Dimethoxymethane

Toxicity to aquatic algae and cyanobacteria

Description of key information

The pieces of information that build the weight of evidence are the following:

A) in vivo study from Burlion N & Galloy A (1991)

Purity of min. 99.9%

Mehod not fully described

EC50 (5d): 6000 mg/L

B) QSAR for acute prediction from Pavan M (2015)

Fully documented with QPRF and QMRF

EC50 (96h): 874.12 mg/L

C) QSAR for chronic prediction from Pavan M (2012)

Fully documented with QPRF and QMRF

NOEC (30d): 145.770 mg/L

D) Read-across for acute toxicity from Pavan M (2015)

Analogue approach justified with data matrix (source chemical: dimethoxyethane)

EC50 (72h): 9120 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:

874.12 mg/L

EC10 or NOEC for freshwater algae:

145.77 mg/L

Additional information

The weight of evidence approach is justified as determined from more than one piece of information (independent sources). We claim the reliability, relevance, adequacy and quality of the weight of evidence:

-     Reliability: Klimisch score of 2 is assigned to the pieces of information. 

-     Relevance:

o  Relevance of test material: substance purity is >99.9% in the laboratory test. The test material is equivalent to the submission substance identity. Relevance for QSAR is defined in QPRF and QMRF. The target Dimethoxymethane and the source 1,2-dimethoxyethane can be considered sufficiently structurally and mechanistically similar to apply the read-across approach. Relevance of the read-across approach is supported by structural similarity between the source and the target chemicals and is also supported by a close similarity in terms of mechanism of action, physicochemical and reactivity properties relevant for acute aquatic toxicity on algae.

o  Relevance of test method and conditions: whereas deficiencies are noted in laboratory test, the tested method follows, broadly speaking, the internationally approved test guidelines. Relevance for QSAR is defined in QPRF and QMRF. Relevance of the read-across is supported by the key study status of the source study.

o  Relevance of the endpoint: the values obtained extend over 3 different approaches and show a clear evidence of low aquatic toxicity to algae:

-> In vivo test: EC₅₀(5d): 6000 mg/L

-> QSAR prediction: EC₅₀(96h): 874.12 mg/L and NOEC: 145.77 mg/L

-> Read-across prediction: EC₅₀(72h): 9120 mg/L

o  Relevance of alternative methods: relevance of QSAR is defined in QPRF and QMRF. Relevance of the read-across is supported by the clear analogy between the source and the target chemicals. 

-     Adequacy: the clear trend resulting from 3 different approaches allow a clear decision related to classification: the endpoint are higher than the cut-off values for classification as acute or chronic aquatic hazard.

-     Quantity: four pieces of information are considered.