4-mesyl-2-nitrotoluene

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

One generation study according to OECD 415, dose levels 0, 2, 15, 100 mg/kg bw/day: Histopathological changes were seen in the testes at 100 mg/kg and were accompanied by significant reduction in fertility. No histopathological changes were noted at 15 or 2 mg/kg. In addition, in these dose groups there was no effect on reproductive parameters or on the development of pups dosed via milk during lactation and maintained on control diet after weaning until sexual maturity.

Link to relevant study records

Reference

Endpoint:

one-generation reproductive toxicity

Remarks:

based on test type (migrated information)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

30 January - 20 November 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP compliant, guideline study, available as unpublished report, no restrictions, fully adequate for assessment

Qualifier:

according to guideline

Guideline:

OECD Guideline 415 [One-Generation Reproduction Toxicity Study (before 9 October 2017)]

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.34 (One-Generation Reproduction Toxicity Test)

Deviations:

no

Principles of method if other than guideline:

not applicable

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

other: Alpk:APfSD (Wistar-derived)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 5-6 weeks
- Weight at study initiation: (157-203 g (males), 131-181 g (females)
- Fasting period before study: none
- Housing: The rats were housed, sexes separately, in multiple rat racks. They were housed in litters initially, two males or two females per cage after they had been assigned to experimental groups and during the pre-mating period; one male was housed with one female for mating; females were housed individually during gestation and with their litter during lactation and were provided with shredded paper bedding material. F0 males and females from the same group were housed in adjacent cages. F1 animals were housed four per cage
- Diet: CT1 diet ad libitum
- Water: mains water ad libitum
- Acclimation period: at least 1 week

ENVIRONMENTAL CONDITIONS
- Temperature: 18-25°C
- Humidity: 30-76%
- Air changes: at least 15 per hr
- Photoperiod: 12 hrs dark / 12 hrs light

IN-LIFE DATES: From: 7 February 2006 To: 20 November 2006

Route of administration:

oral: gavage

Vehicle:

CMC (carboxymethyl cellulose)

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: Formulated as suspensions in 1% carboxymethyl cellulose (CMC). The dose preparations were made daily until 21 February, after this time they were made at approximately weekly intervals. Dose preparations were not corrected for the purity of the test substance. Dosing preparations were dosed orally at 1.0 mL/100 g bodyweight.

Details on mating procedure:

- M/F ratio per cage: 1:1
- Length of cohabitation: up to 14 days
- Proof of pregnancy: sperm in vaginal smear referred to as day 1 of gestation
- After successful mating each pregnant female was caged individually throughout gestation and post partum

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The mean concentrations for all batches of dosing preparations analysed were within 10% of the nominal concentration. The largest deviation from the nominal concentration was seen at the lowest dose group, 0.2 mg/mL, this was judged to not affect the integrity of the study. The homogeneity of 4-mesyl-2-nitrotoluene in dosing preparations at concentrations of 0.2, 1.5 and 10 mg/mL, was determined and considered satisfactory, percentage deviations from the overall mean were within 6%. The reanalysis of 4-mesyl-2-nitrotoluene in dosing preparations at concentrations of 0.2 mg/mL and 10 mg/mL when stored at room temperature was interpreted as being acceptable for 9 days and 14 days respectively. The data produced showed results with a variance from approx 78% to 111% of the initial analysed concentration. Data generated previously at 0.5 mg/mL and 100 mg/mL showed stability to be acceptable for 16 days at room temperature (Rattray N J (2005) NMST: 90 Day oral toxicity study in rats, Unpublished Syngenta report PR1311-REG).

Duration of treatment / exposure:

10 weeks pre-mating, during mating, throughout gestation and until termination of the parental generation. F1 animals were not dosed.

Frequency of treatment:

daily

Details on study schedule:

F1 animals were selected to determine if the NMST received in utero or via the milk would affect reproductive development. The first generation pups (F1) were retained with their dams until selection of pups at day 29 post partum. 20/sex/group were selected from the first generation pups (F1) groups 0, 2 and 15 mg/kg/day only. One male and one female were selected from 20 litters per group, with the exception of group 2 where 2 males and 2 females were selected from one litter as there were only 19 suitable litters. The selected F1 animals were not dosed.

