2,2,2-trichloroethane-1,1-diol

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Experimental test result performed using standard test guidelines

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

no

Specific details on test material used for the study:

- Name of test material: 2,2,2-Trichloroethane-1,1-diol (Chloral hydrate)
- Molecular formula: C2-H3-Cl3-O2
- Molecular weight: 165.4026g/mol
- Smiles notation: C(C(O)O)(Cl)(Cl)Cl
- InChl: RNFNDJAIBTYOQL-UHFFFAOYSA-N
- Substance type: Organic
- Physical state: Solid

Analytical monitoring:

not specified

Vehicle:

no

Details on test solutions:

The test solution was prepared in aseptic condition. The test item 2,2,2-trichloroethane-1,1-diol was prepared by adding 70mg of test item in 350 ml of BBM to get the final concentration of 200 mg/L. The remaining test solutions were prepared by dilution from the above stock solution. To have a better growth and visibility of cells, the initial cell density of the culture was kept 1 X 104cells/ml. Care was taken to have a homogeneous solution for the experiment.

Test organisms (species):

Chlorella vulgaris

Details on test organisms:

The fresh water green alga Chlorella vulgaris, was used as the test system (organism). Sterile, unicellular, suspension cultures of algae were used

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

not specified

Test temperature:

24±2°C.

pH:

not specified

Dissolved oxygen:

not specified

Salinity:

not specified

Conductivity:

not specified

Nominal and measured concentrations:

6.25 mg/l, 12.5 mg/l, 25 mg/l, 50 mg/l, 100 mg/l and 200 mg/l

Details on test conditions:

Study Type: Static
Exposure Duration: 72 Hours
Temperature: 24 °C ±2°C.
Light Quality: White Fluorescent Light
Light Intensity: 1500Lux
Photoperiod: 16 Hour Light Period : 8 Hour Dark Period
RPM Speed: 120 Revolutions per minute
Water: Deionized Water
Test vessel size: 100ml
Test volume: 60ml
Dilution water: Bold’s Basal Medium
Test concentration: Six test concentration were: 6.25 mg/l, 12.5 mg/l, 25 mg/l, 50 mg/l, 100 mg/l and 200 mg/l
Replicates per concentration: Three replicates for Control, Two replicates for each test concentration

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Reported statistics and error estimates:

To obtain a quantitative concentration-response relationship by regression analysis,alinearizing transformation of the response data into probit was performed. Using the same, effective concentration (ECX) was determined.

Growth and growth inhibition were quantified from measurements of the algal biomass density (cell counts) as a function of time. The study end point was inhibition of growth, expressed as logarithmic algal biomass increase (average growth rate) during the exposure period. From cell numbers and average growth rates in a series of test solutions and the respective test item concentration, EC50 value was determined.

Average specific growth rate and percentage inhibition after an interval of 72 hours

	CONTROL		6.25mg/l		12.5mg/l		25mg/l		50mg/l		100mg/l		200mg/l
Average Specific Growth rate (µ )	R1	1.586	R1	1.525	R1	1.5	R1	1.489	R1	1.487	R1	1.463	R1	1.290
	R2	1.561	R2	1.498	R2	1.494	R2	1.479	R2	1.471	R2	1.409	R2	1.269
	R3	1.570
Mean of Avg. Specific growth rate	1.572		1.511		1.497		1.484		1.479		1.436		1.280
Percentage Inhibition (%I)	_		3.860		4.773		5.623		5.938		8.671		18.607

Validity criteria fulfilled:

not specified

Conclusions:

After 72 hours of exposure to various nominal test concentrations of disodium 2,2,2-trichloroethane-1,1-diol (CAS No. 302-17-0) to freshwater green alga Chlorella vulgaris, EC50 was found to be >200 mg/l graphically through probit analysis.

Executive summary:

The effect of test item2,2,2-trichloroethane-1,1-diol, CAS No. 302-17-0 was studied on the growth of fresh water green algaChlorella vulgaris.The study was conducted following OECD guideline 201- Alga growth inhibition test. The test concentration chosen for the study were 6.25mg/l, 12.5mg/l, 25mg/l, 50 mg/l, 100mg/l and 200 mg/l. The test concentrations were prepared using stock solution of the test item using mineral media. The green alga was exposed to the test concentration for a period of 72 hours to observe average specific growth rate and % growth inhibition under the effect of the test item. EC50 calculated graphically through probit analysis was observed to be >200 mg/l.

This value indicates that the substance 2,2,2-trichloroethane-1,1-diol (Chloral hydrate) is not toxic to aquatic algae and hence considered as Not classified as per CLP classification criteria.

Description of key information

After 72 hours of exposure to various nominal test concentrations of disodium 2,2,2-trichloroethane-1,1-diol (CAS No. 302-17-0) to freshwater green alga Chlorella vulgaris, EC50 was found to be >200 mg/l graphically through probit analysis.

This value indicates that the substance 2,2,2-trichloroethane-1,1-diol (Chloral hydrate) is not toxic to aquatic algae and hence considered as Not classified as per CLP classification criteria.

Key value for chemical safety assessment

EC50 for freshwater algae:

200 mg/L

Additional information

Different experimental studies of the substance 2,2,2-trichloroethane-1,1-diol (Chloral hydrate) were reviwed for the toxicity aquatic algae and cyanobacteria endpoint. The same is summarised below as key and supporting studies:

In key study, the effect of test item 2,2,2-trichloroethane-1,1-diol, CAS No. 302-17-0 was studied on the growth of fresh water green algaChlorella vulgaris.The study was conducted following OECD guideline 201- Alga growth inhibition test. The test concentration chosen for the study were 6.25mg/l, 12.5mg/l, 25mg/l, 50 mg/l, 100mg/l and 200 mg/l. The test concentrations were prepared using stock solution of the test item using mineral media. The green alga was exposed to the test concentration for a period of 72 hours to observe average specific growth rate and % growth inhibition under the effect of the test item. EC50 calculated graphically through probit analysis was observed to be >200 mg/l.

While in the supporting data obtained from J-check database, the growth rate concentration (ErC50) value of Chloral hydrate in aquatic algae (Scenedesmus quadricauda) in 72 hrs on the basis of growth effect was found to be >95 mg/l .And no observed effect concentration for growth rate (NOECr) was found to be 15 mg/l. Therefore the EC50 may be considered greater than 100 mg/L for Chloral hydrate. Also this chemical has a harmonized classification that does not indicate the chemical to cause aquatic toxicity.

Further supporting data from peer reviewed journal indicates the effective concentration (EC0) value based on analogous methods of the cell multiplication inhibition test of Chloral hydrate in aquatic algae (Scenedesmus quadricauda) in 7 days was determined to be 2.8 mg/l.

Hence considering the key study value and harmonized classification, the substance 2,2,2-trichloroethane-1,1 -diol (Chloral hydrate) is concluded to be not toxic to aquatic algae and hence considered as Not classified as per CLP classification criteria.