Mono-, and di-(sec-hexadecyl)naphthalene

Endpoint summary

Description of key information

Acute Toxicity, Oral-LD50>5000mg/kg for rat (OECD TG 401)
Acute Toxicity, Inhalation-Read-across data available. No testing required based on weight of evidence.
Acute Toxicity, Dermal-LD50>2000mg/kg for rabbit (OECD TG 402)

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Acceptable, well-documented study report similar or equivalent to OECD 401.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Taconic Farms, Germantown, NY
- Weight at study initiation: Male: 245-374g; Female: 189-270g
- Fasting period before study: overnight

Route of administration:

oral: gavage

Vehicle:

unchanged (no vehicle)

Doses:

5 mg/kg

No. of animals per sex per dose:

5 per sex

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Signs of toxicity were recorded at ~ 1/2, 1 and 4 hours after study substance administration and daily thereafter with the exception of weekends. Body weights were recorded prior to fasting and on Days 0, 7, and 14.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight, and gross pathology

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 5 000 mg/kg bw

Based on:

test mat.

Mortality:

There were no deaths following administration of the study substance.

Clinical signs:

other: There were several clinical observations noted in one or more animals: decreased activity, urogenital staining (yellow), anogenital staining (yellow-brown), chromodacryorrhea, and alopecia (forelimbs).

Gross pathology:

There were no treatment-related gross pathological changes.

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Based on the parameters of this study, the acute oral LD50 for the study substance is >5.0 g/kg in the rat. This finding does not warrant the classification as an acute oral toxicant under the new Regulation (EC) 1272/2008 on classification, labeling, and packaging of substances and mixtures (CLP) or under the Directive 67/518/EEC for dangerous substances and Directive 1999/45/EC for preparations.

Executive summary:

In this study, ten rats were given a single 5.0 g/kg dose of the study substance by oral gavage. The rats were then observed for 14 days and a gross examination was performed at the termination of the study period. All animals survived to termination of the study period. There was an increase in mean and individual body weights in relation to the pre-fast body weights. Decreased activity, urogenital and anogenital staining, alopecia and chromodacryorrhea were observed in one or more animals. There were no treatment-related gross pathological changes. Based on the parameters of this study, the acute oral LD50 for the study substance is >5.0 g/kg in the rat. This finding does not warrant the classification of the study substance as an acute oral toxicant under the new Regulation (EC) 1272/2008 on classification, labeling, and packaging of substances and mixtures (CLP) or under the Directive 67/518/EEC for dangerous substances and Directive 1999/45/EC for preparations.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Acceptable, well-documented study report similar or equivalent to OECD 402. GLP.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Hazleton Research Products, Inc. - Denver, PA
- Age at study initiation: young adult
- Weight at study initiation: Male: 2.5-3.0 kg; Female: 2.4-2.9
- Housing: Individually housed in suspended cages with wire mesh bottoms
- Diet (e.g. ad libitum): ~ 125 g of Purina rabbit chow no. 5326 daily
- Water (e.g. ad libitum): House water ad libitum

Type of coverage:

occlusive

Vehicle:

unchanged (no vehicle)

Duration of exposure:

24 hours

Doses:

2 mg/kg

No. of animals per sex per dose:

5 per sex

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Body weights were recorded on Days 0, 7, and 14. Clinical observations were recorded at 1 and 4 hours after study substance administration and daily thereafter except on weekends.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight, gross pathology

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Mortality:

There were no deaths following administration of the study substance.

Clinical signs:

other: Soft stool, decreased fecal output, and decreased food consumption were noted in one or more animals.

Gross pathology:

There were no treatment-related gross pathological changes.

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The LD50 for acute dermal toxicity of the study substance is greater than 2000 mg/kg bw in the New Zealand White rabbit. This finding does not warrant classification of the study substance as an acute dermal toxicant under the new Regulation (EC) 1272/2008 on classification, labeling, and packaging of substances and mixtures (CLP) or under the Directive 67/518/EEC for dangerous substances and Directive 1999/45/EC for preparations.

Executive summary:

The study substance was administered as a single dose for 24 hours to ten white rabbits at a concentration of 2000 mg/kg to assess acute dermal toxicity. Animals were observed for fourteen days following exposure. All animals survived to the termination of the study period. An increase in mean and individual body weights was observed during the study and soft stool, decreased fecal output, and decreased food consumption were noted in one or more animals. There were no treatment-related gross pathological changes. Based on the conditions of this study, the dermal LD50 for the study substance is greater than 2.0 gm/kg. This finding does not warrant classification of the study substance as an acute dermal toxicant under the new Regulation (EC) 1272/2008 on classification, labeling, and packaging of substances and mixtures (CLP) or under the Directive 67/518/EEC for dangerous substances and Directive 1999/45/EC for preparations.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Additional information

The study substance has a low order of acute toxicity in animals by the dermal and oral routes of exposure. All animal studies were performed on the study substance in a manner similar or equivalent to currently established OECD guidelines.

The acute toxicity of the study substance is expected to be low by the inhalation route of exposure based on data for structurally similar substances. Three separate studies for structurally similar alkylated naphthalenes (alkyl carbon number of 3 or greater) report no toxicity in acute inhalation toxicity studies. These studies are adequate for read-across based on similar functionality and metabolism of the test materials with the study substance. Available data demonstrate that extensive oxidation of the aromatic nucleus of naphthalene and shorter-chain length alkylated naphthalenes (alkyl carbon number less than 3), does not occur with longer alkylated naphthalene derivatives (alky carbon number of 3 or greater), where the major metabolites involve side-chain oxidation and do not include reactive harmful intermediates (i.e. aromatic epoxides). Experimental as well as modeling data indicate that this trend is expected to continue as alkyl chain length increases. In addition, it is known in general that certain physical properties vary in a predictable manner as alkyl chain length increases, making a compound less favorable for absorption as carbon number increases. All read-across data are for test materials with alkyl carbon number greater than 3 but less than the study substance (alkyl carbon number of 16). Therefore, the toxicity exhibited by the read-across data would be a worst case estimate of the likely toxicity of the study substance. Taken together, the three read-across studies provide adequate weight of evidence to support low acute inhalation toxicity of the study substance. 

Based on these data, the study substance is determined to be minimally toxic by the oral, dermal, and inhalation routes of exposure.

Justification for classification or non-classification

The study substance has a low order of toxicity via ingestion where the LD50 is>5000 mg/kg; via dermal exposure where the LD50 is >2000 mg/kg ; and via inhalation where the LD50s for aerosol exposures to supporting substances are > 5mg/l. Based on these data classification is not warranted under the new Regulation (EC) 1272/2008 on classification, labeling and packaging of substances and mixtures (CLP) or under the Directive 67/518/EEC for dangerous substances and Directive 1999/45/EC for preparations.