Propyl chloroformate

Short-term toxicity to fish

Description of key information

Parent compound: Acutely toxic to fish.
Hydrolysis product propanol: With high probability acutely not harmful to fish.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

LC50

Effect concentration:

3.16 mg/L

Additional information

QSAR-disclaimer

In Article 13 of Regulation (EC) No 1907/2006, it is laid down that information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI (of the same Regulation) are met.

According to Annex XI of Regulation (EC) No 1907/2006 (Q)SAR results can be used if (1) the scientific validity of the (Q)SAR model has been established, (2) the substance falls within the applicability domain of the (Q)SAR model, (3) the results are adequate for the purpose of classification and labeling and/or risk assessment and (4) adequate and reliable documentation of the applied method is provided.

For the assessment of propanol (CAS 71-23-8) (Q)SAR results were additionally used for the estimation of the short-term toxicity to fish. The criteria listed in Annex XI of Regulation (EC) No 1907/2006 are considered to be adequately fulfilled and therefore the endpoint(s) sufficiently covered and suitable for risk assessment.

Therefore, and for reasons of animal welfare additional experimental studies on aquatic toxicity are not provided

 

Parent compound propyl chloroformate (CAS 109-61-5):

The acute toxicity of propyl chloroformate was investigated in a static GLP study according to OECD 203 with Danio rerio. The 96h LC50 was determined to be 3.16 mg/L (nominal, no analytical verification, BASF AG, 1998). Based on this result, propyl chloroformate is considered acutely toxic to fish. However, as the dissolved substance is expected to rapidly hydrolyse in contact with water (t1/2 < 1 h), available data of the hydrolysis product propanol are additionally used to assess the aquatic toxicity of the chloroformate to fish.

 

Hydrolysis product propanol (CAS 71-23-8):

The acute toxicity of propanol to fish was studied in a flow-through test according to APHA with Pimephales promelas (Brooke et al., 1984). The LC50 was determined to be 4480 mg/L (test 1) and 4630 mg/L (test 2) (nominal, analytically verified). The toxicity to fish was additionally evaluated by a QSAR calculation with KATE2020, which estimated 96 h LC50 values of 1800 and 3100 mg/L, depending on the classification of the test substance (BASF SE, 2022). The substance is within the applicability domain of the model.

Based on these results, propanol is considered to be acutely not harmful to fish.

 

Propyl chloroformate hydrolyses rapidly to propanol, HCl and CO2 (DT50= 29.5 min). However, since the pH remained within acceptable limits, the clearly higher toxicity compared to propanol must be due to the reactivity of unhydrolysed propyl chloroformate at the beginning of the test. The pre-weighed test substance was added to the test water using an ultra-turrax stirrer; afterwards fish were placed into the aquaria. This procedure took all-in-all about 20 min. It is presumed that the remaining unhydrolysed propyl chloroformate at the beginning of the test caused the observed adverse effects.

The higher toxicity may be explained by reactions with nucleophiles (such as -NH2, -SH and –OH) on biological macromolecules.