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EC number: 255-002-6
CAS number: 40615-36-9
The results for the Inhibition of the growth
rate are presented in table 1.
Table1: Inhibition of growth rate
after 24 h, 48 h and 72 h exposure.
Nominal test item loading rate [mg/L]
test item conc.
Inhibition of Growth rate [%]
* The measured concentration is below
the Limit of Quantification but above the Limit of Detection.
In the control, the test item was not
detected. The measured test item concentrations in the test item
treatments were <LOQ - 0.46% of the nominal loading rates (see table 2).
As the measured test item concentrations are not within ± 20 % of the
nominal loading rates, according to OECD 201 (2006) and OECD 23 (2000),
all results are given in relation to the analytically measured test item
concentrations. Therefore, the geometric mean of all four measurement
times (0, 24, 48, and 72 hours) was calculated.
Table2: Analytically measured test
item concentrations after 0 h, 24 h, 48 h and 72 h exposure. Measured
concentrations which are < LOQ are presented in brackets. LOQ: Limit of
Quantification (1 mg/L). LOD: Limit of Quantification = 0.16 mg/L.
Sampling time [h]
Measured test item concentration [mg/L]
Geometric mean test item conc. [mg/L]
< LOQ (0.193)
< LOQ (0.194)
< LOQ (0.200)
< LOQ (0.189)
< LOQ (0.294)
< LOQ (0.289)
< LOQ (0.256)
< LOQ (0.299)
< LOQ (0.311)
< LOQ (0.524)
< LOQ (0.537)
< LOQ (0.517)
< LOQ (0.519)
< LOQ (0.593)
< LOQ (0.949)
< LOQ (0.947)
< LOQ (0.936)
< LOQ (0.955)
n.d. = not detected
CRITERIA OF VALIDITY
- The biomass (cell concentration) in the
control has increased by a factor of 161.6 and therefore ≥ 16 during the
- The mean coefficient of variation for
section-by-section growth rate (day 0 - 1, 1 - 2 and 2 - 3) in the
control is 12.5 % and therefore ≤ 35 %.
- The coefficient of variation of average
specific growth rate during the test period in the control replicates is
0.9 % and therefore ≤ 7 %.
- The test is valid according to OECD Test
Guideline 201 (23 March 2006).
In a 72-hour acute toxicity study,
cultures of Pseudokirchneriella subcapitata, Strain No. 61.81 SAG
were exposed to 4,4'-Dimethoxytrityl chloride at measured concentrations
of 0, 0.194, 0.289, 0.537, 0.947, 1.8 mg test item/L (nominal: 0, 25,
50, 100, 200 and 400 mg test item/L) under static conditions in
accordance with the OECD guideline 201. As the measured test item
concentrations were not within ± 20 % of the nominal loading rates, all
results are given in relation to the analytically measured test item
concentrations. As most measured test item concentrations are below the
LOQ (i.e. 1 mg/L), the measured concentrations were used for calculation
of the effect concentrations. The chemical analysis was conducted using
the method with the lowest LOQ possible with the available equipment at
the test site. The signal to noise ratio would be too low for a lower
LOQ (in the range of or below the Limit of detection). The NOEC and EC50
values based on growth rate were 0.537 and 1.629 mg a.i./L,
The following abnormalities were
noted: The microscopic examination after 72 hours did not show any
obvious abnormality, except for in the highest treatment group (400
mg/L) some algal cells were thickened.
This toxicity study satisfies the
guideline requirements for algae growth inhibition study according to
OECD guideline 201.
Test Organism: Pseudokirchneriella
Test Type (Flowthrough, Static, Static
In a 72-hour algae growth inhibition
test cultures of Pseudokirchneriella subcapitata were exposed to
4,4'-Dimethoxytrityl chloride at measured concentrations of 0, 0.194,
0.289, 0.537, 0.947, 1.8 mg test item/L under static conditions in
accordance with the OECD 201 (2006) and GLP.
The following effect levels - based on
the growth rate - are calculated:
- 72 h ErC50: 1.629 mg/L (95 % C.L.
1.079 – 2.417 mg/L);
- 72 h NOErC: 0.537 mg/L
- 72 h LOErC: 0.947 mg/L.
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