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Administrative data

Key value for chemical safety assessment

Effects on fertility

Description of key information

No study on toxicity on reproduction with the target substance MCPP-P 2-EHE is available. But a multi-generation study according OECD TG 416 with MCPP-P acid, which is the main hydrolysis product of MCPP-P 2-EHE in vivo is used for read-across.

The test item MCPP-P 2-EHE hydrolyses fast to the corresponding degradation products - acid (MCPP-P acid, CAS 16484-77-8) and alcohol (2-ethylhexan-1-ol, CAS 104-76-7). In a study on developmental toxicity and teratogenicity (OECD TG 414, NOAEL= 191 mg/kg bw/day) with the alcohol the NOAEL was higher as the ones determined for MCPP-P acid. The alcohol is not classified with respect to developmental toxicity or toxicity to fertility (please refer to the ECHA Disseminated dossier of CAS 104-76-7). Therefore, the read-across was based on the main degradation product - MCPP-P acid.

The continuous administration of MCPP-P acid to rats as a constant homogeneous addition to the diet over two generations caused only marginal signs of systemic toxicity in the highest dose group (500 ppm) in F0 and F1 parents (increased absolute and relative kidney weights without any correlating morphological findings). Adverse substance-induced effects which were noted for the progeny of the F0 and/or F1 parents were an increased pup mortality in the 500 ppm (F1a, F1b and F2 litters) and 100 ppm (F1b litters only) groups and retarded growth/development of the high dose F1a and F2 pups.

20 ppm were tolerated by both parental generations and their offspring without any changes which could be causally related to the test substance administered.

MCPP-P acid had no adverse effects on reproductive parameters or reproductive organs of the parental animals of both generations (F0 and F1) and of all groups (20, 100 and 500 ppm).

The NOAEL concerning reproductive function is 500 ppm (corresponding to 50 mg/kg bw/day).

The NOAEL concerning systemic toxicity for F0 and F1 parental animals as well as for developmental toxicity for the F1 and F2 progeny is 20 ppm (corresponding to 2 mg/kg bw/day). Thus, there was no indication for specific developmental toxicity as the effects in the progeny occurred at a dose level of parental toxicity.

Link to relevant study records
Reference
Endpoint:
two-generation reproductive toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
14 June 1989 - 17 April 1990
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 416 (Two-Generation Reproduction Toxicity Study)
Version / remarks:
1983
Qualifier:
according to guideline
Guideline:
EPA OPP 83-4 (Reproduction and Fertility Effects)
Version / remarks:
November 1984
Qualifier:
according to guideline
Guideline:
other: Testing Guidelines for Toxicology Studies pp.45-48, Japan/MAFF
Version / remarks:
1985
GLP compliance:
yes
Limit test:
no
Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Karl THOMAE, Biberach an der Riss, Germany
- Age at study initiation: (P) 35±1 wks
- Weight (mean) at study initiation: (P) Males: 126.2 g; Females: 114.7 g; (F1) Males: 100 g; Females: 90 g
- Housing: housed individually in type DK III stainless steel wire mesh cages (during mating periods, the males designated for mating were kept individually in Makrolon cages type M III; the pregnant animals and their litters were also housed in Makrolon type M III cages
- Diet: ad libitum; Kliba maintenance diet rat/mouse/hamster GLP 343 meal
- Water: ad libitum (those animals selected for urinalysis had no access to food and water in the cages used to take urine samples)
- Acclimation periods: 8 days (for P0 animals only)
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24°C
- Humidity (%): 30-70%
- Photoperiod (hrs dark / hrs light):12 hours/12 hours

Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Details on exposure:
DIET PREPARATION
- Rate of preparation of diet: substance preparations were prepared at intervals of not more than 35 days
- Mixing: test substance was mixed with a small amount of food in a Bosch household mixer, an appropriate amount of food was then added to obtain the desired concentration, while mixing was carried out in a laboratory mixer



Details on mating procedure:
- M/F ratio per cage: 1:1 ratio
- Proof of pregnancy: sperm in vaginal smear referred to as "day 0" and the following day "day 1" p.c. (post coitum)
If an animal of the P0 or P1 generation parental animals had not produced any offspring these animals were mated again with control animals to assess their fertility.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
The content of MCPP-P acid in the test substance/food mixes was determined by HPLC-method.
Duration of treatment / exposure:
whole lifetime (P0 generation), during which two matings and rearings of offspring took place
Frequency of treatment:
fed in diet, continuously
Details on study schedule:
At least 70 days after the beginning of treatment the animals were allowed to mate in a 1:1 ratio (P0). Females were allowed to litter and rear their pups (F1a generation pups) until either day 4, when the pups were culled to 8 pups/litter preferably with 4 males and four females/litter or day 21 after parturition. At least 10 days after the last weaning of the F1a generation pups, the P0 parental animals were mated again in a ratio of 1:1 for the F1b generation and the females were allowed to rear their pups as the F1a generation. After the F1b generation had been weaned, the P0 generation was fasted for 16 hours before sacrifice.
After weaning, the F1a pups were used to establish the F2 generation by choosing 25 males and 25 females from each dose group with all litters being represented if possible. The F1a generation received the test substance at the same concentration as their parents, and at least 98 days after formation of the P1 generation parental animals, the males and females were mated at a ratio of 1:1 avoiding mating of siblings. Females were allowed to litter (F2 pups) and at day 4 after parturition, culling to 8 pups/female was carried out. After the F2 pups had been weaned the P1 generation was fasted for 16 hours before sacrifice.
All pups, which were not used for establishing the next generation, were sacrificed after weaning.
Dose / conc.:
0 ppm (nominal)
Dose / conc.:
20 ppm (nominal)
Remarks:
ca. 2 mg/kg bw/day
Dose / conc.:
100 ppm (nominal)
Remarks:
ca. 10 mg/kg bw/day
Dose / conc.:
500 ppm (nominal)
Remarks:
ca. 50 mg/kg bw/day
No. of animals per sex per dose:
25
Control animals:
yes, plain diet
Details on study design:
- Dose selection rationale:
On the basis of the results of repeated–dose toxicity studies, which indicated a renal impairment being more pronounced in males than in females in dosages ranging from 450 ppm down to 100 ppm, the following doses were chosen for the reproduction study with MCPP: 20 ppm: as the expected no adverse effect level, 100 ppm: as a concentration with possibly minimal toxic effects (e.g. increased kidney weights), and 500 ppm: as the dose in which toxic effects were expected (e.g. kidney impairment) in the parental animals, but which should not induce mortality in these animals.


Parental animals: Observations and examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily
The nesting, littering, and lactation behavior of the dams were generally evaluated in the mornings in connection with the daily clinical inspection of the dams. Only if there were any special findings (e.g., animal could not litter, umbilical cord not cut), these specific findings were documented with the dam concerned.
DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily
BODY WEIGHT: Yes
- Time schedule for examinations: once a week
Exceptions:
During each mating period (1st and 2nd matings of the P0 and mating of the P1 generation parental animals) the females were weighed on the day of positive evidence of sperm (day 0 p.c.) and on days 7, 14 and 20 post coitum. Females without litters were not weighed during the lactation period of the dams used in parallel. After weaning of the last F1a pups the female P0 generation parental animals were weighed weekly until the beginning of the 2nd mating interval (in parallel to the male P0 generation parental animals).

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
Food consumption of the males was not determined any longer after the 10th (P0 generation parental animals) or 14th (P1 generation parental animals) test week until sacrifice. Furthermore, there was no determination of food consumption in the females during the mating period, animals without positive evidence of sperm (during the gestation period of the dams used in parallel) and animals without litter (during the lactation period of the dams used in parallel). Food consumption was not determined between days 14 and 21 after parturition as envisaged in the test guidelines cited under 2.
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes
Litter observations:
STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: yes
On day 4 p.p., the individual litters were standardized in such a way that, where possible, each litter contained 4 male and 4 female pups (always the first 4 pups/sex and litter were taken for further rearing). If it was not possible in single litters to have 4 pups/sex, it was proceeded in such a way that 8 pups per litter were present for further rearing (e.g., 5 male and 3 female pups). Standardization of litters was not performed in litters with ≤ 8 pups.

PARAMETERS EXAMINED
The following parameters were examined in [F1, F2] offspring:
Number and sex of pups, stillbirths, live births, postnatal mortality, presence of gross anomalies, weight gain, physical or behavioral abnormalities, anogenital distance (AGD)

GROSS EXAMINATION OF DEAD PUPS: yes, for external and internal abnormalities; possible cause of death was determined for pups born or found dead.

BEHAVIORAL TESTS (Neurotoxicity)
All surviving pups were tested for the gripping reflex (on day 13), the hearing test (acoustic startle on day 21) and the pupillary reflex test (on day 20).

