 100% mortality at 48 hours, the definitive test used nominal loading rates of 0, 1, 3, 10, 30 and 100 mg/L. The 48-hour EL50 (immobilisation) was calculated

to be 91.4 mg/L (95% CI: 51.3 - >99.5mg/L). The maximum loading rate causing no immobilisation was 10.5 mg/L.

 

Long-term toxicity to aquatic invertebrates

A key study was performed to assess the effect of the test substance on the reproduction of Daphnia magna over a 21-day period following the method described in OECD 211. The 14 and 21-Day EL50 (immobilisation) values, based on nominal loading rates, for the parental Daphnia generation (P1) were calculated to be 1.1 and 0.91 mg/l loading rate WAF with 95% confidence limits of 0.64-2.1 mg/l loading rate WAF and 0.51 - 1.6 mg/l loading rate WAF respectively. The 21-Day EL50 (reproduction) value based on nominal loading rates was calculated to be 0.66 mg/l loading rate WAF with 95% confidence limits of 0.37-1.2 mg/l loading rate WAF. The "Lowest Observed Effect Loading rate" (LOEL) was considered to be 0.37 mg/l loading rate WAF on the basis that at this loading rate significantly (P 0.05) fewer young per adult were produced when compared to the control. The "No Observed Effect Loading rate" (NOEL) was considered to be 0.12 mg/l loading rate WAF on the basis that at this loading rate there were no significant mortalities (immobilisation) observed in the parental generation (P1) and that there were no significant differences (P ≥ 0.05) between the control and the 0.12 mg/l loading rate WAF test group in terms of numbers of live young produced per adult by Day 21.

 

Toxicity to aquatic algae

The acute toxicity of the water accommodated fraction (WAF) of test material to the freshwater alga, Selenastrum capricornutum was investigated in a key study according to OECD method 201 to establish the approximate toxicity of the test substance. The test was performed at 24 ± 1°C under static conditions with a control (0 mg/L) and five concentrations of WAF (1.7, 3.3, 6.5, 13, 25, and 50 mg/L). The dilution water was sterile enriched media adjusted to a pH of 7.5 ± 0.1. The five WAFS were prepared by formulating individual concentrations of the test substance and dilution water in mixing vessels equipped with a magnetic stirrer, stirring the mixtures for approximately 24 hours, settling the mixtures for approximately four hours, and siphoning the water phase containing the WAF. During the mixing period, the vortex extended approximately 5% of the distance from the water surface to the bottom of the mixing vessels. No insoluble material was noted during the test. Exposure of freshwater alga to the test material resulted in a 96 hour EC50 of 6.4 mg/L (95% confidence interval = 5.7 to 7.3 mg/L) when calculated using cells/ml, and 15 mg/L (95% confidence interval = 14 to 16 mg/L) when determined using the average specific growth rate. The 96 hour NOEC is 1.7 mg/L when determined using either the number of cells/ml and 3.3 mg/L using the average specific growth rate. The determination of whether toxic effects were algistatic or algicida was performed at the conclusion of the test. A 0.5 mL aliquot of test media from each 100 mg/L vessel was transferred into a flask containing 100 mL of fresh media and incubated under test condition for 96 h. Algae increased form the initial density of 720 to 90, 000 cells/mL indicating the test substance was algistatic rather than algicidal.

 

Toxicity to microorganisms

The potential impact of test material on microbial metabolism, as represented by the consumption of oxygen, was investigated using the "Activated Sludge, Respiration Inhibition Test" as prescribed by OECD (1984) and detailed in WCC Protocol OECD209. The test duration was a three-hour exposure period to the test material followed by up to ten minutes for the measurement of oxygen consumption. The study design was comprised of a single nominal exposure concentrations1000 ppm, tested in duplicate; a duplicate control group; and an assessment of the sensitivity of the inoculum used in the test to a reference toxicant (3,5-dichlorophenol). The activated sludge respiration test with test material passed the quality control criteria for an acceptable test. The EC50calculated for the reference toxicant was 29 rng/L, within the acceptable range of 5 to 30 mg/L. The two control replicates produced oxygen consumption rates within the required 15 % of each other, 90.0 and 106.7 mg O2/L*hr, which is also required for the validity of the test. The oxygen consumption rates observed for the activated sludge microbe exposure to the test material was 57.6 and 98.2 mg O2/L*hr respectively. These values translate into inhibitions of 41.1% and 0% as compared to control. Statistical analysis of the results reveal that there does not exist a statistically significant difference between the oxygen consumption rates of the microbes exposed to the test material and the non-exposed control microbes. Given an average inhibition of 20.6% and assuming that the relationship between concentration and effect is linear, an extrapolated EC 50 value equals 2433 mg/L.