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Description of key information

In two experimental studies, the acute toxicity of Lyral by the oral and dermal is low LD50 > 4971 (rats) and > 5000 (rabbits) mg/kg bw, respectively. For the inhalation route route to route extrapolation has been done, also showing low acute inhalation toxicity: > 28000 mg/m3. 

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: GLP-compliant, according to OECD TG 401.
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 401 (Acute Oral Toxicity)
GLP compliance:
yes
Test type:
standard acute method
Limit test:
no
Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Blue Spruce Farms, Altamont, New York
- Weight at study initiation: 180-280 gm (after fasting)
- Fasting period before study: 18 hours
- Housing: individually in stainless steel 1/2'' wire mesh cages
- Diet: Wayne Lab Blox, ad libitum
- Water: fresh tap water, fit for human consumption, ad libitum
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3
- Humidity (%): 30-70
- Photoperiod (hrs dark / hrs light): 12 / 12
Route of administration:
oral: gavage
Vehicle:
unchanged (no vehicle)
Details on oral exposure:
- Rationale for the selection of the starting dose: based on the results of a dose-range finding study
Doses:
In the range-finding study: 0.5, 1.6 and 5 mL/kg bw.
In the main study: 4.0, 4.5, 5.0, 5.5 and 6.0 mL/kg bw
No. of animals per sex per dose:
In the dose-range finding study: 2/sex/dose
In the main study: 5/sex/dose
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days in the main study and 72 hours in the dose-range finding study.
- Frequency of observations and weighing: before the study (after fasting) and at day 14 in the main study and day 3 in the dose-range finding study
- Necropsy of survivors performed: yes (in the main study)
- Other examinations performed: clinical signs, body weight
Sex:
female
Dose descriptor:
LD50
Effect level:
> 3 976 mg/kg bw
Based on:
test mat.
Remarks on result:
other: Calculated based on the relative density of 0.9941 and LD50 of > 4 mL/kg bw
Sex:
male
Dose descriptor:
LD50
Effect level:
> 4 971 mg/kg bw
Based on:
test mat.
Remarks on result:
other: Calculated based on the relative density of 0.9941 and LD50 of > 5 mL/kg bw.
Sex:
male/female
Dose descriptor:
LD50
Effect level:
> 4 971 mg/kg bw
Based on:
test mat.
Remarks on result:
other: Calculated based on the relative density of 0.9941 and LD50 > 5 mL/kg bw.
Mortality:
In the dose-range finding study, one of the rats died at 5 mL/kg bw. In the main study, 3 of 10 rats died at 4.0 (2 m, 1 f) and 4.5 mL/kg bw (3 f), 4 of 10 rats died at 5.0 (1 m, 3 f) and 5.5 mL/kg bw (1 m, 3 f), and 5 of 10 rats died at 6 mL/kg bw (2 m, 3 f).
Clinical signs:
In the dose-range finding study, signs observed included decreased activity, flaccid body tone, ptosis, abnormal stance, hunched body position, red exudate around nasal area, chromodacryorrhea, pilorection and vasodilation.
In the main study, signs observed included ptosis, prostration, decreased activity, flaccid body tone and abnormal stance.
Body weight:
All animals in the 4 mL/kg bw, 4.5 mL/kg bw and 5 mL/kg bw gained weight during the study. Two animals in 5.5 mL/kg bw and 2 animals in 6 mL/kg bw groups lost weight during the studies.
Gross pathology:
Necropsy of the animals dying on study revealed distended, fluid-filled intestines and bladder, bright red lungs and blanched adrenals. Terminal necropsy of the remaining animals revealed no visible lesions at any dose level.
Interpretation of results:
not classified
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
In the acute oral toxicity study with rats, the LD50 was > 3976 mg/kg bw for female rats, > 4971 mg/kg bw/day for male rats and > 4971 mg/kg bw for both sexes combined.
Executive summary:

In the oral study, performed according to a protocol similar to OECD guideline 401 and without GLP, LD50 values of >3976 mg/kg bw and >4971 mg/kg bw were obtained for female and male Sprague-Dawley rats, respectively. The combined LD50 value for both sexes was >4971 mg/kg bw. The observed clinical signs included ptosis, prostration, decreased activity, flaccid body tone and abnormal stance. Necropsy of the animals dying during the study revealed distended, fluid-filled intestines and bladder, bright red lungs and blanched adrenals. Terminal necropsy of the remaining animals revealed no visible lesions at any dose level.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
LD50
Value:
4 971 mg/kg bw
Quality of whole database:
The quality is sufficiently high because the selected study has been performed according to OECD guidline 401 and is GLP compliant.