CLINICAL CHEMISTRY: Yes
Blood was taken from the retro-orbital venous plexus in the morning from non-fasted, not anesthetized animals. The following parameters were determined: alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, sodium, potassium, chloride, inorganic phosphate, calcium, urea, creatinine, glucose, total bilirubin, total protein, albumin, globulins, triglycerides, cholesterol, and magnesium

URINALYSIS: Yes
With the exception of the sediment examination and the specific gravity, all the urine constituents were determined semi quantitatively using test strips. The following parameters were examined: Volume, appearance, nitrite, pH, protein, glucose, ketones, urobilinogen, bilirubin, blood, specific gravity, and sediment.
Postmortem examinations (parental animals):
Parental animals of the P0 and P1 generations were subjected to gross pathology after weighing of animals. Organs (liver, kidneys, testes, vagina, cervix, uterus, ovaries, epididymides, seminal vesicles, coagulation gland, prostate, pituitary gland) were all subjected to a histopathological examination in all animals from the control and 500 ppm groups. In addition livers, kidneys, and gross lesions in the 20 and 100 ppm groups were studied likewise.
Postmortem examinations (offspring):
GROSS NECROPSY/HISTOPATHOLOGY / ORGAN WEIGTHS
Culled (i.e. all pups which were sacrificed on day 4 p.p. as a result of standardization) and surplus pups (i.e. all pups reared until day 21 p.p. except those F1a generation pups selected as the basis of the P1 parental generation) were sacrificed on day 21 after birth or subsequent days by means of CO2, examined externally and eviscerated, and their organs were assessed macroscopically. If there were notable findings or if abnormalities were found in the daily clinical observation of the animals after their delivery, the affected animals were, if it was deemed necessary, examined additionally using appropriate methods. All stillborn pups and all pups that died during rearing were examined externally and eviscerated, and their organs were assessed macroscopically. If there were notable findings or if abnormalities were found in the daily clinical observation of the animals after their delivery, the affected animals were, if it was deemed necessary, examined additionally using appropriate methods.



Statistics:
Dunnett's Test was used for statistical evaluation of all parametric data such as food consumption (parental animals), body weights and body weight change (parental animals and pups).
Fisher's Exact Test was used for statistical evaluation of all quantitative data such as developmental stages, gripping and pupillary reflex, hearing test, number of live and dead pups, and the different indices (e.g. male and female mating index, male and female fertility index, gestation index, live birth index, viability index, lactation index).
Differences between control and treated groups were considered significant at p ≤ 0.05 (indicated with a) or p ≤ 0.01 (indicated with b). For clinical chemistry the means for the dose groups were compared with those for the control group using the analysis of variance (ANOVA and DUNNETT's test). The assessment to whether certain characteristics on urinalyses differed in degree in the control and test groups was carried out using the chi2 test in appropriate two-by-two contingency tables.
Reproductive indices:
Female and male reproduction data were calculated using relevant data and formulas.
Offspring viability indices:
The total number of pups delivered and the number of live born and stillborn pups was noted, and the live birth index was calculated for F1a, F1b and F2 litters.
Clinical signs:
effects observed, non-treatment-related
Description (incidence and severity):
Only some spontaneous findings without any relation to dose occurred in a few animals of all groups including the controls. Mainly minor skin lesions, swelling of limbs or alopecia were found; furthermore, one control male showed a palpable mass at the flank towards the end of the study and for one 100 ppm male broken incisivi and chromodacryorrhea, which was also noted for one high dose female, were recorded. There were no particular substance-related clinical findings in P0 females during gestation periods for F1a or F1b litters. Without any dose-response relationship insufficient/no nesting activity was observed for several dams of all groups during gestation (F1a and F1b).Moreover, during the gestation period for the F1b pups blood in bedding was found in one high dose female and hemophthalmia in one 100 ppm dam, which died subsequently.
Mortality:
mortality observed, non-treatment-related
Description (incidence):
There were 2 P0 females (100 ppm) which died spontaneously; these deaths are not associated with treatment. One animal died during gestation of F1b litter (day 10 p.c.) and the other died during the delivery of F1b pups.
Body weight and weight changes:
effects observed, non-treatment-related
Description (incidence and severity):
During the whole study the mean body weights/body weight gains of the males and of the females (including gestation and lactation periods) do not show any influence of the test substance on these parameters. All differences between the controls and the animals of the substance-treated groups are assessed to be within the expected range of biological variation. This includes the few isolated statistically significant differences concerning body weight gain between the male controls and the 500 ppm males (week 9-10) and the female control and the 100 ppm group (week 4-5; lactation days 14-21 (F1 a) and week 18-19).
Food consumption and compound intake (if feeding study):
no effects observed
Description (incidence and severity):
There were no differences of biological relevance between the controls and the substance-treated groups concerning the food consumption of the P0 males during the premating period and the food intake of the P0 females during premating, gestation and lactation periods.
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
Urinalysis findings:
no effects observed
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:
not examined
Histopathological findings: neoplastic:
not examined
Reproductive function: oestrous cycle:
not examined
Reproductive function: sperm measures:
not examined
Reproductive performance:
no effects observed
Description (incidence and severity):
The male and female fertility indices for P0 maternal animals are shown in tabes 3 and 4.


Key result
Dose descriptor:
NOAEL
Remarks:
systemic toxicity
Effect level:
100 ppm
Based on:
test mat.
Sex:
female
Basis for effect level:
other: Increased mean absolute and relative kidney weights without any correlating morphological findings in next high group (500 ppm)
Key result
Dose descriptor:
NOAEL
Remarks:
systemic toxicity
Effect level:
20 ppm
Based on:
test mat.
Sex:
male
Basis for effect level:
other: Increased relative mean kidney weight at mid and high dose levels
Key result
Dose descriptor:
NOAEL
Remarks:
reproductive function
Effect level:
500 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
reproductive performance
Remarks on result:
other: highest dose tested
Key result
Critical effects observed:
no
Clinical signs:
effects observed, non-treatment-related
Description (incidence and severity):
Only some spontaneous findings were recorded in single P1 males and females during premating like microphthalmia (control group), chromodacryorrhea (100 ppm), maloclusion (20 ppm and 500 ppm) and alopecia (500 ppm). No particular clinical findings were noted for P1 dams except no or insufficient nesting activity, which was recorded for several dams of all groups including the control and which occurred without any dose-response relationship.
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, non-treatment-related
Description (incidence and severity):
Body weights and body weight gains were not adversely affected by the administration of the test substance to the parental animals of test groups (20, 100 and 500 ppm) during the whole study period including gestation and lactation periods of the dams for F2 litters. All differences between the controls and the substance-treated groups are regarded as spontaneous, including the sporadic and sometimes even statistically significantly increased or decreased body weight gains of the females in test groups 20 ppm, 100 ppm and 500 ppm during premating, gestation and lactation, which occurred without any dose-response relationship.
Food consumption and compound intake (if feeding study):
no effects observed
Description (incidence and severity):
No impairment of food consumption was recorded for the substance-treated P1 parental animals when compared to the controls, neither during the premating period nor during the gestation and lactation period of the P1females. All differences between the groups are without any biological relevance.
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
Urinalysis findings:
no effects observed
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
In comparison to controls, there was a statistically significant increase in the relative and absolute mean kidney weights of treated animals for which no correlating morphological finding was found at light microscopy (see tables 1 and 2).
Gross pathological findings:
no effects observed
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined
Reproductive function: oestrous cycle:
not examined
Reproductive function: sperm measures:
not examined
Reproductive performance:
no effects observed
Description (incidence and severity):
The male and female fertility indices are seen in tables 5 and 6. All pregnant females gave birth to litters with live-born pups. Consequently the gestation index was 100% for all groups. The live birth index was not substantially influenced.
Key result
Dose descriptor:
NOAEL
Remarks:
systemic toxicity
Effect level:
20 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: lower relative kidney weights in mid and high dose level
Key result
Dose descriptor:
NOAEL
Remarks:
reproductive function
Effect level:
500 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
reproductive performance
Remarks on result:
other: highest dose tested
Key result
Critical effects observed:
no
Clinical signs:
effects observed, non-treatment-related
Description (incidence and severity):
No abnormal clinical symptoms were recorded for the F1a and F1b pups. Only some clinical findings (e.g. shortened tail, lesion of hindlimbs and traumatic lesion of cornea) were detected in very few F1a and F1b pups of different groups without a clear dose-response relationship. These findings are finally assessed as spontaneous ones.
Mortality / viability:
mortality observed, treatment-related
Description (incidence and severity):
The number of pups, which died or were cannibalized from day 1 to day 4 post partum (before culling), was statistically increased in the 500 ppm group (F1a and F1b) and also marginally increased in the 100 ppm group of F1b in the 100 ppm group in comparison to the control group. As a consequence of the increased pup death from day 1 to 4 post partum in the F1a pups of the 500 ppm group the viability index of this group was significantly reduced. The lactation index, an indicator of pup survival from day 4 to 21 post partum, was not influenced by administration of the test substance, nor was the sex ratio affected (for details see tables 7 and 8).
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Only body weight gains of the high dose F1a pups were marginally impaired in comparison to the controls on days 7-14 p.p., which has to be attributed to the test substance administration. The statistically significantly reduced weight gain of the 100 ppm F1b pups, however, is assessed as a spontaneous effect due to the missing dose-response relationship (see table 9).
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:
not examined
Urinalysis findings:
not examined
Sexual maturation:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
effects observed, non-treatment-related
Description (incidence and severity):
The examination of stillborn pups, pups that died intercurrently, culled pups and surplus pups of F1a and F1b litters did not reveal any difference of biological relevance between the test groups either in the type or in the number of pup necropsy observations. The statistically significant increase of 20 ppm pups of the F1b generation, which showed findings at necropsy, is mainly caused by a higher number of pups with dilated renal pelvis; however, this finding is also present in the historical control data. Only very few of the large number of examined pups of all groups showed some other spontaneous findings like incisors sloped, hydroureter and focal liver necrosis.
Histopathological findings:
not examined
Behaviour (functional findings):
no effects observed
Description (incidence and severity):
As to the several morphological development stages monitored up to weaning there were no biologically relevant differences between the control and the substance-treated F1a or F1b pups. The statistically significantly lower number of F1b pups of test groups receiving 100 and 500 ppm with pinna unfolding on time and the statistically significantly higher number of low dose F1b pups with eye opening on time are not assessed as substance-related effects due to missing dose-response relationship.
Developmental immunotoxicity:
not examined
Key result
Dose descriptor:
NOAEL
Remarks:
systemic toxicity
Generation:
F1a
Effect level:
100 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: F1a pubs showed a lower mean pub body weight in comparison to the controls on days 7-14 p.p. at highest dose level
Key result
Dose descriptor:
NOAEL
Remarks:
systemic toxicity
Generation:
F1b
Effect level:
20 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: slightly increased number of F1b pubs iat mid and high level which died or were cannibalized and reduced viability index
Key result
Critical effects observed:
no
Clinical signs:
effects observed, non-treatment-related
Description (incidence and severity):
For a few pups some spontaneous findings like edema of the hindlimbs, lesion of/or shortened tail and lesion of hind-and/or forelimbs were recorded without any dose-response relationship.
Mortality / viability:
mortality observed, treatment-related
Description (incidence and severity):
The number of pups, which died or were cannibalized from days 0-4 p.p. was increased in the 500 ppm-group in comparison to the control group and as a consequence, the viability index as an indicator of the pups' viability during the first 4 days after birth was lowest in this test group; this has to be assessed as a substance-induced effect. The statistically significantly increased number of cannibalized pups in the 20 ppm group, however, is regarded as an incidental finding, which was mainly caused by one dam, which cannibalized already 7 out of the 16 pups cannibalized in total. The lactation index as an indicator how pups were nursed during the rest of their rearing varied for F2 pups between 100% (20 ppm) and 97% (500 ppm) and did not show any substantial differences between the groups (see table 10).
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
The mean pup body weights of the 500 ppm group are statistically significantly lower in comparison to the relevant control values on days 14 and 21 p.p.; moreover, weight gain of these pups is impaired on days 4-7, 7-14 and 4-21 p.p., which has to be attributed to the test substance administration.
All other differences between the groups concerning pup body weight data of the F2 generation are of spontaneous nature.
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:
not examined
Urinalysis findings:
not examined
Sexual maturation:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
effects observed, non-treatment-related
Description (incidence and severity):
All recorded pup necropsy observations (e.g. incisors sloped, cataract, dilated renal pelvis etc.) occurred without a clear dose-response relationship. They were recorded for a very few pups of different groups with or without involvement of the control group and are assessed as being of spontaneous origin.
Histopathological findings:
not examined
Behaviour (functional findings):
effects observed, treatment-related
Description (incidence and severity):
The statistically significantly lower number of high dose pups, which showed auditory canal opening on time is probably connected with the retarded, substance-related growth of these pups.
As to the morphological development stages monitored up to weaning, the number of pups of test groups 20, 100 and 500 ppm showing pinna unfolding on time was statistically significantly reduced in comparison to the control group; however, due to missing dose-response relationship and the unexpected high number of control pups with a positive test result, this is finally assessed as an incidental finding. This is also assumed for the lower number of pups of the intermediate dose group with a positive test result on eye opening (see table 12).
In behavioral test, no substantial differences could be noted between the F2 pups of test groups 20,100, 500 ppm and the control pups. The observable differences are without any biological relevance
Developmental immunotoxicity:
not examined
Key result
Dose descriptor:
NOAEL
Remarks:
systemic toxicity
Generation:
F2
Effect level:
100 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: significant lower mean body weight and higher number of pubs with delayed auditory canal opening at high dose level (500 ppm)
Key result
Critical effects observed:
no
Key result
Reproductive effects observed:
no

