Registration Dossier

Administrative data

Endpoint:
screening for reproductive / developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report Date:
2018

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 421 (Reproduction / Developmental Toxicity Screening Test)
Version / remarks:
2016
Deviations:
no
Remarks:
No deviations occurred that negatively impacted the integrity of the study.
GLP compliance:
yes
Justification for study design:
Per OECD 421.

Test material

Reference
Name:
Unnamed
Type:
Constituent
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 3M Company, Lot 16
- Expiration date of the lot/batch: 31 March, 2019
- Purity test date: 01 May, 2017

Test animals

Species:
rat
Strain:
Wistar
Details on species / strain selection:
Species and strain are recognized in OECD 421 as being appropriate for a reproductive/developmental screening study.
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles
- Females nulliparous and non-pregnant: Yes
- Age at study initiation: Males: 11 weeks, Females: 12 weeks
- Weight at study initiation: Body weight at allocation was within ±20% of the mean weight for each sex.
- Fasting period before study: None
- Housing: During exposure, the animals were housed individually in the inhalation unit. After each exposure, the animals returned to their home cages. Animals were housed in Makrolon cages with a bedding of wood shavings (Lignocel, Rettenmaier & Söhne GmbH & Co, Rosenberg, Germany) and strips of paper (Enviro-dri, Shepherd Specialty Papers, Michigan, USA) and a wooden block (ABEDD, Vienna, Austria) as environmental enrichment. After allocation, the animals were housed four rats to a cage (separated by sex). For mating, one male and one female were housed together. Mated females were housed individually in Makrolon cages, which were placed in another cage rack. The location of the mated females in the new cage racks was determined by the date of mating (females found sperm-positive on the same date were considered a ‘lot’) and by the animal number (within each lot the mated females was housed in the order of animal number).
- Diet (e.g. ad libitum): Food and drinking water was provided ad libitum from the arrival of the rats until the end of the study, except during exposure and unless precluded by the performance of certain laboratory investigations. From their arrival, the rats received a cereal-based (closed formula) rodent diet (VRF1 (FG)) from a commercial supplier (SDS Special Diets Services, Witham, England). Each batch of diet was analysed by the supplier for nutrients and contaminants. The certificate of analysis pertaining to the batch used in this study (3041) is included in the study report in Annex 04. The food was provided as a powder in stainless steel cans, covered by a perforated stainless steel plate to prevent spillage. The food in the cans were refreshed at least once weekly. Each cage was supplied with domestic mains tap-water suitable for human consumption (quality guidelines according to Dutch legislation based on EC Council Directive 98/83/EC). The water was given in polypropylene bottles, which were cleaned weekly and filled as needed. Results of the routine physical, chemical and microbiological examination of drinking water as conducted by the supplier are made available to the test facility. In addition, the supplier periodically (twice per year) analyses water samples taken at the premises for a limited number of physical, chemical and microbiological variables.
- Water (e.g. ad libitum): ad libitum
- Acclimation period: At least 5 days
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24
- Humidity (%): 29.7-65
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12/12
IN-LIFE DATES: From: 29 September, 2017 To: 10 December, 2017

Administration / exposure

Route of administration:
inhalation: gas
Type of inhalation exposure (if applicable):
whole body
Vehicle:
air
Details on exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: 2.2 m^3 whole body exposure units (based on the design by Hazleton Systems, Inc., Aberdeen, MD, USA). These chambers were constructed of stainless steel, with glass doors on two sides which allowed observation of the animals during exposure. The test atmosphere was introduced at the top and exhausted at the bottom of the chamber.
- Method of holding animals in test chamber: During exposure, animals were housed individually in Type II Macrolon cages. Each whole body chamber could accommodate 60 cages. Animals were rotated twice weekly with respect to their position in the exposure chamber.
- Source and rate of air:
- Method of conditioning air:
- System of generating particulates/aerosols:
- Temperature, humidity, pressure in air chamber: 19-25 C, 30-70% humidity
- Air change rate: At least 10 air changes per hour.
- Treatment of exhaust air: No data

