Piperidine

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

Fertility, oral, mouse, non-GLP, non-Guideline: NOAEL for reproductive toxicity: > 400 mg/kg bw / day (Bempong, 1983).

Link to relevant study records

Reference

Endpoint:

fertility, other

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

Mice were daily exposed to piperidine dissolved in ethanol for a period of 100 days and examined for induction of sperm abnormality and reproductive toxicity.

GLP compliance:

not specified

Specific details on test material used for the study:

- Name of test material (as cited in study report): piperidine
- no further data

Species:

mouse

Strain:

other: C57BL/J6 x DBA2

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Laboratory Animal Division, Mogul Corporation, Madison, Wisconsin
- Age at study initiation: (P) 8 to 10 wks
- Weight at study initiation: (P) Males and Females: 20 to 26 g
- Diet: Purina Lab Chow, ad libitum
- Water: ad libitum

ENVIRONMENTAL CONDITIONS
- no data

Route of administration:

oral: drinking water

Vehicle:

ethanol

Remarks:

0.001 % ethanol

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
- piperidine was dissolved in ethanol

VEHICLE
- Concentration in vehicle: 400 mg/kg bw/day in 0.001 % ethanol

Details on mating procedure:

- M/F ratio per cage: 1/2
- Length of cohabitation: 7 days
- Proof of pregnancy: vaginal plug
- After successful mating each pregnant female was caged (how): single

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

Exposure period: 100 days
Premating exposure period (males): 1 week
Premating exposure period (females): 1 week
Duration of test: 100 days

Frequency of treatment:

daily exposure (ad libitum)

Details on study schedule:

The treatment groups consisted of (1) control female x control male (C x C); (2) piperidine-treated female x piperidine treated male (PD x PD).
Ethyl methanesulfonate (EMS) served as positive control.
In the study piperidine was used as negative control.

Dose / conc.:

400 mg/kg bw/day (nominal)

No. of animals per sex per dose:

15 to 25 females

Control animals:

other: aqueous solution containing 0.001 % ethanol ad libitum

Details on study design:

- Dose selection rationale: Concentrations between 600 and 800 mg/kg bw/day killed between 70 and 90% of exposed animals within 10 days.

Positive control:

Positive control animals were exposed to 250 mg/kg bw/day of ethylmethane sulfonate (EMS) prepared in deionized water.

Sperm parameters (parental animals):

Sperm Morphology Study
- Preliminary investigation showed that significant levels of sperm damage are observed after about 40 continuous days of treatment; accordingly, on day 40 and every subsequent 5 days, treated and control animals (3 animals per group) were sacrificed and both left and right vas deferens removed by dissection. Sperm were squeezed into saline solution (0.9%) and slides prepared and stained in eosin-Y.

Litter observations:

Fertility Studies
- Fifteen to 20 pregnant females were sacrificed by cervical dislocation on day 18 of pregnancy; the uteri were removed and examined for the site of implantation and foetal death. Five females in each treatment group were allowed to reach term and the number of offspring per female recorded.

Statistics:

Chi square and t-test were used for comparison of fertility index, abnormal sperm morphology, moles per pregnancy, and foetal death per implant between the test compound and the control groups.

Reproductive indices:

Fertility index expressed as the ratio of the number of pregnant females to the number of females mated in a specified mating period.

Reproductive function: sperm measures:

no effects observed

Description (incidence and severity):

The percentage of abnormal sperm was in the range of the vehicle control (determined at 40, 50, 60, 70, 80 and 90 days of treatment).

The fertility index, determined weekly after 2 to 12 weeks of piperidine exposure, was in the range of 80 to 100 % (vehicle control 85 - 100 %).
The number of dead fetuses/pregnancy was also not influenced by 2 to 12 weeks of piperidine treatment.
Females which were allowed to deliver litter had with the exception of week 4 with 7 pubs/female, 8.5 - 10 pups/female after 1 to 3 and 4 to 10 weeks of piperidine treatment (weekly determination; vehicle control: 8.5 - 10 pups/female).

In the EMS-treated matings, reduced fertility indices were observed.
The number of dead fetuses/pregnancy was also influenced by 2 to 12 weeks of EMS treatment of about 0.8 to 1.4.
Females which were allowed to deliver litter had 6 pups/female after 1 to 10 weeks of EMS treatment (weekly determination; vehicle control:
8.5 - 10 pups/female).