The homogeneous distribution of the test substance in the rat food used was also confirmed. According to the results of the concentration control analyses the minimum content of the test substance in the food was generally guaranteed.

Table 1: Mean values of absolute kidney weights (in g) in males and females of the P0 and P1 generation

 

0 ppm

20 ppm

100 ppm

500 ppm

Males P0

3.376 ± 0.287

3.38 ± 0.337

3.492 ± 0.281

3.694 ± 0.231**

Females P0

2.098 ± 0.146

2.12 ± 0.186

2.157 ± 0.142

2.286 ± 0.166**

Males P1

3.084 ± 0.239

3.136 ± 0.324

3.326 ± 0.3*

3.562 ± 0.282**

Females P1

2.03 ± 0.16

2.107 ± 0.201

2.048 ± 0.157

2.189 ± 0.181**

*P ≤ 0.05; ** P ≤ 0.01 (Dunnett-Test, two-sided)

Table 2: Mean values of relative kidney weights (in g) in males and females of the P0 and P1 generation

 

0 ppm

20 ppm

100 ppm

500 ppm

Males P0

0.61 ± 0.047

0.624 ± 0.042

0.646 ± 0.049*

0.687 ±0.048**

Females P0

0.668 ± 0.043

0.677 ± 0.054

0.685 ± 0.039

0.731 ± 0.051**

Males P1

0.57 ± 0.053

0.6 ± 0.048

0.625 ± 0.052**

0.664 ± 0.043**

Females P1

0.688 ±0.043

0.71 ± 0.048

0.725 ± 0.051*

0.746 ± 0.045**

*P ≤ 0.05; ** P ≤ 0.01 (Dunnett-Test, two-sided)

Table 3: Male fertility indices for P0 males (in %)

 

0 ppm

20 ppm

100 ppm

500 ppm

Concerning F1a litter

100

88

96

96

Concerning F1b litter

100

92

96

100

Observable differences concerning the male fertility indices for F1a and F1b between the groups are assessed as being of spontaneous nature and not related to the test substance administration. All values are in the range of the historical control.

Table 4: Female fertility indices and live birth data for P0 females (in %)

 

0 ppm

20 ppm

100 ppm

500 ppm

Female fertility index concerning F1a litter

100

88

96

96

Live birth index concerning F1a litter

96

98

97

95

Female fertility index concerning F1b litter

100

96

96

100

Live birth index concerning F1b litter

97

98

96

97

Table 5: Male fertility indices for P1 males (in %)

 

0 ppm

20 ppm

100 ppm

500 ppm

Concerning F2 litter

100

100

92

96

Table 6: Female fertility indices and live birth data for P1 females (in %)

 

0 ppm

20 ppm

100 ppm

500 ppm

Female fertility index concerning F2 litter

100

100

92

96

Live birth index concerning F2 litter

99

98

97

97

Table 7: Summary of F1a litter data regarding mortality and viability

 

0 ppm

20 ppm

100 ppm

500 ppm

Pubs died

6 (1.7%)

2 (0.7%)

9 (2.6%)

9 (2.5%)

Pubs cannibalized

2 (0.6%)

4 (1.4%)

8 (2.3%)

14 (3.9%)b

Pubs dead (day 1 to 4)

7 (2%)

6 (2.1%)

13 (3.8%)

20 (5.9%)a

Pubs surviving days 0 to 4 (viability index)

341 (98%)

277 (98%)

324 (96%)

316 (93%)b

Pubs surviving days 4 to 21 (lactation index)

200 (100%)

169 (100%)

190 (99%)

188 (100%)

Significantly different from control: a= P<0.05; b= P<0.01; pubs dead=pubs died + scarified moribund + cannibalized

Table 8: Summary of F1b litter data regarding mortality and viability

 

0 ppm

20 ppm

100 ppm

500 ppm

Pubs died

5 (1.3%)

7 (2%)

13 (3.7%)b

9 (2.3%)

Pubs cannibalized

1 (0.3%)

5 (1.4%)

4 (1.1%)

8 (2%)a

Pubs dead (day 1 to 4)

4 (1%)

7 (2.1%)

9 (2.7%)

11 (2.9%)

Pubs surviving days 0 to 4 (viability index)

379 (99%)

330 (98%)

324 (96%)a

363 (96%)b

Pubs surviving days 4 to 21 (lactation index)

199 (100%)

179 (97%)

172 (98%)

199 (100%)

Significantly different from control: a= P<0.05; b= P<0.01; pubs dead=pubs died + scarified moribund + cannibalized

Table 9: Summary of F1a and F1b pub body weight data in g (days 7-14 p.p.)

 

0 ppm

20 ppm

100 ppm

500 ppm

Males (F1a)

18.3 ± 1.42

18.2 ± 1.34

17.9 ± 1.50

17.2 ± 1.15b

Females (F1a)

17.9 ± 1.31

17.7 ± 1.31

17.3 ± 1.42

16.9 ± 1.27a

Males + females (F1a)

18.1 ± 1.34

18.0 ± 1.27

17.6 ± 1.41

17.0 ± 1.19

Males (F1b)

18.2 ± 1.19

17.8 ± 1.36

16.9 ± 2.27b

17.3 ± 1.75

Females (F1b)

17.7 ± 1.12

17.3 ± 1.36

16.1 ± 2.61b

17.0 ± 1.72

Males + females (F1b)

18.0 ± 1.12

17.5 ± 1.31

16.5 ± 2.34a

17.2 ± 1.71

Significantly different from control: a= P<0.05; b= P<0.01

Table 10: Summary of F2 litter data regarding mortality and viability

 

0 ppm

20 ppm

100 ppm

500 ppm

Pubs died

14 (4.3%)

6 (2.1%)

21 (6.9%)b

28 (7.8%)

Pubs cannibalized

3 (0.9%)

16 (5.5%)b

5 (1.6%)

10 (2.8%)

Pubs dead (day 1 to 4)

16 (5%)

20 (7%)

22 (7.4%)

19 (5.5%)

Pubs surviving days 0 to 4 (viability index)

305 (95%)

262 (92%)

275 (93%)

314 (91%)

Pubs surviving days 4 to 21 (lactation index)

193 (99%)

179 (100%)

167 (98%)

183 (97%)

Significantly different from control: a= P<0.05; b= P<0.01; pubs dead=pubs died + scarified moribund + cannibalized

Table 11: Summary of F2 pub body weight data in g (days 4-21 p.p.)