Remarks:

Doses / Concentrations:
0 (control), 2, 15, 100 mg/kg/day
Basis:
other: nominal in CMC

No. of animals per sex per dose:

26 (F0 generation), 20 (F1 generation 0, 2 and 15 mg/kg/day only)

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: The dose levels were selected from a previous 90 day toxicity study with this test substance (Rattray N J (2005) NMST: 90 Day oral toxicity study in rats, Unpublished Syngenta report PR1311-REG) carried out in the Alpk:APfSD rat. At a dose level of 100 mg/kg/day it was anticipated that the reproductive performance of the males would be compromised as the test substance is a known testicular toxin. Testis and epididymis weights were expected to be reduced causing a decrease in sperm production. No severe signs of toxicity were expected. A dose level of 15 mg/kg/day was selected as the intermediate dose and a dose level of 2 mg/kg/day was the low dose level.

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: F0 animals daily throughout the pre-mating period, at the time of dosing. After the pre-mating period males were observed daily at the time of dosing. After the pre-mating period F0 females were observed daily until mating occurred and then on days 1, 8, 15 and 22 of gestation. Post partum F0 females were observed daily at the time of dosing. F1 animals were observed at weekly intervals. All rats were observed at termination.

BODY WEIGHT: Yes
- Time schedule for examinations: F0 animals were recorded daily throughout the pre-mating period, at the time of dosing. After the pre-mating period body weights for males were recorded daily at the time of dosing. After the pre-mating period body weights of F0 females were recorded daily until mating occurred and then on days 1, 8, 15 and 22 of gestation. Post partum F0 female body weights were recorded daily at the time of dosing. The body weights of all F1 animals were recorded at weekly intervals. All rats were weighed at termination.

FOOD CONSUMPTION AND UTILISATION: Yes
- Time schedule for examinations: Food consumption for each cage of F0 rats was recorded throughout the pre-mating periods and calculated, at weekly intervals, as a mean value. The food utilisation value per cage was calculated as the body weight gained by the rats in the cage per 100 g of food eaten. Food consumption was also recorded for F0 females during gestation and post partum and calculated on a weekly basis. Food consumption for selected F1 animals was recorded from the time the first animal was placed in each cage and calculated, at weekly intervals, as a mean value.

WATER CONSUMPTION: No

Oestrous cyclicity (parental animals):

Daily vaginal smears were taken and examined from all F0 females for 3 weeks prior to mating. Daily vaginal smears were taken and examined from all F0 females to determine when mating had occurred as indicated by the presence of sperm in the smear. A female with a sperm positive vaginal smear was separated from the male and had no further smears taken.

Sperm parameters (parental animals):

Parameters examined in all F0 and F1 males: testis weight, epididymis weight, cauda epididymis weight, sperm number and motility, sperm morphology

Litter observations:

STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: no

PARAMETERS EXAMINED
The following parameters were examined in F1 within 24 hours of parturition (day 1) and on days 5, 8, 15, 22 and 29 post partum: number and sex of pups, stillbirths, live births, postnatal mortality, presence of gross anomalies, weight, physical or behavioural abnormalities. Since pups were not individually identified, data were recorded by sex and litter. The pups selected as the F1 generation were weighed on day 29 post partum to give the initial
body weight values.

Postmortem examinations (parental animals):

SACRIFICE
All surviving rats and those requiring euthanasia were killed by exsanguination under terminal anaesthesia induced by halothane Ph. Eur. vapour. Males were sacrificed after completion of the mating period.
F0 females were terminated: as soon as any parturition difficulties were observed or after day 25 of gestation when there was no evidence of littering or on day 29 post partum after successful rearing of their litter.

GROSS NECROPSY
- Gross necropsy consisted of an external observation and a detailed examination of all cranial, thoracic and abdominal organs and structures. The number of implantation sites was recorded for all F0 females which had been mated. For any female where implantation sites could not be clearly seen in the uterus, ammonium polysulphide was used to determine pregnancy status. The selected F1 animals were terminated when they were 17 weeks old by exsanguination under terminal anaesthesia induced by halothane Ph. Eur. vapour. Any selected F1 animals found dead or terminated intercurrently were discarded without further examination.

ORGAN WEIGHTS:
- following organs weighed: right cauda epididymis, left epididymis (including cauda), right epididymis (including cauda), prostate gland, seminal vesicles (with prostate and coagulating gland), left testis, right testis, ovaries (F1 only)

HISTOPATHOLOGY:
- following tissues examined: testes and epididymes.

