Triphenyl phosphate

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

No effects on fertility were observed in a one-generation study on rats and no effects on reproductive organs were reported in recently performed subacute and subchronic toxicity studies on rats. Thus, based on these results, triphenyl phosphate showed no evidence of toxicity to fertility.

A comprehensive assessment of in silico, in vitro and in vivo data on potenial endocrine modulating properties revealed no reliable evidence of a specific and biologically relevant endocrine activity of triphenyl phosphate.

Link to relevant study records

Reference

Reference 1

Endpoint:

one-generation reproductive toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Also assessed by OECD.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 415 [One-Generation Reproduction Toxicity Study (before 9 October 2017)]

Principles of method if other than guideline:

Method: other: see freetext

GLP compliance:

not specified

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Route of administration:

oral: feed

Vehicle:

not specified

Details on exposure:

exposure period 91 days

Details on mating procedure:

TPP was administered in the diet for 91 days in a subchronic study. At the completion of this study, females were mated with males from the same group. All remained on the same diet as in the subchronic study until day 20 of gestation when dams were sacrificed.

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

Exposure period: 91 days
Duration of test: 3 months

Frequency of treatment:

daily

Remarks:

Doses / Concentrations:
0.25, 0.5, 0.75 or 1 % in feed (= 166, 341, 516, 690 mg/kg)
Basis:
no data

No. of animals per sex per dose:

Four treated groups and an untreated control each consisting of 40 rats/sex

Control animals:

yes, concurrent no treatment

Details on study design:

TPP was administered in the diet for 91 days in a subchronic study. At the completion of this study, females were mated with males from the same group. All remained on the same diet as in the subchronic study until day 20 of gestation when dams were sacrificed.

Parental animals: Observations and examinations:

see below

Oestrous cyclicity (parental animals):

see below

Sperm parameters (parental animals):

no effects

Litter observations:

no effects observed

Postmortem examinations (parental animals):

no adverse effects noted

Postmortem examinations (offspring):

no adverse effects noted

Statistics:

no data

Reproductive indices:

see below

Offspring viability indices:

see below

Clinical signs:

no effects observed

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Histopathological findings: non-neoplastic:

no effects observed

Other effects:

effects observed, treatment-related

Reproductive function: oestrous cycle:

no effects observed

Reproductive function: sperm measures:

no effects observed

Reproductive performance:

no effects observed

No findings reported. Food consumption increased in pregnant dams (not dose depedant).

Dose descriptor:

NOEL

Effect level:

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

Sex:

male/female

Basis for effect level:

other: no adverse effects were reported

Critical effects observed:

no

Clinical signs:

no effects observed

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

Sexual maturation:

no effects observed

Histopathological findings:

no effects observed

No adversed effects were observed.

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

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

Sex:

male/female

Basis for effect level:

other: Examination of the foetuses indicated no effect on body weight, crown-rump length, and sex distribution. There were no external variations or skeletal variations which could be related to TPP exposure.

Critical effects observed:

no

Reproductive effects observed:

no

OBSERVATION: no findings reported
FOOD CONSUMPTION: increased in pregnant dams (not dose-dependent)
BODY WEIGHT: decreased during pregnancy (non-significant)
NECROPSY: no significant differences in number of corpora lutea,  implants, implantation efficiency, viable fetuses and number of early or  late deaths. 
As there was no effect on the litter size (indirectly measured by the  number of viable fetuses and implants) and both sexes were treated in the  study, these findings indicate that fertility is not adversely affected  by TPP in male and female rats.
parental NOEL = 690 mg/kg bw

Conclusions:

Parental NOEL = 690 mg/kg bw

Executive summary:

Fertility and developmental toxicity were examined in a dietary study in Sprague-Dawley rats at doses of 0, 0.25, 0.50, 0.75, 1.0% corresponding to 0, 166, 341, 516 or 690 mg/kg bw/day. Forty males and forty females per group were treated for 3 months and mated afterwards. Animals were treated further throughout mating and gestation and killed at day 20 of gestation.

Effects on fertility- The study included treatment of males and females for three months prior to mating throughout gametogenisis and during mating and gestation. No significant differences were recorded in the number of corpora lutea, implants, implantation efficiency, viable fetuses and the number of early or late deaths between treated and control rats. No significant signs of parental toxicity were detected. As there were no effects on the litter size (indirectly measured by the number of viable fetuses and implants) and both sexes were treated in the study, these findings indicate that fertility is not adversely affected by TPP in male and female rats. The NOEL was 690 mg/kg bw/day.

