Choline hydroxide

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
Please refer also to Read Across Statement attached in Section 13

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
In this read-across approach data choline chloride are used to fill data gaps for choline hydroxide, in accordance with Regulation No 1907/2006 (REACH), Annex XI. The basis for this read-across approach is the “Read-Across Assessment Framework” (RAAF) (ECHA 2017). The read-across hypothesis for the analogue approach is that choline hydroxide and choline chloride exhibit a similar (eco)toxicological profile. This is due to the fact that both choline salts as quaternary alkylammonium salts dissociate readily into the respective ions when getting into contact with water and the choline cation is what is left to be considered (US EPA, 2010). Thus, the different choline salts are used to for hazard assessment. According to the RAAF this approach is covered by scenario 1: “(Bio)transformation to common compound(s)”.
“This scenario covers the analogue approach for which the read-across hypothesis is based on (bio) transformation to common compound(s). For the REACH information requirement under consideration, the property investigated in a study conducted with one source substance is used to predict the properties that would be observed in a study with the target substance if it were to be conducted. Similar properties or absence of effect are predicted. The predicted property may be similar or based on a worst-case approach.” (ECHA 2017).

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Source chemical:
2-hydroxy-N,N,N-trimethylethanaminium chloride
Molecular formula: C5H14ClNO
SMILES: [Cl-].C[N+](C)(C)CCO
CAS: 67-48-1
Purity: not specified

Target chemical:
Choline hydroxide
Molecular formula: C5H15NO2
SMILES: [OH-].C[N+](C)(C)CCO
CAS: 123-41-1
Purity: 96 %

3. ANALOGUE APPROACH JUSTIFICATION
Upon contact with water, choline hydroxide is expected to dissociate into the cationic form (choline) and the anionic form (hydroxide ions); the hydroxy moiety dissociates and essentially ceases to exist upon mixing with water in preparation for application and in the body. The latter will be even skipped because both choline hydroxide and choline chloride are only distributed as aqueous solution, i.a. due to their hygroscopic properties. The choline cation is what is left to be considered (US EPA, 2010). Due to the structural similarities, i.e. the identical organic cation, which contains a positively charged nitrogen, and small, negatively charged inorganic anion (for choline base: Hydroxide), this is a reasonable and scientifically expectable conclusion, which allow one to draw the generalized conclusion, that Choline salts in general dissociate readily in water into the corresponding positively charged quaternary hydroxyl alkylammonium ion and the negatively charged inorganic anion (OECD SIDS, 2004). The choline cation therefore, is the moiety of interest. Based on the fact that in the environment and in biological fluids the same compounds are formed from the source and the target substances, the same (eco)toxicological profile of choline hydroxide and choline chloride is expected. Therefore, the read-across approach is justified. Thus, the available studies for the source substance choline chloride were used to fill data gaps for choline hydroxide for several environmental and toxicological endpoints.

Reason / purpose for cross-reference:

read-across source

Duration:

21 d

Dose descriptor:

LC50

Effect conc.:

> 95.5 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

other: parental mortality

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

58.9 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks on result:

other: 95 % CL: 37.7 - 83.7 mg/L

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

30.2 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

95.5 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

reproduction

Details on results:

- Mortality of control: The mortality rate of the parent Daphnia in the control area was 0 % at the end of the exposure. in nominal concentration 10 % on day 14 and 21 mortality 10 and 20 % observed. This meets the criteria of less than 20 %, which was a condition for the study to be established. The criteria for the study to be valid, i.e. less than or equal to 20 %, were met. No dormant eggs were observed in the control and in each test concentration.