Postmortem examinations (offspring):

SACRIFICE
- All surviving pups and those requiring euthanasia were killed by exsanguination under terminal anaesthesia induced by halothane Ph. Eur. vapour. All pups (except those selected to be F1 parents) were killed on approximately day 29 post partum.

GROSS NECROPSY
- All pups were given a macroscopic examination post mortem.

ORGAN WEIGHTS: no

HISTOPATHOLOGY: no

Statistics:

All data were evaluated using analysis of variance and/or analysis of covariance for each specified parameter using the MIXED procedure in SAS (SAS Institute Inc. SAS/STAT 9.1 User's Guide, Cary, NC: SAS Institute Inc, 2004).

Clinical signs:

effects observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Reproductive function: oestrous cycle:

no effects observed

Reproductive function: sperm measures:

effects observed, treatment-related

Reproductive performance:

effects observed, treatment-related

CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS): One female in the 2 mg/kg/day group was found dead in week 4 and one female in the 100 mg/kg/day group was killed due to clinical signs in week 14. These deaths were considered to be incidental to treatment in the absence of similar findings in the remaining animals in these groups. Salivation was observed in 12 males and 14 females in the 100 mg/kg/day group from weeks 3 to 13.

BODY WEIGHT (PARENTAL ANIMALS): There was a small increase in weight in females in the 15 and 100 mg/kg/day groups during the pre-mating period. There was no effect on body weight in females in the 2 mg/kg/day group or males at any dose level. There were no effects on body weights during gestation or post partum.

FOOD CONSUMPTION AND UTILISATION (PARENTAL ANIMALS): There were no effects on food consumption. Food utilisation was reduced (less efficient) in males in the 100 mg/kg/day group in weeks 9-10 pre-mating and overall (weeks 1-10).

REPRODUCTIVE FUNCTION: OESTROUS CYCLE (PARENTAL ANIMALS): No treatment-related effects.

REPRODUCTIVE FUNCTION: SPERM MEASURES (PARENTAL ANIMALS): There was a marked effect on sperm numbers in almost all males in the 100 mg/kg/day group. Due to the marked reduction in the number of sperm evaluated it was not possible to interpret the potential effects of NMST on sperm motility or morphology in 100 mg/kg/day males. There were no effects on sperm number, motility or morphology in F0 or selected F1 males in the 2 or 15 mg/kg/day groups.

REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS): No treatment-related effects on the length of pre-coital interval or length of gestation. There was a marked effect on fertility in the 100 mg/kg/day group where only 2 litters were produced from 26 pairings. There was no evidence of an effect in the 2 or 15 mg/kg/day groups. There were no whole litter losses. As there were only two litters in the high group and one of these contained only 2 pups, the effect of 100 mg/kg/day NMST on litter size, pup survival, pup sex distribution or pup body weight could not be evaluated. There was no effect on the proportion of pups born live, pup survival, pup sex distribution or pup clinical observations in the 2 or 15 mg/kg/day groups. Pup weights were higher than control in the 15 mg/kg/day group on day 29.

ORGAN WEIGHTS (PARENTAL ANIMALS): Right cauda epididymis, epididymides and testes weights were reduced in 25 of the 26 F0 males in the 100 mg/kg/day group. There were no effects on organ weights in F0 males in the 2 or 15 mg/kg/day groups.

GROSS PATHOLOGY (PARENTAL ANIMALS): The majority of male rats in the 100 mg/kg/day group had reduced epididymides and reduced and/or flaccid testes. There were no similar findings in males in the 2 or 15 mg/kg/day groups.

HISTOPATHOLOGY (PARENTAL ANIMALS): The majority of male rats in the 100 mg/kg/day group had marked tubular degeneration within the left testes and marked reductions of spermatozoa. There were no similar findings in males in the 2 or 15 mg/kg/day groups.

Dose descriptor:

NOEL

Effect level:

15 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: oral administration of 100 mg/kg/day 4-mesyl-2-nitrotoluene (NMST) for a 10 week period resulted in effects on the testes leading to infertility

Clinical signs:

no effects observed

Mortality / viability:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Sexual maturation:

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings:

no effects observed

VIABILITY (PUPS): There was no effect on survival with at least 93% of pups in all groups surviving to day 29.

CLINICAL SIGNS (PUPS): No treatment-related clinical observations.

