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Diss Factsheets

Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
other: Read across from analogue substance
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2020

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
yes
Remarks:
See details on "Principles of method if other than guideline"
Principles of method if other than guideline:
Guideline requires external fetal sex to be compared with internal sex in all foetuses (examined for both skeletal and soft tissue malformations). External fetal sex was compared with internal sex only in foetuses examined for soft tissue malformations, in foetuses examined for skeletal malformations it was not possible. The viscera of these foetuses were carefully removed by a very small incision from the abdominal cavity to stain the entire skeleton. This deviation from the test guideline did not affect the reliability of the study.
GLP compliance:
yes (incl. QA statement)
Limit test:
no

Test material

Constituent 1
Reference substance name:
4-hydroxybenzenesulphonic acid
EC Number:
202-691-6
EC Name:
4-hydroxybenzenesulphonic acid
Cas Number:
98-67-9
Molecular formula:
C6H6O4S
IUPAC Name:
p-hydroxybenzenesulphonic acid

Test animals

Species:
rat
Strain:
other: Wistar CRL
Details on test animals or test system and environmental conditions:
Species: Albino laboratory rat
Selection of animal species: Laboratory rat has been chosen because our testing laboratory has long experience with this species and therefore the historical data on key parameters are available and because rat is recommended according to the OECD 414 guideline.
Strain: Wistar CRL (SPF quality - guaranteed)
Supplier: SPF breeding, supplied via VELAZ s.r.o., Lysolajské údolí 15/53, 165 00 Prague 6, Czech Republic, RČH CZ 11760500
Sex: Sexually adult females and males
Age at start of the study: Dose-range finding experiment: 12 weeks, Main study: 12 weeks
Acclimatization: Dose-range finding experiment: 6 days, Main study: 6 days
Total number of animals: Dose-range finding experiment: total number of animals before mating: 24 females and 12 males (6 probably pregnant females per group)
Main study: total number of animals before mating: 100 females and 25 males (23 probably pregnant females per group)
Housing conditions: Dose-range finding experiment and main study: SPF conditions according to internal SOP No. 12
Light cycle: 12 hour light/12 hour dark
Microclimate: 22 ± 3 °C, relative humidity 30 – 70 %
Animal per cage: Before mating 2 rats of the same sex in one cage, during mating period – one male and two females in one cage were housed. Pregnant females were then placed individually.
Bedding: Sterilized clean shavings of soft wood or sterilized LIGNOCEL (raw material - spruce; producer: J.Rettenmaier & söhne, Germany).
Food: Complete pelleted diet for rats and mice in SPF breeding (Altromin Spezialfutter) was used.
Manufacturer: Altromin Spezialfutter GmbH & Co. KG, Germany. Diet was sterilized before using.
Water: Free access to drinking water (water ad libitum). Water quality corresponded to Regulation No. 252/2004 Czech Coll. of Law, Health Ministry. Quality standard ČSN 757 111.
Selection of animals: Pregnant females were randomly assigned to the experimental groups after determination of pregnancy.
Identification of animals: The animals were identified by the colour marks (colour for veterinary usage) on their fur, each cage was marked with the number of animals, sex, cage number, name of the test item and dose level of the a.i..

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
other: Aqua pro iniectione
Details on exposure:
The test item has been supplied as ca 66.3 % w/w 4-hydroxybenzensulphonic acid aqueous solution. Therefore, a dose of 1000 mg of a.i./kg body weight is equivalent to approximately 1510 mg of the test item replenished with aqua pro iniectione to volume 10 mL/kg body weight.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Stability and homogeneity of the test item application forms were determined by measuring of a peak area of the test item by a high-performance liquid chromatography based on a method developed at the test facility. Measuring was performed on two concentrations of application form: 10 mg of a.i./10 mL and 1000 mg of a.i./10 mL.

Homogeneity
The samples were taken after 20 minutes of mixing by magnetic stirrer (500 rpm) from 3 given places - the bottom, the middle and the surface of the beaker content for the determination of homogeneity of both application forms. Two samples were taken from each place.

