Dimethyl octadecylphosphonate

Endpoint summary

Description of key information

A subacute toxicity study was performed to assess the repeated dose toxicity of dimethyloctadecylphosphonate (also known as DMOP). The study was an OECD 422 ‘combined 28-day repeated dose toxicity study with the reproduction/developmental toxicity screening test’ in which males were exposure for 36 days and females were exposed for 47-60 days. From the results presented in this report a parenteral No Observed Adverse Effect Level (NOAEL) of 300 mg/kg/day was established. 

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: oral

Remarks:

combined repeated dose and reproduction / developmental screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

July 2012 to March 2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

Deviations:

no

GLP compliance:

yes

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Deutschland, Sulzfeld, Germany
- Age at study initiation: approximately 11 weeks
- Weight at study initiation: Males weighed ca. 292 to 299 g (mean group weights), females weighed ca. 201 to 204 g (mean group weights)
- Fasting period before study: No
- Housing: Housed in groups of 5 with the exception of the mating period when 1 female was housed with 1 male and post mating when females were housed individually
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18-24
- Humidity (%): 40-70
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: To: 02 September 2012 to 01 November 2012

Route of administration:

oral: gavage

Vehicle:

propylene glycol

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:

DIET PREPARATION
- Rate of preparation of diet (frequency):
- Mixing appropriate amounts with (Type of food):
- Storage temperature of food:

VEHICLE
- Justification for use and choice of vehicle (if other than water): based on trial formulations at Wil Research Europe
- Concentration in vehicle: 20, 60 and 200 mg/g nominal
- Amount of vehicle (if gavage): 5 ml/kg body weight
- Lot/batch no. (if required):
- Purity:

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analysis performed on samples prepared for use on 03 September 2012. No test substance was found in the Group 1 formulations (control group). The concentrations analysed in the formulations of Group 2, 3 and 4 were in agreement with target concentrations (i.e. mean accuracies between 90% and 110%).
The formulations of Group 2 and 4 were homogeneous (i.e. coefficient of variation ≤ 10%). Group 3 was not tested for homogeneity.
Formulations at the entire range were stable when stored at room temperature under normal laboratory light conditions for at least 5 hours (i.e. relative difference ≤ 10%).
The long term storage samples were stable at ≤-70°C for at least 12 days.

Duration of treatment / exposure:

Males were exposed for 36 days, i.e. 3 weeks prior to mating, during mating, and up to the day prior to scheduled necropsy. Females were exposed for 47-60 days, i.e. during 3 weeks prior to mating, during mating, during post-coitum, and during at least 4 days of lactation (up to the day prior to scheduled necropsy).

Frequency of treatment:

Daily

Remarks:

Doses / Concentrations:
0
Basis:
other: mg/kg body weight/day

Remarks:

Doses / Concentrations:
100
Basis:
other: mg/kg body weight/day

Remarks:

Doses / Concentrations:
300
Basis:
other: mg/kg body weight/day

Remarks:

Doses / Concentrations:
1000/600
Basis:
other: mg/kg body weight/day

No. of animals per sex per dose:

10 males and 10 females

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Dose levels were selected based on results of a 10-day dose ranging finding study
- Rationale for animal assignment (if not random): random assignment
- Rationale for selecting satellite groups: not selected.
- Post-exposure recovery period in satellite groups: not applicable
- Section schedule rationale (if not random):

Positive control:

Not included.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: at least twice daily
- Cage side observations were performed and findings for individual animals are reported.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Daily. Also weekly examinations performed outside the home cage.

BODY WEIGHT: Yes
- Time schedule for examinations: day 1 of exposure and at lest weekly thereafter. Mated females weighed on days 0, 4, 7, 11, 14, 17 and 20 post coitum and during lactation on days 1 and 4.

FOOD CONSUMPTION : Yes
- Food consumption for each animal determined weekly with the exception of during the mating period, nor for non-mated females.