 

0 ppm

20 ppm

100 ppm

500 ppm

Males (F2)

46.8 ± 4.07

45.1 ± 3.53

45.2 ± 3.25

43.4 ± 5.17a

Females (F2)

43.8 ± 3.50

42.5 ± 3.22

42.5 ± 3.33

40.5 ± 5.90a

Males + females (F2)

45.2 ± 3.64

43.8 ± 3.26

43.8 ± 3.18

41.9 ± 5.59a

Significantly different from control: a= P<0.05; b= P<0.01

Table 12: Summary of pubs physical development (F2 litter)

 

0 ppm

20 ppm

100 ppm

500 ppm

Pinna unfolding:

Litters tested

Pubs tested

Pubs reaching criteria

 

25

25

22

24

305

262

275

314

302 (99%)

236 (90%)b

254 (92%)b

290 (92%)b

Auditory canal opening

Litters tested

Pubs tested

Pubs reaching criteria

 

25

25

22

24

193

179

167

183

191 (99%)

175 (98%)

167 (100%)

171 (93%)b

Eye opening

 

Litters tested

25

25

22

24

Pubs tested

193

179

167

183

Pubs reaching criteria

185 (96%)

169 (94%)

149 (89%)a

171 (93%)

Significantly different from control: a= P<0.05; b= P<0.01

Conclusions:
The continuous administration of MCPP-P acid to rats as a constant homogeneous addition to the diet over two generations caused only marginal signs of systemic toxicity in the highest dose group (500 ppm) in F0 and F1 parents (increased absolute and relative kidney weights without any correlating morphological findings).
Adverse substance-induced effects which were noted for the progeny of the F0 and/or F1 parents were an increased pup mortality in the 500 ppm (F1a, F1b and F2 litters) and 100 ppm (F1b litters only) groups and retarded growth/development of the high dose F1a and F2 pups.
20 ppm were tolerated by both parental generations and their offspring without any changes which could be causally related to the test substance administered.
MCPP-P acid had no adverse effects on reproductive parameters or reproductive organs of the parental animals of both generations (F0 and F1) and of all groups (20, 100 and 500 ppm).
The NOAEL concerning reproductive function is 500 ppm (corresponding to 50 mg/kg bw/day).
The NOAEL concerning systemic toxicity for F0 and F1 parental animals as well as for developmental toxicity for the F1 and F2 progeny is 20 ppm (corresponding to 2 mg/kg bw/day). Thus, there was no indication for specific developmental toxicity as the effects in the progeny occurred at a dose level of parental toxicity.
Executive summary:

A two-generation reproduction toxicity study according to OECD TG 416 and GLP was conducted with MCPP-P acid (CAS 7085-19-0, racemic form). Groups of 25 male and female Wistar rats were given 0, 20, 100, or 500 ppm (0, 2, 10 and 50 mg/kg bw/day) test substance in the diet for their whole lifetime (P0 generation). At least 70 days after the beginning of treatment, P0 animals were mated to produce a first litter (F1a) and subsequently re-mated to produce a second litter (F1b, retained only until weaning). Groups of 25 males and 25 females selected from F1a pups as P1 parental generation were offered diets containing 0; 20; 100 and 500 ppm of the test substance post weaning, and the breeding program was repeated to produce F2 litter. For all parental animals, food consumption was recorded and animals were assessed by gross pathology, histopathological examination, analysis of blood and urinalysis. In the highest dose group of 500 ppm, both parental generations showed increased absolute and relative kidney weights in both sexes. In the mid-dose group, increased relative kidney weights were detected for males only in the P0 animals and increased absolute (males only) and relative (both sexes) kidney weights in the P1 parental animals. In the lowest dose group of 20 ppm, both parental generations did not show any abnormalities concerning clinical and clinicochemical examinations, urinalysis and pathology. The NOAEL for systemic maternal toxicity is 100 ppm for P0 females and 20 ppm for P0 males and 20 ppm for both sexes of the P1 parental generation. For the F1a and F1b pubs, a slightly increased number of pubs which died or were cannibalized (days 0-4 p.p.) and consequently reduced viability indices were observed at the highest does group of 500 ppm accompanied by marginal impairment of F1a pub body weight gain between days 7-14 p.p. For the F2 pubs at this dose level this was observed as well. In addition, F2 pubs showed a lower mean pub body weight in comparison to the controls on days 4-7, 7-14 and 4-21 p.p. and higher number of pubs with delayed auditory canal opening. At 100 ppm, only F1 pubs showed slightly increased number of F1b pubs which died or were cannibalized and reduced viability index, F2 pubs showed nothing abnormal. For the lowest dose group, F1 and F2 pubs showed no abnormality.

Finally, the continuous administration of MCPP-P acid to rats as a constant homogeneous addition to the diet over two generations caused only marginal signs of systemic toxicity in the highest dose group (500 ppm) in F0 and F1 parents (increased absolute and relative kidney weights without any correlating morphological findings).

Adverse substance-induced effects which were noted for the progeny of the F0 and/or F1 parents were an increased pup mortality in the 500 ppm (F1a, F1b and F2 litters) and 100 ppm (F1b litters only) groups and retarded growth/development of the high dose F1a and F2 pups.

20 ppm were tolerated by both parental generations and their offspring without any changes which could be causally related to the test substance administered.

MCPP-P acid had no adverse effects on reproductive parameters or reproductive organs of the parental animals of both generations (F0 and F1) and of all groups (20, 100 and 500 ppm).

The NOAEL concerning reproductive function is 500 ppm (corresponding to 50 mg/kg bw/day).

The NOAEL concerning systemic toxicity for F0 and F1 parental animals as well as for developmental toxicity for the F1 and F2 progeny is 20 ppm (corresponding to 2 mg/kg bw/day). Thus, there was no indication for specific developmental toxicity as the effects in the progeny occurred at a dose level of parental toxicity.

Effect on fertility: via oral route
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
50 mg/kg bw/day
Study duration:
subchronic
Species:
rat
Quality of whole database:
OECD TG 416 (Read-Across)
Effect on fertility: via inhalation route
Endpoint conclusion:
no study available
Effect on fertility: via dermal route
Endpoint conclusion:
no study available
Additional information

A two-generation reproduction toxicity study according to OECD TG 416 and GLP was conducted with MCPP-P acid (CAS 7085-19-0, racemic form). Groups of 25 male and female Wistar rats were given 0, 20, 100, or 500 ppm (0, 2, 10 and 50 mg/kg bw/day) test substance in the diet for their whole lifetime (P0 generation). At least 70 days after the beginning of treatment, P0 animals were mated to produce a first litter (F1a) and subsequently re-mated to produce a second litter (F1b, retained only until weaning). Groups of 25 males and 25 females selected from F1a pups as P1 parental generation were offered diets containing 0; 20; 100 and 500 ppm of the test substance post weaning, and the breeding program was repeated to produce F2 litter. For all parental animals, food consumption was recorded and animals were assessed by gross pathology, histopathological examination, analysis of blood and urinalysis. In the highest dose group of 500 ppm, both parental generations showed increased absolute and relative kidney weights in both sexes. In the mid-dose group, increased relative kidney weights were detected for males only in the P0 animals and increased absolute (males only) and relative (both sexes) kidney weights in the P1 parental animals. In the lowest dose group of 20 ppm, both parental generations did not show any abnormalities concerning clinical and clinicochemical examinations, urinalysis and pathology. The NOAEL for systemic maternal toxicity is 100 ppm for P0 females and 20 ppm for P0 males and 20 ppm for both sexes of the P1 parental generation. For the F1a and F1b pubs, a slightly increased number of pubs which died or were cannibalized (days 0-4 p.p.) and consequently reduced viability indices were observed at the highest does group of 500 ppm accompanied by marginal impairment of F1a pub body weight gain between days 7-14 p.p. For the F2 pubs at this dose level this was observed as well. In addition, F2 pubs showed a lower mean pub body weight in comparison to the controls on days 4-7, 7-14 and 4-21 p.p. and higher number of pubs with delayed auditory canal opening. At 100 ppm, only F1 pubs showed slightly increased number of F1b pubs which died or were cannibalized and reduced viability index, F2 pubs showed nothing abnormal. For the lowest dose group, F1 and F2 pubs showed no abnormality.

Finally, the continuous administration of MCPP-P acid to rats as a constant homogeneous addition to the diet over two generations caused only marginal signs of systemic toxicity in the highest dose group (500 ppm) in F0 and F1 parents (increased absolute and relative kidney weights without any correlating morphological findings).

Adverse substance-induced effects which were noted for the progeny of the F0 and/or F1 parents were an increased pup mortality in the 500 ppm (F1a, F1b and F2 litters) and 100 ppm (F1b litters only) groups and retarded growth/development of the high dose F1a and F2 pups.

20 ppm were tolerated by both parental generations and their offspring without any changes which could be causally related to the test substance administered.

MCPP-P acid had no adverse effects on reproductive parameters or reproductive organs of the parental animals of both generations (F0 and F1) and of all groups (20, 100 and 500 ppm).

The NOAEL concerning reproductive function is 500 ppm (corresponding to 50 mg/kg bw/day).

The NOAEL concerning systemic toxicity for F0 and F1 parental animals as well as for developmental toxicity for the F1 and F2 progeny is 20 ppm (corresponding to 2 mg/kg bw/day). Thus, there was no indication for specific developmental toxicity as the effects in the progeny occurred at a dose level of clear parental toxicity (MCPP-P Task Force 92/10869; 1992).