TEST ATMOSPHERE
- Brief description of analytical method used: The actual concentration of the test substance in the test atmospheres was measured by total carbon analysis (Sick Maihak EuroFID Total Hydrocarbon Analyzer; Sick Instruments Benelux, Hedel, the Netherlands). Test atmosphere samples were taken continuously from the exposure chamber at the animals’ breathing zone and were passed to the total carbon analyzer (TCA) through a sample line.
- Samples taken from breathing zone: Yes
Details on mating procedure:
- M/F ratio per cage: 1:1
- Length of cohabitation: Until mating occurred (no other details in report).
- Proof of pregnancy: sperm in vaginal smear referred to as day 0 of pregnancy.
- After successful mating each pregnant female was caged (how): Individually
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
The actual concentration of the test substance in the test atmospheres was measured by total carbon analysis (Sick Maihak EuroFID Total Hydrocarbon Analyzer; Sick Instruments Benelux, Hedel, the Netherlands).
Duration of treatment / exposure:
Females were exposed to the test atmospheres during a premating period of 2 weeks (5 days/week, 10 exposure days in total), during mating, gestation and lactation. Mated females were not exposed to the test substance between gestation day 19 and lactation day 4 in order to allow the females to litter. Daily exposure was resumed on lactation day 5 up to day 13 of lactation. The total number of exposure days was 31 days for males and 38-42 days for females.
Frequency of treatment:
Daily (except females between gestation day 19 and lactation day 4)
Details on study schedule:
The test substance was administered by inhalation whole body exposure (6 hours/day) at target concentrations of 0 (control), 250 +/- 6, 748 +/- 17, and 1498 +/- 24 ppm to groups of 12 male and 12 female rats during a premating period of 2 weeks (5 days/week, 10 total exposure days), during mating, gestation, and lactation. Mated females were not exposed to the test substance between gestation day 19 and lactation day 4 in order to allow the females to litter. Daily exposure was resumed on lactation day 5 up to day 13 of lactation. Adult male rats were sacrificed after at least 28 days of treatment. Parental female rats were sacrificed on day 14 of lactation. Pups were sacrificed on day 13 of lactation.
Doses / concentrationsopen allclose all
Dose / conc.:
0 ppm
Remarks:
Control
Dose / conc.:
250 ppm
Dose / conc.:
748 ppm
Dose / conc.:
1 498 ppm
No. of animals per sex per dose:
12
Control animals:
yes, concurrent no treatment
Details on study design:
- Dose selection rationale: The test concentrations were selected based on the results of a 28-day study with MTDID 28136 in Sprague Dawley rats and a 14-day range finding study in Wistar Han rats.
- Rationale for animal assignment: Random
Positive control:
None

Examinations

Parental animals: Observations and examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Each animal was observed daily in the morning hours by cage-side observations and, if necessary, handled to detect signs of toxicity. All cages were checked again in the afternoon for dead or moribund animals to minimize loss of animals from the study.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Morning, night and half-way through the 6 hour exposure period.

BODY WEIGHT: Yes
- Time schedule for examinations: The body weight of each animal was recorded at least once during the acclimatization period and at initiation of treatment (day 0). Subsequently, males were weighed weekly. Four males in the 250 ppm group were weighed additionally on day 2 of exposure due to body weight loss.
Females were weighed once per week during the premating and mating period. Mated females were weighed on days 1, 7, 14 and 20 during presumed gestation and on day 0, 4, 7 and 13 of lactation. Non-mated females were weighed once per week after the mating period. Body weight changes was calculated over the different weighing days. In addition, the animals were weighed on their scheduled necropsy date in order to calculate the correct organ to body weight ratios.

