Reaction mass of 4,4'-isopropylidenediphenol and phenol

Toxicity to reproduction

Administrative data

Endpoint:

one-generation reproductive toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Data source

Reference

Reference 1

Reference Type:

publication

Title:

CORRIGENDUM: Toxicity Evaluation of Bisphenol A Administered by Gavage to Sprague Dawley Rats From Gestation Day 6 Through Postnatal Day 90

Author:

K. Barry Delclos et al.

Year:

2016

Bibliographic source:

TOXICOLOGICAL SCIENCES, 153(1), 212

Reference 2

Reference Type:

publication

Title:

Unnamed

Year:

2014

Materials and methods

Principles of method if other than guideline:

Bisphenol A was administered by oral gavage from gestation day 6 through the start of labor and then directly to pups from postnatal day (PND) 1 (day of birth = PND 0) until termination at PND 90 ± 5 to Sprague-Dawley rats from the NCTR breeding colony (Sprague-Dawley/CD23/NCTR BR). Bisphenol A doses were 2.5, 8, 25, 80, 260, 840, 2,700, 100,000, and 300,000 μg/kg body weight (bw)/day.

Vehicle (0.3% carboxymethylcellulose) and naïve control groups were included to assess any effects of the gavage procedure on the endpoints measured. Two doses (0.5 and 5.0 μg/kg bw/day) of the synthetic estrogenic substance ethinyl estradiol (EE2) were also included.

The litter was the unit of statistical analysis and the target litter number was 20 per dose group (actual n = 18 – 23). Rats were fed soy- and alfalfa-free diet and caged in polysulfone cages with hardwood chip bedding, glass water bottles with food-grade silicone stoppers. Prior to mating female rats were randomized to treatment groups stratified by body weight to give approximately equivalent mean body weights in each group. During mating females were examined daily for presence of an in situ vaginal plug or sperm-positive smear.

Data collected included body weights, weekly feed consumption, litter parameters, anogenital distances at PND 1 and PND 90, measures of sexual development (vaginal opening and time to first estrus for females; nipple retention, testicular descent, and preputial separation for males), vaginal cytology, clinical chemistry, organ weights, and histopathology. Vaginal cytologies were collected from PND 69 until termination in animals utilized for histopathology; the cytology data were used to attempt to terminate the females in estrus. A subset of females was also removed from dosing at PND 90 ± 5 and assessed for cyclicity from PND 150 to PND 170. For clinical chemistry, blood was taken from subsets of pups at PND 15, PND 80 and at terminal necropsy on PND 90 ± 5. Sperm motility, testicular spermatid head count, caudal epididymal sperm count, and sperm morphology were assessed at terminal necropsy. Organ weights collected at terminal necropsy included adrenals, brain, dorsolateral and ventral prostate, epididymides, heart, kidneys, liver, ovaries, pituitary (after fixation), seminal vesicles with coagulating gland, spleen, testes, thymus, thyroid (after fixation), uterus, epididymal, ovarian and parametrial (combined), and retroperitoneal fat pads. Organs evaluated microscopically included adrenals, aorta (thoracic), bone marrow (femur), brain, right epididymis, heart, kidneys, liver, 5th left mammary gland (inguinal) from both sexes, ovaries, oviduct, pancreas, pituitary, prostate (dorsolateral and ventral), seminal vesicles with coagulating gland, spleen, right testis, thymus, thyroid, uterus, and vagina.

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

4,4'-isopropylidenediphenol

EC Number:

201-245-8

EC Name:

4,4'-isopropylidenediphenol

Cas Number:

80-05-7

Molecular formula:

C15H16O2

IUPAC Name:

2,2-bis(4-hydroxyphenyl)propane

Specific details on test material used for the study:

- purity: >99 %

Test animals

Species:

rat

Strain:

other: Sprague-Dawley/CD23/NCTR BR

Sex:

male/female

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

CMC (carboxymethyl cellulose)

Details on mating procedure:

Males were placed in wire-bottomed breeding cages for acclimation approximately 48 h prior to introduction of the female. The breeding pairs were housed together and the females were examined daily until evidence of mating had occurred or for 14 days, whichever occurred first. Either the presence of an in situ copulation plug or sperm in the vaginal smear was considered evidence of mating [gestation day (GD) 0] and triggered separation of the breeding pair. The males were removed from the study and euthanized after a successful mating and the female was placed in a separate solid-bottomed polysulfone cage with hardwood chip bedding.