Reported statistics and error estimates:

- LC50 with corresponding 95 % CL: cannot be calculated
- EC50 with corresponding 95 % CL: calculated by Probit method
- NOEC and LOEC: The cumulative number of juveniles produced per adult in control and test concentration after 21 d was tested by Dunnett multiple comparison method
- Method of calculating mean measured concentrations: Time-weighted Mean

Table 1. Measured concentrations

Nominal concentration [mg/L]	0h New	1h Old	10d New	11d Old	20d New	21d Old
0.00	N.D.	N.D.	N.D.	N.D.	N.D.	N.D.
3.20	3.10	3.10	3.30	2.50	3.20	1.90
10.00	9.70	9.70	10.30	8.10	9.90	6.60
32.00	33.50	32.80	34.20	25.70	32.10	23.70
100.00	104.00	101.00	104.00	87.00	101.00	77.30
New: freshly prepared test solution. Old: test solutions 24 h after freshly prepared.

Table 2. Percent of nominal concentration

Nominal concentration [mg/L]	0h New	1h Old	10d New	11d Old	20d New	21d Old
0.00	--	--	--	--	--	--
3.20	97 %	97 %	103 %	78 %	100 %	59 %
10.00	97 %	97 %	103 %	81 %	99 %	66 %
32.00	105 %	103 %	107 %	80 %	100 %	74 %
100.00	104 %	101 %	104 %	87 %	101 %	77 %
New: freshly prepared test solution. Old: test solutions 24 h after freshly prepared.

Table 3. Cumulative number of died parental Daphnia

Nominal concentration [mg/L]	Cumulative Number of Died Parental Daphnia after 21 days [Mortality rate in %]
0.00	0 (0)
3.20	0 (0)
10.00	2 (20)
32.00	0 (0)
100.00	0 (0)

Table 4. Time to first brood production

Nominal concentration [mg/L]	Time to First Brood Production [Days]
0.00	8.3
3.20	7.9
10.00	8.9
32.00	8.3
100.00	11.2

Table 5. Cumulative numbers of juvenile produced per adult

Nominal Concentration [mg/L]	Mean cumulative numbers of juveniles produced per adult for 21 days
	0 - 6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21
0.00	0 - 0	1.0	11.8	12.0	14.0	36.5	36.6	43.0	66.4	66.4	74.2	105.9	106.1	111.5	140.0	140.0
3.20	0 - 0	4.8	10.6	11.0	24.0	37.6	37.6	50.1	67.2	67.2	82.4	106.5	106.5	116.9	164.0	146.0
10.00	0 - 0	0.1	8.3	9.0	9.90	32.6	32.8	39.8	63.5	63.5	70.3	103.8	103.9	109.5	142.0	142.0
32.00	0 - 0	3.7	8.8	8.8	13.3	30.6	30.7	41.4	58.3	58.3	72.4	94.1	94.1	115.4	136.1	136.1
100.00	0 - 0	0.0	0.0	0.3	0.80	2.70	4.10	4.10	5.60	7.5	8.9	9.5	11.8	11.8	11.8	11.8

Table 6. Cumulative numbers of juvenile produced per adult alive for 21 days

Nominal concentration [mg/L] (Measured concentration [mg/L])
Vessel No.	0.00	3.20 (2.83)	10.00 (9.00)	32.00 (30.20)	100.00 (95.50)
1	162	150	D	140	13
2	151	136	147	147	12
3	152	143	125	114	5
4	142	150	D	168	12
5	150	154	139	125	11
6	136	124	151	125	12
7	128	152	152	142	10
8	118	140	129	129	17
9	121	162	140	149	11
10	140	149	153	122	15
Mean	140.0	146.0	142.0	136.1	11.8
S.D.	14.4	10.7	10.7	16.1	3.2
Inhibition ratio [%]	-	-4.3	-1.4	2.8	91.6
Significant difference	-	N.S.	N.S.	N.S.	*
D: No calculation performed since parental Daphnia was dead during the 21-days testing period N.S.: Indicate a no-significant difference by Dunnett multiple comparison procedure *: Indicate a significant difference by Dunnett multiple comparison procedure

Validity criteria fulfilled:

yes

Remarks:

Scientific criteria for acute toxicity testing to aquatic invertebrates seemed to be fulfilled.