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No

WATER CONSUMPTION : Yes (subjective appraisal, not measured)
- Time schedule for examinations: N/A

OPHTHALMOSCOPIC EXAMINATION: No
- Time schedule for examinations:
- Dose groups that were examined:

HAEMATOLOGY: Yes
- Time schedule for collection of blood: At end of study, prior to necropsy exam.
- Anaesthetic used for blood collection: Yes (isofluorane)
- Animals fasted: Yes
- How many animals: 5/sex/group
- Parameters checked in table [No.?] were examined. methods Table 1

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: At end of study, prior to necropsy exam.
- Animals fasted: Yes
- How many animals: At end of study, prior to necropsy exam.
- Parameters checked in table [No.?] were examined. Methods Table 2.

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: Yes (functional observations)
- Time schedule for examinations: Males were tested during week 5 and females were tested towards the end of the scheduled lactation period.
- Dose groups that were examined: 5 males and 5 females from all dose groups were examined
- Battery of functions tested: hearing ability, pupillary reflex, static righting reflex, grip strength, locomotor activity

OTHER: Developmental/reporductive measurements were also performed in this study; they are reported in IUCLID section 7.8.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes, see table 3 in methods for scedule of necropsy examinations. All animals were subjected to macroscopic examination of the cranial, thoracic and abdominal tissues and organs, with special attention being paid to the reproductive organs. Descriptions of all macroscopic abnormalities were recorded.

HISTOPATHOLOGY: Yes (see table) A full list of tissues for a selected 5/sex/group was harvested and preserved in 10% buffered formalin.A full list of tissues was also harvested from animals kiiled in extremis. (see table 4)

Organ weights
selected organs were weighed from 5/sex/group at nexcropsy examination

Other examinations:

Reprotoxicity/developmental toxicity parameters were also measured, these are reported in IUCLID section 7.8

Statistics:

The following statistical methods were used to analyze the data:
− If the variables could be assumed to follow a normal distribution, the Dunnett-test based on a pooled variance estimate was applied for the comparison of the treated groups and the control groups for each sex.
− The Steel-test was applied if the data could not be assumed to follow a normal distribution.
− The Fisher Exact-test was applied to frequency data.
− The Kruskal-Wallis nonparametric ANOVA test was applied to motor activity data.
All tests were two-sided and in all cases p < 0.05 was accepted as the lowest level of significance.
Group means were calculated for continuous data and medians were calculated for discrete data
(scores) in the summary tables. Test statistics were calculated on the basis of exact values for means
and pooled variances. Individual values, means and standard deviations may have been rounded off
before printing. Therefore, two groups may display the same printed means for a given parameter, yet
display different test statistics values.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

At 1000 mg/kg one male was euthanized in extremis after adverse clinical signs and severe weight loss (28% loss by Day 11) were seen. In general, animals at 1000 mg/kg had adverse treatment-related effects, and the dose level was switched to 600 mg/kg from Day 14 onwards. One female at 600 mg/kg was euthanized after having a total litter loss. She had given birth to only a single pup. Clinical signs noted in animals treated at 1000 mg/kg bw/day included hunched posture, piloerection, diarrhoea, salivation, lethargy, lean appearance in the males. Lowering the dose to 600 mg/kg bw /day resulted in resolution of these symptoms with the exception of salivation (seen in all treated groups) which was related to taste or possible irritancy of the test substance.

Mortality:

mortality observed, treatment-related

Description (incidence):

At 1000 mg/kg one male was euthanized in extremis after adverse clinical signs and severe weight loss (28% loss by Day 11) were seen. In general, animals at 1000 mg/kg had adverse treatment-related effects, and the dose level was switched to 600 mg/kg from Day 14 onwards. One female at 600 mg/kg was euthanized after having a total litter loss. She had given birth to only a single pup. Clinical signs noted in animals treated at 1000 mg/kg bw/day included hunched posture, piloerection, diarrhoea, salivation, lethargy, lean appearance in the males. Lowering the dose to 600 mg/kg bw /day resulted in resolution of these symptoms with the exception of salivation (seen in all treated groups) which was related to taste or possible irritancy of the test substance.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

1000 mg/kg bw/day: Significant weight loss.After lowering the dose to 600 mg/kg bw/day animals regained weight although remained lighter than controls. at 300 mg/kg bw/day males had lower weght gain on day 15 & during mating period

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

REduced whilst treated at 1000 mg/kg bw/day. Returned to normal when dose lowered to 600 mg/kg bw/day.

