4-(3-phenylpropyl)pyridine

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

Findings of decreased reproductive function only at maternally toxic doses.

Link to relevant study records

Reference

Endpoint:

screening for reproductive / developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS: Crl:CD (SD) rats, male and female, 9-10 week old (initiation of dosing)
- Source: Charles River (UK) Ltd.
- Females (if applicable) nulliparous and non-pregnant: yes
- Age at study initiation: 9-10 wks
- Weight at study initiation: 333-411 g (males); 202-254 g (females) - Fasting period before study:
- Housing: solid floor polypropylene cages with stinless steel mesh lids and softwood flake bedding. Males housed in groups; females housed in groups until after mating, then housed individually.
Cages were changed weekly.
- Diet (e.g. ad libitum): Rodent 2018C Teklad Global certified diet, ad libitum- Water (e.g. ad libitum): municipal supply, ad libitum. - Acclimation period: 14 days
DETAILS OF FOOD AND WATER QUALITY:

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 +/- 2
- Humidity (%): 55 +/- 15 - Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12
- IN-LIFE DATES: From: To:

Route of administration:

oral: gavage

Vehicle:

arachis oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:

VEHICLE
- Justification for use and choice of vehicle (if other than water): maximal solubility
- Concentration in vehicle:
- Amount of vehicle (if gavage): 4 ml/kg bw
- Lot/batch no. (if required):
- Purity:

Details on mating procedure:

- M/F ratio per cage: 1:1
- Length of cohabitation: until positive evidence of mating was noted; maxiumum 14 days
- Proof of pregnancy: sperm in vaginal smear referred to as day 0 of pregnancy
- After 14 days of unsuccessful pairing replacement of first male by another male with proven fertility.
- After successful mating each pregnant female was caged: individually

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Stability and homogeneity of the test material formulation were previously determined. A previous study showed that the formulations were stable for at least 21 days. Formulations were prepared every 2 weeks and stored at 4 °C.
Samples were taken of each test material formulation and analysed for concentration of the test material. The results indicate that the prepared formulations were within ± 10% of the target concentration.

Duration of treatment / exposure:

Males: 28 days. Females: 47 days

Frequency of treatment:

once daily, 7 days per week

Dose / conc.:

30 mg/kg bw/day (nominal)

Dose / conc.:

100 mg/kg bw/day (nominal)

Dose / conc.:

150 mg/kg bw/day (nominal)

Remarks:

Recovery Group, males and females, dosed for 42 days then maintained for 14 additional days without dosing with test material. Initial dose for non-pregnant animals was lowered from 250 mg/kg/d to 150 mg/kg/d.

No. of animals per sex per dose:

12

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: based on outcome of a 14-day dose-range finding study

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: prior to initial dosing and daily thereafter
- Cage side observations checked were included.

DETAILED CLINICAL OBSERVATIONS: Yes. prior to initial dosing and daily thereafter

BODY WEIGHT: Yes
- Time schedule for examinations: prior to initial dosing, daily thereafter and at sacrifice

FOOD CONSUMPTION AND COMPOUND INTAKE
- Food consumption for each animal determined: Yes although route of administration is not dietary

WATER CONSUMPTION AND COMPOUND INTAKE: Yes

Oestrous cyclicity (parental animals):

no

Sperm parameters (parental animals):

no

Litter observations:

STANDARDISATION OF LITTERS
- Performed on days 0 and 4 postpartum: yes
- If yes, maximum of [...] pups/litter ([...]/sex/litter as nearly as possible); excess pups were killed and discarded.

PARAMETERS EXAMINED
The following parameters were examined in F1 offspring: precoital interval, mating index, fertility index, partuition duration and index, pre- and post implantation loss,implanation index, live birth index, viability index, delivery index number and sex of pups, postnatal mortality, presence of gross anomalies, body weights, physical or behavioural abnormalities, anogenital distance (AGD), presence of nipples/areolae in male pups.

GROSS EXAMINATION OF DEAD PUPS: yes, for external and internal abnormalities; possible cause of death was not determined for pups born or found dead

ASSESSMENT OF DEVELOPMENTAL NEUROTOXICITY: no

ASSESSMENT OF DEVELOPMENTAL IMMUNOTOXICITY: no

Postmortem examinations (parental animals):

SACRIFICE
- Male animals: All male animals were sacrificed by Na pentocarbitone followed by exsanguination on day 43.
- Maternal animals: All surviving animals, as above, on day 5 post-partum
- Recovery animals: All surviving animals, as above, on day 14 after males (day 57).

GROSS NECROPSY
- Gross necropsy consisted of external and internal examinations including adrenals, brain, epididymides, heart, kidneys, liver, ovaries, spleen, testes, thymus, thyroid, uterus.


