Sodium phenoxyacetate hemihydrate

Endpoint summary

Description of key information

The substance has a low acute toxicity to rats when applied orally or by inhalation.

LD50oral > 5000 mg/kg bw

LC50inhalation > 5.09 mg/L.

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

Study period:

2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: A study according to the EU and OECD methods, including GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 423 (Acute Oral toxicity - Acute Toxic Class Method)

Qualifier:

according to guideline

Guideline:

EU Method B.1 tris (Acute Oral Toxicity - Acute Toxic Class Method)

GLP compliance:

yes

Test type:

acute toxic class method

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Deutschland.
- Age at study initiation: Ca. 8 w.
- Weight at study initiation: 181 - 205 g
- Fasting period before study: From the evening before dosing to 3 h after dosing.
- Housing: Single caging
- Diet: SNIFF R/M-H ad libitum
- Water: Tap water ad libitum
- Acclimation period:At least 7 d.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): ca. 20.0
- Humidity (%): 30 - 70
- Air changes (per hr): 12
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: gavage

Vehicle:

water

Details on oral exposure:

A peroral administration was performed once in the morning by stomach intubation using a metal gavage.
The dose volume was 10 mL per kg body weight. The individual dose volumes were calculated using the body weights determined on the day of the administration.

Doses:

300 and 2000 mg/kg bw. See below.

No. of animals per sex per dose:

3 rats per step.

Control animals:

no

Details on study design:

The sequence of dosing of the test substance was:
Step 1: 300 mg/kg bw.
Step 2: 300 mg mg/kg bw.
Step 3: 2000 mg/kg bw.
Step 4: 2000 mg/kg bw.

Statistics:

No.

Sex:

female

Dose descriptor:

LD50

Effect level:

> 5 000 mg/kg bw

Based on:

test mat.

Mortality:

Mortality: All animals survived until the scheduled termination of the study.

Clinical signs:

Observations in life: All animals did not show any clinical signs during the entire observation period.

Body weight:

Body weights: All animals gained weight in both weeks p.a.

Gross pathology:

Necropsy findings: No abnormal findings were made in all animals at the necropsy 14 d p.a.

No toxic effects of the test substance were noted by signs in life and post mortem at a dose of 2000 mg test substance per kg body weight. No mortality occurred.

As no animals died, the LD50, oral was determined to be > 2000 mg/kg body weight. Based on the guidance given in OECD guideline 423 (annex 2c), the LD50, oral can be assessed to be > 5000 mg/kg body weight.

Interpretation of results:

practically nontoxic

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

No toxic effects of the test substance were noted by signs in life and post mortem at a dose of 2000 mg test substance per kg body weight.The LD50 is >5000 mg/kg body weight.

Executive summary:

The acute toxic class (ATC) method according to the EU- and OECD-guidelines was applied to investigate the acute oral toxicity of sodium phenoxyacetate in rats.

No toxic effects of the test substance were noted by signs in life and post mortem at a dose of 2000 mg test substance per kg body weight. No mortality occurred. As no animals died, the oral LD50 was determined to be > 2000 mg/kg body weight. Based on the guidance given in OECD guideline 423 (annex 2c), the oral LD50 can be assessed to be > 5000 mg/kg body weight.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

5 000 mg/kg bw

Quality of whole database:

Guideline study. The LD50 is not 5000 mg/kg, as one is forced to enter in the field above, but the LD50 > 5000 mg/kg.

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 436 (Acute Inhalation Toxicity: Acute Toxic Class Method)

Version / remarks:

2009

Deviations:

yes

Remarks:

The optimum MMAD achieved was 5.75 μm instead of 1-4 μm stated in the guidelines, due to the nature of the test item.

Qualifier:

according to guideline

Guideline:

EU Method B.2 (Acute Toxicity (Inhalation))

Version / remarks:

2008

Deviations:

yes

Remarks:

The optimum MMAD achieved was 5.75 μm instead of 1-4 μm stated in the guidelines, due to the nature of the test item.