Dose descriptor:

NOAEL

Remarks:

fertility

Effect level:

400 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: corresponding to the highest dose tested

Critical effects observed:

no

No negative results to the offspring were reported.

Dose descriptor:

NOAEL

Generation:

F1

Based on:

test mat.

Remarks on result:

not determinable due to absence of adverse toxic effects

Critical effects observed:

no

Reproductive effects observed:

not specified

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

400 mg/kg bw/day

Study duration:

subacute

Species:

hamster

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

In a reproduction study the test item (purity unknown) was administered to 15 to 25 females and an unknown number of males of C57BL/J6 x DBA2 mice and Syrian golden hamsters per dose in the drinking water at a dose level of 400 mg/kg bw/day (dissolved in 0.001 % ethanol) (Bempong 1983). On day 40 and every 5 subsequent days treated and control male mice and hamsters (3 per group) were analysed for sperm damage. On day 18 of pregnancy 15 to 20 pregnant female mice were sacrificed and analysed for implantation sites and foetal death. Five female mice per group were allowed to reach term and the number of offspring per female was recorded. The Fertility index was determined. In a preliminary range finding study dose levels of 600 to 800 mg/kg bw per day killed 70 and 90 % of the exposed animals within 10 days.

There were no compound related effects on reproductive toxicity in mice and hamsters. The percentage of abnormal sperm was in the range of the vehicle control (determined at 40, 50, 60, 70, 80 and 90 days of treatment). The fertility index, determined weekly after 2 to 12 weeks of exposure, was in the range of 80 to 100 % (vehicle control 85 - 100 %). The number of dead foetuses per pregnant animal was also not influenced by 2 to 12 weeks of treatment with the test item. Females which were allowed to deliver litter had with the exception of week 4 with 7 pubs/female, 8.5 - 10 pups/female after 1 to 3 and 4 to 10 weeks of treatment with the test compound (weekly determination; vehicle control: 8.5 - 10 pups/female). No data about the parental toxicity were given. The test item was used as a negative control in a reproductive study with N-chloropiperidine.

Due to incomplete documentation no NOAEL for general systemic toxicity of the parental animals was given.

The oral NOAEL for reproductive toxicity was estimated as 400 mg/kg bw/day in females and males.

 

A possible impairment of fertility due to exposure to the test item was obtained from, a 4-month inhalation toxicity study in rats (see IUCLID Section 7.5.2, Bazarov 1973). At the concentration of 10 mg/m³ histopathological examination revealed a decrease in the number of normal spermatogonia and degeneration of the seminiferous tubules in the testes, while at 2 mg/m³ no effects were observed. The effect was not reversible within one month. Overall, there is insufficient documentation for an adequate evaluation of the toxicological potential of the test item. Therefore, this study was disregarded.

Effects on developmental toxicity

Description of key information

Developmental toxicity, inhalative, rat, GLP, non-Guideline: NOAEC for developmenmtal toxicity/teratogenicity:

> 280 mg/m³ (80 ppm); NOAEC for maternal toxicity: 71 mg/m³ (20 ppm) (HRC/BG Chemie, 1990).

Link to relevant study records

Reference

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Principles of method if other than guideline:

In the study an intermediate product in manufacturing was investigated on pregnancy and in utero development of the rat, exposure. The test item was administered by whole-body inhalation exposure for six hours daily from Day 6 to Day 15 of pregnancy inclusive. On Day 20, animals were sacrificed and subjected to post mortem examination, litter values were determined, and foetuses were subsequently examined for visceral or skelietal anomalies.

GLP compliance:

yes

Limit test:

no

Specific details on test material used for the study:

- Name of test material (as cited in study report): piperidine
- Analytical purity: 99.3%

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River, Portage, Michigan, U.S.A.
- Age at study initiation: 8 - 10 weeks old, sexually mature
- Weight at study initiation: Batch A (weight range 164 - 205 g); Batch B (weight range 186 - 221 g)
- Housing: five per cage in suspended polypropylene cages
- Diet: Labsure Laboratory Animal Diet No. 1, ad libitum
- Water: tap water, ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18.5 - 21.5
- Humidity (%): 33 - 58
- Photoperiod (hrs dark / hrs light): 12 /12

Route of administration:

inhalation: vapour

Type of inhalation exposure (if applicable):

whole body

Vehicle:

air

Details on exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- The test substance was metered onto the sintered glass disc from a plastic disposable syringe mounted on an infusion pump (Precidor ® type 5003).
- 0il-free dried compressed air was passed through the frit, the test substance evaporated and the vapour laden air was passed into the inlet
of the exposure chamber.