FOOD CONSUMPTION AND COMPOUND INTAKE: The food in the feeders was refreshed once per week. The food consumption was measured per cage over the same periods as the body weight are measured, except during the mating period when food intake was not recorded. The results were expressed in g per animal per day.
Oestrous cyclicity (parental animals):
Vaginal smears to evaluate the oestrous cycle length and normality were made daily from the start of the pre-treatment period until confirmation of mating. Smears were made, stained and examined in all females. An additional vaginal smear were made at the day of sacrifice. These smears were only analysed and reported in case of inconclusive results of histopathology of uterus and vagina.
Sperm parameters (parental animals):
Male reproductive organs examined in P male parental generations:
testis weight, epididymis weight, prostate weight
Litter observations:
STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: Yes
On lactation day 4 the litter size was adjusted by eliminating extra pups by random selection to yield, as nearly as possible, four pups per sex per litter.

PARAMETERS EXAMINED
The following parameters were examined in F1 offspring:
number and sex of pups, stillbirths, live births, postnatal mortality, presence of gross anomalies, weight gain, physical or behavioural abnormalities, anogenital distance (AGD), presence of nipples/areolae in male pups, T4 hormone determination. Pups were sacrificed on day 13 of lactation.

GROSS EXAMINATION OF DEAD PUPS:
Yes, for external and internal abnormalities; possible cause of death was not determined for pups born or found dead.
Postmortem examinations (parental animals):
SACRIFICE
- Male animals: All surviving animals: Adult male rats were sacrificed after at least 28 days of treatment.
- Maternal animals: All surviving animals: Parental female rats were sacrificed on day 14 of lactation.

GROSS NECROPSY
- Gross necropsy consisted of external and internal examinations including the cervical, thoracic, and abdominal viscera.

HISTOPATHOLOGY / ORGAN WEIGHTS
t necropsy, the epididymides, prostate, seminal vesicles and coagulation glands, testes, levator ani plus bulbocavernosus (LABC) muscle complex, Cowper’s glands, glans penis, thyroid gland, and lungs (with trachea and larynx) of all adult male rats were weighed and tissue and organ samples were collected and preserved. Tissue samples of the ovaries, uterus (including cervix), and vagina were obtained at necropsy for all adult female rats and organ weights were obtained for the ovaries and uterus’. Other tissues collected at necropsy included all gross lesions and noses of five adult males and females per exposure group.
Postmortem examinations (offspring):
SACRIFICE
- These animals were subjected to postmortem examinations (macroscopic and/or microscopic examination) as follows: A necropsy was performed on stillborn pups and pups dying during the study and macroscopic abnormalities were recorded. At necropsy of the dams and litter, at or shortly after day 13 of lactation, pups were examined externally for gross abnormalities and will be sacrificed whilst under CO2/O2 anaesthesia and necropsied.

GROSS NECROPSY
- Gross necropsy consisted of external and internal examinations including the cervical, thoracic, and abdominal viscera.

HISTOPATHOLOGY / ORGAN WEIGTHS
The thyroid gland was collected and examined for 2 pups per litter.
Reproductive indices:
- number of adult females with normal or abnormal oestrous cycle and cycle duration
- number of females placed with males (and vice versa)
- number of females (not) mated and number of males (not) mated
- number of females (not) pregnant
- number of males that became sire
- number of females killed moribund or found dead
- number of females completing delivery
- number of females with liveborn pups
- number of females with (all) stillborn pups
- total and mean number of implantation sites
- Pre-coïtal time (period)
- Duration of gestation
- Male mating index
- Female mating index
- Male fertility index
- Female fertility index
- Female fecundity index
- Gestation index
Offspring viability indices:
- total and mean number of pups delivered (liveborn + stillborn)
- total number of liveborn pups
- total number of stillborn pups
- total and mean number of live pups(/litter) at day n
- total number of culled pups
- total number of pups lost (dead, missing, cannibalized) (period)
- number and incidence of litters lost entirely (period)
- total and mean number of live male pups at day n
- Number of lost implantations
- Post-implantation loss
- Live birth index
- Stillborn index
- Viability index
- Sex ratio