Effects on developmental toxicity

Description of key information

No study on teratogenicity with the target substance MCPP-P 2-EHE is available. But two OECD TG 414 studies with MCPP-P acid, which is the main hydrolysis product of MCPP-P 2-EHE in vivo are used for read-across. Both compounds have similar toxicological profiles with respect to dose level and target organ. There were no indications of any specific developmental toxicity or teratogenicity in both OECD TG 414 studies, neither in rabbits nor in rats. The lowest NOAEL for maternal as well as for developmental toxicity including teratogenicity was 50 mg/kg bw/day for rats and rabbits.

Link to relevant study records

Referenceopen allclose all

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
15 July 1991 - 27 August 1991
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Version / remarks:
1981
Qualifier:
according to guideline
Guideline:
EPA OPP 83-3 (Prenatal Developmental Toxicity Study)
Version / remarks:
November 1984
GLP compliance:
yes
Limit test:
no
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- batch No.of test material: 91-1

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: room temperature
- Stability under test conditions: The stability of the test substance suspensions over a period of up to 24 hours at room temperature was demonstrated.









Species:
rabbit
Strain:
Himalayan
Remarks:
Chbb:HM (outbred strain)
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Karl Thomae, Biberach an der Riss, FRG
- Age at study initiation: between 21 and 26 weeks old
- Weight at study initiation: mean 2.542 kg
- Housing: singly in type K 300/8 stainless steel wire mesh cages supplied by BECK ER & CO., Castrop-Rauxel, FRG
- Diet and water: ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 24 °C
- Humidity (%): 30 - 70 %
- Air changes (per hr): no data (fully air-conditioned rooms)
- Photoperiod (hrs dark / hrs light): 12 / 12
Route of administration:
oral: gavage
Vehicle:
other: 0.5% aqueous carboxymethyl cellulose solution (Tylose CB 30.000)
Details on exposure:
The volume administered each day was 10 mL/kg body weight. The calculation of the volume administered was based on the individual body weight determined at the beginning of the administration period (day 7 p.i.).

PREPARATION OF DOSING SOLUTIONS: Each day the test substance suspensions were freshly prepared shortly before the test substance was administered. For the preparation of the suspensions, an appropriate amount of the test substance was weighed and subsequently suspended in a 0.5% aqueous carboxymethyl cellulose solution using a high speed sonicator (Ultra Turrax, JANKE & KUNKEL KG, FRG). A magnetic stirrer was used to keep the suspensions homogeneous during treatment of the animals.

VEHICLE
- Justification for use and choice of vehicle: Carboxylmethyl cellulose (CMC)
- Concentration in vehicle: 0.5% aqueous CMC solution
- Amount of vehicle (if gavage): 10 mL/kg
- Purity: purified carboxylmethyl cellulose supplied by Hoechst AG (Tylose CB 30,000)
Analytical verification of doses or concentrations:
yes
Remarks:
HPLC
Details on analytical verification of doses or concentrations:
Analytical verifications of the stability of the test substance suspensions of the test substance for a period of at least 24 hours at room temperature were carried out for a similar batch in a prenatal range-finding study in rats. Samples of the test substance suspensions were sent to the analytical laboratories twice during the study period for verification of the concentrations. The samples which were sent for the first concentration control analysis toward the beginning of the administration period were also used to verify the homogeneity for the samples of the low and the high concentrations (5 and 50 mg/kg body weight/day). 6 samples (2 from the top, middle and bottom in each case) were taken for each of these concentrations from the beaker with a magnetic stirrer running. Moreover retain samples of the test substance suspension (test group 50 mg/kg bw/day) were sent to the analytical laboratories for additional verification of the analytical result. The test substance suspensions were analyzed by HPLC.
Details on mating procedure:
After an acclimatization period, the does were fertilized by means of artificial insemination. This implied that 0.2 mL of a synthetic hormone which releases LH and FSH from the anterior pituitary lobe (Receptal®, trademark of HOECHST AG, Frankfurt) was injected intramuscularly to the female rabbits about 1 hour before insemination. The pooled ejaculate samples used for the artificial insemination were derived from male Himalayan rabbits of the same breed as the females. The male donors were kept under conditions (air conditioning, diet, water) comparable to those of the females participating in this study. The day of insemination was designated as day 0 (beginning of the study) and the following day as day 1 post insemination (p.i.).
Duration of treatment / exposure:
During the period of major organogenesis (day 7 to day 19 p.i.).
Frequency of treatment:
Once a day always at approx. the same time of day.
Duration of test:
On day 29 p.i., all surviving females were sacrificed in a randomized order and examined macroscopically. The fetuses were dissected from the uterus and further investigated with different methods.
Dose / conc.:
5 mg/kg bw/day
Dose / conc.:
20 mg/kg bw/day
Dose / conc.:
50 mg/kg bw/day
No. of animals per sex per dose:
15
Control animals:
yes, concurrent vehicle
Details on study design:
- Due to technical reasons, the study was carried out in 3 sections. Each dose group was represented in each section. A treatment interval of 7 days elapsed before the next section.
- Dose selection rationale: 5 mg/kg bw/day as the expected NOAEL, 20 mg/kg bw/day as a dose which might be a minimal toxic effect level for dams and/or fetuses, 50 mg/kg bw/day as the dose with maternally toxic effects at which findings in fetuses may also be obtained. The selection of doses for the present examination was based on the results of several previous studies.

Maternal examinations:
CLINICAL EXAMINATIONS: Yes
The animals were examined for clinical symptoms at least once a day, or more often when clinical signs of toxicity were elicited (days 0 - 29 p.i.). A check for mortality was made twice a day on working days or once a day (Saturday, Sunday or on public holidays) (days 0 - 29 p.i.).
BODY WEIGHT: Yes
All animals were weighed on days 0, 2, 4, 7, 9, 11, 14, 16, 19, 21, 23, 25 and 29 p.i. The body weight change of the animals was calculated from these results. Furthermore, the corrected body weight gain was calculated after terminal sacrifice (terminal body weight on day 29 p.i. minus weight of the uterus before it was opened minus body weight on day 7 p.i.).
FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes
The consumption of food was determined daily during the entire study period.
POST-MORTEM EXAMINATIONS: Yes
On day 29 p.i., the surviving dams were sacrificed in randomized order by intravenous injection of a pentobarbital and the fetuses were dissected from the uterus. Dams which died intercurrently as well as the contents of the uterus from these animals were investigated, if possible in the same way as at terminal sacrifice (exception: uterus weight).
After the dams had been sacrificed, they were necropsied and assessed by gross pathology.The uterus and the ovaries were removed and the following data were recorded:
- Weight of uterus before it was opened
- Number of corpora lutea
- Number and distribution of implantation sites classified as: live fetuses or dead implantations (early resoprtions, late resoprtions, dead fetuses)

