(R)-3,7-dimethyloct-6-enal

Endpoint summary

Additional information

Skin irritation

Skin irritation of the test substance was assessed in several BASF tests:

In a Draize test, 0.5 mL of undiluted racemate citronellal (CAS 106-23-0) was applied to the intact skin of Vienna White rabbits (3 males and 3 females) for 24 hrs under occlusion, readings of erythema and edema scores were done at 24, 48 and 72 hrs and 8 days after start of the exposure (BASF AG 1980b). Clear indications of skin irritation was found with a mean erythema score of 2.21 and edema score of 2.05 (including all animals and readings after 24, 48 and 72 hours). After 8 days, erythema (mean score 1) and desquamation were still visible in all animals.

 

In a further skin irritation test, 2 Vienna White rabbits were treated for 5 min and 2 hrs under occlusion and readings were performed 24, 48 hrs and 5, 8 days after application (BASF AG 1980a). Dermal irritation was observed resulting in mean scores (including both animals and reading after 24 and 48 h) for erythema of 2.0 and edema of 1.75 after test substance application for 5 min or 2 hours. Erythema (mean score 1) and desquamation persisted up to day 8.

Since no test according to todays testing standards is available, the available studies are assessed in a weight of evidence approach which covers both longer and shorter treatment times. Occlusive application in both studies represents a worst case exposure scenario. Prolonging the treatment time from 5 min to 24 hours increased erythema and edema scores only slightly from 2.0 and 1.75 up to 2.21 and 2.05, respectively. Overall, on the basis of the scores observed for erythema and edema (>2), the lack of reversibility and the desquamation observed even at low exposure times warrant a classification as "irritating to skin" (R38) and

"skin irritant" (category 2).  

 

Eye irritation

In the chosen key study, i.e. an eye irritation test comparable to OECD Guideline 405, 0.1 ml undiluted racemate citronellal (CAS 106 -23 -0) was instilled into one eye of 6 Vienna White rabbits each (BASF AG 1980). Reactions were scored after 24, 48 and 72 h and after 8 days. Only slight changes were observed with mean scores of 0 for corneal opacity , 0.1 for iritis, 1.1 for conjunctival redness and 0.2 for chemosis (including all animals and readings after 24, 48 and 72 hours). Effects were reversible within 8 days except for slight conjunctival redness in 4/6 animals and a slight corneal opacity in 2/6 animals, that occurred at the 8 day observation timepoint only.

 

In line, application of 50 µl of the structurally similar test substance citral (CAS 5392 -40 -5) to the conjunctival sac of one eye of two Vienna White rabbits resulted in mean scores (including 24 and 48 h readings) of 1/1 for corneal opacity, 0/0 for iritis, 1/2 for conjunctiva redness and 1/1.5 for chemosis for animal 1/animal 2, respectively (BASF 1978). Corneal opacity and chemosis were fully reversible within 7 days, whereas the conjunctival redness declined but not completely resolved during the study period (score 1/1 after 8 days).

 

Overall, slight and mostly reversible eye irritation has been observed for the racemate citronellal and the structurally related citral. On the basis of the mean scores for conjunctival redness, the lack of reversibility within 7 days and an expected reversibility over a longer time period, i.e. 21 days, a classification as "irritating to eyes" (Category 2) according to CLP, and a non classification according to (67/548/EEC) is warranted.

 

Justification for classification or non-classification

The present data fulfill the criteria laid down in 67/548/EEC and 1272/2008/EEC, and a classification "irritating to skin" (R38) and "skin irritant" (category 2) is warranted.

The present data on eye irritation do not fulfill the criteria laid down in 67/548/EEC. According to 1272/2008/EEC, a classification as "irritating to eyes" (Category 2) is warranted.