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1300 (Acute inhalation toxicity)

Version / remarks:

1998

Deviations:

yes

Remarks:

The optimum MMAD achieved was 5.75 μm instead of 1-4 μm stated in the guidelines, due to the nature of the test item.

GLP compliance:

yes (incl. QA statement)

Test type:

acute toxic class method

Limit test:

yes

Specific details on test material used for the study:

Batch No.: 31233510

Species:

rat

Strain:

Wistar

Remarks:

CRL (WI) BR

Sex:

male/female

Details on test animals or test system and environmental conditions:

Species and strain: Rat, CRL (WI) BR of Wistar origin
Source: TOXI-COOP ZRT. H-1103, Budapest, Cserkesz u. 90.
Hygienic level at arrival: SPF
Hygienic level during the test: Good conventional
Number of animals: 6 animals in the main study (3 male and 3 female)
Sex: Male and female. Female were nulliparous, non-pregnant
Age of animals: Young adult rats, 8-12 weeks old (at start of the study)
Planned body weight range at starting: The weight variation was exceed ± 20% of the mean weight for either sex
Acclimatization time: At least 5 days

Animal health: Only healthy animals were used. The breeder certified the healthy status.
Hygienic level during the test: Good conventional
Housing: Group caging (up to 3 animals, by sex, per cage)
Cage type: Polypropylene/polycarbonate (type III) with stainless steel mesh lids.
Bedding: Laboratory bedding
Light: 12 hours daily, from 6.00 a.m. to 6.00 p.m.
Temperature: 22 ± 3 °C
Relative humidity: 30 - 70 %
Ventilation: Above 10 air exchanges/hour by central air-condition system.
Housing/Enrichment: Rats are group-housed to allow social interaction, and with deep wood sawdust bedding, to allow digging and other normal rodent activities.

Feed: ssniff® SM R/M-Z+H "Autoclavable complete feed for rats and mice – breeding and maintenance" produced by ssniff Spezialdiäten GmbH, D-59494 Soest Germany, ad libitum.
The food is periodically analysed and is considered not to contain any contaminants that could reasonably be expected to affect the purpose or integrity of the study.
Water: Tap water from watering bottles ad libitum. The drinking water is periodically analysed and is considered not to contain any contaminants that could reasonably be expected to affect the purpose or integrity of the study.
Bedding: Lignocel® Hygienic Animal Bedding produced by J. Rettenmaier & Söhne GmbH+Co.KG (Holzmühle 1, D-73494 Rosenberg, Germany). The quality of the bedding material is guaranteed by the supplier. The bedding is considered not to contain any contaminants that could reasonably be expected to affect the purpose or integrity of the study.

Route of administration:

inhalation: dust

Type of inhalation exposure:

nose only

Vehicle:

clean air

Mass median aerodynamic diameter (MMAD):

5.75 µm

Geometric standard deviation (GSD):

2.95

Remark on MMAD/GSD:

During the technical phase of the study, the test item was milled in the mortar in order to increase the particles under 4 μm, but the testing with the milled test item was not successful as the MMAD was worse than prior the milling and was above 10 μm. Therefore the test item for the exposure was used as supplied and no preparation was required.

Details on inhalation exposure:

Technical trials prior to animal exposure: Due to the nature of the test item, the optimum MMAD at 5 mg/L concentration during the technical trials was approximately 6 μm. Based on the results of the technical trials and available toxicological information, it was decided to start the main study at target concentration of 5 mg/L with optimum MMAD ~ 6 μm.

Atmosphere generation: The test item was aerosolised using a Wright Dust Feeder II. (CH Technologies (USA), located at the top of the exposure chamber. Compressed air was supplied by means of an oil-free compressor and passed through a suitable filter system prior to introduction to the dust generator.

