1,3-dihydroxyacetone

Endpoint summary

Key value for chemical safety assessment

Toxic effect type:

dose-dependent

Effects on fertility

Description of key information

No maternal or fetal toxicity has been observed in a developmental toxicity study in rats, treated orally with the test material up to the highest dose of 1000 mg/kg bw/day. In addition, no indication of any toxicity was observed in a subchronic oral toxicity study in rats. Histological examinations did not indicate toxic effects on reproductive organs of the test animals treated up to 1000 mg/kg bw/day for 90 days. The substance was shown to be neither genotoxic nor carcinogenic in rats after dermal treatment. In addition, the substance is physiologically available: Its phosphorylated form takes part in glycolysis, and it is an intermediate product of fructose metabolism.

The absence of any toxic effects suggests that at present there is no need for further information and/or testing on reproduction toxicity beyond those which are being applied already.

Effect on fertility: via oral route

Endpoint conclusion:

no study available

Effects on developmental toxicity

Description of key information

The potential effects of the test material on embryo-foetal development were evaluated in a prenatal study in which pregnant rats received doses of 100, 300 or 1000 mg/kg bw/day by the oral route (gavage) during the sensitive period of organogenesis. As expected, no maternal toxic effects were observed up to the limit dose level of 1000 mg/kg bw/day. No teratogenic or embryotoxic effects were observed at any dose level. Accordingly, the NOELs for both maternal and developmental toxicity was 1000 mg/kg bw/day i.e. the highest dose tested in this study.

The study is of high quality, i.e. performed under GLP regulation and according to international accepted Guidelines (Klimisch Score 1).

Link to relevant study records

Reference

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2007-01-22 to 2007-10-29

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:

adopted 22 Jan. 2001

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.31 (Prenatal Developmental Toxicity Study)

Version / remarks:

dated 29 April 2004

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.3700 (Prenatal Developmental Toxicity Study)

Version / remarks:

dated August 1998

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Japanese Guideline (Ministry of Agriculture, Forestry and Fisheries, Test Data for Registration of Agricultural Chemicals, 12 Nohsan No. 8147, Teratology (2-1-18))

Version / remarks:

dated 24 Nov. 2000

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Species:

rat

Strain:

Wistar

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: RCC Ltd, Laboratory Animal Services, Fuellinsdorf, Switzerland
- Age at study initiation (pairing): 11 weeks
- Weight at study initiation: 192 - 232 g
- Fasting period before study: no
- Housing: individually in Makrolon cages (type-3) with wire mesh tops and standardized granulated softwood bedding
- Diet: pelleted standard Kliba Nafag 3433 ad libitum
- Water: tap-water ad libitum
- Acclimation period: 7 days prior to pairing

ENVIRONMENTAL CONDITIONS
- Temperature: 22 +/- 3°C
- Humidity: 30-70%
- Air changes: 10 - 15 per hr
- Photoperiod: 12 hrs dark / 12 hrs light

IN-LIFE DATES: From: 2007-01-22 To: 2007-06-11

Route of administration:

oral: gavage

Vehicle:

water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:

VEHICLE
- Justification for use and choice of vehicle (if other than water): water
- Concentration in vehicle: Group 1 (Control): 0 mg/mL
Group 2 (100 mg/kg bw/day): 10 mg/mL
Group 3 (300 mg/kg bw/day): 30 mg/mL
Group 4 (1000 mg/kg bw/day): 100 mg/mL

- Amount of vehicle (if gavage): 10 mL/kg bw
- Frequency of preparation: Daily
- Administration within 4 hours after preparation of dose formulations.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The analytical verification (identity, concentration, homogeneity, stability) was performed during the course of the study under GLP regulation.
Samples of dose formulations (top, middle, bottom) were taken from each group at 2 different treatment days. The test item concentrations were determined by HPLC coupled to an UV detector and quantified with the area under the peak.
The identity of the test item was confirmed. The test material concentration in all samples were found to be in the predefined acceptance range of +/-20% of the nominal content. The homogenous distribution of the test item in the dose formulations was demonstrated.
In conclusion, the results obtained during formulation analysis confirmed the correct preparation and storage of application formulations during the conduct of this study.

