Registration Dossier

Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2012
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Remarks:
Conducted according to the up and down procedure (UDP) recommended by the US EPA Health Effects Test Guidelines (EPA, 2002). However, the duration of exposure to nicotine mist (20 minutes) was 12-fold shorter than 4 hours (240 minutes).

Data source

Reference
Reference Type:
publication
Title:
Nicotine Delivery to Rats via Lung Alveolar Region-Targeted Aerosol Technology Produces Blood Pharmacokinetics Resembling Human Smoking
Author:
Xuesi M. Shao, MD; Bin Xu, PhD; Jing Liang, MD, PhD; Xinmin (Simon) Xie, MD, PhD; Yifang Zhu, PhD and Jack L. Feldman, PhD
Year:
2012
Bibliographic source:
Nicotine Tob Res. 2013 Jul; 15(7): 1248-1258

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
other:
Version / remarks:
The study was performed equivalent or similar to EPA Health Effects Test Guidelines: Acute inhalation toxicity (1998).
Deviations:
not applicable
Principles of method if other than guideline:
Different exposure time of 20 min (cf. 4h) than recommended in relevant inhalation guidelines.
GLP compliance:
not specified
Remarks:
No statement about the GLP status of the study was published.
Test type:
other: Up and down procedure
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid
Specific details on test material used for the study:
-(s)-(-)-nicotine freebase (liquid, 99%), ordered from Alfa Aesar Co.
-pH 7.4 and 8.0.

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
-8–11-week-old
-body weight 250–400g
-housed in the vivarium under a 12-hr light/dark cycle
-ad libitum access to food and water.

ENVIRONMENTAL CONDITIONS:
no data

Administration / exposure

Route of administration:
inhalation: aerosol
Type of inhalation exposure:
nose only
Vehicle:
other: water
Mass median aerodynamic diameter (MMAD):
2.5 µm
Geometric standard deviation (GSD):
1.8
Details on inhalation exposure:
- 3-jet Collison nebulizer (BGI Inc.)
- air pressure gauge (Ashcroft@ filled gauge, 0–100 psi, Cole-Parmer)
- air flowmeter with a valve (150-mm Direct Reading, 23 LPM, Cole-Parmer) that regulated the airflow rate and the pressure entering the nebulizer
- homemade nose-only exposure chamber
- rat holders (Model #: CHT-250, CH Technologies Inc.). About 30ml nicotine solution was put in the nebulizer jar.
- Exposure of rats to the aerosol in a nose-only system, one at a time with a fixed air pressure (40 psi).
Analytical verification of test atmosphere concentrations:
yes
Remarks:
Mass concentrations measured with a one-stage cascade impactor (SKC Inc.).
Duration of exposure:
20 min
Concentrations:
Ordered concentration progression in a rage of 5%-56% nicotine. Concentration progression factor of antilog 0.25=1.78.
No. of animals per sex per dose:
7 male rats in sum
Control animals:
no
Details on study design:
- Duration of observation period following administration: 24 hours
- Necropsy of survivors performed: no
- Other examinations performed: Arterial blood sample collection and plasma nicotine level measurement
Statistics:
Computer program (AOT425StatPgm, US EPA) was used to calculate the LC50 and its confidence intervals

Results and discussion

Effect levels
Key result
Sex:
male
Dose descriptor:
LC50
Effect level:
2.3 mg/L air
Based on:
test mat.
95% CL:
>= 1.24 - <= 4.07
Exp. duration:
20 min
Remarks on result:
other: Using the Habers law, according to point 3.1.2.1. (c) of the CLP Regulation (Cn x t = constant), the converted LC50 (4 hours) of nicotine is 0.19 mg/L.
Mortality:
Exposure to 2.3 mg/L nicotine in air for 20 min causes death in 50% of rats.
Some of the rats died within 1-3 min after the end of nicotine aerosol exposure period of 20 min.
Clinical signs:
other: Exposure in the high concentration range caused a Straub tail within 20-60 s. Within 1-2.5 min rats became apneic, interspersed with gasps.

Applicant's summary and conclusion

Interpretation of results:
Category 2 based on GHS criteria
Conclusions:
An LC50 (20 min) of 2.3 mg/L air was reported for nicotine aerosol, with a confidence interval of 1.24 - 4.07 mg/L (pH 8.0), based on the mass concentration of aerosol at the breathing zone 7.17 mg/L at 40 psi.
Using the Habers law, according to point 3.1.2.1. (c) of the CLP Regulation (Cn x t = constant), the converted LC50 (4 hours) of nicotine is 0.19 mg/L.
Executive summary:

Nicotine was tested using the up and down procedure (UDP) recommended by the US EPA Health Effects Test Guidelines (2002). Seven rats were exposed to nicotine aerosol in a nose-only system. The mass median aerodynamic diameter (MMAD) was within the range of respirable droplet size recommended by USEPA. Exposure to 2.3 mg/L for 20 minutes caused death in 50% of rats.Signs and symptoms were observed. Furthermore, arterial and venous blood samples were collected and plasma level was measured after a 2 min exposure period.