Stability
The samples were taken from the middle of the beaker content at required time intervals (0, 30, 60, 90 and 120 minutes) for the determination of stability of both application forms. Two samples were taken at all time intervals. Time interval 0 min represents for both concentration levels the time after 20 minutes of mixing by magnetic stirrer at 500 rpm.
Details on mating procedure:
After acclimatization females were mated with males (1 male and 2 females). Vaginal smears were carried out daily in the morning to control fertilization (first time: 24 hours after the first removing to male). Presence of sperm was examined. Day 0 of pregnancy was the day on which sperm in vaginal smears were observed. Pregnant females were randomly distributed to experimental groups.
Duration of treatment / exposure:
Exposition lasted from implantation (the 5th day after fertilization) to one day prior to the day of scheduled euthanasia (the 19th day after fertilization). Male rats serve only for mating (they were not administered the test item or examined)
The test item was administered in graduated dose levels of a.i. to pregnant females from implantation (gestation day 5) to one day prior to the day of scheduled euthanasia (gestation day 19).
The concentrations of all dose levels of active ingredient were adjusted to ensure the administration of 1 mL per 100 g of body weight.
The application form (test item in aqua pro iniectione) was administered to the stomach by gavage. The vehicle control group was administered by aqua pro iniectione in the same volume by gavage.
Frequency of treatment:
The animals were treated 7 days per week at the same time (8.00 – 10.00 am).
Duration of test:
29/09/2020-29/06/2021
Doses / concentrationsopen allclose all
Dose / conc.:
1 000 mg/kg bw/day (nominal)
Remarks:
based on active ingredient
Dose / conc.:
500 mg/kg bw/day (nominal)
Remarks:
based on active ingredient
Dose / conc.:
250 mg/kg bw/day (nominal)
Remarks:
based on active ingredient
Dose / conc.:
0 mg/kg bw/day (nominal)
No. of animals per sex per dose:
Total number of animals: 24 females + 12 males (6 females and 3 males per dose-group)
Control animals:
yes, concurrent vehicle
Details on study design:
Vaginal smears: daily in mating period. These smears were stained and examined microscopically for presence of spermatozoa. Day 0 of pregnancy was the day when sperm were observed.
Body weight: on the 1st, 5th, 8th, 11th, 14th, 17th and 20th day of pregnancy
Food consumption: on the 5th, 8th, 11th, 14th, 17th and 20th day of pregnancy
Mortality control: daily - during the acclimatization, mating and pregnancy
Health condition control: daily - during the acclimatization, mating and pregnancy
General clinical observations: daily - during the administration period
Laboratory examinations:
- biometry of organs: on the 20th day of pregnancy
- biometry of thyroid gland: after fixation
- pathological examination of females: on the 20th day of pregnancy
- pathological examination of foetuses and AGD measuring: on the 20th day of pregnancy
- microscopical examination: after processing of selected foetuses
- histopathological examination of thyroid gland: after processing
- determination of thyroid hormones: after sampling of all samples

Examinations

Maternal examinations:
The body weight of pregnant females was recorded on automatic balances with group mean computing module. First weighing was performed on the 1st day of pregnancy and then on the 5th, 8th, 11th, 14th, 17th and 20th day of pregnancy.
Food consumption was determined at three-day intervals; it coincided with the terms of body weight recording.

Mortality of females
All rats were examined for vitality or mortality changes daily during the acclimatization, mating and pregnancy.

Health condition control of females
The health condition was controlled daily during the acclimatization period, during the mating period and during pregnancy. Pre-experimental control of all females was performed to ensure that only the females exhibiting normal behavioral activity would be entered into the study. In administration period this observation was performed before application and immediately after application.

Clinical observations of the females
During the administration period clinical observation was made in order to record possible clinical effects of the test item application and all changes in behaviour of females. Females were observed in natural conditions in their cages after application, once a day 3 hours after test item application each day.

Thyroid Hormones
Blood samples from the pregnant females were assessed for serum levels of thyroid hormones (T3 - Triiodothyronine, T4 - Thyroxine, TSH- Thyroid Stimulating Hormone) by ELISA kits (manufacturer BioVendor, Brno, Czech Republic).