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not specified

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

At 600 mg/kg significant increases in ALAT; (both sexes, also for females at 300 mg/kg), potassium (males) and cholesterol (females) were noted along with a significant decrease in total protein (males, also seen for males at 300 mg/kg

Urinalysis findings:

not examined

Behaviour (functional findings):

no effects observed

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Absolute and relative liver weights were higher for 600 mg/kg both sexes and relative thyroid weights were lower for females. Liver weights (%) were increased in 300 mg/kg males and to a lesser extent in females (absolute and %).

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

1000 mg/kg mortality: emaciated, GI tract gas distension, irregular surface forestomach & small thymus. Mesenteric LN: discoloration. 600 mg/kg females: dark or red discolorated mesenteric LN in 4 females and 1 male and 1 female at 100 mg/kg.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Stomach - local iritation noted - all treated groups. Mesenteric lymph nodes congestion/sinus histiocytosis at 600 mg/kg, Adrenals vacuolation zona glomerulosa 600 mg/kg

Histopathological findings: neoplastic:

no effects observed

Details on results:

Hearing ability, pupillary reflex, static righting reflex and grip strength were normal in all selected animals. There was a variation in motor activity; this did not indicate a relationship with treatment. All groups showed a similar habituation profile with very high activity in the first interval that decreased over the duration of the test period.

Dose descriptor:

NOAEL

Remarks:

parenteral

Effect level:

ca. 300 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: see 'Remark'

Critical effects observed:

not specified

Male body weight summary (g)

GROUP1 CONTROL			GROUP2 100MG/KG	GROUP3 300MG/KG	GROUP4 600MG/KG
PRE MATING DAY1	MEAN	293	297	299	292
WEEK1	ST.DEV	10.0	6.8	6.1	9.3
	N	10	10	10	10
DAY8	MEAN	312	317	316	277**
WEEK2	ST.DEV	13.2	9.7	7.1	20.9
	N	10	10	10	10
DAY11	MEAN	318	324	321	272**
WEEK2	ST.DEV	13.4	11.7	8.8	30.6
	N	10	10	10	10
DAY15	MEAN	324	333	329	289**
WEEK3	ST.DEV	15.4	13.8	11.1	14.7
	N	10	10	10	9

MATING PERIOD DAY1	MEAN	Group 1 342	Group 2 348	Group 3 340	Group 4 313**
WEEK1	ST.DEV	16.0	15.0	12.7	12.6
	N	10	10	10	9
DAY8	MEAN	352	355	347	320**
WEEK2	ST.DEV	19.4	18.0	14.4	12.2
	N	10	10	10	9
DAY15	MEAN	365	368	356	330**
WEEK3	ST.DEV	22.0	19.7	16.0	13.3
	N	10	10	10	9

Female body weight summary (g)

GROUP1 CONTROL			GROUP2 100MG/KG	GROUP3 300MG/KG	GROUP4 600MG/KG
PRE MATING DAY1	MEAN	202	201	201	204
WEEK1	ST.DEV	6.8	7.3	4.1	7.7
	N	10	10	10	10
DAY8	MEAN	211	209	212	202
WEEK2	ST.DEV	7.2	7.3	6.1	12.0
	N	10	10	10	10
DAY11	MEAN	213	211	216	209
WEEK2	ST.DEV	5.3	7.5	7.6	9.1
	N	10	10	10	10
DAY15	MEAN	216	213	219	219
WEEK3	ST.DEV	5.0	8.9	8.4	7.8
	N	10	10	10	10

