Supernatant from the crystallisation of L-threonine from the broth filtrate from the fermentative production of L-threonine

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

2008

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP study according to OECD guideline 414 (adopted 2001). Study was originally judged Klimisch 1. However, according to the "Practical guide 6: How to report read-across and categories" the maximum score for read-across is 2.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2012

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.3700 (Prenatal Developmental Toxicity Study)

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: Japanese Testing Guideline 12 NohSan No. 8147 (2000)

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Biofert Plusz

IUPAC Name:

Biofert Plusz

Details on test material:

-Name of test material (as cited in study report): Biofert Plusz
Details are presented in "Confidential details on test material"

Test animals

Species:

rat

Strain:

Wistar

Details on test animals or test system and environmental conditions:

TEST ANIMALS
-Strain: HanRcc: WIST(SPF)
-Source: Harlan Laboratories Ltd., Laboratory Animal Services, Füllinsdorf / Switzerland
-Age at study initiation: 11 weeks
-Weight at study initiation: 181 to 234 g
-Housing: individually
-Certified diet (analysis available) ad libitum
-Tap water ad libitum
-Acclimation period: 7 days. Under test conditions after health examination. Only animals without any visible signs of illness were used for the study

ENVIRONMENTAL CONDITIONS
-According to Guideline

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Remarks:

(Milli-Q-water)

Details on exposure:

PREPARATION OF DOSING SOLUTIONS
The dose formulations were prepared every third day, based upon the dry mass (28.1%) of the main component in the provided test item. Therefore, a correction factor of 3.56 was used. Prior to dose formulation, the contents of the test item container were homogenized to avoid uneven distribution of the dry mass. Homogeneity of the test item in the vehicle was maintained during the daily administration period using a magnetic stirrer.

Dosing volume: 10 mL/kg bw

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Dose formulations were stored in the refrigerator (+2 to +8 °C) in glass beakers. On the first treatment day samples from the control group as well as three samples (top, middle, and bottom) of about 2 g of each concentration were taken prior to dosing for analysis of concentration and homogeneity. Samples of about 2 g of each concentration were taken from the middle only to confirm stability (3 days). The test item content in all samples was found to be within the accepted range of +/- 20% of the nominal content (ranged from 111.4 – 119.8 % of the nominal concentration). In addition, the homogeneous distribution of Biofert Plusz in Milli-Q-Water was demonstrated. The application formulations were considered to be stable for at least 3 days when kept in the refrigerator.

Details on mating procedure:

After acclimatization, females were housed with sexually mature males (1:1; same source and strain; synchronized timing to initiate the nightly mating), until evidence of copulation was observed. The day of mating was designated as day 0 post coitum when a) the daily vaginal smear was sperm positive, or b) a copulation plug was observed. The fertility of these males had been proven and was continuously monitored.

Duration of treatment / exposure:

days 6-20 of gestation

Frequency of treatment:

once daily

Duration of test:

Scheduled necropsy on day 21 of gestation

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 100, 300 and 1000 mg/kg bw/d (highest dose level tested corresponds to the limit dose recommended in OECD 414)
Basis:
nominal conc.
(based on dry mass)

No. of animals per sex per dose:

22 dams per dose

Control animals:

yes, concurrent vehicle

Details on study design:

Dose selection rationale: Based on a preliminary dose-range-finding study

Examinations

Maternal examinations:

-Viability / Mortality: Twice daily
-Clinical Signs: Daily during acclimatization and up to day of necropsy
-Food Consumption: Recorded at 3-day intervals (days 0-3, 3-6, 6-9, 9-12, 12-15, 15-18 and 18-21)
-Body Weights: Daily from day 0 until day 21
-Termination: Gestational day 21. Females were sacrificed by CO2 asphyxiation and the foetuses were removed by Caesarean section
-Necropsy: Gross macroscopic examination of all internal organs with emphasis on the uterus, uterine contents, position of foetuses in the uterus and the number of corpora lutea. Uteri incl. contents of all females with live foetuses were weighed during necropsy to enable the calculation of the corrected body weight gain

Ovaries and uterine content:

Ovaries and uterine content was examined after termination. Examinations included gravid uterus weight, number of corpora lutea, number of implantations and numbers of early and late resorptions

Fetal examinations:

-Number of live, dead and abnormal foetuses
-Foetal sex ratios
-Foetal body weights
-External examinations: All per litter
-Soft tissue and head examinations (half per litter): micro-dissection technique; combination of serial sections of the head and micro-dissection of the thorax and abdomen
-Skeletal examinations (half per litter): Foetuses were eviscerated, Alizarin red S staining

Statistics:

Dunnett-test, Steel-test and Fisher's exact-test

Historical control data:

Yes

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:no effects

Details on maternal toxic effects:
Although mean food consumption in high-dosed animals was significantly reduced on gestational days 6 – 9, this finding was not considered as adverse (no effect on body weight and reduction was < 10 %).

Effect levels (maternal animals)

1

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day (nominal)

Based on:

other: (dry mass of the liquid test item)

Basis for effect level:

other: maternal toxicity

2

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day (nominal)

Based on:

other: (dry mass of the liquid test item)

Basis for effect level:

other: developmental toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
There was a significantly higher incidence of incompletely ossified sternebrae in high-dosed animals. Since this incidence was in the range of the historical control data it was considered to reflect the range of natural biological variability.

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

In a GLP study according to OECD guideline 414 with Wistar rats, no maternal and developmental toxicity was detected even at the high dose level of 1000 mg/kg bw/d (related to dry weight).