Biometry and histopathological examination of thyroid gland
During macroscopic examination the thyroid glands were removed from all pregnant females and were preserved in fixation medium. The thyroid weights were determined after fixation. For histopathological processing the routine histological paraffin technique with synoptic haematoxylin-eosin staining was used. The histopathology of thyroid glands was performed in all groups


Ovaries and uterine content:
Biometry of uterus and macroscopical examination of females
On the 20th day of pregnancy the females were euthanized. The revision of the external surface of the body was performed. During macroscopy, all orifices, the cranial, thoracic and abdominal cavities were examined and uterus (incl. the cervix) was removed and weighed. In gravid uteri, the number of viable foetuses, number of dead foetuses, number of early resorption (implantation without recognizable embryo/foetus) and number of late resorption (dead embryo or foetus with external degenerative changes) were recorded. The numbers of corpora lutea of both ovaries were recorded.
Uteri of non-pregnant females were examined to confirm the non-pregnant status (by the help of ammonium sulphide staining according to the internal SOP M/6 - Prenatal Developmental Toxicity).

Reproduction parameters
In uteri, the number of viable foetuses, number of dead foetuses and number of resorptions (implantation without recognizable embryo/foetus or dead embryo or foetus with external degenerative changes) were recorded. Number of corpora lutea on ovaries was also recorded. Preimplantation and postimplantation losses were calculated from number of implantations (number of foetuses plus number of resorptions), corpora lutea and resorptions.
Fetal examinations:
Pathological examination of foetuses and anogenital distance (AGD) measurement
Sex, individual body weights and anogenital distance (AGD) of foetuses were recorded. A digital calliper was used for AGD measurements. Corrected AGD was calculated according to the formula: AGD divided by the cube root of body weight.
Each foetus was examined for external alterations: symmetry of fore and hind limbs, number of fingers, closing or opening of eye fissures and external auditory canal, symmetry of head, integrity of superior palatum, status of umbilicus and genital papilla were observed.
One half of each litter (one half of female and male foetuses) was examined for soft tissue alterations using careful gross dissection.
Second half of each litter was processed and microscopically examined for skeletal alterations according to the internal SOP M/6 - Prenatal Developmental Toxicity. Single staining displayed only ossified skeletal structures was used: the foetuses were fixed in ethanol, macerated in potassium hydroxide solution, stained with Alizarin red and placed in glycerine-based solution.
The skeletal examination was performed using a stereomicroscope and included examination of skull, clavicle, scapula, sternebra and sternum, ribs, vertebrae, pelvic girdle, fore limb/hind limb.
Statistics:
For statistical evaluation the software Statgraphic® Centurion (version XV, USA) was used. The data from control group were compared with data from treated groups.
The parametric tests were used for statistical evaluation of:
• body weight of females (5th, 8th, 11th, 14th, 17th, 20th day of pregnancy)
• corrected body weight (subtraction weight of uterus from terminal body weight of females)
• food consumption (per interval)
• mean weight of foetuses (males, females, both sex)
• anogenital distance
• thyroid hormones
• biometry of thyroid gland (absolute and relative weight)
• biometry of uteri (absolute and relative weight)
• preimplantation (IUDE) and postimplantation (IUDL) losses
Indices:
number of corpora lutea, number of implantations, number of resorptions
number of live foetuses (males, females, both sex)
number of dead foetuses

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:
no effects observed
Description (incidence and severity):
Clinical examinations of treated maternal animals detected no clinical symptoms of toxicity related to treatment with the test item. The behavior, health condition and clinical status of treated maternal animals were similar compared to the control animals.
Mortality:
no mortality observed
Body weight and weight changes:
no effects observed
Description (incidence and severity):
The test item had no adverse effect on the growth of maternal animals. The body weight of treated maternal animals increased comparably with controls during pregnancy, and individual variability in body weight increments was normal for the species, sex and age of animals used in the study.
Food consumption and compound intake (if feeding study):
no effects observed
Description (incidence and severity):
Food consumption of treated mothers was balanced with controls except the statistically significant increase of food consumption in females at the middle dose level from the 11th day up to 14th day of pregnancy. This dose-independent increase in food consumption was not considered to be of toxicological significance.
Haematological findings:
no effects observed
Description (incidence and severity):
Haematological examination did not show significant differences between dosed and control group animals.
Behaviour (functional findings):
no effects observed
Gross pathological findings:
no effects observed
Description (incidence and severity):
Macroscopic examination was performed in all females (including non-pregnant females). The uterus dilatation (the change is likely related with oestrous cycle) was detected in three females, respectively, for the three groups, 0, 250 and 500 mg of a.i./kg bw/day.
No finding related with treatment was noted at necropsy in treated females.