Reference 2

Endpoint:

fertility, other

Remarks:

other: repeated dose toxicity studies

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

1 (reliable without restriction)

Reason / purpose for cross-reference:

reference to same study

Principles of method if other than guideline:

OECD Guideline 407 and 408 Studies

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Wistar

Route of administration:

oral: feed

Analytical verification of doses or concentrations:

yes

Duration of treatment / exposure:

28 day and 90 day study

Frequency of treatment:

frequently via food

Remarks:

Doses / Concentrations:
up to 508 mg/kg bw/day in male rats and up to 701 mg/kg bw/day in female rats
Basis:
other: 28 day repeated dose toxicity study

Remarks:

Doses / Concentrations:
up to 583 mg/kg bw/day in male rats and up to 632 mg/kg bw/day in female rats
Basis:
other: 90 day repeated dose toxicity study

No. of animals per sex per dose:

5 per sex/dose in the 28 day study and 10 per sex/dose in the 90 day study

Control animals:

yes, concurrent vehicle

Details on study design:

see IUCLID chapter 7.5.1

Dose descriptor:

NOAEL

Remarks:

systemic toxicity

Effect level:

>= 105 mg/kg bw/day (actual dose received)

Sex:

male/female

Basis for effect level:

other: 90 day repeated dose toxicity study

Remarks on result:

other: Generation not specified

Dose descriptor:

NOAEL

Remarks:

reproductive organ toxicity

Effect level:

>= 583 mg/kg bw/day (actual dose received)

Sex:

male/female

Basis for effect level:

other: 90 day repeated dose toxicity study

Remarks on result:

other: Generation not specified

Reproductive effects observed:

not specified

Repeated dose toxicity of triphenyl phosphate was investigated in two comprehensive guideline studies performed according to OECD TG 407 and 408 and conducted in compliance with GLP. In the 28 day study the test item was given in dietary concentrations of 0, 250, 1000 or 4000 ppm to 5 male and 5 female Wistar rats per dose group. This corresponds to averaged (over the whole study) test substance intakes of 23, 104 or 508 mg/kg bw/day in males and 39, 161 or 701 mg/kg bw /day in females.

In the 90 day study the test item was given in dietary concentrations of 0, 300, 1500 or 7500 ppm to 10 male and 10 female Wistar rats per dose group. This corresponds to averaged (over the whole study) test substance intakes of 20, 105 or 583 mg/kg bw/day in males and 22, 117 or 632 mg/kg bw /day in females.

The overall NOAEL for repeated dose toxicity is established at 105 mg/kg bw/day based on effects on liver weight in the 90 day study. There were no effects on the weight of the gonads (males: testes and epididymes, seminal vesicles including coagulating glands; females ovaries, uterus including cervix, vagina) or the microscopic examined integrity of the gonads (males: epididymides, prostate, seminal vesicles and testes; females: uterus and ovaries, vagina) at any dose tested.

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

583 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

Fertility and developmental toxicity were examined in a one-generation dietary study in Sprague-Dawley rats at doses of 0, 0.25, 0.50, 0.75, 1.0% corresponding to 0, 166, 341, 516 or 690 mg/kg bw/day (Welsh et al. 1987). Forty males and forty females per group were treated for 3 months and mated afterwards. Animals were treated further throughout mating and gestation and laparotomy was performed on all females at day 20 of gestation.

No significant signs of parental toxicity were detected. As there were no effects on pregnancy rate, litter size (indirectly measured by the number of viable fetuses and implants), corpora lutea, implants, implantation efficiency, viable foetuses, number of early and late deaths or average percent resorbed. Examination of the foetuses indicated no effect on body weight, crown-rump length, and sex distribution. There were no external variations or skeletal variations which could be related to TPP exposure. On the basis of this one generation reproductive toxicity study TPP has no effect on fertility or developmental toxicity at any dietary concentration tested (Welsh, 1987). The NOEL for reproductive toxicity obtained in this study is 690 mg/kg bw/day.

In a developmental toxicity study on rabbits following OECD 414 with gavage application of triphenyl phosphate in doses of 32, 80 and 200 mg/kg bw/day the external, thoracic and abdominal examination of the dams with special attention being paid to the reproductive organs, showed no macroscopic abnormalities (Peter, 2015).

Repeated dose toxicity of triphenyl phosphate was investigated in two comprehensive guideline studies performed according to OECD TG 407 and 408 and conducted in compliance with GLP. In the 28 day study (Eiben, 2007) the test item was given in dietary concentrations of 0, 250, 1000 or 4000 ppm to 5 male and 5 female Wistar rats per dose group. This corresponds to averaged (over the whole study) test substance intakes of 23, 104 or 508 mg/kg bw/day in males and 39, 161 or 701 mg/kg bw /day in females.

In the 90 day study (van Otterdijk, 2015) the test item was given in dietary concentrations of 0, 300, 1500 or 7500 ppm to 10 male and 10 female Wistar rats per dose group. This corresponds to averaged (over the whole study) test substance intakes of 20, 105 or 583 mg/kg bw/day in males and 22, 117 or 632 mg/kg bw /day in females.

