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Diss Factsheets

Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 403 (Acute Inhalation Toxicity)
Deviations:
yes
Remarks:
: limit test with five instead of three animals per sex.
Qualifier:
according to guideline
Guideline:
EU Method B.2 (Acute Toxicity (Inhalation))
Qualifier:
according to guideline
Guideline:
EPA OPPTS 870.1300 (Acute inhalation toxicity)
Qualifier:
according to guideline
Guideline:
other: JMAFF Notification No 8147
GLP compliance:
yes
Test type:
other: Limit test, traditional protocol
Limit test:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
Propanoic acid, 2-hydroxy-, 2-ethylhexyl ester, (2S)-
EC Number:
606-097-1
Cas Number:
186817-80-1
Molecular formula:
C11H22O3
IUPAC Name:
Propanoic acid, 2-hydroxy-, 2-ethylhexyl ester, (2S)-
Constituent 2
Reference substance name:
2-ethylhexyl-S-lactate
IUPAC Name:
2-ethylhexyl-S-lactate
Details on test material:
Batch no.: 0805000655
Purity: 99 %

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River France, L'Arbresle Cedex, France and Charles River Deutschland, Sulzfeld, Germany.
- Age at study initiation: approximately 11 weeks old.
- Weight at study initiation: body weight variation was within ± 20 % of the sex mean (males: 315 gram, females: 216 gram).
- Fasting period before study: no.
- Housing: Before exposure: Group housing in labeled Macrolon cages (type IV; height 18 cm) containing sterilized sawdust as bedding material (Litalabo, S.P.P.S., Argenteuil, France). Paper (Enviro-dri, Wm. Lillico & Son (Wonham Mill Ltd), Surrey, United Kingdom) was supplied as cage-enrichment. After exposure: Group housing as described above, except that a paper sheet was introduced into the cage covering the bedding and cage enrichment to prevent suffocation in case of bad health condition. At the end of the Day of exposure the paper sheet was removed.
- Diet (e.g. ad libitum): Free access to pelleted rodent diet (SM R/M-Z from SSNIFF@Spezialdiäten GmbH, Soest, Germany) except during exposure to the test substance.
- Water (e.g. ad libitum): Free access to tap water except during exposure to the test substance.
- Acclimation period: Acclimatisation period was at least 5 days before start of treatment under laboratory conditions.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21.0 ± 3.0 °C (actual range: 19.7-21.5 °C).
- Humidity (%): relative humidity of 40-70 % (actual range: 38-78 %).
- Air changes (per hr): approximately 15 air changes per hour.
- Photoperiod (hrs dark / hrs light): 12 hours artificial fluorescent light and 12 hours darkness per day.

IN-LIFE DATES: 16 June 2010 to 30 June 2010

Administration / exposure

Route of administration:
inhalation: aerosol
Type of inhalation exposure:
nose only
Vehicle:
air
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: The design of the exposure chamber is based on the flow past nose-only inhalation chamber (Am. Ind. Hyg. Assoc. J. 44(12): 923-928, 1983). The chamber consisted of three animal sections with eight animal ports each. Each animal port had its own atmosphere inlet and exhaust outlet.
- Method of holding animals in test chamber: The animals were placed in restraining tubes and connected to the animal ports.
- Source and rate of air: The number of animal sections and number of open inlets were adapted to the air flow in such a way that at each animal port the theoretical air flow was at least 1 L/min, which ensures an adequate oxygen supply to the animals. The main inlet of the test atmosphere was located at the top section and the main outlet was located at the bottom section. The direction of the flow of the test atmosphere guaranteed a freshly generated atmosphere for each individual animal.
All components of the exposure chamber in contact with te test material were made of stainless steel, glass, rubber or plastic. To avoid exposure of the personnel and contamination of the laboratory the exposure chamber was placed in a fume hood, which maintained at a slight negative pressure.
- System of generating particulates/aerosols: An aerosol was generated by nebulization of the test substance by means of a nebulizer (type 950, Hospitak Inc., Lindenhurst, NY, UAS). The primary aerosol was diluted with pressurized air before it entered the exposure chamber. The mean total airflow was 26 L/min.
- Method of particle size determination: The droplet size distribution was characterized twice during the exposure period. The samples were drawn (2 L/min) from the test atmosphere through a tube mounted in one of the free animal ports of the middle section of the exposure chamber. The samples were collected with an 8 stage Marple personal cascade impactor containing fiber glass filters (SKC 225-713, glass fiber, Westech, Upper Stondon, Bedfordshire, England). Amounts of test substance collected were measured gravimetrically. Subsequently the Mass Median Aerodynamic Diameter (MMAD) and the Geometric Standard Deviation (GSD) were determined.
- Treatment of exhaust air: From the exposure chamber the test atmosphere was passed through a filter before it was released to the exhaust of the fume hood.
- Temperature, humidity, pressure in air chamber: The temperature and relative humidity were measured with a humidity and temperature indicator (E+E Elektronik, Engerwitzdorf, Austria) and were recorded after the animals were placed in the experimental set-up and at 30 minute intervals after initiation of the exposure. The probe was inserted in a tube mounted in one of the free animal ports of the middle section of the exposure chambger. The temperature of the atmosphere was between 20.7 and 20.9 °C and relative humidity was between 25 and 30%. These conditions were considered appropriate for this relatively short 4 hours exposure duration.

