Trimethyl orthoformate

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

Study period:

20 March 1989

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Remarks:

NOEC based on oxygen generation, but no overall NOEC given. Can not be used for classification since no data are given on biomass or growth rate. No results are shown other than endpoint, no details on the substance other than name (eg purity), no details on test conditions or test substance analysis.

Qualifier:

according to guideline

Guideline:

other: DIN-Entwurf 38412 Teil 12

Deviations:

not specified

GLP compliance:

not specified

Analytical monitoring:

not specified

Details on sampling:

The report mentions that a range should be measured, and that no effects were observed up to a concentration of 1000 mg/L

Vehicle:

not specified

Details on test solutions:

The report mentions that a range should be measured, and that no effects were observed up to a concentration of 1000 mg/L
The stock solutiion was prepared at 10 g/L

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

No details given

Test type:

not specified

Water media type:

freshwater

Limit test:

no

Total exposure duration:

24 h

Hardness:

No details

Test temperature:

No details

pH:

No details

Dissolved oxygen:

No details

Salinity:

No details

Nominal and measured concentrations:

The report mentions that a range should be measured, and that no effects were observed up to a concentration of 1000 mg/L
The stock solutiion was prepared at 10 g/L

Details on test conditions:

No details

Reference substance (positive control):

not specified

Duration:

24 h

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

other: O2 generation

Details on results:

No details

Results with reference substance (positive control):

No details

Reported statistics and error estimates:

No details

Validity criteria fulfilled:

not specified

Conclusions:

The study suggests the absence of acute aquatic toxicity of the test item to alge, but it is considered deficient as it is at variance to recent (2010) standards. Given the short half-life of the substance in aqueous media (see hydrolysis as function of pH) the result is considered acceptable for classification and risk assessment purposes.

Executive summary:

Toxicity of trimethylorthoformate (CAS 149-73-5) to algae was determined in a test according to German draft guideline DIN 38412 Part 12. The study is not comparable to nowadays (2010) standards and therefore not reliable.

The test algae (Desmodesmus subspicatus) were exposed during 24 h. as test organism. Details on methodology is very sparse, neither test concentrations nor information on the test item were given. No GLP compliance was stated.

Results revealed a NOEC based on O₂ generation of ≥ 1000 mg/L.

As the test results indicate no effect at all on the phytosynthesis rate in a concentration of at least 10 times the regulatory cut-off for acute aquatic toxicity it is to conclude that the absence of acute effects to algae seems likely.

Based upon the classification criteria according to the Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008, the test item is not to classified on the basis of this study.

Description of key information

NOEC based on oxygen generation > 1000mg/L
The study suggests the absence of acute aquatic toxicity of the test item to algae, but it is considered deficient as it is at variance to recent (2010) standards.  Given the short half-life of the substance in aqueous media (see hydrolysis as function of pH) the result is considered acceptable for classification and risk assessment purposes.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

1 000 mg/L

Additional information

Scholz (1989) investigated the acute toxicity of trimethyl orthoformate to algae. No analytical information was reported in the study report, however, it can be concluded from the hydrolysis as a function of pH study of Fischer (2004), reported in section 5.12 of this dossier, that under the conditions of the study trimethyl orthoformate would have hydrolyzed to some degree to its metabolites. At pH 7 the half-life for hydrolysis is <12h and at pH 9 approximately 200h. Acute toxicity studies on algae are typically conducted at a pH within the range of 7-9. The aqueous hydrolysis products of trimethyl orthoformate are methanol and formic acid. Therefore, under the conditions of an acute toxicity study on algae the formic acid should be present in the form of a salt. Salts of formic acid are known to exhibit very low toxicity to aquatic organisms (USEPA HPV Chemical Challenge Program, “Formates Category”). Indeed results for sodium formate are in the same ballpark (1000mg/L) as the result reported by Scholz. Methanol is also known to exhibit low toxicity to aquatic organisms and an EC50 >1000mg/L is reported in the Formate Category HPV document.

In conclusion, whilst the study of Scholz contains several deficiencies the result obtained can be considered useful for classification and risk assessment purposes when taken together with the hydrolysis study of Fischer (2004). As such trimethyl orthoformate should be considered non-toxic to algae.

Based upon the classification criteria according to the Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008, the test item is considered not classified on the basis of this study.