The overall NOAEL for repeated dose toxicity is established at 105 mg/kg bw/day based on effects on liver weight in the 90 day study. The overall NOEL for reproductive toxicity obtained in the repeated dose toxicity studies, based on macroscopic and microscopic evaluations of male and female reproductive organs, is established with the higest dose tested of 583 mg/kg bw/day. There were no effects on the weight of the gonads (males: testes and epididymes, seminal vesicles including coagulating glands; females ovaries, uterus including cervix, vagina) or the microscopic examination of the gonads (males: epididymides, prostate, seminal vesicles and testes; females: uterus and ovaries, vagina) at any dose tested.

In conclusion, no effects on fertility were observed in a one-generation study and no effects on reproductive organs were reported in recently performed subacute and subchronic toxicity studies on rats and a developmental toxicity study on rabbits. Thus, based on these results, triphenyl phosphate showed no evidence of toxicity to fertility. The overall NOEL for reproductive toxicity obtained in fertlity and repeated dose toxicity studies is thus established with 690 mg/kg bw/day.

Triphenyl phosphate (11042-J) is currently (status: 05/2020) within the testing procedure of the National Toxicology Program (NTP) with the following tests:

-  2 week toxicity study on 5 B6C3F1/N mice per sex with doses of 0, 1875, 3750, 7500, or 30000 ppm triphenyl phosphate in food (C20720; status: data in review)

-  ‘Modified One-Generation Reproduction Study’ on Harlan Sprague Dawley rats, including neurotoxicology assessment (MOG11042; status for the respective dose-range finding study with administration via food: data in review)

Assessment of endocrine modulating effects:

A comprehensive literature search was conducted to identify data on potential human health relevant endocrine modulating properties of triphenyl phosphate. The data was assigned to the OECD Conceptual Framework for Testing and Assessment of Endocrine Disrupters levels 1 to 5.

With regard to OECD CF level 1 triphenyl phosphate is determined as ‘non-binder to the estrogen receptor’ (OECD QSAR Toolbox, version 4.4).

Triphenyl phosphate showed mainly negative and few positive results in in vitro screening assays that can be assigned to OECD CF level 2, but no conclusive picture is given. Activities were seen in general at cytotoxic concentrations and/or in the micromolar range, i.e. at about 6 magnitudes lower concentrations than triphenyl phosphate detected in human tissues, and are thus not relevant for the in vivo situation. Based on the available information there is no indication of a specific endocrine activity in vitro.

This conclusion is in line with the available animal studies.

With regard to OECD CF level 3 there is only one standard (comparable to guideline) study available, the uterotrophic assay on rats and mice. In this test immature female mice and rats were subcutaneously injected for three consecutive days with high doses of triphenyl phosphate (TPP) or diphenyl phosphate (DPP). The uterotrophic bioassay did not shown any increase in uterine weight for any of the TPP or DPP doses in either mice or rats.

With regard to OECD CF level 4 the available guideline compliant repeated dose toxicity studies with up to 90 day exposure in rats and the results of a one-generation reproduction toxicity study in rats, as well as a 3-week dermal and a developmental toxicity study in rabbits give no indication of a potential interference of triphenyl phosphate with endocrine parameters. The overall NOAEL for reproductive toxicity is determined with 690 mg/kg bw/day, the highest dose tested in the one-generation study.

An OECD CF level 5 study for triphenyl phosphate on rats, the ‘Modified One-Generation Reproduction Study’, is currently being undertaken under the auspices of the US National Toxicology Program.

All in all we concur with the conclusion given in the Minutes of the 62nd Meeting of the Member State Committee of December 2018 for triphenyl phosphate, where the evaluating ‘UK MSC member explained that on the basis of the currently available human health data they had no verified concern on ED’. (ECHA, 2018)

Effects on developmental toxicity

Description of key information

There are no findings indicating any adverse effects on the development of rat fetuses up to the highest tested dose level of 1% in the diet (690 mg/kg bw/day) in rats treated for 3 months prior to mating, throughout mating and up to day 20 of gestation.

In a recently performed developmental toxicity study on rabbits (OECD 414) with oral gavage doses of up to and including 200 mg/kg bw/day triphenyl phosphate showed no toxicologically significant effects on maternal and developmental prarmeters investigated. The NOAEL was at least 200 mg/kg bw/day. No higher doses could be tested in pregnant rabbits based on toxicity observed in dose range finding studies.

In a study on pregnant mice with intraperitoneal injection of 0, 5, 25, or 50 mg/kg triphenyl phosphat on gestational days (GD) 8, 10, 12, and 14 and sacrifice on GD 19, no treatment related effects of TPhP on resorptions, gross morphological defects, skeletal defects, fetal weight, crown rump length, placental weights, and anogenital index were recorded (Philbrook, 2018). A significant increase (p<.05) in placental weights of mice exposed to 25 mg/kg TPhP compared to the unexposed controls was found. However, at the next higher dose of 50 mg/kg bw placental weights were comparable to control levels.

Link to relevant study records

Reference

Reference 1

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study.