Conclusions:

The study is reported in the freely available IUCLID 4 substance dataset from ESIS. The experiment was conducted according to OECD 211 with GLP compliance. Available data indicate that the study was well-performed. As result, the NOEC(21d) was determined as 30.2 mg/L, based on time-weighted mean of measured concentrations.

Executive summary:

A long-term experiment was conducted with the aquatic invertebrate Daphnia magna in order to determine the impact of Choline chloride on the reproduction rate during an exposure duration of 21 days (MOE Japan, 1999). The study was conducted according to OECD 211 and under GLP compliance. The nominal test concentrations were reported as 0, 3.2, 10, 32 and 100 mg/L, whereby the measured concentrations (based on time-weighted mean of measured concentrations) were as followed: 0, 2.83, 9.00, 30.2 and 95.5 mg/L. 10 replicates per concentration and 1 individual per replicate were implemented. The stability of the test substance was confirmed by IR absorption spectrum. A photoperiod of 16 h light and 8 h dark was produced. The green algae Chlorella vulgaris served as food during the exposure duration. Potassium dichromate was used as reference substance, resulting in an EC50(48h) of 0.079, based on mobility). The effect data for choline chloride, based on reproduction, were reported as followed: LC50(21d) > 95.50 mg/L (parental mortality), EC50(21d): 58.9 mg/L (95 % CL: 37.7 - 83.7 mg/L), NOEC(21d): 30.2 mg/L and LOEC(21d): 95.5 mg/L. The results are based on the time-weighted mean of measured concentrations. Based on the fact that in the environment and in biological fluids the same compounds are formed from the source and the target substances, the choline moiety is the considered fraction of the source substance. Thus, this conclusion can also be drawn for the target substance choline hydroxide.

Description of key information

There are no studies on the Long-term toxicity to aquatic invertebrates available for the source substance choline hydroxide.

However, there are studies available for the close analogue Choline chloride.

 

RA_CAS 67-48-1_Daphnia magna_OECD 211_time-weighted mean of measured concentrations: LC50(21d) > 95.50 mg/L (parental mortality), EC50(21d): 58.9 mg/L (95 % CL: 37.7 - 83.7 mg/L), NOEC(21d): 30.2 mg/L, LOEC(21d): 95.5 mg/L

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

NOEC

Effect concentration:

30.2 mg/L

Additional information

No information about long-term effects towards aquatic invertebrates is available for Choline hydroxide.

To fulfil this endpoint, a read-across to Choline chloride (CAS 67-48-1) is intended, since both substances possess a strong structural similarity and substance characteristics. For the detailed justification of this procedure, please refer to the separate read-across statement by Chemservice S.A. (2013).

A long-term experiment was conducted with the aquatic invertebrate Daphnia magna in order to determine the impact of the reliable read-across substance Choline chloride (CAS 67-48-1) on the reproduction rate during an exposure duration of 21 days (MOE Japan, 1999). The study was conducted according to OECD 211 and under GLP compliance. The nominal test concentrations were reported as 0, 3.2, 10, 32 and 100 mg/L, whereby the measured concentrations (based on time-weighted mean of measured concentrations) were as followed: 0, 2.83, 9.00, 30.2 and 95.5 mg/L. 10 replicates per concentration and 1 individual per replicate were implemented. The stability of the test substance was confirmed by IR absorption spectrum. A photoperiod of 16 h light and 8 h dark was produced. The green algae Chlorella vulgaris served as food during the exposure duration. Potassium dichromate was used as reference substance, resulting in an EC50(48h) of 0.079, based on mobility). The effect data for choline chloride, based on reproduction, were reported as followed: LC50(21d) > 95.50 mg/L (parental mortality), EC50(21d): 58.9 mg/L (95 % CL: 37.7 - 83.7 mg/L), NOEC(21d): 30.2 mg/L and LOEC(21d): 95.5 mg/L. The results are based on the time-weighted mean of measured concentrations.