Animal Exposure Conditions:
The animals were held in polycarbonate restraining tubes and exposed “nose-only” under dynamic air flow conditions, using an anodised aluminium Flow Past Exposure Chamber (CR Equipment SA, Switzerland). The inhalation chamber used is modular and for this study was assembled from 4 identical vertical modules, with 8 animal ports in each module. The animals were distributed on one module (levels 1, counted from the top) of the exposure chamber. Each module of the chamber consists of two concentric cylinders with inner diameter of 25 mm and 80 mm, respectively. The height of the modules is 110 mm. In this system the air carrying the test substance enters primary from above in the central cylinders and is distributed in each module through 8 radial tubes (diameter: 5 mm, length: 40 mm) to the animal ports, i.e. to the openings (diameter: 30 mm) on the wall of the outer cylinder where the animal restraining tubes can be attached. From the animal ports the air turns back into the outer cylinder towards the vacuum pump. In the particular set-up the radial tubes as well as the animal ports in the lowest module were closed by plastic stoppers. In such a way the air containing particles of the test item could flow out from the central plenum only through the 16 openings of the two upper levels. Here 6 animal ports were occupied by the animals, 1 by the Temperature-Humidity Sensor, 1 port was used for sampling on aerosol filters and the Cascade Impactor. All eight animal ports on the 2nd level (but not the radial tube) were closed by a plastic stopper.
The total volume of the exposure chamber was 2.24 L. The air flow rate of 19.3 L/min (1.2 L/min to each animal port) excluded re-breathing of the animals and ensured the continuous presence of fresh aerosol and of natural oxygen concentration in the breathing zones.

The temperature of the air was regulated by a heat exchanger. The air was not humidified in order to avoid modification of particle size distribution.

Analytical verification of test atmosphere concentrations:

yes

Remarks:

Gravimetrically.

Duration of exposure:

4 h

Remarks on duration:

The four-hour exposure period was not started until the theoretical chamber concentration equilibration, calculated according to Silver S. D. (1946), has been reached.

Concentrations:

Target concentration: 5 mg/L.

No. of animals per sex per dose:

3m + 3f.

Control animals:

no

Details on study design:

Particle Size Analysis:
Particle size analysis of generated atmospheres was performed using a 7-stage cascade impactor type 02-150 (IN-TOX Products, N.M., USA). During the exposure period samples were collected three times with one sample taken during the first hour of exposure and one during the last hour. The log-probit plots of the resulting data was used to calculate the mass median aerodynamic diameter (MMAD), Geometric Standard Deviation (GSD) and percentage < 4 μm (considered to be inhalable in the rat).
Chamber airflow rates, test atmosphere temperature and test atmosphere relative humidity were monitored continuously.

Actual Test Atmosphere Concentrations
The actual concentration of generated atmosphere was measured at regular intervals during exposures by pulling a suitable, known volume of test atmosphere from the exposure chamber, through GF10 glass fibre filters (GE Healthcare Life Science, Whatman GmbH, Germany). Since it was proved that the concentration is stable within ±10% during the technical trials then at least 8 samples were taken during each exposure. Sampling was performed shortly after chamber equilibration and then uniformly distributed, at regular intervals. Samples were collected from a vacant animal exposure port (animals breathing zone). The actual sampling schedule employed was dependent on the required sample volume in order to obtain adequate quantities of test item.
The amount of material collected on glass fibre filters was determined gravimetrically.

Morbidity/Mortality were checked twice daily.
Clinical observations were performed after one, two and three hours exposure whilst the animals are still restrained. Following exposure clinical observations were performed at least twice on the day of exposure and then at least once daily for fourteen days.
Cage-side observations included changes in the skin and fur, eyes and mucous membranes and also respiratory, circulatory, autonomic and central nervous system, somatomotor activity and behaviour pattern. Particular attention was directed to observation of tremors, convulsions, salivation, diarrhoea, lethargy, sleep and coma.
Body weights were recorded on the day of exposure day 0 (prior to exposure) and days 1, 3, 7 and 14.
Necropsy/Pathology: A gross necropsy was performed on all animals euthanised by exsanguination following intra-peritoneal injection of pentobarbital solution at the end of the observation period.
A complete examination of the abdominal and thoracic cavities was made and special attention was given to the respiratory tract for macroscopic signs of irritancy or local toxicity.
Histopathology: During necropsy no organs were found with macroscopic abnormalities therefore no organ has been preserved.