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Qualifier:

according to guideline

Guideline:

EU Method B.31 (Prenatal Developmental Toxicity Study)

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.3700 (Prenatal Developmental Toxicity Study)

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River, Chatillon sur Chalaronne, France
- Nulliparous, non-pregnant and untreated females were used at inititation of the study.
- Age at delivery: 17-19 weeks; mating with adult and proven fertile males at WIL Research
- Fasting period before study: none
- Housing: individually
- Diet: ad libitum
- Water: ad libitum

Route of administration:

oral: gavage

Vehicle:

CMC (carboxymethyl cellulose)

Remarks:

1% aqueous solution

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
The required amount of test substance was grinded to a fine powder in a grinding mill. Subsequently, the powder was suspended in the vehicle. Formulations (w/w) were prepared daily within 6 hours prior to dosing and were homogenized to a visually acceptable level.

VEHICLE
- Justification for use and choice of vehicle (if other than water): 1% aqueous carboxymethyl cellulose was chosen based on trial formulations performed at WIL.
- Amount of vehicle (if gavage): 5 ml/kg bw

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analyses were conducted on a single occasion during the treatment phase (26 November 2014), according to a validated method (Project 506608). Samples of formulations were analyzed for homogeneity (highest and lowest concentration) and accuracy of preparation (all concentrations). Stability in vehicle over 6 hours at room temperature was also determined (lowest concentration only).

Details on mating procedure:

After acclimatization, females were housed with sexually mature males (1:1) in special automatic mating cages i.e. with synchronized timing to initiate the nightly mating period, until evidence of copulation was observed. This system reduced the variation in the copulation times of the different females. The females were removed and housed individually if:
a) A copulation plug was observed, and / or
b) The daily vaginal smear was sperm positive.
The day of mating was designated day 0 post coitum.
Male rats of the same source and strain were used only for mating. These male rats are in the possession of RCC and were not considered part of the test system. The fertility of these males had been proven and was continuously monitored.

Duration of treatment / exposure:

Day 6 - 28 post coitum inclusive

Frequency of treatment:

once daily

Duration of test:

All animals surviving to the end of the observation period (Day 29 post-coitum) and the female with premature delivery were euthanised by intravenous injection of pentobarbital (approx. 1 mL/kg Euthasol®20%) and subjected to an external, thoracic and abdominal examination, with special attention being paid to the reproductive organs and the fetuses.

No. of animals per sex per dose:

Each group consisted of 22 mated female rabbits.

Control animals:

yes, concurrent vehicle

Details on study design:

Rationale for dose levels
Dose levels were selected based on the results of a dose range finding study (Project 505943; see APPENDIX 6). In this latter study dose levels of 83, 250 and 750 mg/kgmg/kg bw/day were tested. Due to severe toxicity, all females at 750 mg/kgmg/kg bw/day and one female at 250 mg/kgmg/kg bw/day had to be euthanized before scheduled necropsy. Another female at 250 mg/kgmg/kg bw/day was noted with clinical signs (pale appearance on Days 22 and 23 post-coitum and reduced production of (pale) faeces from Day 17 post-coitum). She had no food consumption from Days 16-23 post-coitum and body weight loss (up to -6%). No signs of toxicity were noted for the remaining females at 250 mg/kgmg/kg bw/day and all females at 83 mg/kgmg/kg bw/day. Based on these data, dose levels of 32, 80 and 200 mg/kgmg/kg bw/day were selected for the present prenatal developmental toxicity study.

Maternal examinations:

Females were checked daily for the presence of clinical signs. Food consumption and body weight were determined at periodic intervals.
All animals surviving to Day 29 post-coitum were subjected to an examination post-mortem and external, thoracic and abdominal macroscopic findings were recorded. A laparohysterectomy was performed on each surviving female of the groups.

Ovaries and uterine content:

The uteri, placentae and ovaries were examined, and the numbers of fetuses, early and late resorptions, total implantations and corpora lutea were recorded. Gravid uterine weights were recorded, and net body weights and net body weight changes were calculated.

Fetal examinations:

External, visceral, and skeletal findings were recorded as developmental variations (alterations in anatomic structure that are considered to have no significant biological effect on animal health or body conformity and/or represent slight deviations from normal) or malformations (those structural anomalies that alter general body conformity, disrupt or interfere with normal body function, or may be incompatible with life).

External:
Each viable fetus was examined in detail and weighed. All live fetuses were euthanized by administration of approximately 0.3 mL (= 60 mg) of sodium pentobarbital (Euthasol® 20%; AST Farma B.V., Oudewater, The Netherlands) into the oral cavity using a small flexible plastic or metal feeding tube. Nonviable fetuses (the degree of autolysis was minimal or absent) were examined and weighed. For late resorptions a gross external examination was performed.

Visceral (Internal):
All fetuses were examined for visceral anomalies by dissection in the fresh (non-fixed) state. The thoracic and abdominal cavities were opened and dissected using a technique described by Stuckhardt and Poppe (Ref. 1). This examination included the heart and major vessels. Fetal kidneys were examined and graded for renal papillae development as described by Woo and Hoar. The sex of all fetuses was determined by internal examination.