Exposure chamber
- The exposure chambers were constructed from stainless steel and glass and were of approximately 0.5 m³ internal volume.
- Oil-free dried compressed air at 100 liters per minute entered the base of the vapour generator. The vapour-laden air passed through the glass elutriation column and entered the chamber inlet duct.
- The chambers were maintained at 10 mm H2O below ambient pressure by an extract fan connected to the exhaust manifold.
- Each chamber was fitted with parts for withdrawal of chamber air samples for analytical purposes. Routinely a part mid-centre of the chamber side wall was used.
- During exposure the rats were held in individual compartments of stainless steel wire mesh cages.

Procedure
The animals were put into the exposure cages and placed within the chambers appropriate to each group. The chamber doors were sealed and the air turned on.
The syringes were filled with the test substance in a fume cupboard. The syringes were then connected to the vapour generators with a PTFE tube and mounted onto the infusion pumps. The mechanism was advanced until the test substance just reached the glass frit. The initial volume in each syringe was recorded.
Exposure commenced when the infusion pumps were switched on and working at the setting appropriate to generate the desired chamber-air concentrations.
After six hours the infusion pumps were switched off and the volume of test substance remaining in the syringes was recorded.
The atmosphere within the chambers was allowed to clear before the rats were unladed and returned to their holding cages. Air control rats were sham exposed, under similar conditions to air only.

Chamber temperature and relative humidity
Chamber air temperature and relative humidity were monitored continuously with a wet and dry bulb hygrometer and recorded at hourly intervals throughout each exposure.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The concentration of the test item present in the exposure chambers was determined at least 3 times during each exposure.
Samples of test atmosphere were withdrawn at 2 liters per minute through a fritted glass bubbler containing 2,2,4-trimethylpentane as the trapping agent. The actual volumes withdrawn were measured using a wet-type gas meter (Model DM3B, Alexander Wright and Co. (Westminster) Ltd.).
The sample solutions were made up to volume (25 ml for the Preliminary study or 20 ml for the Main study) in a volumetric flask with further 2,2, 4-trimethylpentane.
Analysis was by flame ionisation gas chromatography using external standards.

Details on mating procedure:

- Proof of pregnancy: vaginal plug and sperm in vaginal smear referred to as day 0 of pregnancy

Duration of treatment / exposure:

day 6 to day 15 of pregnancy

Frequency of treatment:

daily, 6 hours per day

Duration of test:

up to day 20 of pregnancy

Dose / conc.:

0.017 mg/L air (nominal)

Remarks:

corresponding to 5 ppm

Dose / conc.:

0.071 mg/L air (nominal)

Remarks:

corresponding to 20 ppm

Dose / conc.:

0.28 mg/m³ air (nominal)

Remarks:

corresponding to 80 ppm

Dose / conc.:

0.015 mg/L air (analytical)

Remarks:

corresponding to 4.2 ppm

Dose / conc.:

0.077 mg/L air (analytical)

Remarks:

corresponding to 21.9 ppm

Dose / conc.:

0.279 mg/L air (analytical)

Remarks:

corresponding to 80.0 ppm

No. of animals per sex per dose:

15 of the first batch (A) and 10 of the second batch (B).

Control animals:

yes, sham-exposed

Details on study design:

- Sex: female
- Dose selection rationale: In a preliminary study the signs of evidence of respiratory distress at 160 ppm - during and following exposure -precluded this level from consideration in the present Main study.

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily, for obvious changes or signs of reaction to treatment.

DETAILED CLINICAL OBSERVATIONS: no data

BODY WEIGHT: Yes
- Time schedule for examinations: All animals were weighed initially (=Day 2 of pregnancy for Batch A, =Day 1 of pregnancy for Batch B) and on Day 2 (for Batch B), 3, 6, 8, 10, 12, 14, 16, 18 and 20.

FOOD CONSUMPTION AND COMPOUND INTAKE: Yes, from weighday to weighday. As animals were gang-housed, food intake was measured on a cage basis.