Acute toxicity: via inhalation route

Link to relevant study records
Reference
Endpoint:
acute toxicity: inhalation
Data waiving:
other justification
Justification for data waiving:
other:
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
LC50
Value:
28 000 mg/m³
Quality of whole database:
The quality is sufficiently high because the reasoning is sound and this as well as the calculation has been well documented.

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:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study predates GLP but is similar to OECD TG 402
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 402 (Acute Dermal Toxicity)
Principles of method if other than guideline:
A single dose of 5000 mg/kg bw was applied to a group of 10 rabbits. Animals were observed for 14 days and necropsied.
GLP compliance:
no
Test type:
fixed dose procedure
Limit test:
yes
Species:
rabbit
Strain:
not specified
Sex:
not specified
Type of coverage:
not specified
Vehicle:
not specified
Duration of exposure:
No data
Doses:
5000 mg/kg bw
No. of animals per sex per dose:
10/dose
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs
Statistics:
A statistical analysis was not performed.
Sex:
not specified
Dose descriptor:
LD50
Effect level:
> 5 000 mg/kg bw
Based on:
test mat.
Mortality:
One of the rabbits died on observation day 7 and one on observation day 13. No further mortalities occurred.
Clinical signs:
One rabbit which died on day 7 appeared emaciated, lethargic and ptotic and had discharge from nose and eyes on the day prior to death.
Gross pathology:
Necropsy signs of the rabbit which died on day 7 included dried fecal material in the anogenital region, nose and mouth exudate, small spleen, mottled kidneys and red portions of large intestine. The other one showed also mottled kidneys and, in addition, blotchy liver and yellowish nodules on liver.
Other findings:
Skin irritation:
- redness: slight in 5, moderate in 4, severe in 1;
- edema: slight in 2, moderate in 8.
Interpretation of results:
not classified
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
An LD50 of > 5000 mg/kg bw was obtained in the acute dermal toxicity study with rabbits.
Executive summary:

In the acute dermal toxicity study with rabbits (strain unspecified), predating GLP and OECD guidelines, a single application of 5000 mg/kg bw of Lyral resulted in 2 out of 10 rabbits dying on days 7 and 13 of the observation period. No data on the type of coverage and exposure duration were provided. One rabbit which died on day 7 appeared emaciated, lethargic and ptotic and had discharge from nose and eyes on the day prior to death. Necropsy signs of the rabbit which died on day 7 included dried fecal material in the anogenital region, nose and mouth exudate, small spleen, mottled kidneys and red portions of large intestine. The other one showed also mottled kidneys and, in addition, blotchy liver and yellowish nodules on liver. Skin irritation signs were observed in all animals: slight erythema was noted in 5, moderate in 4 and severe in 1 rabbit. Slight edema was observed in 2 and moderate edema was observed in 8 rabbits.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
LD50
Value:
5 000 mg/kg bw
Quality of whole database:
The quality of the study is sufficiently high. The study available predates GLP and is similar to OECD TG 402, but acceptable for assessment with a klimisch score of 2.

Additional information

Two studies are available for the evaluation of acute oral toxicity of Lyral. The key study is the one of Pharmakon Research International (1982), performed according to a protocol similar to OECD guideline 401 and with GLP. The LD50 values of >3976 mg/kg bw and >4971 mg/kg bw were obtained for female and male Sprague-Dawley rats, respectively. The combined LD50 value for both sexes was >4971 mg/kg bw. The observed clinical signs included ptosis, prostration, decreased activity, flaccid body tone and abnormal stance. Necropsy of the animals dying during the study revealed distended, fluid-filled intestines and bladder, bright red lungs and blanched adrenals. Terminal necropsy of the remaining animals revealed no visible lesions at any dose level.

