Registration Dossier

Data platform availability banner - registered substances factsheets

Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Ecotoxicological information

Long-term toxicity to fish

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

In accordance with column 2 of REACH Annex IX, the long term testing on fish does not need to be conducted as the chemical safety assessment according to Annex I has not indicated a need to investigate further the effects on aquatic organisms. For butenes, the calculated 30 day NOEC for fish is 2.05 mg/L to 2.67 mg/L. This range was derived from the members of the butenes category: but-1-ene (CAS 106-98-9), 2-butene (CAS 107-01-7) and 2-methylpropene (CAS 115-11-7) using QSAR estimates (Nabholz and Mayo-Bean 2009). These data are used in supporting read across.

The estimated EL50 TLM calculated values for long term toxicity to fish was for butene/ but-1 -ene 2.827 mg/L, for 2 -butene 3.290 mg/L for 2 -methylpropene 3.219 mg/L. The lowest value has been taken forward as the key value for chemical safety assessment.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish
Effect concentration:
2.05 mg/L

Additional information

Butenes are gases at standard temperature and pressure and are expected to partition primarily to air, therefore aquatic toxicity tests may not be relevant. In addition, it is technically difficult to maintain aqueous concentrations of gases for toxicity testing.

Measured data are not available for butenes for this endpoint. Due to the practical difficulties associated with the ecotoxicity testing of gases (i.e. maintaining exposure concentrations), the use of QSAR toxicity estimates is an appropriate alternative. The ECOSAR model is a reliable and appropriate QSAR model to apply to butenes as it is based on a related chemical dataset that calculates the toxicity of neutral organic hydrocarbons whose mode of action is non-polar narcosis. The endpoint calculated here is therefore a reasonable estimate of the baseline toxicity.

A QSAR (ECOWIN v1 ECOSAR, Nabholz and Mayo-Bean 2009) has been used to give an indication of the toxicity of butenes to freshwater fish. The calculated 30 day ChV are 3.23 mg/L for but-1-ene, 3.77 mg/L for 2-butene and 2.90 mg/L for 2-methylpropene. These ChV values correspond to 30 day NOECs of 2.29 mg/L, 2.67 mg/L and 2.05 mg/L respectively.