Propan-2-ol

Toxicity to terrestrial plants

Link to relevant study record(s)

Reference

Endpoint:

toxicity to terrestrial plants: long-term

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2021

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

Detailed information covering the calculation model and the physico-chemical data used as input are in the attached document.

The target lipid model (TLM) is a framework that relates toxicity to the physicochemical properties of a nonpolar organic constituent. The TLM has been applied to soils and sediment using equilibrium partitioning (EqP) model. This framework utilizes organic carbon partition coefficients (KOC) to convert aquatic based effect levels (CW) to bulk soil- and sediment-based effect levels. The combined TLM-EqP framework was validated previously for soil and sediment acute and chronic toxicity endpoints. The substance is considered within the scope of the TLM and EqP frameworks.

Principles of method if other than guideline:

The target lipid model (2015) and equilibrium partitioning model as described in the cited references were used to determine soil or sediment effect levels following an estimation of initial loading of the registered substance in the substrate. A full explanation of the calculation method is provided in the 'attached justification'.

For model description and justification of QSAR prediction: see fields 'justification for type of information' and 'attached justification'

Species:

Brassica rapa

Plant group:

Dicotyledonae (dicots)

Species:

Avena sativa

Plant group:

Monocotyledonae (monocots)

Species:

Brassica rapa

Duration:

14 d

Dose descriptor:

EC50

Effect conc.:

105.26 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

seedling emergence

Species:

Brassica rapa

Duration:

21 d

Dose descriptor:

EC10

Effect conc.:

20.17 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

Remarks on result:

other: chronic endpoints were estimated using typical acute-to-chronic ratio of 5.22 (McGrath et al., 2018)

Species:

Avena sativa

Duration:

14 d

Dose descriptor:

EC50

Effect conc.:

163.03 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

seedling emergence

Species:

Avena sativa

Duration:

21 d

Dose descriptor:

EC10

Effect conc.:

31.23 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

Remarks on result:

other: chronic endpoints were estimated using typical acute-to-chronic ratio of 5.22 (McGrath et al., 2018)

Conclusions:

The 2-propanol estimated 14-day LC50 values is 163.03 mg/kg based on seedling emergence and the 21-day EC10 value is 31.23 mg/kg dw based on growth for the terrestrial plant monocot species Avena sativa.

The 2-propanol estimated 14-day LC50 values is 105.26 mg/kg based on seedling emergence and the 21-day EC10 value is 20.17 mg/kg dw based on growth terrestrial plant dicot species Brassica rapa.

The values were estimated using the Petrotox computer model.

Executive summary:

The target lipid model (TLM) has been applied to soils and sediment using equilibrium partitioning (EqP) model. As such, modeled data are considered fit for purpose.

Description of key information

A QSAR using the Target Lipid Model (TLM) and the Equilibrium Partitioning Model (EqP) reported long-term LL₅₀ and NOELR values of 610 mg/kg soil dry weight and 117 mg/kg soil dry weight, respectively for Avenia sativa and LL₅₀ and NOELR values of 395 mg/kg soil dry weight and 75.7 mg/kg soil dry weight, respectively, for Brassica rapa.

These values are supported by the following result: IC₅₀ (germination) = 2104 mg/kg, 3 day, Lactuca sativa (Reynolds, 1977)

Additional information

The target lipid model (TLM) has been applied to soils and sediment using equilibrium partitioning (EqP) model. As such, modelled data are considered fit for purpose.

Detailed information covering the calculation model, physico-chemical data used as input and the results are attached in section 13.2 of IUCLID.

The toxicity of iso-propyl alcohol (IPA) to the seed germination of the dicotyledon Lactuca sativa (garden lettuce) was assessed in a published non-guideline study that predates GLP requirements for ecotoxicity studies (Reynolds, 1977). This laboratory study used Great Lakes garden lettuce seeds sown in aluminium boxes (4.2 x 2.1 x 1.6 cm) with glass windows in the lids, containing 0.5% agar (8 mL) in which appropriate weights of IPA were dissolved. Germination at 30ºC was recorded after 3 days. The results indicate that 35 mM of IPA caused 50% inhibition of the germination of lettuce seeds. The molecular weight of IPA is 60.1 g/mol and thus, the 50% inhibition value can be calculated to be 2104 mg/kg in the agar.

 

This study did not investigate any monocotyledon species and with only one dicotyledon species reported, it is difficult to establish an effect level that will be representative of the effects of IPA on seedling emergence of higher plants.

Although the reliability of this study could not be sufficiently assessed, the result based on a 96 hours test supports that IPA also beyond 24h exposure does not pose significant hazard to invertebrates. Also, these results are consistent with observations on acute fish studies performed over 48 hours in a static test as well as in a flow through test, proving that the substance does not volatilize from test water within 48 hours.