HISTOPATHOLOGY / ORGAN WEIGHTS
The tissues indicated were prepared for microscopic examination and weighed: adrenal glands, aorta, bone including marrow (from femur and sternum), brain, cecum, coagulation gland, colon, duodenum, epididymis/seminal vesicles/prostate/testes or ovaries/uterus, esophagus, eyes, heart, ileum, jejunum, kidneys, liver, lungs with bronchi, mandibular and mesenteric lymph nodes, mammary gland, muscle, ovaries, pancreas, pituitary gland, prostate, oesophagus, rectum, salivary glands, seminal vesicles, skin, spinal cord and sciatic nerve, spleen, stomach, thymus, thyroid gland, trachea, testes, tongue, urinary bladder, uterus/cervix, vagina

Postmortem examinations (offspring):

SACRIFICE
- The F1 offspring not selected as parental animals (not included in this study design)
- These animals were subjected to postmortem examinations (macroscopic)

Clinical signs:

no effects observed

Dermal irritation (if dermal study):

not examined

Mortality:

mortality observed, treatment-related

Description (incidence):

There were several females in the original high dose group (250 mg/kg bw/d) which died by day 3 or were euthanized in extremis. There were 2 females killed in extremis on days 40 and 42 in the 150 mg/kg/d group and an additional 2 females killed in extremis on days 40 and 41 in the 100 mg/kg/d group, all after difficulties in parturition.

Body weight and weight changes:

no effects observed

Food efficiency:

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

no effects observed

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not examined

Other effects:

no effects observed

Reproductive function: oestrous cycle:

no effects observed

Description (incidence and severity):

irregular estrous cycle in mid and high dose females

Reproductive function: sperm measures:

no effects observed

Reproductive performance:

no effects observed

Some mortality in females of mid and high doses (days 40-41), with difficulties in parturition. Animals in the mid and high dose groups showed irregular estrous cycle, longer gestation length, post implantation loss, difficulties during parturition, decreased delivery index.

Key result

Dose descriptor:

NOAEL

Effect level:

> 30 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

reproductive function (oestrous cycle)

reproductive performance

other: deaths at mid and high doses

Remarks on result:

other: decreased reproductive success at high doses

Remarks:

Likely due to maternal toxicity as these doses are 3-5 fold higher than general NOAEL

Key result

Critical effects observed:

no

Clinical signs:

no effects observed

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

Food efficiency:

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:

no effects observed

Histopathological findings:

not examined

Other effects:

no effects observed

Behaviour (functional findings):

not examined

Developmental immunotoxicity:

not examined

Key result

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

> 150 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Remarks on result:

not determinable due to absence of adverse toxic effects

Key result

Critical effects observed:

no

Key result

Reproductive effects observed:

no

There was some mortality along with difficulties in parturition among the mid and high dose females. See table of reproductive effects. These effects can be attributed to generalized systemic effects, as the adult NOAEL for the repeated dose toxicity portion of the study is 30 mg/kg bw/d. There were no adverse reproductive toxicity effects reported at this dose.

Parameter	Dose group: 100 mg/kg bw/d	Dose group: 250/150 mg/kg bw/d
Non-pregnant	0/12	3/11
Pregnant	12/12	8/11
No offspring	4/12	4/8
Parturition successful	8/12	4/8
With live offspring	5/8	1/4
With no live offspring on Lactation day 4	5/8	1/4
With live offspring on Lactation day 5	2/5	0/1

Adverse effects were observed in maternal animals at doses above 30 mg/kg bw/d, while no toxicity was observed in male sires.  There were no findings of toxicity in offspring.  The parental NOAEL (adults in repeated dose portion of the OECD 422 study) is 30 mg/kg bw/d. The NOAEL for reproductive toxicity to the offspring is > 150 mg/kg bw/d.  

Conclusions:

A screening test was undertaken on the test substance in an OECD 422 study design (combined repeated dose and reproductive/developmental toxicity screening study) in CD rats at doses of 30, 100 and 150 mg/kg bw/d. Adverse effects were observed in maternal animals at doses above the overall adult NOAEL of 30 mg/kg bw/d, (deaths after difficult partuition, irregular estrus cycle, decreased fertility index and increased post-implantation loss). This is likely a reflection of maternal toxicity, as doses were up to 5 time higher than the overall NOAEL. No toxicity was observed in male sires or in offspring. The parental NOAEL (maternal toxicity effects) is 30 mg/kg bw/d. The NOAEL for reproductive toxicity to the offspring is > 150 mg/kg bw/d (highest dose tested).

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

30 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

adequte

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 screening test was undertaken on the test substance in an OECD 422 study design (combined repeated dose and reproductive/developmental toxicity screening study) in CD rats at doses of 30, 100 and 150 mg/kg bw/d.  Adverse effects were observed in maternal animals at doses above the overall adult NOAEL of 30 mg/kg bw/d, (deaths after difficult parturition, irregular estrus cycle, decreased fertility index and increased post-implantation loss).  This is likely a reflection of maternal toxicity, as doses were up to 5 time higher than the overall NOAEL. No toxicity was observed in male sires or in offspring; the substance showed no evidence of teratogenic effects. The parental NOAEL (maternal toxicity) is 30 mg/kg bw/d. The NOAEL for reproductive toxicity to the offspring is > 150 mg/kg bw/d (highest dose tested).

Effects on developmental toxicity

Description of key information

Not a developmental toxin

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Mode of Action Analysis / Human Relevance Framework

Not applicable

Justification for classification or non-classification

In a repeated dose/reproductive toxicity screening study in rats, there were adverse effects observed in fertility and parturition only at maternally toxic doses. No developmental toxicity or teratogenicity was observed, and the NOAEL is the highest doses tested (150 mg/kg bw/d). The findings of the test do not meet the criteria for classification and labelling according to Regulation EC No. 1272/2008, and the substance is not classified.