MATING PERIOD DAY1	MEAN	Group 1 224	Group 2 220	Group 3 223	Group 4 228
WEEK1	ST.DEV	8.8	11.7	9.1	6.0
	N	10	10	10	10
DAY8	MEAN	255	244
WEEK2	ST.DEV	−−−	7.6
	N	1	3
DAY15 WEEK3	MEAN ST. DEV N		262 −−− 1
day 22week 4			2981

*/** Dunnett-test based on pooled variance significant at 5% (*) or 1% (**) level

GROUP1 CONTROL				GROUP2 100MG/KG	GROUP3 300MG/KG		GROUP4 600MG/KG
POSTCOITUM DAY0	MEAN		224	225	224		225
	ST.DEV.		4.4	14.7	10.5		6.2
	N		9	9	9		10
DAY4	MEAN		237	238	238		238
	ST.DEV.		6.9	11.8	6.4		6.5
	N		9	9	9		10
DAY7	MEAN		245	244	244		245
	ST.DEV.		6.6	13.5	7.6		8.3
	N		9	9	9		10
DAY11	MEAN		258	257	258		258
	ST.DEV.		7.8	14.5	10.5		10.0
	N		9	9	9		10
DAY14	MEAN		273	264	268		268
	ST.DEV.		11.7	16.8	9.8		11.7
	N		8	9	9		10
DAY17	MEAN		296	282	294		288
	ST.DEV.		14.2	22.7	14.1		15.6
	N		8	8	9		10
DAY20	MEAN		328	308	330		316
	ST.DEV.		15.1	35.4	21.2		24.1
	N		7	9	9		10
LACTATION DAY1		MEAN	254	250		252		251
		ST.DEV.	7.3	13.2		10.8		10.8
		N	8	9		9		10
DAY4		MEAN	265	258		264		261
		ST.DEV.	10.2	15.8		10.4		10.5
		N	8	9		9		10

Food consumption (g/animal/day)

GROUP1 CONTROL			GROUP2 100MG/KG	GROUP3 300MG/KG	GROUP4 600MG/KG
PRE MATING DAYS1−8	MEAN	20	20	20	12
WEEKS 1−2	ST.DEV	0.3	0.4	0.1	1.5
	N(CAGE)	2	2	2	2
DAYS 8−15	MEAN	21	20	21	16
WEEKS 2−3	ST.DEV	0.3	0.1	0.8	2.1
	N(CAGE)	2	2	2	2
DAYS15−22	MEAN	21	20	21	22
WEEKS 3−4	ST.DEV	0.0	0.3	0.1	0.2
	N(CAGE)	2	2	2	2
MEANOFMEANS OVERPREMATING PERIOD	MEAN	21	20	20	17
MATING PERIOD DAYS 1−8	MEAN	23	21	22	19
WEEKS 1−2	ST.DEV	0.1	0.4	1.2	0.4
	N(CAGE)	2	2	2	2
DAYS 8−15	MEAN	22	20	20	19
WEEKS 2−3	ST.DEV	0.3	0.3	0.6	0.5
	N(CAGE)	2	2	2	2
MEANOF MEANS OVERMATING PERIOD	MEAN	22	21	21	19
FEMALES
		GROUP1	GROUP2	GROUP3	GROUP4
		CONTROL	100MG/KG	300MG/KG	600MG/KG
PRE MATING DAYS 1−8	MEAN	15	15	15	10
WEEKS 1−2	ST.DEV	0.2	0.1	0.5	1.3
	N(CAGE)	2	2	2	2
DAYS 8−15	MEAN	16	15	16	16
WEEKS 2−3	ST.DEV	0.0	0.3	0.5	0.7
	N(CAGE)	2	2	2	2
DAYS 15−22	MEAN	16	15	16	17
WEEKS 3−4	ST.DEV	0.3	0.6	0.8	0.4
	N(CAGE)	2	2	2	2
MEANOF MEANS OVERPREMATING PERIOD	MEAN	16	15	16	14

Conclusions:

In conclusion, treatment with dimethyl octadecylphosphonate (DMOP) by oral gavage in male and female Wistar Han rats at dose levels of 100, 300, 600 and 1000 mg/kg body weight/day revealed parental toxicity at 600 mg/kg body weight/day.