Ovaries and uterine content:
The ovaries and uterine were removed and examined: Yes
Cesarean sections were performed on day 29 p.i.
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Number of dead and live fetuses: Yes
- Other: Individual placental weights were recorded.
Fetal examinations:
Examination of the fetuses after dissection from the uterus: At necropsy each fetus was weighed and examined macroscopically for any external findings. Furthermore, the viability of the fetuses and the condition of the placentae, the umbilical cords, the fetal membranes and fluids were examined. Individual placental weights were recorded.
Soft tissue examination of the fetuses: After the fetuses had been sacrificed by CO2, the abdomen and thorax were opened in order to be able to examine the organs in situ before they were removed. The heart and the kidneys were sectioned in order to assess the internal structure.
The sex of the fetuses was determined by internal examination of the gonads. If heads of fetuses revealed severe findings (e.g. anophthalmia, microphthalmia, hydrocephalus, or cleft palate), the heads of these fetuses were severed from the trunk, fixed in BOUIN's solution and later processed and assessed according to WILSON's method. About 10 transverse sections were prepared per head. After the examination the heads treated in this way were discarded.
Skeletal examination of the fetuses: After the soft tissue examination all fetuses were placed in ethyl alcohol for staining of the skeletons (with the possible exception of the skulls) according to a modified method of DAWSON. The stained skeletons were placed on an illuminated plate and examined, evaluated and assessed. After the examination the stained skeletons were retained by litter.
- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: all per litter
- Skeletal examinations: Yes: all per litter
- Head examinations: Yes: animals with heads revealing severe findings
Statistics:
DUNNETT's Test was used for statistical evaluation of food consumption, body weight, body weight change, corrected body weight gain (net maternal body weight change), weight of the uterus before it was opened, weight of fetuses, weight of placentae, corpora lutea, implantations, pre- and postimplantation losses, resorptions and live fetuses.
FISHER's Exact Test was used for statistical evaluation of conception rate, mortality (of the dams) and all fetal findings.
Indices:
Calculations of conception rate (in %) and pre- and postimplantation losses (in %) were carried out.
Clinical signs:
effects observed, non-treatment-related
Description (incidence and severity):
One doe of test group 1 (5 mg/kg body weight/ day) died spontaneously on day 7 p.i. immediately after the first gavaging (but without any clear indications for misgavaging). Furthermore, two does showed minor skin lesions in the laryngeal area (50 mg/kg body weight/day). There were no abnormal clinical findings for any other does in the study.
Mortality:
mortality observed, non-treatment-related
Description (incidence):
One low dose dam was found dead on day 7 p.i. Although this female died immediately after the first gavaging, no clear indications for misgavaging, but some unspecific lung lesions were found at necropsy.
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
effects observed, non-treatment-related
Description (incidence and severity):
All differences between the groups including the statistically significantly increased food consumption of the high dose group (50 mg/kg body weight/day) on days 27 - 28 p.i. (post treatment period) and the statistically significantly reduced food intake of the 5 and 20 mg/kg does on days 0 - 7 p.i. are assessed as being of spontaneous nature and without any biological significance.
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:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Description (incidence and severity):
All values for uteri weights lie within the range of biological variation. This includes the relatively low mean gravid uterus weight in the 50 mg/kg bw/day group, which is caused by an incidentally lower number of live fetuses/doe in comparison to the control group.
Gross pathological findings:
effects observed, non-treatment-related
Description (incidence and severity):
Only some spontaneous necropsy findings were recorded for single animals of all dose groups including the controls. Most of these findings have to be related to the sacrifice of the animals (lungs with edema and/or marginal emphysema); moreover, agenesia of gallbladder (one control animal), lung with focal hemorrhages in one lobe (animal in 5 mg/kg body weight/day group) which died intercurrently), skin lesions (two animals in 50 mg/kg body weight/day group) and blind ending uterine horns (one animal in 50 mg/kg body weight/day group) were observed.
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined
Number of abortions:
no effects observed
Pre- and post-implantation loss:
no effects observed
Total litter losses by resorption:
not examined
Early or late resorptions:
effects observed, non-treatment-related
Description (incidence and severity):
There was a slight, statistically significant increase in the number of late resorptions at 50 mg/kg body weight/ day (see table 1). However, the total number of late resorptions in this group (5 of a total of 96 implantations) was small, and in the context of the overall postimplantation loss, was considered not to be associated with treatment. The respective values calculated for the high dose group are fully in the historical control range.
Dead fetuses:
no effects observed
Changes in pregnancy duration:
not examined
Description (incidence and severity):
Migrated Data from removed field(s)
Field "Effects on pregnancy duration" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsMaternalAnimals.MaternalDevelopmentalToxicity.EffectsOnPregnancyDuration): not examined
Changes in number of pregnant:
not examined
Key result
Dose descriptor:
NOAEL
Effect level:
50 mg/kg bw/day
Based on:
test mat.
Basis for effect level:
other: no signs of adverse maternal toxicity in highest dose level of 50 mg/kg bw/day
Key result
Abnormalities:
no effects observed
Fetal body weight changes:
not examined
Description (incidence and severity):
Migrated Data from removed field(s)
Field "Fetal/pup body weight changes" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsFetuses.FetalPupBodyWeightChanges): no effects observed
Reduction in number of live offspring:
not examined
Changes in sex ratio:
no effects observed
Changes in litter size and weights:
not examined
Changes in postnatal survival:
not examined
External malformations:
effects observed, non-treatment-related
Description (incidence and severity):
Only one type of external variation (pseudoankylosis) was found, which occurred without any relation to dosing. It was seen in single fetuses of all groups except test group which received 50 mg/kg body weight/day. There were no so-called unclassified observations (like placentae fused) in any of the fetuses.
Skeletal malformations:
effects observed, non-treatment-related
Description (incidence and severity):
Malformations of the fetal skeletons were noted for 2 out of 97 control fetuses (in 1 out of 14 litters) and 1 out of 96 intermediate dose fetuses (in 1 out of 15 litters). These malformations were related to the vertebral column (cervical/thoracic vertebral body/bodies fused and/or of irregular shape) and the ribs (fused).The variations elicited were related to the skull (splitting of skull bones, epactal bone between nasal and frontal bones), the ribs (accessory 13th rib(s) and rudimentary cervical rib(s)), the vertebral column (accessory thoracic vertebra) and the sternum (sternebra(e) of irregular shape, fused or accessory sternebra). Most of these skeletal variations occurred without a clear dose-response relationship and/or without any biologically relevant, statistically significant differences between the groups; however, the occurrence of fused or irregular-shaped sternebra(e) and consequently the fetal and litter incidence of overall skeletal variations was clearly increased in the 20 mg/kg bw/day group. Both findings were also found quite frequently in the historical control data. Therefore and because no dose-response relationship is present, the increased number of fetuses with skeletal variations in the intermediate dose group is assessed as being of spontaneous nature. In all groups signs of retardations (incomplete or missing ossification of skull bones, vertebral column and sternebra(e)) were found; they occurred in a comparable frequency in the control and the substance-treated groups. All differences between the groups concerning fetal skeletal retardations are without any biological relevance.
Visceral malformations:
effects observed, non-treatment-related
Description (incidence and severity):
One control and one high dose fetus each showed soft tissue malformations. For the control fetus agenesia of gallbladder was observed, while the high dose fetus had a septal defect, which led also to a dilated aortic arch and a dilated aorta descendens. All soft tissue malformations present at a low incidence in the historical control data and are assessed as being of spontaneous nature. Variations were detected in each group including the control; all occurred without a clear dose-response relationship and/or can be found at a comparable incidence in the historical control data. Aside from a separated origin of carotids, a very common finding in the rabbit strain used, another soft tissue variation (heart with traces of interventricular foramen/septum membranaceum) was also found quite frequently.Furthermore, one fetus of the low and intermediate dose group each (5 and 20 mg/kg body weight/day) exhibited hypoplasia of gallbladder and another one (20 mg/kg body weight/day) showed dilated renal pelvis. One control fetus showed a so-called unclassified observation (focal liver necrosis).
Key result
Dose descriptor:
NOAEL
Effect level:
50 mg/kg bw/day
Based on:
test mat.
Basis for effect level:
other: no indications for adverse developmental toxicity or teratogenicity found up to the highest dose tested (50 mg/kg bw/day)
Key result
Abnormalities:
no effects observed
Key result
Developmental effects observed:
no

Table 1: Summary of basic results

 

control

5 mg/kg bw/day

20 mg/kg bw/day

50 mg/kg bw/day

No. of inseminated rabbits

15

15

15

15

No. of pregnant rabbits

15

15

15

14

No. of implantations/rabbit

7.3

7.1

6.8

6.9

No. of late resorptions/rabbit

0.1

0.0

0.1

0.4 (a)

No. of live fetuses/rabbit

6.9

6.5

6.4

5.9

Mean fetal weight (g)

40.2

40.1

39.5

40.7

No. of fetuses with incomplete ossification of sternebrae

28

30

23

30

Significantly different from control: a = P<0.05; b= P< 0.01

 

Conclusions:
The developmental toxicity study with MCPP-P acid (R-isomer, CAS 16484-77-8) in rabbits showed a NOAEL for maternal and developmental toxicity including teratogenicity 50 mg/kg bw/day, the highest dose level tested.
Executive summary:

A developmental toxicity study according to OECD TG 414 was conducted with 15 inseminated female Himalayan rabbits treated each daily orally by gavage with MCPP-P acid (R-isomer, CAS 16484-77-8). Doses of 0, 5, 20 and 50 mg/kg bw suspended test substance (vehicle: 0.5% aqueous carboxymethyl cellulose) was administered from day 7 through day 19 p.i. with a standard dose volume of 10 mL/kg. Food consumption and body weights of the animals were recorded regularly throughout the study period and the state of health of the animals was checked each day. On day 20 post coitum, all females were sacrificed and assessed by gross pathology. The fetuses were dissected from the uterus, sexed, weighed and further investigated for any external, soft tissue and/or skeletal findings. No signs of toxicity were elicited throughout the study period, neither for maternal nor for developmental toxicity up and including the highest dose tested. Based on the results of this full-scale prenatal toxicity study, the no observed adverse effect level (NOAEL) for maternal as well as developmental toxicity including teratogenicity is 50 mg/kg bw/day for MCPP-P acid (R-isomer) in rabbits.

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
9 July 1991 - 31 July 1991
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Version / remarks:
1981
Qualifier:
according to guideline
Guideline:
EPA OPP 83-3 (Prenatal Developmental Toxicity Study)
Version / remarks:
November 1984
GLP compliance:
yes
Limit test:
no
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- batch No.of test material: 91-1

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: room temperature
- Stability under test conditions: The stability of the test substance suspensions over a period of up to 24 hours at room temperature was demonstrated.
Species:
rat
Strain:
Wistar
Remarks:
Chbb:THOM (SPF)
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Karl Thomae, Biberach an der Riss, FRG
- Age at study initiation: about 61 to 66 days old
- Weight at study initiation: mean 222.8 g
- Housing: housed singly in type DK III stainless steel wire mesh cages supplied by BECKER & CO., Castrop-Rauxel, FRG
- Diet and water: ad libitum (ground Kliba 343 feed rat/mouse/hamster)
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 24 °C
- Humidity (%): 30 - 70 %
- Air changes (per hr): no data (fully air-conditioned rooms)
- Photoperiod (hrs dark / hrs light): 12 / 12
Route of administration:
oral: gavage
Vehicle:
other: 0.5% aqueous carboxymethyl cellulose solution (Tylose CB 30.000)
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
Each day the test substance suspensions were freshly prepared shortly before the test substance was administered. For the preparation of the suspensions, an appropriate amount of the test substance was weighed and subsequently suspended in a 0.5% aqueous carboxymethyl cellulose solution using a high speed sonicator (Ultra Turrax, JANKE & KUNKEL KG, FRG). A magnetic stirrer was used to keep the suspensions homogeneous during treatment of the animals.
The volume administered each day was 10 mL/kg body weight. The calculation of the volume administered was based on the individual body weight determined at the beginning of the administration period (day 6 p.c.).

