D-tetramethrin

Endpoint summary

Description of key information

An in vivo skin irritation study has been conducted on test item tetramethrin according to OECD guideline no. 404, and based on results it was concluded that the test item tetramethrin tech. grade is classified as non-irritant to the intact skin of New Zealand white rabbits

In an in vivo eye irritation study that has been conducted on test item tetramethrin according to OECD guideline no. 405 and EPA OPPTS 870.2400 (Acute Eye Irritation), no eye irritation was observed, indicating the substance not being irritant to eyes.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Reference 1

Endpoint:

skin irritation: in vitro / ex vivo

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

an in vitro skin irritation study does not need to be conducted because adequate data from an in vivo skin irritation study are available

Reference 2

Endpoint:

skin irritation: in vivo

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The source substance is the racemic form of the target substance d-tetramethrin. Tetramethrin does consist of 50% d- and l-form, and both do exist as cis and trans isomers. Hence, the target substance does consist of d-cis-tetramethrin, d-trans-tetramethrin, l-cis-tetramethrin and l-trans-tetramethrin, whereas the target substance only contains the first two (i.e. d-cis-tetramethrin, d-trans-tetramethrin).
Both, the source as well as the target substance, do have a cis/trans ratio of approximately 1/4 and obviously do share same molecular formula and mass, functional groups and other properties. Thus, the source substance by definition does contain ~50% of the d-form and the l-form is not expected to be significantly different with respect to its toxic properties. Acute effects to skin and eyes as well as skin sensitisation has been assessed in GLP guideline toxicity studies to assess acute toxicity effects to skin and eyes. Accordingly, data do indicate that racemic tetramethrin and thus also d-tetramethrin is not affecting eyes and skin by irritation in rabbits, nor does it cause skin sensitizing properties in guinea pigs. Results of d-tetramethrin are not expected to significantly differ from the racemic mixture, considering that this contained the d-enantiomer as the main component.
2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The d-tetramethrin with a purity > 80 % does contain its corresponding l-form as an impurity in the range of < 7%, other impurities from the manufacturing process are individually below 1% (w/w) each. The source substance that has been tested was having a purity of approx. 98% as tetramethrin with a cis/trans ratio of 1/4 and a d-form/l-form ratio of ~50/50.
3. ANALOGUE APPROACH JUSTIFICATION
Source and Target substance do share identical structure and molecular weight, only differentiating by the fact that the source substance is a racemic mixture, whereas the target substance represents almost pure d-form. Thus, behaviour regarding skin and eye irritating effects as well as skin-sensitisation are not being affected significantly by stereochemistry, and being fully comparable, thus justifying using available data on rodent toxicity properties on the racemic form for read-across to the d-enantiomer.
4. DATA MATRIX
Composition comparison
D-tetramethrin (target) tetramethrin (source)
D-trans tetramethrin 70 - 80% 40 – 50%
D-cis tetramethrin 10 - 20% 7 – 11 %
L-trans tetramethrin 0 – 5% 35 – 40%
L-cis tetramethrin 0 – 2% 7 – 11%

Reason / purpose for cross-reference:

read-across source

Irritation parameter:

erythema score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

4

Irritation parameter:

edema score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

4

Interpretation of results:

GHS criteria not met

Conclusions:

It is concluded that the test item racemic tetramethrin is classified as non-irritant to the intact skin of New Zealand white rabbits,due to absence of any erythema or edema effects and thus this result is also being used for the d-enantiomer d-tetramethrin.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Reference 1

Endpoint:

eye irritation: in vitro / ex vivo

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

an in vitro eye irritation study does not need to be conducted because adequate data from an in vivo eye irritation study are available

Reference 2

Endpoint:

eye irritation: in vivo

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The source substance is the racemic form of the target substance d-tetramethrin. Tetramethrin does consist of 50% d- and l-form, and both do exist as cis and trans isomers. Hence, the target substance does consist of d-cis-tetramethrin, d-trans-tetramethrin, l-cis-tetramethrin and l-trans-tetramethrin, whereas the target substance only contains the first two (i.e. d-cis-tetramethrin, d-trans-tetramethrin).
Both, the source as well as the target substance, do have a cis/trans ratio of approximately 1/4 and obviously do share same molecular formula and mass, functional groups and other properties. Thus, the source substance by definition does contain ~50% of the d-form and the l-form is not expected to be significantly different with respect to its toxic properties. Acute effects to skin and eyes as well as skin sensitisation has been assessed in GLP guideline toxicity studies to assess acute toxicity effects to skin and eyes. Accordingly, data do indicate that racemic tetramethrin and thus also d-tetramethrin is not affecting eyes and skin by irritation in rabbits, nor does it cause skin sensitizing properties in guinea pigs. Results of d-tetramethrin are not expected to significantly differ from the racemic mixture, considering that this contained the d-enantiomer as the main component.
2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The d-tetramethrin with a purity > 80 % does contain its corresponding l-form as an impurity in the range of < 7%, other impurities from the manufacturing process are individually below 1% (w/w) each. The source substance that has been tested was having a purity of approx. 98% as tetramethrin with a cis/trans ratio of 1/4 and a d-form/l-form ratio of ~50/50.
3. ANALOGUE APPROACH JUSTIFICATION
Source and Target substance do share identical structure and molecular weight, only differentiating by the fact that the source substance is a racemic mixture, whereas the target substance represents almost pure d-form. Thus, behaviour regarding skin and eye irritating effects as well as skin-sensitisation are not being affected significantly by stereochemistry, and being fully comparable, thus justifying using available data on rodent toxicity properties on the racemic form for read-across to the d-enantiomer.
4. DATA MATRIX
Composition comparison
D-tetramethrin (target) tetramethrin (source)
D-trans tetramethrin 70 - 80% 40 – 50%
D-cis tetramethrin 10 - 20% 7 – 11 %
L-trans tetramethrin 0 – 5% 35 – 40%
L-cis tetramethrin 0 – 2% 7 – 11%

Reason / purpose for cross-reference:

read-across source

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

4

Irritation parameter:

iris score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

2

Irritation parameter:

conjunctivae score

Remarks:

redness

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

3

Irritation parameter:

chemosis score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

4

Interpretation of results:

GHS criteria not met

Conclusions:

The results indicate that the test item racemic tetramethrin is "non-irritant' to the eyes of New Zealand white rabbits based on the scores at 24, 48 and 72 hours under the testing conditions adopted.
Accordingly, this result is also used for d-tetramethrin, making up half of racemic tetramethrin.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

In lack of negative response to skin and eyes in in vivo studies, the substance is not subject to classification and labelling according to CLP (Regulation EC No. 1272/2008). No data on respiratory irritation are available, but as no negative observations were made in the acute inhalation study and no negative experience from handling and use is available, the substance is also not subject to classification as respiratory irritant (STOT SE 3).