At 1000/600 mg/kg bw/day there was enlargement/discolouration of mesenteric lymph nodes, microscopic findings in adrenals and mesenteric lymph node. A loss in bodyweight and poor clinical condition was noted during treatment at 1000 mg/kg bw/day which improved when the dose was lowered to 600 mg/kg bw/day. Irritation of the stomach (irritation, inflammation and erosion/ulceration) was seen 600 and at 300 mg/kg. This is considered to be a local contact finding and not indicative of systemic toxicity.

Increased liver weight (absolute and relative) and hepatocellular hypertrophy was found at 300 (minimal severity) and 600 mg/kg (minimal to slight severity) however, this was an adaptive change which was considered non-adverse.

It may therefore be concluded that rats treated at 300 mg/kg showed evidence of adaptive change or local contact irritation. Systemic toxicity was not identified.

Based on these results, the following No Observed Adverse Effect Level (NOAEL) was derived:
Parental NOAEL: 300 mg/kg/day (males/females)

Executive summary:

Dimethyl octadecylphosphonate (DMOP) was administered by daily oral gavage to male and female Wistar Han rats at dose levels of 0, 100, 300 and 1000 (Days 1-13 of treatment) mg/kg. Due to toxicity observed at 1000 mg/kg, the dose level of Group 4 was lowered to 600 mg/kg from Day 14 of treatment onwards. Males were exposed for 36 days, i.e. 3 weeks prior to mating, during mating, and up to termination. Females were exposed for 47-60 days, i.e. during 3 weeks prior to mating, during mating, during post-coitum, and during at least 4 days of lactation.

Formulation analysis showed that the formulations were prepared accurately, were homogenous, and were stable for at least 5 hours at room temperature.

Mortality (one male), adverse clinical signs, reduced food consumption and severe weight loss were noted mostly for males when initially exposed to M-5925 at 1000 mg/kg. After lowering the dose level to 600 mg/kg from Day 14 onwards, the animals’ condition improved. While the body weights and body weight gains remained lower for the males for the treatment duration, this was not considered to be adverse since the gains were at the level or higher than controls when re-calculated from the time the dose level was lowered. Fasted blood samples harvested prior to necropsy examination revealed increases in ALAT in both sexes at 600 mg/kg and females at 300 mg/kg, and other changes that were inconsistent across the sexes (increased potassium (males) and cholesterol (females), decreased total protein (males). None of these changes was associated with a histopathological correlate and they were not considered to be of toxicological significance.

Additional treatment related findings at 600 mg/kg were characterized by increased absolute and relative liver weights and hepatocellular hypertrophy (considered to be a non-adverse adaptive change), microscopic findings (vacuolation of the zona glomerulosa, minimal to slight) in the adrenals in both sexes. Microscopic findings on the stomach were noted which were typical of local contact irritation and included irritation, inflammation and erosion/ulceration and there was congestion

/erythrophagocytosis in the mesenteric lymph nodes (correlating with necropsy findings of enlargement and discoloration) in females and increased incidence/severity of sinus histiocytosis of the same lypmh node in males. The adaptive liver change and local contact irritation in the stomach were also noted for rats at 300 mg/kg. Due to the nature of these findings they were not considered to represent systemic toxicity.

No toxicologically significant changes were noted in functional observations or haematology parameters investigated up to 600 mg/kg.

It may therefore be concluded that rats treated at 300 mg/kg showed evidence of adaptive change or local contact irritation. Systemic toxicity was not identified. Based on these results, the following No Observed Adverse Effect Level (NOAEL) was derived:

Parental NOAEL: 300 mg/kg/day (males/females)

Endpoint conclusion

Dose descriptor:

NOAEL

300 mg/kg bw/day

Study duration:

subacute

Species:

rat

Additional information

DMOP was administered by daily oral gavage to groups of 10 male and 10 female Wistar Han rats at dose levels of 0, 100, 300 and 1000 (Days 1-13 of treatment) mg/kg. Due to toxicity observed at 1000 mg/kg, the dose level of Group 4 was lowered to 600 mg/kg from Day 14 of treatment onwards. Males were exposed for 36 days, i.e. 3 weeks prior to mating, during mating, and up to termination. Females were exposed for 47-60 days, i.e. during 3 weeks prior to mating, during mating, during post-coitum, and during at least 4 days of lactation. 