The heads were removed from approximately one-half of the fetuses in each litter and placed in Bouin's solution (Klinipath, Duiven, The Netherlands). Tissues were then transferred to a 70% aqueous ethanol (Klinipath, Duiven, The Netherlands) for subsequent processing and soft-tissue examination of all groups using the Wilson sectioning technique. After examination, the tissues were stored in 10% formalin. The heads from the remaining one-half of the fetuses in each litter of all groups were examined by a mid-coronal slice.

All carcasses, including the carcasses without heads, were eviscerated, skinned and fixed in identified containers containing 96% aqueous ethanol (Klinipath, Duiven, The Netherlands) for subsequent examination of skeletons.

Skeletal:
The eviscerated fetuses from all groups, following fixation in 96% aqueous ethanol, were macerated in potassium hydroxide (Merck, Darmstadt, Germany) and stained with Alizarin Red S (Klinipath, Duiven, The Netherlands) by a method similar to that described by Dawson. Subsequently, the skeletal examination was done on all fetuses.

The specimens of all groups will be archived in glycerin (Klinipath, Duiven, The Netherlands) with bronopol (Alfa Aesar, Karlsruhe, Germany) as preservative.

A few bones were not available for skeletal examination because they were accidentally damaged or lost during processing. The missing bones were listed in the raw data; evaluation by the fetal pathologist and study director determined there was no influence on the outcome of the individual or overall skeletal examinations, or on the integrity of the study as a whole.

Statistics:

The following statistical methods were used to analyze the data:
- If the variables could be assumed to follow a normal distribution, the Dunnett-test (many-to-one t-test) based on a pooled variance estimate was applied for the comparison of the treated groups and the control group.
- The Steel-test (many-to-one rank test) was applied if the data could not be assumed to follow a normal distribution.
- The Fisher Exact-test was applied to frequency data.
- The Mann Whitney test was used to compare mean litter proportions (percent of litter) of the number of viable and dead fetuses, early and late resorptions, total resorptions, pre- and post-implantation loss, and sex distribution.
- Mean litter proportions (percent per litter) of total fetal malformations and developmental variations (external, visceral and skeletal), and each particular external, visceral and skeletal malformation or variation were subjected to the Kruskal-Wallis nonparametric ANOVA test to determine intergroup differences. If the ANOVA revealed statistically significant (p<0.05) intergroup variance, Dunn’s test was used to compare the compound-treated groups to the control group.

All tests were two-sided and in all cases p < 0.05 was accepted as the lowest level of significance. Group means were calculated for continuous data and medians were calculated for discrete data (scores) in the summary tables. Test statistics were calculated on the basis of exact values for means and pooled variances. Individual values, means and standard deviations might be rounded off before printing. Therefore, two groups might display the same printed means for a given parameter, yet display different test statistics values.

No statistics were applied for data on maternal survival, pregnancy status, group mean numbers of dead fetuses, early and late resorptions, and pre- and post-implantation loss.

Indices:

For each litter the following calculations were performed:

Pre-implantation loss (%) = (number of corpora lutea - number of implantation sites) divided by the number of corpora lutea x 100
Post-implantation loss (%) = (number of implantation sites - number of live fetuses) divided by the number of implantation sites x 100
The fetal developmental findings were summarized by: 1) presenting the incidence of a given finding both as the number of fetuses and the number of litters available for examination in the group; and 2) considering the litter as the basic unit for comparison, calculating the number of affected fetuses as a mean litter proportion on a total group basis, where:

Viable fetuses affected/litter (%) = number of viable fetuses affected/litter divided by the number of viable fetuses/litter x 10

Historical control data:

available

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Gross pathological findings:

no effects observed

Number of abortions:

no effects observed

Pre- and post-implantation loss:

no effects observed

Total litter losses by resorption:

no effects observed

Dead fetuses:

no effects observed

Changes in pregnancy duration:

no effects observed

Description (incidence and severity):

Migrated Data from removed field(s)
Field "Effects on pregnancy duration" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsMaternalAnimals.MaternalDevelopmentalToxicity.EffectsOnPregnancyDuration): no effects observed
Field "Description (incidence and severity)" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsMaternalAnimals.MaternalDevelopmentalToxicity.DescriptionIncidenceAndSeverityEffectsOnPregnancyDuration): one femaled in the high dose group delivered early

Changes in number of pregnant:

no effects observed

Details on maternal toxic effects:

Maternal toxic effects:no effects

Details on maternal toxic effects:
No toxicologically significant changes were noted in any of the maternal parameters investigated in this study (i.e. mortality, clinical signs, body weights, food consumption, and macroscopic examination) in the tested doses of up to and including 200 mg/kg bw/day. Higher doses were shown to induce strong toxicity (mortality at 750 and 250 mg/kg bw/day) in the dose range finding studies and were thus not included in the main study.