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) the daily vaginal smear was sperm positive or
b) a copulation plug was observed.
The day of mating was designated day 0 post coitum.
Male rats of the same source and strain were used for mating only. These male rats were in the possession of performing lab, 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:

once daily in the morning from day 6 through to day 20 post coitum (last treatment)

Frequency of treatment:

daily

Duration of test:

20 days past coitum

Dose / conc.:

100 mg/kg bw/day (nominal)

Dose / conc.:

300 mg/kg bw/day (nominal)

Dose / conc.:

1 000 mg/kg bw/day (nominal)

No. of animals per sex per dose:

22 pregnant females per group (1 control and 3 dose groups)

Control animals:

yes

Details on study design:

- Dose selection rationale: Dosages were based on the results of a 14-day GLP dose-range-finding study in rats (oral), where no adverse effects were observed.
- Rationale for animal assignment: Computer-generated random algorithm

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: twice daily

BODY WEIGHT: Yes
- Time schedule for examinations: daily from day 0 until day 21 post coitum

FOOD CONSUMPTION: Yes
- Food consumption was recorded on 3-day intervals: days 0-3, 3-6, 6-9, 9-12, 12-15, 15-18 and 18-21 post coitum for each animal

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 21 post coitum
- Organs examined: all internal organs, with emphasis on the uterus, uterine contents, position of fetuses in the uterus and number of corpora lutea

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
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

Fetal examinations:

- External examinations: Yes [all per litter ]
- Soft tissue examinations: Yes [half per litter ]
- Skeletal examinations: Yes [half per litter]
- Head examinations: Yes [half per litter ]
- Sex
- Weight

Statistics:

The following statistical methods were used to analyze body weights, food consumption, reproduction and skeletal examination data:
- Means and standard deviations of various data were calculated and included in the report.
- If the variables could be assumed to follow a normal distribution, the Dunnett many-one t-test, based on a pooled variance estimate, was used for intergroup
comparisons (i.e. single treatment groups against the control group).
- The Steel test (many-one rank test) was applied when the data could not be assumed to follow a normal distribution.
- Fisher's Exact test for 2x2 tables was applied if the variables could be dichotomized without loss of information.

Indices:

According to guideline

Clinical signs:

no effects observed

Description (incidence and severity):

No signs of discomfort or clinical symptoms from the treatment with the test item were observed.

Mortality:

no mortality observed

Description (incidence):

All females survived until scheduled necropsy.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Mean body weight and mean body weight gain were not affected by treatment with the test item.
Mean corrected body weight gain (corrected for the gravid uterus weight) was similar in all groups (14.4%, 14.2%, 14.6% and 13.4% in order of ascending dose level).

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

Mean food consumption was not affected by treatment with the test item in any group (-1.2%, -1.6% and -1.6% in groups 2, 3 and 4, respectively, compared to the control group).

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:

not examined

Gross pathological findings:

no effects observed

Description (incidence and severity):

During macroscopic examination, no abnormal findings were noted.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Other effects:

not examined

Number of abortions:

no effects observed

Pre- and post-implantation loss:

no effects observed

Description (incidence and severity):

Post-implantation losses and the mean number of fetuses per dam were not affected by treatment with the test item at all dose levels.
In group 3, a statistically significant higher pre-implantation loss was noted, resulting in a statistically significant lower number of implantation sites. Since pre-implantation loss occurs before treatment start and in the absence of dose-dependency this difference was considered to be incidental.

Total litter losses by resorption:

no effects observed

Early or late resorptions:

no effects observed

Dead fetuses:

no effects observed

Changes in pregnancy duration:

no effects observed

Changes in number of pregnant:

not examined

Other effects:

no effects observed

Details on maternal toxic effects:

Maternal toxic effects:no effects

Details on maternal toxic effects:
There was no difference in food consumption, mean body weight and corrected body weight gain between the test item groups and the control group. No macroscopic findings were noted during necropsy of the females.

Key result

Dose descriptor:

NOEL

Effect level:

> 1 000 mg/kg bw/day

Based on:

test mat.

Remarks on result:

not determinable due to absence of adverse toxic effects

Key result

Abnormalities:

no effects observed

Fetal body weight changes:

no effects observed

Description (incidence and severity):

Mean fetal weights were not affected by treatment with the test item. Mean fetal weights were 4.8 g, 4.8 g, 5.0 g and 5.0 g in order of ascending dose level when calculated on a litter basis for male and female fetuses combined data. The statistically significantly higher values in groups 3 and 4 were considered to be incidental.

