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EC number: 239-825-8 | CAS number: 15733-22-9
Table 1: Cell density at different test substance concentrations during test (average* values)
Nominal concentration (mg/L)
Average Cell Density(initial cell density: 5,000 cells/mL)
After 24 h
After 48 h
After 72 h
* Number of samples: control: 6 flasks; each test substance concentration level: 3 vessels
Table 2: Yield y and percentage inhibition of y during the test period and results of the Williams Test (α = 0.05, one-sided) with the yield y
Yield y [mg/L] and % inhibition of y
Table 3: Validity criteria
Criterion from the guideline
Validity criterion fulfilled
The biomass in the control cultures should have increased exponentially by a factor of at least 16 within the 72-hour test period.
The mean coefficient of variation for section-by-section specific growth rates (days 0-1, 1-2 and 2-3, for 72-hour tests) in the control cultures must not exceed 35%
The coefficient of variation of average specific growth rates during the whole test period in replicate control cultures must not exceed 7% in tests with Pseudokirchneriella subcapitata and Desmodesmus subspicatus. For other less frequently tested species, the value should not exceed 10%.
The influence of p-chloro-m-cresol on the growth of the green alga subspicatus (formerly Scenedesmus subspicatus) was investigated by Vinken & Wydra (2007) in a 72 hours static test according to the following guidelines: OECD 201 (2006), Directive 92/69/EEC, C.3 (1992). The calculated average growth rates decreased in a dose dependent manner. The 72 h NOEC value was 9.8 mg a.i./L, based on the lack of a statistical growth inhibition at these concentrations. Based on the mean area under the growth curve, the 72-hour EbC50 value was 17.2 mg a.i./L. Based on growth rate, the 72-hour ErC50 and the Er10 values were 30.6 mg a.i./L and 13.37 mg a.i./L, respectively. Mean measured concentrations ranged from 97 % at test start to 89 % at test end of the nominal concentration during the test. Therefore, all endpoints were based on nominal concentrations of the test item.
Validity criteria for the acceptance of the test can be considered as fulfilled.
NOErC (72 h) = 9.8 mg/L (nominal, Desmodesmus subspicatus), read-across
ErC50 (72 h) = 30.62 mg/L (nominal, Desmodesmus subspicatus), read-across
No study investigating the toxicity of sodium p-chloro-m-cresolate (CAS 15733-22-9) to algae is available. Therefore, in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 a read-across to the source substance (p-chloro-m-cresol, CAS 59-50-7) which isthe main transformation product of the target substancesodium p-chloro-m-cresolate (CAS 15733-22-9) is applied.
The source substancep-chloro-m-cresol is the common compound in this analogue approach and is solely responsible for the (absence of) effects.Thus, the source substance is considered a suitable representative for the evaluation of the toxicity of the target substance to aquatic organisms. The read-across approach is justified in detail within the analogue justification in IUCLID section 13.
One key (Vinken & Wydra 2007) is available investigating the toxicity of p-chloro-m-cresol (CAS 59-50-7) to aquatic algae. The key study was conducted according to OECD 201 (2006) and Directive 92/69/EEC, C.3 (1992). Algae were exposed to the test item for 72 hours under static conditions to nominal concentrations of 0, 0.95, 3.1, 9.8, 3.1, 9.8, 31, 100 mg/L. Cell concentrations were measured after 24, 48 and 72 hours. The calculated average growth rates decreased in a dose dependent manner. The 72-hour NOEC value was 9.8 mg/L, based on the lack of a statistical growth inhibition at these concentrations. Based on the mean area under the growth curve, the 72-hour EbC50 value was 17.2 mg/L. Based on growth rate, the 72-hour ErC50 value was 30.6 mg/L. Mean measured concentrations ranged from 97 % at test start to 89 % at test end of the nominal concentration during the test. Therefore, all endpoints were based on nominal concentrations of the test item.
Based on the available results from a structurally similar source substance (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) which is the main transformation product of the target substance and is characterized by a similar ecotoxicological profile and comparable structure, it can be concluded that sodium p-chloro-m-cresolate has effects in the same range as the target substance.
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