Dose descriptor:

NOAEL

Effect level:

>= 200 mg/kg bw/day (actual dose received)

Basis for effect level:

other: maternal toxicity

Dose descriptor:

NOAEL

Effect level:

>= 200 mg/kg bw/day (actual dose received)

Basis for effect level:

other: developmental toxicity

Abnormalities:

no effects observed

Fetal body weight changes:

no effects observed

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:

no effects observed

Changes in sex ratio:

no effects observed

Changes in litter size and weights:

no effects observed

External malformations:

no effects observed

Skeletal malformations:

no effects observed

Visceral malformations:

effects observed, non-treatment-related

Description (incidence and severity):

Treatment at 200 mg/kg bw/day resulted in a higher incidence of lungs with absent accessory lung lobe(s). While in the control and mid dose groups only one fetus (A015-03 and A048-02, respectively) each was noted with this malformation, the incidence increased to 3(3) fetuses (litter) in the high dose
group (A067-03, A069-07, A074-04). This resulted in a litter proportion of 1.6% which was at the upper limit of the available historical control range for this finding (MAX: 1.7%). In addition, 2 dead fetuses from litter 78 that were delivered preterm on Day 29 post-coitum (A078-03 and A078-05) had absent
accessory lung lobes. The total litter proportion of fetuses at 200 mg/kg bw/day with absent accessory lung lobe(s) thus increased from 1.6% (given in Table 1.15; APPENDIX 1) to 2.4%. This litter proportion was clearly above the range of available historical control data. Lungs with absent accessory lung lobe(s) is a more common finding in New Zealand White rabbits. The historical control data from this laboratory consisted of 17 developmental studies with this strain in which in total 2787 (315) control fetuses (litters) were examined. In 10 of these studies fetuses with absent accessory lung lobe(s) were found, i.e. in total 20 (17) control fetuses (litter). The highest incidence was 3(3) fetuses (litter) seen in 2 studies. As in the high dose group of the present study the incidence of lungs with absent accessory lobe(s) was only slightly higher with in total 5(4) fetuses (litter) including the 2 fetuses from the preterm delivered litter, it was considered as an incidence finding and thus not to be toxicologically relevant.

Details on embryotoxic / teratogenic effects:

Details on embryotoxic / teratogenic effects:
There were no developmental findings up to and including 200 mg/kg bw/day that were considered to be toxicologically relevant.
No toxicologically relevant changes were noted in any of the developmental parameters investigated in this study (i.e. litter size, sex ratio, fetal body weights, external, visceral and skeletal developmental malformations or variations, visceral variations). Higher doses were shown to induce strong toxicity (mortality at 750 and 250 mg/kg bw/day) in the dose range finding studies and were thus not included in the main study.

Dose descriptor:

NOAEL

Effect level:

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

Sex:

male/female

Basis for effect level:

other: No toxicologically relevant changes were noted in any of the developmental parameters investigated in this study.

Abnormalities:

not specified

Developmental effects observed:

no

Accuracy, homogeneity and stability of formulations were demonstrated by analyses.

Executive summary:

Triphenyl phosphate was tested in a prenatal developmental toxicity study in pregnant New Zealand rabbits following OECD TG 414. The test item was administered once daily by oral gavage from Days 6 to 28 post-coitum at doses of 0, 32, 80 and 200 mg/kg bw/day in 1% aqueous carboxymethyl cellulose. The doses were chosen on the basis of dose range finding studies that showed strong toxicity (including mortality) at 750 and 250 mg/kg bw/day.

Females were checked daily for the presence of clinical signs. Food consumption and body weight were determined at periodic intervals. Formulations prepared on one day during treatment were analyzed for accuracy, homogeneity and stability.

All animals surviving to Day 29 post-coitum were subjected to an examination post-mortem and external, thoracic and abdominal macroscopic findings were recorded. A laparohysterectomy was performed on each surviving female of the groups. The uteri, placentae and ovaries were examined, and the numbers of fetuses, early and late resorptions, total implantations and corpora lutea were recorded. Gravid uterine weights were recorded, and net body weights and net body weight changes were calculated. The fetuses were weighed, sexed and examined for external, visceral and skeletal malformations and developmental variations. All live fetuses were euthanized. One half of the fetuses were decapitated and the heads were fixed in Bouin’s fixative. All fetuses were dissected and examined for visceral anomalies and subsequently fixed in 96% aqueous ethanol. The fetuses of all groups were stained with Alizarin Red S for skeletal examinations.

No toxicologically significant changes were noted in any of the maternal parameters investigated in this study (i.e. mortality, clinical signs, body weights, food consumption, and macroscopic examination). No toxicologically relevant changes were noted in any of the developmental parameters investigated in this study (i.e. litter size, sex ratio, fetal body weights, external, visceral and skeletal developmental malformations or variations, visceral variations).

Based on the results of this prenatal developmental toxicity study, both the maternal and developmental No Observed Adverse Effect Levels (NOAELs) for triphenyl phosphate were established as being at least 200 mg/kg bw/day, since no adverse effect was observed. No higher doses could be tested in pregnant rabbits based on dose range finding studies.