Analytical verification of doses or concentrations:

yes

Duration of treatment / exposure:

Bisphenol A was administered by oral gavage from gestation day 6 through the start of labor and then directly to pups from postnatal day (PND) 1 (day of birth = PND 0) until termination at PND 90 ± 5

Frequency of treatment:

daily

Doses / concentrations

Doses / concentrations 1

Remarks:

2.5, 8, 25, 80, 260, 840, 2,700 µg/kg/day

Doses / concentrations 2

Remarks:

100,000, and 300,000 µg/kg/day

No. of animals per sex per dose:

The litter was the unit of statistical analysis and the target litter number was 20 per dose group (actual n = 18 – 23).

Control animals:

yes, concurrent no treatment

yes, concurrent vehicle

Examinations

Statistics:

Corrigendum published in TOXICOLOGICAL SCIENCES, 153(1), 2016, 212: Although details of the statistical analyses performed are included in the Supplementary Materials provided with this article (Toxicological Sciences 139 (1), 174–197, 2014), it should have been noted that the pairwise comparisons of dose groups to the vehicle control were not corrected for multiple comparisons for the data reported in Tables 4 and 7–9. By convention, histopathologydata are not corrected in National Toxicology Program studies.

Results and discussion

Results: P0 (first parental generation)

Effect levels (P0)

Dose descriptor:

NOAEL

Effect level:

2.7 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

Target system / organ toxicity (P0)

Critical effects observed:

not specified

Results: F1 generation

Effect levels (F1)

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

2.7 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

sexual maturation

clinical biochemistry

histopathology: non-neoplastic

Overall reproductive toxicity

Reproductive effects observed:

yes

Lowest effective dose / conc.:

100 mg/kg bw/day (actual dose received)

Treatment related:

yes

Relation to other toxic effects:

reproductive effects in the absence of other toxic effects

Dose response relationship:

yes

Relevant for humans:

yes

Any other information on results incl. tables

Clear adverse effects of BPA, including depressed gestational and postnatal body weight gain, effects on the ovary (increased cystic follicles, depleted corpora lutea, and antral follicles), and serum hormones (increased serum estradiol and prolactin and decreased progesterone), were observed only at the two high doses of BPA

Applicant's summary and conclusion

Conclusions:

Under the conditions of this study, BPA had clear adverse effects at doses of 100,000 and 300,000 µg/kg bw/day, with the majority of these effects observed in females. In the study defined “low BPA” dose range of 2.5–2700 g/kg bw/day, which was the primary focus of this study, potential effects could not be clearly linked to treatment as they were observed sporadically across the dose groups and did not occur in a consistent grouping across organs as did effects of EE2 (0.5 and 5.0 µg/kg bw/day) or “high BPA” (100,000 and 300,000 µg/kg bw/day).

Executive summary:

The primary goals of the subchronic study reported here were to identify adverse effects induced by orally (gavage) administered BPA below the NOAEL, to characterize the dose response for such effects and to determine doses for a subsequent chronic study. Sprague Dawley rat dams were dosed daily from
gestation day 6 until the start of labor, and their pups were directly dosed from day 1 after birth to termination. The primary focus was on seven equally spaced BPA doses (2.5–2700 g/kg bw/day). Also included were a naive control, two doses of ethinyl estradiol (EE2) to demonstrate the estrogen responsiveness of the animal model, and two high BPA doses (100,000 and 300,000 g/kg bw/day) expected from guideline studies to produce adverse effects. Clear adverse effects of BPA, including depressed gestational and postnatal body weight gain, effects on the ovary (increased cystic follicles, depleted corpora lutea, and antral follicles), and serum hormones (increased serum estradiol and prolactin and decreased proges-
terone), were observed only at the two high doses of BPA. BPA-induced effects partially overlapped those induced by EE2, consistent with the known weak estrogenic activity of BPA.