Reaction Mass of 4-tert-butyl-2-hydroxycyclohexyl methacrylate and 5-tert-butyl-2-hydroxycyclohexyl methacrylate

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Test vessels were observed for immobile D. magna at 24 and 48 h after test initiation. D. magna were recorded as immobile if no movement was observed within 15 seconds following gentle agitation if the test vessel and after gently touching with a glass rod.

Vehicle:

no

Details on test solutions:

The definitive test was conducted with dilutions prepared from a saturated solution of TBE, producing test concetrations of 6.25, 12.5, 25, 50 and 100 % saturation.The saturated solution was prepared by adding TBE (100.02 mg) to Elendt M4 medium (1 L) and ultrasonicating for 60 mins. An aliquot (ca. 950 mL) of the saturated solution was siphoned from the flask, taking care to exclude undissolved test item, for use as the 100 % saturated solution. The remaining solution was serially diluted (1:2 v/v) with Elendt M4 medium to produce the required test concentrations. The control contained Elendt M4 medium only.

Test organisms (species):

Daphnia magna

Details on test organisms:

D. magna (water flea) were used for this study. They were bred within the laboratory by acyclical parthenogenesis and the neonates used were < 24 h old at test initiation.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

Elendt M4 media was measured prior to test initiation.299 mg CaCO3/L

Test temperature:

Min/ max temperature recorded at test initiation, 24 and 48 h.Range: 20.5-21.2 °C

pH:

Measured at test initiation, 24 and 48 h.Range: 7.83-7.94

Dissolved oxygen:

Measured at test initiation, 24 and 48 h.Range: 88.9-94.0 % of air saturation

Nominal and measured concentrations:

Nominal: 6.25, 12.5, 25, 50 and 100 % saturationMeasured: 1.35, 2.70, 5.29, 10.2 and 26.1 mg/L, respectively.

Details on test conditions:

Four test vessels, each containing 100 mL of treated or control media, were prepared for each treatment group. Five neonates (<24 h old) were added to each vessel within 30 mins of test solution preparation.Test vessels consisted of glasss crystallising dishes of ca. 200 mL capacity, covered with Perspex lids to prevent dust contamination and evaporation of the test solution.Test vessels were observed for immobile D. magna at 24 and 48 h after test initiation. D. magna were recorded as immobile if no movement was observed within 15 seconds following gentle agitation of the test vessel and after gently touching with a glass rod.Temperature, pH, conductivity and dissolved oxygen concentration were measured in an additional vessel prepared at each concetration/ control at 0 h, 24 h and 48 h. The Elendt M4 hardenss was measured was determined prior to use in this test.

Reference substance (positive control):

no

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

6.22 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

Analytical samples taken at 0 and 48 h indicated that concentrations of TBE were stable over the test period, with mean measured concentrations of TBE in the range 86-102 % of the initial measured values. The overall mean measured concetrations of TBE were 1.35, 2.70, 5.29, 10.2 and 26.1 mg/L for the 6.25, 12.5, 25, 50 and 100 % saturated solutions, respectively. TBE was not detected in the control samples. See Table 3 for mean measured concentrations of TBE during the definitive test.The number of immobile D. magna recorded over the test period are presented in Table 4. After 24 h exposure; 20 (100 %), 2 (10 %) and 1 (5 %) immobile D. magna were recorded in the 26.1, 10.2 and 5.29 mg/L test groups, respectively. After 48 h exposure, the cummulative number of immobile D. magna were; 20 (100 %), 20 (100 %), 4 (20 %) and 1 (5 %) in the 26.1, 10.2, 5.29 and 2.70 mg/L test groups, respectively. See Table 4 for the cummulative number of immobile D. magna observed during the exposure period.

Reported statistics and error estimates:

Statistical analysis was conducted using the Spearman-Karber (TSK) method. NOEC and EC50 values were based on immobilisation.The 24 and 48 h EC50 values were estimated to be 14.6 (CI: 12.9, 16.5) and 6.22 (CI: 5.42, 7.12), respectively.The 48 h NOEC was estimated 5.29 mg/L.

Table 3       Measured Concetrations of TBE During the Definitive Test

% of Saturated Solution of TBE	Time (h)	Mean Measured Concentration of TBE (mg/L)	Overall Mean Measured Concentration of TBE (mg/L)	Deviation of 48 h Measured Concentration from 0 h Measured Concentration (±%)
Control	0	nd	nd	nd
	48	nd
6.25	0	1.44	1.35	-13
	48	1.25
12.5	0	2.88	2.70	-13
	48	2.52
25	0	5.36	5.29	-3
	48	5.22
50	0	10.07	10.2	+2
	48	10.31
100	0	28.00	26.1	-14
	48	24.13

nd: not detected (LOD = 1.63 µg/L)

Table 4       Cummulative Number of Immobile D. magna Recorded During the Definitive Test

Time (h)	Replicate	Mean Measured Concentration of TBE (mg/L)
		Controls	1.35	2.70	5.29	10.2	26.1
24	I	0	0	0	0	0	5
	II	0	0	0	0	1	5
	III	0	0	0	0	0	5
	IV	0	0	0	1	1	5
	% immobile D. magna	0	0	0	5	10	100
48	I	0	0	0	0	5	5
	II	0	0	0	2	5	5
	III	0	0	1	1	5	5
	IV	0	0	0	1	5	5
	% immobile D. magna	0	0	5	20	100	100

Validity criteria fulfilled:

yes

Conclusions:

The 48 h EC50 (immobilisation) for TBE to D. magna was estimated at 6.22 mg/L, based on overall mean measured concentrations of TBE.The 48 h NOEC (immobilisation) was 5.29 mg/L.

Executive summary:

This study was designed to estimate the median effective concentration (EC50) for immobilisation of Daphnia magna exposed to TBE. The study was conducted over a 48 h period, under static conditions. Four replicate vessels were prepared for each treatment, each containing five D. magna neonates. The study was performed in accordance with OECD Guideline 202 (2004).

Based on the results of a range-finsing test, the definitive test was conducted with solutions prepared as dilutions of a saturated solution of TBE (nominally 100 mg/L). As the test item was only, partially soluble, the method was selected to maximise the solubility of TBE under test conditions. The exposure concetrations were nominally 6.25, 12.5, 25, 50 and 100 % saturation, plus an untreated control. This corresponded to mean measured concetrations of 1.35, 2.70, 5.29, 10.2 and 26.1 mg/L. Analysis of samples taken at 0 and 48 h indicated that TBE was stable over the test period, with measured concentrations of TBE in the range 86 -102 % of the initial values.

The 48 h EC50 (immobilisation) for TBE to D. magna was estimated (using Spearman-Karber method) at 6.22 mg/L, based on overall mean measured concentrations of TBE. The 48 h NOEC (immobilisation) was 5.29 mg/L.

Description of key information

EC₅₀ = 6.22 mg/L, OECD 202, 2004 (GLP); Knight (2016)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

6.22 mg/L

Additional information

The 48 h EC₅₀ and NOEC (immobilisation) values were estimated in a GLP study to be 6.22 and 5.29 mg/L, respectively. Values were based on mean measured concetrations of TBE. The study was conducted in accordance with OECD Guideline 202 (Knight, 2016).