Reference 2

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: detailed publication. Also assessed by OECD.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Principles of method if other than guideline:

Method: other: see freetext

GLP compliance:

not specified

Species:

rat

Strain:

Sprague-Dawley

Route of administration:

oral: feed

Vehicle:

not specified

Duration of treatment / exposure:

91 days

Frequency of treatment:

daily

Control animals:

yes, concurrent no treatment

Details on study design:

Sex: male/female
Duration of test: 3 months

Maternal examinations:

No adverse effects noted

Ovaries and uterine content:

No adverse effects noted

Fetal examinations:

No significant adverse effects noted

Details on maternal toxic effects:

Maternal toxic effects:no effects

Dose descriptor:

NOAEL

Effect level:

>= 690 mg/kg bw/day

Basis for effect level:

other: maternal toxicity

Dose descriptor:

NOAEL

Effect level:

>= 690 mg/kg bw/day

Basis for effect level:

other: teratogenicity

Abnormalities:

not specified

Developmental effects observed:

not specified

OBSERVATION: no findings reported
FOOD CONSUMPTION: increased in pregnant dams (not dose-dependent)
BODY WEIGHT: decreased during pregnancy (non-significant)
NECROPSY: no significant differences in number of corpora lutea,  implants, implantation efficiency, viable fetuses and number of early or  late deaths. 
No increase in skeletal anomalies. 
Slight, non-dose- related increases in visceral variations
("All treated groups had significantly more fetuses with moderate  hydroureter than the control group. However, the high baseline incidence  exhibited in the control group and lack of a clear dose-related response  make the biological significance of this finding unclear. There were also  significantly more fetuses in the treated groups with moderately enlarged  ureters in the region adjacent to the kidney than in the controls. Again,  the incidence was not related to dose since a greater portion of fetuses  were affected in the lower dose levels than in two high levels"). 
No signs of teratogenicity.

Conclusions:

The NOEL for male and female fertility, maternal toxicity and developmental toxicity was 1% of TPP in the diet (690 mg/kg bw/day).

Executive summary:

Fertility and developmental toxicity were examined in a dietary study in Sprague-Dawley rats at doses of 0, 0.25, 0.50, 0.75, 1.0% corresponding to 0, 166, 341, 516 or 690 mg/kg bw/day. Forty males and forty females per group were treated for 3 months and mated afterwards. Animals were treated further throughout mating and gestation and killed at day 20 of gestation.

Effects on fertility- The study included treatment of males and females for three months prior to mating throughout gametogenisis and during mating and gestation. No significant differences were recorded in the number of corpora lutea, implants, implantation efficiency, viable fetuses and the number of early or late deaths between treated and control rats. No significant signs of parental toxicity were detected. As there were no effects on the litter size (indirectly measured by the number of viable fetuses and implants) and both sexes were treated in the study, these findings indicate that fertility is not adversely affected by TPP in male and female rats. Developmental toxicity- Neither maternal toxicity nor changes in the types or numbers of anomalies in the fetuses were detected. All treated groups had significantly more fetuses with moderate hydroureter than the control group. In the opinion of the authors, the high baseline incidence exhibited in the control group and lack of a clear dose-related response make the biological signficance of this finding unclear. There was also significantly more fetuses in the treated groups with moderately enlarged ureters in the region adjacent to the kidney than in the controls. Again, the incidence was not related to dose since a greater proportion of fetuses having at least two soft-tissue variations was significantly higher than in the 0.25, 0.50 and 0.75 but not the 1% TPP groups than in the control group. The 1% group was only slightly, non-significantly higher than the control. The number of litters with fetuses having at least two soft-tissue variations was significantly greater only in the 0.5 and 0.75% groups. The authors concluded that there was no evidence of bioaccumulation or increased reproductive toxicity after exposure to TPP. The NOEL for male and female fertility, maternal toxicity and developmental toxicity was 1% in the diet (690 mg/kg bw/day). No signs of developmental toxicity were seen up to the highest dose tested.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

200 mg/kg bw/day

Study duration:

subacute

Species:

other: rat and rabbit

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

Fertility and developmental toxicity were examined in a dietary study in Sprague-Dawley rats at doses of 0, 0.25, 0.50, 0.75, 1.0% corresponding to 0, 166, 341, 516 or 690 mg/kg bw/day. Forty males and forty females per group were treated for 3 months and mated afterwards. Animals were treated further throughout mating and gestation and killed at day 20 of gestation.