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 20
- Organs examined: not specified

OTHER:
Group mean values, except for food consumption, were calculated using only the values of animals with live young at termination.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
(a) number of corpora lutea
(b) number and distribution of live young
(c) number and distribution of embryofoetal deaths
(d) individual foetal weight from which the litter weight was calculated
(e) foetal abnormalities

Embryofoetal deaths were classified as:
Early: only placenta visible at termination.
Late: both placental and embryonic remnants visible at termination.

Uteri or individual uterine horns without visible implantations were immersed in a 10 % solution of ammonium sulphide to reveal evidence of embryonic death at very early stages of implantation.

Fetal examinations:

- External examinations: Yes: all per litter (Live young were examined externally and weighed.)
- Soft tissue examinations: Yes
- Skeletal examinations: Yes: half per litter for skeletal anomalies
- Head examinations: Yes: half per litter for visceral anomalies

OTHER:
- Half the foetuses in each litter were preserved in Bouin's solution for subsequent free-hand sectioning to discover visceral abnormalities (Wilson technique); the remainder were fixed in 74 OP industrial methylated spirit for subsequent macroscopic examination, evisceration, clearing and alizarin staining (modified Dawson technique) for skeletal examination.
- Young showing suspected abnormalities were processed by the more appropriate technique for clarification of initial observations.
- All foetuses were sexed by gonadal inspection following preservation.

Structural changes were presented as:
- Malformations: rare and/or probably lethal, e.g. exencephialy, anury.
- Anomalies: minor differences from 'normal' that are detected relatively frequently either by free-hand sectioning, e.g. increased renal pelvic dilatation, or at skeletal examination, e.g. bipartite centrum.
- Variants: alternative structures occurring regularly in the control population are classified as variants. These may be permanent structures, e.g. an extra pair of ribs, or they may be transient stages of development, e.g. unossified sternebra(e).

Litter weight and mean foetal weight were calculated from individual foetal weight.

Statistics:

Statistical analysis
Statistical analyses were routinely performed on litter data. Significance tests were normally two-tailed.
- Litter data
The basic sample unit was the litter, and due to the preponderance of non-normal distributions, non-parametric analyses have generally proved the most consistent.
Mean values of litter sizes, pre- and post implantation loss, litter weight, mean pup weight and the incidence of anomalous offspring were generally analysed by the Kruskal-Wallis test.
Intergroup comparisons were made by the non-parametric equivalent of the 't' test together with the Jonckheere test for an ordered series af treatments. Only the test(s) considered to be appropriate were reported.
Where 75 % of the values for a given variable consist of one value, a Fisher's exact test was used and where appropriate, Mantel's test for trend in proportions was also performed.

Indices:

Individual litter values:
pre-implantation loss was calculated as a percentage from the formula: (No. of corpora lutea - no. of implantations)/No. of corpora lutea * 100
Post implantation loss was similarly calculated from the formula: (No. of implantations - no. of live young)/No. of implantations * 100

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Signs of reaction to treatment were observed during daily exposure to piperidine at 20 and 80 ppm.
At 80 ppm, during each exposure animals failed to respond to a knock on chamber door and eyes were shut/half-closed. Licking the inside of the mouth, and pilo-erection were observed. Hunched posture was observed on nearly all occasions. Salivation and rubbing af the chin and paws on the cage, and increased respiration were observed on at most two occasions.
At 20 ppm, observations were confined to no response to knock on chamber door. This was observed on every occasion of exposure. There was one single instance of eyes shut/half-closed and hunched posture.
At 5 ppm there were no signs of reaction during exposure observed.
Following the initiation of treatment at 80 ppm, and outside the periods of exposure, some animals were observed to have areas of red/brown staining of the hair, two were observed with "snuffles" and one showed sneezing and salivation.
No similar reactions were observed at the lower exposure concentrations.

Mortality:

no mortality observed

Description (incidence):

There were no mortalities.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Following the initiation of treatment, bodyweight gains at 80 ppm were retarded compared to controls and remained so throughout treatment. On withdrawal of treatment, gains showed rapid recovery and were generally comparable to controls through to termination, although mean bodyweight remained lower than the control value at termination.
Bodyweight gains at 5 and 20 ppm were essentially similar to controls throughout.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

Following the initiation of treatment food consumption at 80 ppm was reduced and remained lower throughout treatment. Following the withdrawal of treatment, there was some recovery although intake was still slightly reduced compared to controls at termination.
Food consumption at lower levels was generally comparable with controls throughout.

Gross pathological findings:

no effects observed

Description (incidence and severity):

Occasional findings observed at terminal autopsy were not considered to be related to treatment.