BODY WEIGHT (PUPS): In the 100 mg/kg/day pup body weights were generally higher than control but as there were only two litters in this group it is not clear whether this is a true difference. Pup weights were higher than control in the 15 mg/kg/day group on day 29. Total litter weight was similar to control in the 2 and 15 mg/kg/day groups. The lower value in the 100 mg/kg/day group reflects the fact that there were only 2 pups in one of the 2 litters born.

GROSS PATHOLOGY (PUPS): There were no treatment-related macroscopic findings in pups.

ORGAN WEIGHTS (OFFSPRING): No effects on testis and epididymis weight in offspring from 15 and 2 mg/kg/day groups terminated at 17 weeks of age

Dose descriptor:

NOEL

Generation:

F1

Effect level:

15 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no effects on reproductive organ development of offspring selected from dosed F0 animals and retained untreated to approximately 17 weeks of age

Reproductive effects observed:

not specified

Details on results (selected untreated F1 animals from the 2 and 15 mg/kg/day groups)

 

CLINICAL SIGNS AND MORTALITY (F1 ANIMALS): One F1 male from the 15 mg/kg/day was found dead in week 4. This death was considered to be incidental to treatment in the absence of similar findings in the remaining animals in the group. There were no treatment-related findings in the remaining animals.

BODY WEIGHT (F1 ANIMALS): No treatment-related effects

FOOD CONSUMPTION AND UTILISATION (F1 ANIMALS): No treatment-related effects

REPRODUCTIVE FUNCTION: SPERM MEASURES (F1 ANIMALS): There were no effects on sperm motility or count or on sperm morphology in F1 males.

ORGAN WEIGHTS (F1 ANIMALS): No treatment-related effects.

GROSS PATHOLOGY (F1 ANIMALS): No treatment-related effects

Table 2: F0 Intergroup comparison of bodyweights - pre-mating (g) – selected timepoints; adjusted mean values shown for weeks 2-11

	Dose level of 4-mesyl-2-nitrotoluene (mg/kg/day)
	Males				Females
week	0	2	15	100	0	2	15	100
1	177.8	181.5	179.9	176.7	151.3	152.9	151.0	149.9
2	235.3	235.6	235.5	232.1	178.0	177.5	179.0	179.9
4	351.9	349.4	348.9	347.7	221.2	221.8	226.8*	226.0*
6	419.7	415.9	417.0	411.2	252.6	252.5	255.6	259.6*
11	512.7	507.1	511.0	502.7	284.7	285.2	291.2	287.1
* Statistically significant difference from control group mean, p<0.05 (Student’s t-test, 2-sided)

 

Table 3: F0 Intergroup comparison of food utilisation – pre-mating (g food/100 g weight gain)

	Dose level of 4-mesyl-2-nitrotoluene (mg/kg/day)
	Males				Females
weeks	0	2	15	100	0	2	15	100
1-4	23.99	23.55	23.51	23.52	14.23	14.49	14.93	14.98*
5-8	10.38	10.33	10.17	9.81	5.77	5.96	5.65	5.74
9-10	6.88	6.54	6.44	5.56**	3.25	3.17	3.93	2.06
1-10	14.92	14.70	14.49	14.14**	8.52	8.74	8.95	8.61
* Statistically significant difference from control group mean, p<0.05 (Student’s t-test, 2-sided) ** Statistically significant difference from control group mean, p<0.01 (Student’s t-test, 2-sided)

Table 4: F0 Males Intergroup comparison of selected organ weights (g)

		Dose level of 4-mesyl-2-nitrotoluene (mg/kg/day)
organ		0	2	15	100
cauda epididymis (right)	actual	0.250	0.243	0.244	0.139**
	adjusted	0.250	0.242	0.243	0.139**
epididymis (both)	actual	1.401	1.389	1.402	0.894**
	adjusted	1.401	1.388	1.401	0.897**
epididymis (left)	actual	0.692	0.683	0.689	0.441**
	adjusted	0.692	0.682	0.688	0.443**
epididymis (right)	actual	0.709	0.706	0.714	0.453**
	adjusted	0.709	0.706	0.713	0.454**
testes (both)	actual	3.84	3.84	3.81	1.67**
	adjusted	3.84	3.84	3.81	1.67**
testis  (left)	actual	1.91	1.90	1.90	0.83**
	adjusted	1.91	1.90	1.90	0.83**
testis (right)	actual	1.93	1.94	1.92	0.84**
	adjusted	1.93	1.94	1.92	0.84**
** Statistically significant difference from control group mean, p<0.01 (Student’s t-test, 2-sided)