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 5.09 mg/L air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Mortality:

No animals died during the study.

Clinical signs:

other: Only dyspnoea (3/3♂, 3/3♀) and fur staining by test item (3/3♂, 3/3♀) were recorded in the animals during and/or shortly after the exposure. All animals recovered and were symptom-free from the day following exposure until the end of the observation perio

Body weight:

Normal bodyweight gain was noted during the two weeks observation period, with the exception of one female rat with slight bodyweight loss during the period from Day 3-14.

Gross pathology:

No test item-related macroscopic alterations were detected.

Other findings:

Test Atmosphere Concentration:
Target Concentration: 5 mg/L
Mean achieved Concentration: 5.09 mg/L
Standard Deviation: 0.22
Nominal Concentration: 11.35 mg/L

Particle Size Analysis:
Mean achieved concentration (mg/L): 5.09 mg/L
Mean Mass Median Aerodynamic Diameter (MMAD): 5.75 μm
Geometric Standard Deviation (GSD): 2.95
Inhalable Fraction (% < 4μm): 32.0 %

Test Chamber Environmental and Equilibration Data:
Mean Air Flow Application (Inner Plenum) (L/min): 30.1
Air Flow Out (Outer Cylinder) (L/min): 39.9
Temperature (°C): 23.2
Relative Humidity (%):16.5

Interpretation of results:

GHS criteria not met

Conclusions:

The acute inhalation LC50 of the test substance in Wistar rats is >5.09 mg/L.

Executive summary:

An acute inhalation toxicity study according to the OECD guideline 436 was performed. The only study group, consisting of 6 Wistar rats (3 males and 3 females), was exposed to the target concentration of 5 mg test substance/L as an aerosol. The animals were exposed for 4 hours using a nose-only exposure system, followed by a 14-day observation period. Aerosol concentration was measured gravimetrically. The particle size distribution of the test aerosol was determined regularly during the exposure period. Clinical observations and bodyweights were recorded throughout the study and at the end of the scheduled period the animals were euthanised and subjected to a gross examination post mortem.

Results:

Gravimetric results of the test atmosphere analysis:

The mean achieved concentration in the study was 5.09 mg/L. The mass median aerodynamic diameter (MMAD) was 5.75 μm with a geometric standard deviation (GSD) 2.95. The quality of the test atmosphere complied with criteria documented in the guideline, with the exception that the optimum MMAD achieved was 5.75 μm instead of 1 - 4 μm stated in the guidelines, due to the nature of the test item.

Mortality:

No animals died during the study.

Clinical observations:

Only dyspnoea (3/3 m, 3/3 f) and fur stating by test item (3/3 m, 3/3 f) were recorded in the animals during and/or shortly after the exposure. All animals recovered and were symptom-free from the day following exposure until the end of the observation period.

Bodyweight:

Normal bodyweight gain was noted during the two weeks observation period, with the exception of one female rat with slight bodyweight loss during the period from Day 3-14.

Necropsy:

No test item-related macroscopic alterations were detected.

The acute inhalation LC50 of the test substance in Wistar rats is >5.09 mg/L.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LC50

Value:

5 090 mg/m³

Quality of whole database:

Guideline study. The LC50 is not 5090 mg/m³, as one is forced to enter in the field above, but the LC50 > 5000 mg/m³.

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Data waiving:

study waived due to provisions of other regulation

Justification for data waiving:

other:

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Dyspnoea and reddish staining around snout were reported in each of the last 8 reports of the same testing facility on acute inhalation toxicity, with partly quite different test items. It is therefore likely that these signs are not expressions of local or systemic toxicity of the test items but that they are signs of discomfort of the rats restricted in the inhalation tubes.

Justification for classification or non-classification

No classification is derived from the results obtained.