In an older study of MB Research Laboratories (1977), which predated GLP but similar to OECD guideline 401, an LD50 > 5000 mg/kg bw was obtained following a single oral administration of 5000 mg/kg bw Lyral to a group of 10 rats (sex and strain unspecified). Two out of 10 animals died on the first observation day. No further mortalities occurred. Slight lethargy, tremors, flaccid tone and piloerection were observed. At necropsy, 2 rats had dark livers, 2 rats had light yellow intestines and 1 rat had a dark kidney.

In the acute dermal toxicity study with rabbits (strain unspecified), predating GLP, but similar to OECD guideline 402 (MB Research Laboratories, 1977), a single application of 5000 mg/kg bw of Lyral resulted in 2 out of 10 rabbits dying on days 7 and 13 of the observation period. No data on the type of coverage and exposure duration were provided. One rabbit which died on day 7 appeared emaciated, lethargic and ptotic and had discharge from nose and eyes on the day prior to death. Necropsy signs of the rabbit which died on day 7 included dried fecal material in the anogenital region, nose and mouth exudate, small spleen, mottled kidneys and red portions of large intestine. The other one showed also mottled kidneys and, in addition, blotchy liver and yellowish nodules on liver. Skin irritation signs were observed in all animals: slight erythema was noted in 5, moderate in 4 and severe in 1 rabbit. Slight edema was observed in 2 and moderate edema was observed in 8 rabbits.

No data on acute inhalation toxicity of Lyral are available. According to Column 2 of REACH Annex VIII, “in addition to the oral route (8.5.1), for substances other than gases, the information mentioned under 8.5.2 (acute toxicity by inhalation) and 8.5.3 (acute toxicity by the dermal route) shall be provided for at least one other route. The choice for the second route will depend on the nature of the substance and the likely route of human exposure.” In the present case, inhalation exposure is not likely because Lyral has a very low vapour pressure and dermal exposure is the more likely route of exposure. As acute toxicity data on both the oral and the dermal route of exposure is available, testing for acute inhalation toxicity is not necessary. However, the acute inhalation toxicity for Lyral can be derived using data on the acute oral toxicity using the following methodology:

The LD50 of Lyral is > 3976 mg/kg bw, the highest dose tested. This value is rounded off to 4000 mg/kg bw for the calculation. The 4000 mg/kg bw can be converted to 280000 mg/per person (assuming a body weight of 70 kg). An inhalation volume of one person during 4 h (standard exposure time in OECD TG for acute inhalation toxicity) is 5m3 (assuming 10m3/8h for workers). This means that the LC50 concentration in 1m3 and 4 hours exposure is 56000 mg/m3. Taking into account that the absorption during inhalation route can be twice as high as during oral absorption the LC50 for inhalation would become 28000 mg/m3. The maximum saturated vapour pressure for this substance in mg/m3 is (0.0055 Pa x 210000 MW (mg/Mol)) /(8.3 (R, gas constant) x 293°K) = 0.47 mg/m3. The LC50 value of > 28000 mg/m3 cannot be reached because of the saturated vapour concentration of Lyral of 0.47 mg/m3. Though no correction has been done for rat versus human inhalation, the calculation clearly shows that there is no acute inhalation toxicity for Lyral because the LC50 > 28000 mg/m3, while the saturated vapour pressure is 0.47 mg/m3. In addition, in the FFHPVC, 2008, an acute inhalation toxicity study with rats on Lyral is presented (Union Carbide, 1987). Lyral did not cause acute inhalation toxicity at 400 ppm (which is ca. 4000 mg/m3 after conversion (using the formula: 1 ppm=MW/24 mg/m3). This 400 ppm value seems to be far above the saturated vapour pressure of Lyral. It also indicates that no acute inhalation toxicity is expected.


Justification for selection of acute toxicity – oral endpoint
Acute oral toxicity needs to be assessed according to the REACH regulation. Two acute oral toxicity studies are available similar to OECD guideline 401. The most recent study conducted under GLP has been selected.

Justification for selection of acute toxicity – dermal endpoint
Acute dermal toxicity needs to be assessed according to the REACH regulation. The one study available is performed similar to OECD TG 402 and is of sufficient quality

Justification for classification or non-classification

Based on the oral LD50 > 4971 mg/kg bw in rats and the dermal LD50 > 5000 mg/kg bw in rabbits and the calculated inhalation LC50 > 28000 mg/m3 (being far above the saturated vapour pressure) classification for acute toxicity is not warranted in accordance with EU Directive 67/548/EEC (DSD) and EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.