Reduction in number of live offspring:

no effects observed

Changes in sex ratio:

no effects observed

Description (incidence and severity):

No test item-related effects on sex ratio of fetuses were noted in any group.
In group 4, a statistically significantly higher percentage of male fetuses was noted (55.9% compared to 45.0% in the control group). Since this is related to a low percentage of males in the control group, this was considered to be incidental.

Changes in litter size and weights:

no effects observed

Changes in postnatal survival:

not examined

External malformations:

no effects observed

Description (incidence and severity):

No test item-related abnormalities were noted during external examination of fetuses.

Skeletal malformations:

no effects observed

Description (incidence and severity):

During skeletal examination of the fetuses, findings were noted in:
17 out of 134 examined fetuses (in 12 of 22 litters) in group 1
11 out of 136 examined fetuses (in 9 of 22 litters) in group 2
14 out of 129 examined fetuses (in 11 of 22 litters) in group 3
10 out of 130 examined fetuses (in 7 of 21 litters) in group 4.
No test item-related findings were noted. No abnormalities were found in any fetus in any group.
The type and frequencies of commonly noted variations were similar in nature for test item and control group and did not indicate any dose-dependency and were therefore considered not to be test item-related effects.

Visceral malformations:

no effects observed

Description (incidence and severity):

During visceral examination of fetuses, findings were noted in:
52 out of 144 examined fetuses (in 19 of 22 litters) in group 1
57 out of 149 examined fetuses (in 22 of 22 litters) in group 2
51 out of 136 examined fetuses (in 21 of 22 litters) in group 3
48 out of 140 examined fetuses (in 19 of 21 litters) in group 4.
No test item-related findings were noted.
Abnormalities were found in 1 (1 fetus), 2 (2 fetuses), 1 (1 fetuses) and 3 (3 fetuses) litters in order of ascending dose level, each fetus of which had one or more of the following abnormalities: situs inversus, diaphragm tendinous or muscular region locally severely thinned, renal pelvis and ureter severely dilated. One fetus in group 2 had multiple cardiovascular abnormalities, namely aortic arch dilated, pulmonary trunk narrow, interventricular septal defect
and azygos vein persisting into abdomen. Due to the isolated occurrence in individual fetuses these abnormalities were considered to be incidental.
The type and frequencies of commonly noted variations were similar in nature for test item and control group and did not indicate any dose-dependency and were therefore considered not to be test item-related effects.

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
No test item-related malformations or abnormal findings were noted during external, visceral and skeletal/cartilage examination of the fetuses.

Key result

Dose descriptor:

NOEL

Effect level:

> 1 000 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

Abnormalities:

no effects observed

Key result

Developmental effects observed:

no

Treatment related:

no

All females survived until scheduled necropsy. No signs of discomfort or clinical symptoms from the treatment with the test item were observed. There was no difference in food consumption, mean body weight and corrected body weight gain between the test item groups and the control group. No macroscopic findings were noted during necropsy of the females. Twenty-two out of twenty-two (22/22), 22/22, 22/22 and 21/22 females were pregnant in the control, 100 mg/kg/day, 300 mg/kg/day and 1000 mg/kg/day groups, respectively. Post-implantation losses and the mean number of fetuses per dam were not affected by treatment with the test item at all dose levels. No test-item related effects on fetal body weights and sex ratios were noted in any dose group. No test item-related malformations or abnormal findings were noted during external, visceral and skeletal/cartilage examination of the fetuses.

Conclusions:

Under the conditions of this study, the test material did not reveal any teratogenic potential in rats after oral administration up to and including 1000 mg/kg body weight/day.