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
Observation of the animals during exposure revealed piloerection in the majority of animals exposed to 1498 ppm, primarily observed during the first 3 weeks of exposure and the first week after restart of exposure during lactation (a pause was included to allow the animals to deliver their litter). Piloerection was also occasionally observed during exposure of animals to 748 ppm, and on a few days also in single animals of the control and 250 ppm group.
Dermal irritation (if dermal study):
not examined
Mortality:
no mortality observed
Description (incidence):
No animals died during exposure.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Test substance-related reduction in body weight were observed in male and female rats exposed to 1498 and 748 ppm MTDID 28136 which were associated with significant reductions in food consumption when compared to the air-exposed control group (0 ppm). The body weight reductions of females exposed to 1498 ppm were considered adverse since they were consistently > 10% of the control group.
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
Mean food consumption was statistically significantly lower in males and females in the 1498 ppm group throughout the study as compared to the control group. In the 748 ppm group, mean food consumption was statistically significantly lower in males and females during the premating period and in females during the lactation period as compared to the control group. These lower food intakes are considered test substance-related. No effects on food consumption were observed in males and females in the 250 ppm group.
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
no effects observed
Description (incidence and severity):
No statistically significant effects were observed on T4 levels in adult males.
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
Histopathology showed a concentration-dependent degeneration of the nasal olfactory epithelium of levels 3, 4, 5, and 6 in male and female rats exposed to 1498 and 748 ppm. In the control group and rats exposed to 250 ppm, no degeneration of the olfactory epithelium was observed. Other organ and tissue samples noted no significant findings at necropsy.
Histopathological findings: neoplastic:
no effects observed
Description (incidence and severity):
No effects observed.

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:
effects observed, treatment-related
Description (incidence and severity):
An increased number of a-cyclic females was observed in the high concentration group after the start of exposure as compared to the control group. (1, 0, 2 and 5 out of 12 females did not show a regular cycle during exposure in the control group, 250, 748 and 1498 ppm groups, respectively).
Reproductive function: sperm measures:
no effects observed
Description (incidence and severity):
No test article-related changes were observed in the testes or epididymides.
Reproductive performance:
effects observed, treatment-related
Description (incidence and severity):
Functional fertility as measured by the time to pregnancy, gestation length, and number of litters was not affected. Mean number of pups delivered was decreased in pregnant females (dams) exposed to 1498 ppm. Mean number of live pups/litter day 0 are 11.6 (0 ppm), 12.1 (250 ppm), 9.0 (748 ppm), and 9.6 (1498 ppm).

Effect levels (P0)

open allclose all
Key result
Dose descriptor:
NOAEC
Effect level:
ca. 250 ppm (analytical)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
body weight and weight gain
histopathology: non-neoplastic
Remarks on result:
other: See Remarks
Remarks:
The No Observed Adverse Effect Concentration (NOAEC) for general toxicity was 250 ppm.
Key result
Dose descriptor:
NOAEC
Effect level:
ca. 748 ppm (analytical)
Based on:
test mat.
Sex:
female
Basis for effect level:
reproductive function (oestrous cycle)
reproductive performance
Remarks on result:
other: See Remarks
Remarks:
The NOAEC for female fertility was 748 ppm.
Key result
Dose descriptor:
NOAEC
Effect level:
ca. 1 498 ppm (analytical)
Based on:
test mat.
Sex:
male
Basis for effect level:
reproductive function (sperm measures)
Remarks on result:
other: See Remarks
Remarks:
In the absence of adverse reproductive effects in the males, the NOAEC for male reproduction was 1498 ppm.