 

Table 5: F0 Intergroup comparison of reproductive performance

Observation	Dose level of 4-mesyl-2-nitrotoluene (mg/kg/day)
	0	2	15	100
Mean precoital interval (days)	2.81	3.64	2.74	2.80
Mean gestation length (days)	22.3	22.3	22.3	22.5
Successful matings (%)	23/26 (88.5)	24/25 (96.0)	25/26 (96.2)	2/26** (7.7)
Whole litter losses (%)	0/23 (0)	0/24 (0)	0/25 (0)	0/2 (0)
** Statistically significant difference from control group mean, p<0.01 (Student’s t-test, 2-sided)

 

Table 6: F1 Intergroup comparison of litter parameters

Observation		Dose level of 4-mesyl-2-nitrotoluene (mg/kg/day)
		0	2	15	100
Pups born live (%)		268/271 (99.0)	294/296 (99.4)	298/304 (98.2)	11/11 (100)
Litters with all pups born live		20/23	22/24	23/25	2/2
Mean litter size	day 1	11.7	12.3	11.9	5.5*
	day 5	10.9	11.8	10.9	5.5*
	day 8	10.9	11.7	10.9	5.5*
	day 15	10.9	11.7	10.9	5.5*
	day 22	10.9	11.7	10.9	5.5*
	day 29	10.9	11.7	10.9	5.5*
Sex Ratio Day 1 (% males)		51.8	51.5	49.8	58.3
Pup survival (%)	day 5	251/268 (94.3)	283/294 (96.2)	272/298 (93.1)	11/11 (100)
	day 15	251/268 (94.3)	280/294 (95.3)	272/298 (93.1)	11/11 (100)
	day29	250/268 (94.0)	280/294 (95.3)	272/298 (93.1)	11/11 (100)
* Statistically significant difference from control group mean, p<0.05 (Student’s t-test, 2-sided)

Table 7: F0 Intergroup comparison of macroscopic findings

Finding	Dose level of 4-mesyl-2-nitrotoluene (mg/kg/day)
	0	2	15	100
epididymis - reduced	0/26	0/26	0/26	25/26
epididymis – casa - reduced	0/26	0/26	0/26	25/26
testes – reduced	0/26	0/26	0/26	2/26
testes - flaccid	0/26	0/26	0/26	1/26
testes – reduced and flaccid	0/26	0/26	0/26	23/26

 

Table 8: F0 Intergroup comparison of microscopic findings

Finding	Dose level of 4-mesyl-2-nitrotoluene (mg/kg/day)
	0	2	15	100
epididymis – reduced/absent spermatozoa (marked)	0/26	0/26	0/26	25/26
testis – tubular degeneration (slight)	0/26	0/26	0/26	1/26
testis – tubular degeneration (moderate)	0/26	0/26	0/26	4/26
testis – tubular degeneration (marked)	0/26	0/26	0/26	21/26
testis – tubular degeneration (total)	0/26	0/26	0/26	26/26

 

Conclusions:

Oral administration of 100 mg/kg/day 4-mesyl-2-nitrotoluene (NMST) for a 10 week period resulted in effects on the testes leading to infertility. A dose level of 15 mg/kg/day was the NOEL for reproductive effects in animals dosed for a 10 week period, through mating, gestation and post partum. In addition there were no effects on reproductive organ development of offspring selected from these animals and retained untreated to approximately 17 weeks of age.

After oral dosing at 100 mg/kg and above the substance has been shown to reduce the weight of testis and epididymis and to adversely affect both organ histopathology and sperm count. This is accompanied by a clear functional effect on reproduction.

The substance is considered to have met the criteria for classification of Reproductive toxicant Category 1B, H360, May damage fertility (reduce sperm count) according to Regulation (EC) No 1272/2008, Annex I, Part 3. 3.1.3

Executive summary:

Groups of 26 male and 26 female (F0 parents) Alpk:APfSD (Wistar-derived) rats were dosed with 0 (control), 2, 15 or 100 mg/kg/day 4-mesyl-2-nitrotoluene (NMST). After 10 weeks, the animals were mated and allowed to rear the ensuing F1 litters to weaning. The growth of the parental generation, reproductive function, mating behaviour, conception, gestation, parturition, lactation and weaning and the growth and development of the pups were determined.