Pre- and post-implantation loss:

no effects observed

Description (incidence and severity):

no significant differences

Dose descriptor:

NOAEC

Effect level:

0.071 mg/L air (nominal)

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

Changes in sex ratio:

no effects observed

Description (incidence and severity):

no significant differences

Changes in litter size and weights:

no effects observed

Description (incidence and severity):

no significant differences

Skeletal malformations:

no effects observed

Description (incidence and severity):

The incidence and type of malformations and visceral and skeletal anomalies observed did not appear to show a relationship to treatment.
The incidence of skeletal variants was essentially similar among the groups.

Visceral malformations:

no effects observed

Description (incidence and severity):

The incidence and type of malformations and visceral and skeletal anomalies observed did not appear to show a relationship to treatment.

Dose descriptor:

NOAEC

Effect level:

0.28 mg/L air (nominal)

Based on:

test mat.

Basis for effect level:

other: teratogenicity

Abnormalities:

not specified

Developmental effects observed:

not specified

Conclusions:

Based on the results of this study the NOAEC for teratogenicity was 0.28 mg/L (80 ppm) since no adverse developmental effects were observed up to the highest concentration tested.

Executive summary:

In a GLP conform, non-Guideline developmental toxicity study, 25 pregnant Crl:CD®(SD) GR VAF/Plus strain rats per dose were treated by whole-body to vapour of the test item (99.3%, a.i.) at concentrations of 5, 20, or 80 ppm (0.017, 0.071, and 0.28 mg/mL, respectively) during gestation days (GD) 6-15 for 6 hours/day (BG Chemie, 1990). 25 pregnant rats remained untreated for control.

The dams were observed daily for clinical signs, weighed on GD 2, 3, 6, and at 2-day intervals until GD 20 and had food consumption measured for intervals between weigh days. The dams were killed on GD 20 and the ovaries and uteri were examined.

No maternal mortalities occurred during the study period.

In the highest dose group clinical signs were piloerection, hunched posture, salivation and increased respiration. Food consumption was reduced throughout the treatment period and remained reduced upon withdrawal of the treatment until study termination. The body weight gains were retarded throughout treatment but recovered on withdrawal of the test substance after GD 15. At termination the maternal body weights of the high dose animals remained lower compared to the control. No treatment-related necropsy findings were observed.

In the mid-dose group hunched posture was observed only in one instance. No treatment-related effects on body weights or food consumption and no treatment-related necropsy findings were observed.

No clinical signs were observed in the lowest dose group of 5 ppm. Additionally, no effects on body weights or food consumption and no treatment-related necropsy findings were observed.

Based on the results of the study the NOEC for maternal toxicity was established by the authors as being 0.017 mg/L (5 ppm).

Due to non-toxic effects observed in the dams at this exposure level the NOAEC for maternal toxicity is estimated to 0.071 mg/L (20 ppm).

There were no significant differences in litter parameters (litter size, foetal deaths, number of implants and of corpora lutea, pre- and post-implantation losses, litter and mean foetal weights and sex ratios) and in incidences of malformations, visceral and skeletal anomalies and skeletal variations.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

280 mg/m³

Study duration:

subacute

Species:

rat

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Additional information

In a GLP conform, non-Guideline developmental toxicity study, 25 pregnant Crl:CD®(SD) GR VAF/Plus strain rats per dose were treated by whole-body to vapour of the test item (99.3%, a.i.) at concentrations of 5, 20, or 80 ppm (0.017, 0.071, and 0.28 mg/mL, respectively) during gestation days (GD) 6-15 for 6 hours/day (HRC/BG Chemie, 1990). 25 pregnant rats remained untreated for control.

The dams were observed daily for clinical signs, weighed on GD 2, 3, 6, and at 2-day intervals until GD 20 and had food consumption measured for intervals between weigh days. The dams were killed on GD 20 and the ovaries and uteri were examined.

No maternal mortalities occurred during the study period.

In the highest dose group clinical signs were piloerection, hunched posture, salivation and increased respiration. Food consumption was reduced throughout the treatment period and remained reduced upon withdrawal of the treatment until study termination. The body weight gains were retarded throughout treatment but recovered on withdrawal of the test substance after GD 15. At termination the maternal body weights of the high dose animals remained lower compared to the control. No treatment-related necropsy findings were observed.