VEHICLE
- Justification for use and choice of vehicle: carboxylmethyl cellulose (CMS)
- Concentration in vehicle: 0.5% aqueous CMC solution
- Amount of vehicle: 10 mg/mL
- Purity: purified carboxylmethyl cellulose supplied by Hoechst AG (Tylose CB 30.000)
Analytical verification of doses or concentrations:
yes
Remarks:
HPLC
Details on analytical verification of doses or concentrations:
Analytical verifications of the stability of the test substance suspensions up to 24 hours were carried out before the beginning of the study. The stability of the test substance suspensions was checked in a range-finding study in a comparable batch. Samples of the test substance suspensions were sent to the analytical laboratories twice during the study period for verification of the concentrations. The samples which were sent for the first concentration control analysis toward the beginning of the administration period were also used to verify the homogeneity for the samples of the low and the high concentrations (20 and 100 mg/kg body weight/day). 6 samples (2 from the top, middle and bottom in each case) were taken for each of these concentrations from the beaker with a magnetic stirrer running. The test substance suspensions were analyzed by HPLC.
Details on mating procedure:
After an acclimatization period , 4 untreated female rats were mated with one untreated fertile male animal of the same breed. If sperm were detected microscopically in the vaginal smear, the animals were considered to be fertilized. This day was designated "day 0" (beginning of the study) and the following day "day 1" post coitum (p.c.).
Duration of treatment / exposure:
During the period of major organogenesis (day 6 to day 15 p.c.).
Frequency of treatment:
Once a day always at approximately the same time of day.
Duration of test:
On day 20 p.c., all females were sacrificed in a randomized order and examined macroscopically. The fetuses were dissected from the uterus and further investigated with different methods.
Dose / conc.:
20 mg/kg bw/day
Dose / conc.:
50 mg/kg bw/day
Dose / conc.:
100 mg/kg bw/day
No. of animals per sex per dose:
25
Control animals:
yes, concurrent vehicle
Details on study design:
- Due to technical reasons, the study was carried out in 2 sections. Each dose group was represented in each section. A treatment interval of 2 days elapsed before the next section.
- Dose selection rationale: 20 mg/kg bw as the expected NOAEL, 50 mg/kg bw as a dose which might be a minimal toxic effect level for dams and/or fetuses, 100 mg/kg bw as the dose with maternally toxic effects at which findings in fetuses may also be obtained. This doses were fixed for the full-scale prenatal toxicity study on basis of previous prenatal studies.

Maternal examinations:
CLINICAL EXAMINATIONS: Yes
The animals were examined for clinical symptoms at least once a day, or more often when clinical signs of toxicity were elicited (days 0 - 20 p.c.). A check for mortality was made twice a day on working days or once a day (Saturday, Sunday or on public holidays) (days 0 - 20 p.c.).

BODY WEIGHT: Yes
All animals were weighed on days 0, 1, 3, 6, 8, 10, 13, 15, 17 and 20 p.c. The body weight change of the animals was calculated from these results. Furthermore, the corrected body weight gain was calculated after terminal sacrifice (terminal body weight on day 20 p.c. minus weight of the uterus before it was opened minus body weight on day 6 p.c.).

FOOD CONSUMPTION AND COMPOUND INTAKE: Yes
With the exception of day 0, the consumption of food was determined on the same days as was body weight.

POST-MORTEM EXAMINATIONS: Yes
On day 20 p.c., the dams were sacrificed in randomized order by cervical dislocation and the fetuses dissected from the uterus.
After the dams had been sacrificed, they were necropsied and assessed by gross pathology.

The uterus and the ovaries were removed and the following data were recorded:
- Weight of uterus before it was opened
- Number of corpora lutea
- Number and distribution of implantation sites classified as: live fetuses or dead implantations (early resorptions, late resorptions, dead fetuses)
Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Cesarean sections were performed on day 20 p.c.
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Number of dead and live fetuses: Yes
- Other: Individual placental weights were recorded.
Fetal examinations:
The fetuses were dissected from the uterus, sexed, weighed and further investigated for any external, soft tissue and/or skeletal findings.
At necropsy each fetus was weighed, sexed and examined macroscopically for any external findings. The sex was determined by observing the distance between the anus and the base of the genital tubercle and was later confirmed in all fetuses fixed in BOUIN'S solution by internal examination. If there were discrepancies between the "external" and the "internal" sex of a fetus, the fetus was finally sexed according to the appearance of its gonads.
Furthermore, the viability of the fetuses and the condition of the placentae, the umbilical cords, the fetal membranes and fluids were examined.
After these examinations, approximately one half of the fetuses per dam was placed in ethyl alcohol and the other half was placed in BOUIN's solution for fixation and further evaluation.
- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: half per litter
- Skeletal examinations: Yes: half per litter
- Head examinations: No data
Statistics:
DUNNETT's Test was used for statistical evaluation of food consumption, body weight, body weight change, corrected body weight gain (net maternal body weight change), weight of the uterus before it was opened, weight of fetuses, weight of placentae, corpora lutea, implantations, pre- and postimplantation losses, resorptions and live fetuses.
FISHER's Exact Test was used for statistical evaluation of conception rate, mortality (of the dams) and all fetal findings.
Indices:
Calculations of conception rate (in %) and pre- and postimplantation losses (in %) were carried out.
Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Mean body weights of the rats which received 100 mg/kg bw/day were slightly, but statistically significantly lower than the relevant control value on day 8 p.c . At the beginning of the treatment period (days 6 - 8 p.c.) the dams of test 100 mg/kg bw day lost some body weight; in the subsequent time, however, weight gain of the high dose dams sometimes reached or even exceeded (especially on days 8 - 10 p.c.) control values. If the body weight gain of the high dose dams during the whole treatment period, however, is calculated, these dams gained about 18% less than the control dams. The corrected body weight gain (terminal body weight on day 20 p.c. minus weight of the uterus before it was opened minus body weight on day 6 p.c.) was statistically significantly reduced in the test group which received 100 mg/kg bw/day. Body weights and body weight gains of the dams of test groups which received 20 mg/kg/bw day and 50 mg/kg bw/day were similar to those of the controls. All observed differences between these groups are without any biological relevance (see table 1)
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
Food consumption of the intermediate and high dose dams was statistically significantly reduced at the beginning of the treatment period (50 mg/kg bw/day group: days 6-8 p.c; 100 mg/kg bw/day group: days 6 - 10 p.c.; see table 2). The reduction in food intake (up to about 22% less food consumption than the controls) of the high dose dams has to be assessed as being clearly related to the test substance administration. The marginally reduced food consumption of the 50 mg/kg dams, which consumed up to about 9% less food than the controls, however, is assessed as being a spontaneous effect, because it was not accompanied by statistically significant impairments of body weights/weight gains. The food consumption of the dams of test group receiving 20 mg/kg bw/day did not show any differences of biological relevance if compared to the controls. During the post treatment period (days 15 - 20 p.c.) food consumption of the high dose dams reached control values.
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:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Description (incidence and severity):
The uterus weights of the animals were not influenced by the administration of the test substance. The differences between the groups are without biological relevance.
Gross pathological findings:
effects observed, non-treatment-related
Description (incidence and severity):
Edema of the lungs was recorded for one control, one low dose and two high dose dams. A
hemorrhagic liver was recorded for one control rat and one low dose rat showed a hydrometra; neither of these animals became pregnant.
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined
Number of abortions:
no effects observed
Pre- and post-implantation loss:
no effects observed
Total litter losses by resorption:
no effects observed
Early or late resorptions:
no effects observed
Dead fetuses:
not examined
Changes in pregnancy duration:
not examined
Description (incidence and severity):
Migrated Data from removed field(s)
Field "Effects on pregnancy duration" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsMaternalAnimals.MaternalDevelopmentalToxicity.EffectsOnPregnancyDuration): not examined
Changes in number of pregnant:
no effects observed
Description (incidence and severity):
The conception rate varied between 96% (control group) and 80% (20 and 100 mg/kg bw/day groups).
There were no substance-related and/or statistically significant differences of biological relevance between the groups in conception rate, in the mean number of corpora lutea and implantation sites or in the values calculated for the pre- and the postimplantation losses, the number of resorptions and viable fetuses. The differences evident are considered to be incidental and within the normal range of deviations for animals of this strain and age; this includes the incidental, relatively high number of live fetuses in the 100 mg/kg group, which is clearly higher than the corresponding control value (13.9 versus 12.8 live fetuses/dam), but is still fully within the historical control range (11.1 - 14.9 live fetuses/ dam). The high number of live fetuses in the 100 mg/kg group, however, is the reason for the marginally, but statistically significantly lower mean fetal body weight and the increased number of skeletal retardations in this group.
Key result
Dose descriptor:
NOAEL
Remarks:
systemic toxicity
Effect level:
50 mg/kg bw/day
Based on:
test mat.
Basis for effect level:
other: Reduced food consumption days 6-10 p.c. and lower body weight gain days 6-15 at high dose level (100 mg/kg bw/day)
Key result
Abnormalities:
no effects observed
Fetal body weight changes:
not examined
Description (incidence and severity):
Migrated Data from removed field(s)
Field "Fetal/pup body weight changes" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsFetuses.FetalPupBodyWeightChanges): no effects observed
Field "Description (incidence and severity)" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsFetuses.DescriptionIncidenceAndSeverityFetalPupBodyWeightChanges): The mean fetal weights were not influenced by the test substance administration. All values are within the range of biological variation. This includes the marginally, but statistically significantly lower fetal body weight in the 100 mg/kg bw/day group, which is caused by the increased number of live fetuses in this group.
Reduction in number of live offspring:
not examined
Changes in sex ratio:
no effects observed
Changes in litter size and weights:
not examined
Changes in postnatal survival:
not examined
External malformations:
effects observed, non-treatment-related
Description (incidence and severity):
An external malformation was recorded for one control fetus, only. For this fetus, an anasarca was noted. This malformation is also present in the historical control data. The external examination of the fetuses revealed no variations in any group. One so-called unclassified observation (placentae fused) was recorded for one fetus of test group 2 and one fetus of test group 3 (50 or 100 mg/kg body weight/day).
Skeletal malformations:
effects observed, treatment-related
Description (incidence and severity):
Various malformations of the sternum and/or the vertebral column were seen in 10 out of 158 (= 6.3%) fetuses (in 8 out of 24 litters (= 33%)) of the control, in 8 out of 141 (= 5.7%) fetuses (in 6 out of 20 litters (= 30%)) of the 20 mg/kg bw/day group, in 7 out of 155 (= 4.5%) fetuses (in 6 out of 23 litters (= 26%)) of the 50 mg/kg bw/day group and in 4 out of 144 (= 2.8%) fetuses (in 3 out of 20 litters (= 15%)) of the 100 mg/kg bw/day group. These differences were not statistically significant and did not show any dose-response relationship. Most of the skeletal variations recorded appeared without a clear dose-response relationship can be found in a similar frequency in the historical control data and/or the differences between the groups are without biological relevance; the statistically significantly increased number of 100 mg/kg bw/day fetuses, however, which showed rudimentary cervical rib(s), has to be related to the oral administration of the test substance to the dams. In all groups signs of retardations (incomplete or missing ossification of vertebral bodies/arches, sternebra(e), the skull and/or the hyoid bone) were found. In the 100 mg/kg bw/day group the number of fetuses with unossified sternebra(e) and the overall number of fetuses with skeletal retardations is statistically significantly increased (see table 3). The fetal and litter incidence of "not ossified sternebra(e)" is just above the historical control range. The increased number of high dose fetuses with retarded ossification, however, is not assessed as being substance-induced, but has to be related to the incidental, distinctly higher number of live fetuses/ dam in this test group in comparison to the control.
Visceral malformations:
no effects observed
Description (incidence and severity):
The examination of the organs of the fetuses revealed no malformations in any of the groups.
Variations (dilated renal pelvis and/or hydroureter) were detected in all groups without any statistically significant differences between the groups. All values are fully in the range of biological variation. No so-called unclassified observations (like blood coagulum around the placenta or urinary bladder) were recorded.
Other effects:
no effects observed
Description (incidence and severity):
The mean placental weights in all test were not influenced by the test substance administration and were similar to the control values.
Key result
Dose descriptor:
NOAEL
Effect level:
50 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: statistically significantly increased number of fetuses with a skeletal variation (rudimentary cervical rib) at high dose level (100 mg/kg bw/day)
Key result
Abnormalities:
effects observed, treatment-related
Localisation:
skeletal: supernumerary rib
Description (incidence and severity):
no sign of teratogenicity, but rather related to stress in dams
Key result
Developmental effects observed:
no

