6,6-dimethylbicyclo[3.1.1]hept-2-ene-2-propionaldehyde

Toxicity to microorganisms

Description of key information

For Pino Acetald, the 3h-ELR50 was determined to be >1000 mg/L, based on read across from Pinyl isobutyr aldehyde.

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

Additional information

For Pino Acetald no experimental data on toxicity to microorganisms is available, this information can be retrieved from Pinyl isobutyr aldehyde using read across. First the experimental information of Pinyl isobutyr aldehyde is presented and thereafter the read across justification to use this information for Pino Acetald.

Pinyl isobutyr aldehyde

In a 3h activated sludge respiration inhibition study conducted according to OECD TG 209 and GLP, microorganisms in activated sludge were exposed in a combined limit/range-finding test to a blank control and 3 concentrations of the test substance at loading rates of 10, 100 and 1000 mg test substance/L.The substance showed no inhibition of the respiration rate at 10 and 100 mg/L, and 12% inhibition of the respiration rate at 1000 mg/L. Therefore, the ELR50 of the test substance was above 1000 mg/L. The NOELR could not be determined.

Pino Acetald (Cas no.: 33885-51-7) and its toxicity to micro-organisms using read across from Pinyl Isobutyr aldehyde (CAS no.: 33885-52-8)

Introduction and hypothesis for the analogue approach

Pino Acetald is an alpha-Pinene with a propanal chain attached to the methyl group present at the second position. For this substance, no data on toxicity to micro-organisms is available. In accordance with Article 13 of REACH, lacking information can be generated by means of applying alternative methods such as in vitro tests, QSARs, grouping and read-across. For assessing the toxicity to micro-organisms of Pino Acetald, the analogue approach is selected because for a related analogue, reliable toxicity data are present, which can be used for read-across.

Hypothesis: Pino Acetald has similar toxicity to micro-organisms compared to Pinyl Isobutyr aldehyde.

Available experimental information: For Pinyl Isobutyr aldehyde an activated sludge respiration inhibition test is available performed according to OECD TG 209 following GLP receiving a Klimisch score of 1. In addition, for both substances an algae and acute daphnia toxicity test are available all receiving Klimisch 1.

Target chemical and source chemical(s)

Chemical structures of the target chemical and the source chemicals and relevant information on these substances are shown in the data matrix.

Purity / Impurities

Pino Acetald is a mono-constituent with a purity of 98.4% and all impurities are < 2%.

Analogue approach justification

According to Annex XI 1.5 read across can be used to replace testing when the similarity can be based on a common backbone and a common functional group. When using read across the result derived should be applicable for C&L and/or risk assessment and it should be presented with adequate and reliable documentation, which is presented below.

Analogue selection: For Pino Acetald the structural close analogue Pinyl Isobutyr aldehyde is selected for read across because for this substance experimental information on micro-organism toxicity is available.

Structural similarities and differences: Pino Acetald and Pinyl Isobutyr aldehyde have the same backbone and functional groups. They are both alpha-Pinenes with a propanal chain attached. The difference is the addition of two methyl groups to the propanal chain of Pinyl Isobutyr aldehyde. These two additional -CH3 fragment increases the log Kow with 1.0 using KowWIN for prediction.

Bioavailability: Pino Acetald and Pinyl Isobutyr aldehyde have similar bioavailability based on the similarity in chemical structure and physico-chemical properties as presented in the data matrix and based on measured and calculated data (Table 1).

Mode of Action (MoA): Both Pino Acetald and Pinyl Isobutyr aldehyde have an acetal MoA according to ECOSAR and OECD Toolbox.

Conversion: Pino Acetald toxicity to micro-organisms can be predicted from Pinyl Isobutyr aldehyde. A conversion was not needed because the molecular weight conversion balanced the log Kow conversion (179 versus 206 molecular weight and 4.3 versus 5.4 log Kow for Pino Acetald and Pinyl Isobutyr Aldehyde, respectively).

Uncertainty of the prediction: There are no other uncertainties than those which have been addressed above.

Data matrix

The relevant information on physico-chemical properties and toxicological characteristics are presented in the data matrix below.

Conclusions for aquatic toxicity

For Pino Acetald no experimental toxicity to micro-organism test is available, but for the structural analogue Pinyl Isobutyr aldehyde such information is present. When using read across the result derived should be applicable for C&L and/or risk assessment and be presented with adequate and reliable documentation. This documentation is presented in the current document. Pinyl Isobutyr aldehyde has a ELR50 value of >1000 mg/l. As conversion was not needed because the molecular weight conversion balanced the log Kow conversion, the 3h-ELR50 is >1000 mg/L.

Final conclusion on hazard: For Pino Acetald toxicity to micro-organisms is based on the structural analogue Pinyl Isobutyr aldehyde. This results in a 3h-ELR50 of >1000 mg/l.

Data matrix: Information on Pino Acetald and Pinyl Isobutyr aldehyde for assessment of toxicity to micro-organisms.

Common names	Pino Acetald Target	Pinyl Isobutyr aldehyde Source
Chemical structures
Chemical name	6,6-dimethylbicyclo[3.1.1]hept-2-ene-2-propionaldehyde	α,α,6,6-tetramethylbicyclo[3.1.1]hept-2-ene-2-propionaldehyde
CAS no.	33885-51-7	33885-52-8
EC no.	251-717-2	251-718-8
Empirical formula	C12H18O	C14H22O
Molecular weight	178.75	206
Phys-Chem
Physical state	Liquid	Liquid
Water solubility (mg/L)	61 at 24°C (OECD 105)	10.8 at 22°C (OECD 105)
Log Kow	4.3 (OECD TG 117)	5.4 (OECD TG 117)
Aquatic toxicity
Algae (72h-ErC50) (mg/l)	4.2 (OECD 201)	>0.66 (OECD 201)
Algae (72h-ErC10) (mg/l)	1.9 (OECD 201)	0.37 (OECD 201)
Daphnia (48h-EC50) (mg/l)	0.67 (OECD 202)	0.51 (OECD 202)
Micro-organisms (3h-ELR50) (mg/L)	Read across	>1000 (OECD 209)