Executive summary:

The purpose of this study was to assess the effects of the test item on pregnant female rats and embryo-fetal development when administered orally by gavage once daily to mated female rats from day 6 through to day 20 post coitum, inclusive. Each group consisted of 22 mated female rats. The test material was administered once daily at dose levels of:

Group 1: 0 mg/kg bw/day (vehicle control)

Group 2: 100 mg/kg bw/day

Group 3: 300 mg/kg bw/day

Group 4: 1000 mg/kg bw/day

A standard dose volume of 10 mL/kg body weight with a daily adjustment to the actual body weight was used. Control animals were dosed with the vehicle alone (Milli-Q-water). The correct preparation of the application formulations during this study was confirmed using a HPLC method. All females were sacrificed on day 21 post coitum and the fetuses were removed by Caesarean section. The following results were obtained:

MATERNAL DATA

General Tolerability

All females survived until scheduled necropsy. No signs of discomfort or clinical symptoms from the treatment with the test item were observed. No macroscopic findings were noted during necropsy of the females.

Food Consumption and Body Weights

Mean food consumption, mean body weight and corrected body weight gain (corrected for the gravid uterus weight) were not affected by treatment with the test item in any dose group.

Reproduction Data

Post-implantation losses and the mean number of fetuses per dam were not affected by treatment with the test item at all dose levels.

FETAL DATA

Body Weights and Sex Ratios

No test item-related effects on fetal body weights were noted. No test item-related effects on fetal sex ratios were noted in any dose group.

External Examination

During the external examination of the fetuses, no test item-related abnormal findings were noted.

Visceral Examination

No test item-related abnormalities were noted during the visceral examination of fetuses.

Skeletal and Cartilage Examination

No abnormalities, which were considered to be test item-related, were noted during examination of fetal skeleton and cartilages.

Conclusion

In order to detect effects on the pregnant female rat and on embryonic and fetal development, the test material was administered orally by gavage once daily from day 6 through to day 20 post coitum at the dose levels of 100, 300 and 1000 mg/kg bw/day. Treatment with the test item up to and including 1000 mg/kg bw/day resulted in no clinical findings and did not affect embryo-fetal development. Based on these results, the NOEL (No Observed Effect Level) for maternal and fetal organisms was considered to be 1000 mg/kg bw/day. Under the conditions described for this study, the test material did not reveal teratogenic potential up to and including 1000 mg/kg bw/day.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

The study is of high quality (Klimisch Score 1)

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

The effects of the test material on pregnant female rats and embryo-fetal development was investigated when administered orally by gavage once daily to mated female rats from day 6 through to day 20 post coitum, inclusive. Each group consisted of 22 mated female rats. DHA was administered once daily at dose levels of 0, 100, 300, and 1000 mg/kg bw/day. A standard dose volume of 10 mL/kg body weight with a daily adjustment to the actual body weight was used. Control animals were dosed with the vehicle distilled water alone. The correct preparation of the application formulations during this study was confirmed using a HPLC method. All females were sacrificed on day 21 post coitum and the fetuses were removed by Caesarean section. The following results were obtained:

All females survived until scheduled necropsy. No signs of discomfort or clinical symptoms from the treatment with the test item were observed. No macroscopic findings were noted during necropsy of the females.

Mean food consumption, mean body weight and corrected body weight gain (corrected for the gravid uterus weight) were not affected by treatment with the test item in any dose group.

Post-implantation losses and the mean number of fetuses per dam were not affected by treatment with the test item at all dose levels.

No test item-related effects on fetal body weights were noted. No test item-related effects on fetal sex ratios were noted in any dose group.

During the external examination of the fetuses, no test item-related abnormal findings were noted.

No test item-related abnormalities were noted during the visceral examination of fetuses.

No abnormalities, which were considered to be test item-related, were noted during examination of fetal skeleton and cartilages.

Toxicity to reproduction: other studies

Description of key information

No other studies available.

Mode of Action Analysis / Human Relevance Framework

The studies provided are considered to be relevant for human risk assessment.

Justification for classification or non-classification

No maternal or fetal toxicity has been observed in a developmental toxicity study in rats, treated orally with the test material up to the highest dose of 1000 mg/kg bw/day.

Under the conditions described for this study, the test material did not reveal teratogenic potential up to and including 1000 mg/kg bw/day. Moreover, no toxicity on reproductive organs was observed in a subchronic oral toxicity study in rats, i.e. there are no indications that fertility might be affected.

All studies are of high quality, i.e. performed under GLP regulation and according to international accepted Guidelines (Klimisch Score 1).

Therefore, based on all this data, the test material must not be classified with regard to toxicity to reproduction.