Target system / organ toxicity (P0)

open allclose all
Key result
Critical effects observed:
yes
Lowest effective dose / conc.:
748 ppm
System:
respiratory system: upper respiratory tract
Organ:
nasal cavity
Treatment related:
yes
Dose response relationship:
yes
Key result
Critical effects observed:
yes
Lowest effective dose / conc.:
1 498 ppm
System:
other: Body weight
Organ:
other: Overall body weight reduction in the females in the high dose group.
Treatment related:
yes
Dose response relationship:
yes

Results: F1 generation

General toxicity (F1)

Clinical signs:
no effects observed
Description (incidence and severity):
No adverse clinical signs were observed in the pups.
Dermal irritation (if dermal study):
not examined
Mortality / viability:
no mortality observed
Description (incidence and severity):
All pups were live-born and there were no registered stillborn pups. During the first days of lactation three pups in control groups were cannibalized. No pups in the exposed groups died during the first days of lactation. The viability index from day 0-4 was 98% for the control group and 100% for the groups exposed to the test substance.
Body weight and weight changes:
no effects observed
Description (incidence and severity):
No statistically significant effects on mean pup weight were observed.
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
no effects observed
Description (incidence and severity):
Mean pup thyroid weight was comparable in all groups for male and female pups.
Urinalysis findings:
not examined
Sexual maturation:
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Description (incidence and severity):
Mean pup thyroid weight was comparable in all groups for male and female pups.
Gross pathological findings:
no effects observed
Description (incidence and severity):
No treatment-related effects were observed.
Histopathological findings:
not examined
Other effects:
no effects observed
Description (incidence and severity):
No effects on mean anogenital distance was observed in male and female pups. No effect was observed on nipple retention in male pups.

Developmental neurotoxicity (F1)

Behaviour (functional findings):
not examined

Developmental immunotoxicity (F1)

Developmental immunotoxicity:
not examined

Effect levels (F1)

Key result
Dose descriptor:
NOAEC
Generation:
F1
Effect level:
ca. 1 498 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
viability
clinical signs
mortality
body weight and weight gain
clinical biochemistry
organ weights and organ / body weight ratios
gross pathology

Target system / organ toxicity (F1)

Key result
Critical effects observed:
no

Overall reproductive toxicity

Key result
Reproductive effects observed:
yes
Lowest effective dose / conc.:
1 498 ppm (analytical)
Treatment related:
yes
Relation to other toxic effects:
reproductive effects as a secondary non-specific consequence of other toxic effects
Dose response relationship:
yes

Applicant's summary and conclusion

Conclusions:
Based on the adverse reduction in female body weights in the 1498 ppm exposure group as well as the exposure-related histopathological changed in nasal olfactory epithelium observed at 1498 ppm and 748 ppm, the No Observed Adverse Effect Concentration (NOAEC) for general toxicity is 250 ppm. Based on the increased number of females showing a-cyclic oestrous cycles and the lower mean number of pups/litter in the 1498 ppm MTDID 28136 exposure group, the No Observed Adverse Effect Concentration (NOAEC) for fertility is 748 ppm. In the absence of effects on pup sex and survival, pup observations, anogenital distance (AGD) and nipple retention the No Observed Adverse Effect Concentration (NOAEC) for male reproductive toxicity and developmental toxicity was placed at 1498 ppm.
Executive summary:

The objective of this study was to provide data on the potential effects of MTDID 28136 on reproductive performance, pup development, and general toxicity of rats by inhalation exposure. The study was conducted according to OECD 421 (2016) in compliance with OECD GLP. The test concentrations were selected based on the results of a 28-day study with MTDID 28136 in Sprague Dawley rats and a 14-day range finding study in Wistar Han rats. The test substance was administered by inhalation whole body exposure (6 hours/day) at target concentrations of 0 (control), 250 +/- 6, 748 +/- 17, and 1498 +/- 24 ppm to groups of 12 male and 12 female rats during a premating period of 2 weeks (5 days/week, 10 total exposure days), during mating, gestation, and lactation. Mated females were not exposed to the test substance between gestation day 19 and lactation day 4 in order to allow the females to litter. Daily exposure was resumed on lactation day 5 up to day 13 of lactation. Adult male rats were sacrificed after at least 28 days of treatment. Parental female rats were sacrificed on day 14 of lactation. Pups were sacrificed on day 13 of lactation. In-life parameters recorded included clinical signs, body weights, food consumption, mating parameters, gestational and parturition parameters, and litter parameters. At necropsy, the epididymides, prostate, seminal vesicles and coagulation glands, testes, levator ani plus bulbocavernosus (LABC) muscle complex, Cowper’s glands, glans penis, thyroid gland, and lungs (with trachea and larynx) of all adult male rats were weighed and tissue and organ samples were collected and preserved. Tissue samples of the ovaries, uterus (including cervix), and vagina were obtained at necropsy for all adult female rats and organ weights were obtained for the ovaries and uterus’. Other tissues collected at necropsy included all gross lesions and noses of five adult males and females per exposure group. At necropsy, organ weights and tissue samples of the thyroid gland were also obtained for 2 pups/litter on postnatal day 13. Histopathological examination (by light microscope) was performed on the preserved organs and tissues of all animals of the control and high-exposure group. Based on effects observed in the nasal epithelium in animals exposed in the high exposure group, histopathological examination was extended to the intermediate exposure groups. There was no test substance-related mortality. Daily observation revealed piloerection in the 1498 ppm group males and females during the first three weeks of exposure and during the re-start of exposure during lactation. Test substance-related reduction in body weight were observed in male and female rats exposed to 1498 and 748 ppm MTDID 28136 which were associated with significant reductions in food consumption when compared to the air-exposed control group (0 ppm). The body weight reductions of females exposed to 1498 ppm were considered adverse since they were consistently > 10% of the control group. At necropsy, a concentration dependent increase in mean relative lung weight was observed in males of all exposure levels and in females exposed to 1498 ppm MTDID 28136 but were not considered adverse as no correlative changes in lung histopathology was noted. Histopathology showed a concentration-dependent degeneration of the nasal olfactory epithelium of levels 3, 4, 5, and 6 in male and female rats exposed to 1498 and 748 ppm. In the control group and rats exposed to 250 ppm, no degeneration of the olfactory epithelium was observed. Other organ and tissue samples noted no significant findings at necropsy. The number of females showing a-cyclic oestrous cycles was increased at 1498 ppm MTDID 28136 and correlates with the significant-related reductions in body weight and food consumption in this group. Functional fertility as measured by the time to pregnancy, gestation length, and number of litters was not affected. Mean number of pups delivered was decreased in pregnant females (dams) exposed to 1498 ppm. Mean number of live pups/litter day 0 are 11.6 (0 ppm), 12.1 (250 ppm), 9.0 (748 ppm), and 9.6 (1498 ppm). There were no effects of MTDID 28136 on pup survival or pup development. There were no effects on hormone levels (T4) between exposed groups and the control group for adult males nor were there any effects noted in 13-day old male and female pups. Based on the adverse reduction in female body weights in the 1498 ppm exposure group as well as the exposure-related histopathological changed in nasal olfactory epithelium observed at 1498 ppm and 748 ppm, the No Observed Adverse Effect Concentration (NOAEC) for general toxicity is 250 ppm. Based on the increased number of females showing a-cyclic oestrous cycles and the lower mean number of pups/litter in the 1498 ppm MTDID 28136 exposure group, the No Observed Adverse Effect Concentration (NOAEC) for fertility is 748 ppm. In the absence of effects on pup sex and survival, pup observations, anogenital distance (AGD) and nipple retention the No Observed Adverse Effect Concentration (NOAEC) for male reproductive toxicity and developmental toxicity was placed at 1498 ppm.