Table 1: Mean maternal body weight change during gestation days 6 to10.

 

control

20 mg/kg bw/day

50 mg/kg bw/day

100 mg/kg bw/day

Days 6 to 8

7.8 ± 2.91 g

5.5 ± 3.82 g

6.0 ± 4.45 g

-0.2 ± 4.67 g (b)

Days 8 to 10

9.9 ± 3.52 g

11.7 ± 5.04 g

11.4 ± 3.48 g

13.1 ± 5.13 (a)

Significantly different from control: a = P<0.05; b= P< 0.01

Table 2: Mean maternal food consumption during gestation days 6 to10.

 

control

20 mg/kg bw/day

50 mg/kg bw/day

100 mg/kg bw/day

Days 6 to 8

26.5 ± 2.61 g

24.2 ± 2.5 g

23.3 ± 2.58 g (a)

19.9 ± 2.6 g (b)

Days 8 to 10

25.9 ± 2.88 g

25.0 ± 3.03 g

25.3 ± 2.71 g

23.4 ± 3.17 (a)

Significantly different from control: a = P<0.05; b= P< 0.01

Table 3: Summary of basic results

 

control

20 mg/kg bw/day

50 mg/kg bw/day

100 mg/kg bw/day

No. of mated rats

25

25

25

25

No. of pregnant rats

24

20

23

20

No. of implantations/rat

13.8

14.9

13.8

14.9

No. of live fetus/rat

12.8

13.8

13.1

13.9

Mean fetal weight (g)

4.0

4.0

4.0

3.9 (a)

Rudimentary cervical ribs (fetal incidence)

6

5

9

26 (b)

Sternebrae not ossified

6

12

8

24 (b)

Significantly different from control: a = P<0.05; b= P< 0.01

Conclusions:
The developmental toxicity study with MCPP-P acid (R-isomer, CAS 16484-77-8) in rats showed a NOAEL for maternal toxicity of 50 mg/kg bw/day and a NOAEL for developmental toxicity of 50 mg/kg bw/day, while a NOAEL for teratogenicity was obtained at 100 mg/kg bw/day, the highest dose level tested.
Executive summary:

A developmental toxicity study according to OECD TG 414 was conducted with MCPP-P acid (R-isomer, CAS 16484-77-8). Four groups of 25 mated female Wistar rats received doses of 0, 20, 50 and 100 mg/kg bw/day by gavage from day 6 to 15 of gestation. The test substance was given in a 0.5% aqueous carboxymethyl cellulose suspension with a standard dose volume of 10 mL/kg. Food consumption and body weights of the animals were recorded regularly throughout the study period and the state of health of the animals was checked each day. On day 20 post coitum, all females were sacrificed and assessed by gross pathology. The fetuses were dissected from the uterus, sexed, weighed and further investigated for any external, soft tissue and/or skeletal findings. In the 100 mg/kg bw/day dams the statistically significant reduced food consumption during days 6-10 post coitus and the statistically significant lower body weight gain day 6-15 are clearly effects related to dosing.

No adverse effects were seen in the dams at 20 and 50 mg/kg bw/day. Regarding developmental toxicity, only in the highest dose group statistically significantly increased numbers of fetus with skeletal variations (rudimental cervical rib) were observed. The NOAEL for maternal toxicity is 50 mg/kg bw/day, the NOAEL for developmental toxicity is 50 mg/kg bw/day and the NOAEL for teratogenicity is 100 mg/kg bw/day.

Effect on developmental toxicity: via oral route
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
50 mg/kg bw/day
Study duration:
subacute
Species:
rat
Quality of whole database:
OECD TG 414 (Read-Across)
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 developmental toxicity study according to OECD TG 414 was conducted with MCPP-P acid (R-isomer, CAS 16484-77-8). Four groups of 25 mated female Wistar rats received doses of 0, 20, 50 and 100 mg/kg bw/day by gavage from day 6 to 15 of gestation. The test substance was given in a 0.5% aqueous carboxymethyl cellulose suspension with a standard dose volume of 10 mL/kg. Food consumption and body weights of the animals were recorded regularly throughout the study period and the state of health of the animals was checked each day. On day 20 post coitum, all females were sacrificed and assessed by gross pathology. The fetuses were dissected from the uterus, sexed, weighed and further investigated for any external, soft tissue and/or skeletal findings. In the 100 mg/kg bw/day dams the statistically significant reduced food consumption during days 6-10 post coitus and the statistically significant lower body weight gain day 6-15 are clearly effects related to dosing.

No adverse effects were seen in the dams at 20 and 50 mg/kg bw/day. Regarding developmental toxicity, only in the highest dose group statistically significantly increased numbers of fetus with skeletal variations (rudimental cervical rib) were observed. The NOAEL for maternal toxicity is 50 mg/kg bw/day, the NOAEL for developmental toxicity is 50 mg/kg bw/day and the NOAEL for teratogenicity is 100 mg/kg bw/day (MCPP-P Task Force 30R0002/91013; 1993).

An additional developmental toxicity study according to OECD TG 414 was conducted with 15 inseminated female Himalayan rabbits treated each daily orally by gavage with MCPP-P acid (R-isomer, CAS 16484-77-8). Doses of 0, 5, 20 and 50 mg/kg bw suspended test substance (vehicle: 0.5% aqueous carboxymethyl cellulose) was administered from day 7 through day 19 p.i. with a standard dose volume of 10 mL/kg. Food consumption and body weights of the animals were recorded regularly throughout the study period and the state of health of the animals was checked each day. On day 20 post coitum, all females were sacrificed and assessed by gross pathology. The fetuses were dissected from the uterus, sexed, weighed and further investigated for any external, soft tissue and/or skeletal findings.

No signs of toxicity were elicited throughout the study period, neither for maternal nor for developmental toxicity up and including the highest dose tested. Based on the results of this full-scale prenatal toxicity study, the no observed adverse effect level (NOAEL) for maternal as well as developmental toxicity including teratogenicity is 50 mg/kg bw/day for MCPP-P acid (R-isomer) in rabbits (MCPP-P Task Force 40R0002/91014; 1993).

 

Taken together, there were no indications of any specific developmental toxicity or teratogenicity in both OECD TG 414 studies presented, neither in rabbits nor in rats.

 

 

Justification for classification or non-classification

Classification, Labelling, and Packaging Regulation (EC) No 1272/2008
The available experimental test data are reliable and suitable for classification purposes under Regulation (EC) No 1272/2008. The substance is not considered to be classified for reproductive toxicity under Regulation (EC) No 1272/2008, as amended for the ninth time in Regulation (EU) No 2017/776.

Additional information