 

Twenty F1 males and twenty F1 females were selected from the 0, 2 and 15 mg/kg/day groups and maintained untreated until they were 17 weeks of age to determine if the NMST received in utero or via the milk would affect subsequent reproductive organ development. Growth and food consumption were monitored and at termination sperm parameters were assessed and organ weights were recorded.

 

Oral administration of 100 mg/kg/day 4-mesyl-2-nitrotoluene (NMST) for a 10 week period resulted in effects on the testes leading to infertility. A dose level of 15 mg/kg/day was the NOEL for reproductive effects in animals dosed for a 10 week period, through mating, gestation and post partum. In addition there were no effects on reproductive organ development of offspring selected from these animals and retained untreated to approximately 17 weeks of age.

Effect on fertility: via oral route

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

15 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

The available data is considered to be adequate for the purposes of risk assessment, classification and labelling. Appropriate justification has been given as to why generation of further data as specified in Annex IX and Annex X is not considered necessary for this substance (see specific waivers).

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

At a level of 100 mg/kg bw/day dosed to male rats during the pre-mating period of a one generation study a significantly lower testicular weight was accompanied by significant histopathological changes in the testes and by significantly reduced fertility. A clear NOAEL was identified at 15 mg/kg bw/day. The study is considered to be reliable and adequate for the purposes of risk assessment, classification and labelling. Appropriate justification has been given as to why generation of further data as specified in Annex IX and Annex X is not considered necessary for this substance (see specific waivers).

Justification for selection of Effect on fertility via oral route:
Only one study for this endpoint was available.

Effects on developmental toxicity

Description of key information

One generation study according to OECD 415, dose levels 0, 2, 15, 100 mg/kg bw/day: At dose levels of 15 and 2 mg/kg bw/day dosed to female rats during gestation and lactation no effect was seen on reproductive parameters, on the number of pups born or their development to weaning.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Additional information

A guideline developmental toxicity study has not been conducted with the substance. However, data from a modern guideline compliant OECD 415 study has confirmed that a dose of up to 15 mg/kg bw/day dosed to pregnant animals throughout gestation has no effect on the number of pups born live. Moreover, there were no indications of an effect on survival or development of pups in this study. It can be concluded that a dose of up to 15 mg/kg bw/day would have no adverse effects, i.e. the substance would not exhibit developmental toxicity at this dose level. The available data is considered to be adequate for the purposes of risk assessment, classification and labelling. Appropriate justification has been given as to why generation of further data as specified in Annex IX and Annex X is not considered necessary for this substance (see specific waivers).

Justification for selection of Effect on developmental toxicity: via oral route:
As a result of a one-generation reproductive toxicity study (OECD 415), the substance is known to have an adverse effect on fertility at a dose level where other signs of toxicity are minimal. A clear no observed adverse effect level (NOAEL) for effects on fertility and testicular structure was derived. At the NOAEL there was no effect on the number of pups born, on survival, clinical condition or development for up to 17 weeks post-partum. Data derived from the one-generation reproductive toxicity study confirms that at the NOAEL identified for effects on fertility there is no indication of an adverse effect on development in the rat and thus allows a robust risk assessment to be made.

Justification for classification or non-classification

Further information has become available since the current harmonised classification was published in Annex I to Directive 67/548/EEC and transposed to Annex VI to Regulation (EC) No. 1272/2008. The classification based on all currently known and relevant data for the substance is given below.

Following oral repeat dosing in a one-generation study (Milburn 2007) the target organ for the substance was identified as the testis. Reduction in organ weight and significant histopathological changes were seen at dose levels of 100 mg/kg and above. This was accompanied by a reduction in fertility in the rat. The structural effect has therefore been shown to result in a functional deficit in the rat.

The effect on fertility in combination with changes in testicular structure is considered to meet the criteria for classification as Toxic to Reproduction, Category 2, R60, May impair fertility, according to Directive 2001/59/EC, 4.2.3.3.

The effect on fertility in combination with changes in testicular structure is considered to meet the criteria for classification as Reproductive toxicant Category 1B, H360, May damage fertility (reduced sperm count) according to Regulation (EC) No. 1272/2008, Annex I, Part 3. 3.7.2.