Mortality (one male), adverse clinical signs, reduced food consumption and severe weight loss were noted mostly for males when initially exposed to DMOP at 1000 mg/kg. After lowering the dose level to 600 mg/kg from Day 14 onwards, the animals’ condition improved. While the body weights and body weight gains remained lower for the males for the treatment duration, this was not considered to be adverse since the gains were at the level or higher than controls when re-calculated from the time the dose level was lowered. Fasted blood samples harvested prior to necropsy examination revealed increases in ALAT in both sexes at 600 mg/kg and females at 300 mg/kg, and other changes that were inconsistent across the sexes (increased potassium (males) and cholesterol (females), decreased total protein (males). None of these changes was associated with a histopathological correlate and they were not considered to be of toxicological significance.

Additional treatment related findings at 600 mg/kg were characterized by increased absolute and relative liver weights and hepatocellular hypertrophy (considered to be a non-adverse adaptive change¹), microscopic findings (vacuolation of the zona glomerulosa, minimal to slight) in the adrenals in both sexes and congestion /erythrophagocytosis in the mesenteric lymph nodes (correlating with necropsy findings of enlargement and discoloration) in females and increased incidence/severity of sinus histiocytosis of the same lypmh node in males.

Microscopic findings in the stomach were noted which were typical of local contact irritation and included irritation, inflammation and erosion/ulceration. The adaptive liver change and local contact irritation in the stomach were also noted for rats at 300 mg/kg. Due to the nature of these findings they were not considered to represent systemic toxicity¹. No toxicologically significant changes were noted in functional observations or haematology parameters investigated up to 600 mg/kg.

It may therefore be concluded that rats treated at 300 mg/kg showed evidence of adaptive change or local contact irritation but systemic toxicity was not identified. Based on these results, the following No Observed Adverse Effect Level (NOAEL) was derived: Parental NOAEL: 300 mg/kg/day (males/females).

References

1 ECHA Chapter R7a: Endpoint specific guidance, Section 7.5.1.1 Definition of repeated dose toxicity.

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
Key study

Justification for classification or non-classification

Classification according to Regulation (EC) No 1272/2008.

Classification of substances for STOT-RE is normally based on a 90-day repeat dose study. When a study of a shorter duration of treatment is used for classification the guidance values is adjusted on a case-by-case basis and a NOAEL derived from a 28 day study is increased by a factor of 3. The guidance values for classification are shown in the table below and are based on the presence of significant toxic effects.

 

Table 3.9.2.2Equivalent guidance values for 28-day and 90-day studies

Studytype	Species	Unit	Category1 90-day	Category1 28-day	Category2 90-day	Category2 28-day
Oral	Rat	mg/kgbw/d	≤10	≤30	≤100	≤300
Dermal	Rat	mg/kgbw/d	≤20	≤60	≤200	≤600
Inhalation,gas	Rat	ppmV/6h/d	≤50	≤150	≤250	≤750
Inhalation,vapour	Rat	mg/l/6h/d	≤0.2	≤0.6	≤1	≤3
Inhalation,dust/mist/fume	Rat	mg/l/6h/d	≤0.02	≤0.06	≤0.2	≤0.6

(extracted from Guidance on the application of the CLP criteria, ECHA Publication, Version 3, November 2012)

 

The duration of treatment in this OECD 422 study ranged from 36 days (males) to up to 60 days (females). Based on the longer duration of treatment and in consideration of the findings at 1000/600 mg/kg bw/day not being representative of significant toxicity, it is not considered that the NOAEL of 300 mg/kg bw/day merits classification with regard to specific target organ toxicity – repeated exposure (STOT-RE).