Reaction mass of (1S,6R)-3,7,7-trimethylbicyclo[4.1.0]hept-2-ene and (1R,6S)-3,7,7-trimethylbicyclo[4.1.0]hept-2-ene

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Justification for type of information:

DELTA-3-CARENE (source substance) and DELTA-2-CARENE (target substance) are two structurally related substances.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

0.8 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95% confidence limits 0.644 - 0.950 mg/L

Details on results:

- After 24 h of exposure, immobilisations were 0% at 0.66 mg/L, 5% at 0.72 mg/L, 20% at 0.91 mg/L, 30% at 0.92 mg/L, 40% at 1.20 mg/L and 80% at 1.46 mg/L.
- After 48 h of exposure, immobilisations were 5% at 0.66 mg/L, 35% at 0.72 mg/L, 60% at 0.91 mg/L, and 100% at 0.92, 1.20 and 1.46 mg/L.

Results with reference substance (positive control):

On July 2013 (most recent test), the 24 h-EC50 for Potassium dichromate was 0.98 mg/L. Hence, the sensitivity of the clone of Daphnia magna was in agreement with the OECD 202 (expected 24 h-EC50: 0.6-2.1 mg/L at this time.

Reported statistics and error estimates:

The evaluation of the effects was based on the measured test item concentrations. The software ToxRat® Professional was used for the determination of the effective concentrations.

Analytical results:

The analytical results showed that test item concentrations were stable during the test period (within or close to ± 20% of the initial concentration), except at the nominal test concentration of 1.5 mg/L with test substance losses ca. 30% on both days of the study. Moreover, actual concentrations were lower than their corresponding nominal values. Thus, the results were expressed in terms of geometric means of the exposure concentrations: 0.66, 0.72, 0.91, 0.92, 1.20 and 1.46 mg/L.

Table 6.1.3/1: Acute immobilisation of daphnids after 24 and 48 h in the final test

Nominal concentration (mg/L)	Measured concentration (mg/L)	Replicate	Number of daphnids exposed	Response at 24 h		Response at 48 h
				Number	Total %	Number	Total %
Control	Control	1	5	0	0	0	0
		2	5	0		0
		3	5	0		0
		4	5	0		0
1.0	0.66	1	5	0	0	1	5
		2	5	0		0
		3	5	0		0
		4	5	0		0
1.1	0.72	1	5	0	5	2	35
		2	5	0		2
		3	5	1		1
		4	5	0		2
1.3	0.91	1	5	2	20	4	60
		2	5	2		4
		3	5	0		3
		4	5	0		1
1.5	0.92	1	5	2	30	5	100
		2	5	1		5
		3	5	1		5
		4	5	2		5
1.7	1.20	1	5	2	40	5	100
		2	5	2		5
		3	5	1		5
		4	5	3		5
2.0	1.46	1	5	4	80	5	100
		2	5	5		5
		3	5	5		5
		4	5	2		5

 

Table 6.1.3/2: pH and Dissolved oxygen saturation (mg/L) during the final test

Time		Nominal concentration (mg/L)
pH values
		Control	1.0	1.1	1.3	1.5	1.7	2.0
Start t=0 h		7.94	7.96	7.97	7.98	7.98	7.98	7.99
t=24 h	Old	7.80	7.83	7.84	7.84	7.84	7.85	7.86
	Fresh	7.95	7.97	7.98	7.99	8.00	8.00	8.00
End t=48 h		7.84	7.85	7.84	7.84	7.84	7.86	7.87
Dissolved oxygen saturation (mg/L)
Start t=0 h		8.95	8.82	8.84	8.81	8.67	8.68	8.75
t=24 h	Old	8.73	8.78	8.70	8.58	8.65	8.68	8.71
	Fresh	8.70	8.65	8.60	8.62	8.69	8.57	8.56
End t=48 h		8.94	8.74	8.91	8.80	8.66	8.92	8.60

Validity criteria of the study:

Controls:In the control, no daphnids became immobilised nor trapped at the surface of the water nor showed signs of stress.

Dissolved [O2]:The dissolved oxygen concentration at the end of the test was ≥ 60% of the air-saturation value in controls and test vessels.

Thus the validity criteria have been fulfilled in the present study.

Validity criteria fulfilled:

yes

Conclusions:

The 48 h-EC50 for DELTA-3-CARENE to Daphnia magna is 0.80 mg/L with 95% confidence limits of 0.644-0.950 mg/L.

Executive summary:

This study was performed according to OECD Guideline 202 and GLP, to assess the 48 h-acute toxicity of test item DELTA-3-CARENE to Daphnia magna, under static conditions.

Following a preliminary range-finding test, twenty daphnids (four replicates, five daphnids per replicate) were exposed to an aqueous solution of the test item at the required nominal test concentrations 1.0, 1.1, 1.3, 1.5, 1.7 and 2.0 mg/L. The immobility of the daphnids was determined in a semi-static 48 h test by visual observation after 24 and 48 h. The concentrations of the test item were determined by chemical analyses at the start (t=0 h), at t=24 h (new and old solutions) and at the end of the test (t=48 h).

 

The analytical results showed that test item concentrations were stable during the test period (within or close to ± 20% of the initial concentration), except at the nominal test concentration of 1.5 mg/L with test substance losses ca. 30% on both days of the study. Moreover, actual concentrations were lower than their corresponding nominal values. Thus, the results were expressed in terms of geometric means of the exposure concentrations: 0.66, 0.72, 0.91, 0.92, 1.20 and 1.46 mg/L.

 

After 24 h of exposure, immobilisations were 0% at 0.66 mg/L, 5% at 0.72 mg/L, 20% at 0.91 mg/L, 30% at 0.92 mg/L, 40% at 1.20 mg/L and 80% at 1.46 mg/L. After 48 h of exposure, immobilisations were 5% at 0.66 mg/L, 35% at 0.72 mg/L, 60% at 0.91 mg/L, and 100% at 0.92, 1.20 and 1.46 mg/L.

 

Therefore, the 48 h-EC50 for DELTA-3-CARENE to Daphnia magna is 0.80 mg/L with 95% confidence limits of 0.644-0.950 mg/L.

Description of key information

The 48 h-EC50 for DELTA-3-CARENE to Daphnia magna is 0.80 mg/L with 95% confidence limits of 0.644-0.950 mg/L.

 

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.8 mg/L

Additional information

One reliable study is available for the substance itself and is selected as key study. The toxicity of delta-3 -carene to freshwater Daphnia magna was studied according to OECD 202 and GLP. Daphnids were exposed to substance at nominal test concentrations of 1.0, 1.1, 1.3, 1.5, 1.7 and 2.0 mg/L over a test period of 48 hours.

Concentrations were analytically verified at the start and daily until the end of the test (old and new test media). The concentration of the test item was not satisfactorily maintained within ± 20% of the initial concentration throughout the test. Thus, the endpoint was based on the geometric means of the measured concentrations. The 48h-EC50 was determined to be 0.80 mg/L.

The 48h-EC50 is valid for key value for chemical safety assessment and is supported by QSAR results.