In the mid-dose group hunched posture was observed only in one instance. No treatment-related effects on body weights or food consumption and no treatment-related necropsy findings were observed.

No clinical signs were observed in the lowest dose group of 5 ppm. Additionally, no effects on body weights or food consumption and no treatment-related necropsy findings were observed.

Based on the results of the study the NOEC for maternal toxicity was established by the authors as being 0.017 mg/L (5 ppm).

Due to non-toxic effects observed in the dams at this exposure level the NOAEC for maternal toxicity is estimated to 0.071 mg/L (20 ppm).

 

There were no significant differences in litter parameters (litter size, foetal deaths, number of implants and of corpora lutea, pre- and post-implantation losses, litter and mean foetal weights and sex ratios) and in incidences of malformations, visceral and skeletal anomalies and skeletal variations.

Based on the results of this study the NOAEC for teratogenicity was 0.28 mg/L (80 ppm) since no adverse developmental effects were observed up to the highest concentration tested.

 

 

In a GLP conform, non-Guideline preliminary range finding an intermediate product in manufacturing (purity unknown), at dose levels of 1.25, 5, 20, 80 and 160 ppm (0.004, 0.017, 0.071, 0.28, 0.56 mg/L) were administered to 10 pregnant rats per dose by whole-body inhalation exposure for six hours daily from Day 6 to Day 15 of pregnancy inclusive (HRC/BG Chemie, 1990). 10 pregnant rats remained untreated for control. The dams were observed daily for clinical signs, weighed on GD 2, 3, 6, and at 2-day intervals until GD 20 and food consumption was measured for intervals between weigh days. On Day 20 surviving females were sacrificed, subjected to post mortem examination, litter values determined and foetuses were examined for gross abnormalities.

The animals of the highest dose group (160 ppm) were sacrificed after 4 exposures due to respiratory distress. No other maternal mortalities occurred during the study period.

In the two high dose groups (80 ppm , 160 ppm) signs of reaction during exposure included hunched posture, piloerection, noisy snuffling respiration, laboured/gasping respiration, half-closed eyes, licking inside of mouth, rubbing of chin/snout, no response to knock on chamber door, twitching head movements. Daily signs following exposure comprised red/brown staining of hair particularly around the face. Food consumption was reduced and bodyweight gains were retarded throughout the treatment period. Reduced food consumption in the 80 ppm group throughout the treatment period was comparable to the control group on withdrawal of the treatment until study termination. Additionally, the body weight gains recovered on withdrawal of the test substance and were comparable to the control from day 16. At termination the maternal body weights in this group remained lower compared to the control.

In the other dose groups (1.25, 5 and 20 ppm) no clinical signs were observed.

There were no significant differences in litter parameters (foetal deaths, number of implants and of corpora lutea, mean foetal weights and sex ratios) and in incidences of macroscopic changes and malformations on terminal autopsy. At 80 ppm there was an indication of a slightly higher incidence of post implantation loss, but individual values showed that there was only one litter with marked losses. Litter size was slightly lower at 20 and 80 ppm but this was attributed to events occurring prior to treatment - i.e. variations in corpora lutea and pre-implantation losses. No malformations were observed during the gross macroscopic examination of the foetuses.

Based on the results of this study the NOAEC for maternal toxicity was established by the authors as being 0.071 mg/L (20 ppm).

 

Conclusion: No teratogenic activity of the test item was detected in two rat studies. In the inhalation study of HRC/BG Chemie (1990), in which rats were exposed to the test item at concentrations of 5, 20 and 80 ppm (equivalent to 0.017, 0.071 and 0.28 mg/L) for 6 hours per day from day 6 to 15 of pregnancy, these effects were not observed even at the concentration level of 0.28 mg/L. There was no detectable effect of the test item on embryofoetal development.

The foetal no observed adverse effect concentration (NOAEC) was estimated to be 0.28 mg/L while the maternal NOAEC was estimated to be 0.071 mg/L.

Justification for selection of Effect on developmental toxicity: via inhalation route:
Highest quality study.

Justification for classification or non-classification

Classification, Labeling, and Packaging Regulation (EC) No. 1272/2008

The available experimental test data for toxicity to reproduction and developmental toxicity are reliable and suitable for the purpose of classification under Regulation (EC) No.1272/2008. As a result, the substance is not warranted to be classified for toxicity to reproduction and developmental toxicity, under Regulation (EC) No.1272/2008.