Effects on fertility- The study included treatment of males and females for three months prior to mating throughout gametogenisis and during mating and gestation. No significant differences were recorded in the number of corpora lutea, implants, implantation effiiciency, viable fetuses and the number of early or late deaths between treated and control rats. No significant signs of parental toxicity were detected. As there were no effects on the litter size (indirectly measured by the number of viable fetuses and implants) and both sexes were treated in the study, these findings indicate that fertility is not adversely affected by TPP in male and female rats. Developmental toxicity- Neither maternal toxicity nor changes in the types or numbers of anomalies in the fetuses were detected. All treated groups had significantly more fetuses with moderate hydroureter than the control group. In the opinion of the authors, the high baseline incidence exhibited in the control group and lack of a clear dose-related response make the biological significance of this finding unclear. There was also significantly more fetuses in the treated groups with moderately enlarged ureters in the region adjacent to the kidney than in the controls. Again, the incidence was not related to dose since a greater proportion of fetuses having at least two soft-tissue variations was significantly higher than in the 0.25, 0.50 and 0.75 but not the 1% TPP groups than in the control group. The 1% group was only slightly, non-significantly higher than the control. The number of litters with fetuses having at least two soft-tissue variations was significantly greater only in the 0.5 and 0.75% groups. The authors concluded that there was no evidence of bioaccumulation or increased reproductive toxicity after exposure to TPP. The NOEL for male and female fertility, maternal toxicity and developmental toxicity was 1% in the diet (690 mg/kg bw/day). No signs of developmental toxicity were seen up to the highest dose tested.

 

Update 2021-05-02: Quite recently, some results of the ‘Modified One-Generation Reproduction study’ have been published on the NTP homepage in tabular form, as abstract and as poster (presented at the SOT 2021). However, the data shown is neither peer-reviewed, as stated in the poster ‘These data have not yet been evaluated in the NTP data/peer review process and therefore should be regarded as preliminary at this time’, nor complete, as stated in the abstract ‘Studies are currently underway at the NTP to characterize longer-term effects on reproduction, development and developmental neurotoxicity following exposure to TPHP and IPP’. Consequently, the status of this study is still given with ‘Data in Review’.
DOI: https://doi.org/10.22427/NTP-DATA-002-00600-0003-000-1
As soon as the ‘Modified One-Generation Reproduction study’ is fully assessed, peer-reviewed and reported it will be considered for the ED assessment of triphenyl phosphate.

 

Triphenyl phosphate was tested in a prenatal developmental toxicity study in pregnant New Zealand rabbits following OECD TG 414 (Peter, 2015). The test item was administered once daily by oral gavage from Days 6 to 28 post-coitum at doses of 0, 32, 80 and 200 mg/kg bw/day in 1% aqueous carboxymethyl cellulose. The dose levels were chosen on the basis of dose range finding studies that showed strong toxicity (including mortality) at 750 and 250 mg/kg bw/day. Females were checked daily for the presence of clinical signs. Food consumption and body weight were determined at periodic intervals. Formulations prepared on one day during treatment were analyzed for accuracy, homogeneity and stability. All animals surviving to Day 29 post-coitum were subjected to an examination post-mortem and external, thoracic and abdominal macroscopic findings were recorded. A laparohysterectomy was performed on each surviving female of the groups. The uteri, placentae and ovaries were examined, and the numbers of fetuses, early and late resorptions, total implantations and corpora lutea were recorded. Gravid uterine weights were recorded, and net body weights and net body weight changes were calculated. The fetuses were weighed, sexed and examined for external, visceral and skeletal malformations and developmental variations. All live fetuses were euthanized. One half of the fetuses were decapitated and the heads were fixed in Bouin’s fixative. All fetuses were dissected and examined for visceral anomalies and subsequently fixed in 96% aqueous ethanol. The fetuses of all groups were stained with Alizarin Red S for skeletal examinations.

No toxicologically significant changes were noted in any of the maternal parameters investigated in this study (i.e. mortality, clinical signs, body weights, food consumption, and macroscopic examination). No toxicologically relevant changes were noted in any of the developmental parameters investigated in this study (i.e. litter size, sex ratio, fetal body weights, external, visceral and skeletal developmental malformations or variations, visceral variations). Based on the results of this prenatal developmental toxicity study on rabbits, both the maternal and developmental No Observed Adverse Effect Levels (NOAELs) for triphenyl phosphate were established as being at least 200 mg/kg bw/day, since no adverse effects were observed. No higher doses could be tested in pregnant rabbits based on toxicity in dose range finding studies.

 

In conclusion, no relevant effects on fetal development were observed in a one-generation study on rats and a developmental toxicity study on rabbits with triphenyl phosphate. The overall NOEL for developmental toxicity is thus established with 200 mg/kg bw/day, the highest dose that could be tested in rabbits.

Justification for classification or non-classification

Triphenyl phosphate showed no effects on fertility or on developmental toxicity in a one generation reproductive toxicity study on rats. Futhermore, in recently performed repeated dose toxicity studies on rats with up to subchronic oral exposure that included macroscopic and microscopic investigations of male and female gonads, the test substance showed no adverse effects on the reproductive organs. In addition, triphenyl phosphate showed no developmental toxicity in a recently performed Guideline study (OECD 414) on rabbits. Thus, the test substance was shown to exert no adverse effects on fertility of male and female rats and on the development of fetuses in pregnant rats and rabbits. According to EU Regulation 1272/2008 no classification for effects on fertility and for effects on developmental toxicity is warranted for triphenyl phosphate.