TEST ATMOSPHERE
- Brief description of analytical method used: The acutal concentration was detemined nine times during the exposure period. Samples were drawn from the test atmosphere through a tube mounted in one of the free animal ports of the middle section of the exposure chamber. Samples were drawn through a glass fiber filter (type APFC04700, Millipore, Billerica, MA, USA). The collected amount of the test substance in the air sample was measured gravimetrically. Sample volumes were measured by means of a dry gas meter (type G 1.6, Actaris Meterfabriek B.V., Dordrecht, The Netherlands).
- Samples taken from breathing zone: yes
- Stability monitoring: The opacity of the test atmosphere was monitored by means of a real time aerosol monitoring system (Windust Pro, Casella, Amherst, NH, USA). Data obtained with this system were used to illustrate the stability of the aerosol during exposure of the animals.

TEST ATMOSPHERE (if not tabulated)
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): The MMAD and GSD were determined twice. The MMAD was 3.7 µm (GSD 1.8) and 3.9 µm (GSD 1.7).
Analytical verification of test atmosphere concentrations:
yes
Duration of exposure:
ca. 4 h
Concentrations:
The mean actual concentration was 5.6 ± 0.4 mg/L.
No. of animals per sex per dose:
5
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Mortality/viability: Twice daily; body weights: days 1 (pre-administration), 2, 4, 8 and 15 and at death (if found dead after day 1)
- Necropsy of survivors performed: Yes
- Other examinations performed: clinical signs: Three times during exposure for mortality, behavioural signs of distress and effects on respiration, after exposure twice (at 1 and at 3 hours after exposure) on the day of dosing (day 1) and once daily thereafter, until day 15.
Statistics:
No statistical analysis was performed.

Results and discussion

Effect levels
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 5.6 mg/L air (analytical)
Based on:
act. ingr.
Exp. duration:
4 h
Mortality:
Two females were found dead or sacrificed for ethical reasons on day 2 after exposure. No further mortality occurred (see Table 3 in attached background material).
Clinical signs:
other: No clinical signs were noted during exposure. Lethargy, hunched posture, rales and/or piloerection were shown by the surviving animals between days 1 and 4 after exposure. Rales were also noted among two animals at later time points during the observation
Body weight:
Reduced body weight gain and body weight loss was noted among the surviving animals during the first week post-exposure. All surviving animals regained weight during the second week (see Table 5 in attached background material).
Gross pathology:
No abnormalities were found at macroscopic post mortem examinantion of the surviving animals and the animal found dead. Macroscopic examination of the animal sacrificed for ethical reasons during the study revealed pale discolouration of the liver (see Table 6 in attached background material).
Incidental finding included pelvic dilation of the right kidney of one male. This finding is occasionally seen among rats ot this age and strain and was therefore considered not related to treatment.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
The 4-hour LC50 of 2-ethylhexyl-S-lactate in rats is higher than 5.6 mg/L.
Executive summary:

2-ethylhexyl-S-lactate was tested for its acute inhalation toxicity. Five male and five female Wistar rats were exposed to an aerosol concentration of approximately 5.6 mg/L for 4 hours. Two females were found dead or sacrificed for ethical reaons on day 2 after exposure. No further mortality occurred. No clinical signs were noted during exposure. Lethargy, hunched posture, rales and/or piloerection were shown by the surviving animals between days 1 and 4 after exposure. Rales were also noted among two animals at later time points during the observation period. The two females found dead or sacrificed showed lethargy, ventro-lateral recumbency, hunched posture, slow breathing, laboured respiration and/or piloerections prior to death.

Reduced body weight gain and body weight loss was noted among the surviving animals during the first week post-exposure. All surviving animals regained weight during the second week. No abnormalities were found at macroscopic post mortem examination of the surviving animals and the animal found dead. Macroscopic examination of the animal sacrificed for ethical reasons during the study revealed pale discolouration of the liver.

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