Histopathological findings: non-neoplastic:
effects observed, non-treatment-related
Description (incidence and severity):
Absolute and relative weight of thyroid gland and histological examination of thyroid glands did not reveal any changes associated with the application of the test item. Histological examination of thyroid glands revealed only unilateral squamous cell cyst in two control females, two females at the dose level 250 mg of a.i./kg bw/day and in one female at the dose level 500 mg of a.i./kg bw/day. These findings were not treatment related and were likely of spontaneous origin. Examination of serum levels of thyroid hormone revealed slightly increased levels of TSH (0.756 ± 0.444 ng/mL) at the dose level 1000 mg of a.i./kg bw/day. This increase was without dose dependence and statistically non-significant, and this value was within historical control range of our test facility (TSH: 0.165 – 1.442 ng/mL), therefore it is considered incidental finding.
Histopathological findings: neoplastic:
no effects observed
Details on results:
Reproductive parameters:
The number of live foetuses, early and late intrauterine deaths were evaluated on the basis of examination of uterus content.
The reproductive parameters assessed, which were the numbers of implantations, corpora lutea, resorptions, postimplantation losses (IUDL) and preimplantation losses (IUDE), were not adversely affected by the treatment with the test item. The number of resorptions was very slightly increased at the dose level 500 mg of a.i./kg bw/day, but without statistical significance and dose-dependence.
Preimplantation losses (IUDE) were slightly increased at the dose levels 250 and 500 mg of a.i./kg bw/day. However, statistical significance and dose dependence were notobserved. This change is not attributed effect to test item effect.

Maternal developmental toxicity

Number of abortions:
no effects observed
Pre- and post-implantation loss:
no effects observed
Total litter losses by resorption:
no effects observed
Early or late resorptions:
no effects observed
Dead fetuses:
effects observed, non-treatment-related
Description (incidence and severity):
Dead foetuses were observed during necropsy. One dead foetus was observed at the lowest dose level (250 mg of a.i./kg bw/day) and one dead foetus was observed at the highest dose level (1000 mg of a.i./kg bw/day). It is sporadical finding and dead foetuses can be found also in historical control group.
Changes in pregnancy duration:
no effects observed
Changes in number of pregnant:
no effects observed

Effect levels (maternal animals)

Dose descriptor:
NOAEL
Effect level:
> 1 000 mg/kg bw/day (nominal)
Based on:
act. ingr.
Basis for effect level:
body weight and weight gain
changes in number of pregnant
changes in pregnancy duration
clinical biochemistry
clinical signs
dead fetuses
early or late resorptions
effects on pregnancy duration
gross pathology
haematology
histopathology: non-neoplastic
maternal abnormalities
mortality
necropsy findings
number of abortions
ophthalmological examination
organ weights and organ / body weight ratios
pre and post implantation loss
total litter losses by resorption

Maternal abnormalities

Abnormalities:
no effects observed

Results (fetuses)

Fetal body weight changes:
no effects observed
Description (incidence and severity):
The mean values of foetal body weight were slightly decreased (ca 10 %) at the highest dose level (1000 mg of a.i./kg bw/day), but without statistical significance and dose dependence.
Reduction in number of live offspring:
no effects observed
Description (incidence and severity):
Macroscopic structure of examined organs of pregnant females and reproduction parameters (number of females with live foetuses, number of live and dead foetuses, early and late resorptions), were unaffected by treatment with the test item.
Changes in sex ratio:
no effects observed
Changes in litter size and weights:
no effects observed
External malformations:
no effects observed
Description (incidence and severity):
Treatment with the test item was not associated with the occurrence of external malformations.
The mean AGD and corrected AGD of male and female foetuses was comparable between treated and control groups, and therefore, was not affected by the test item application.
Skeletal malformations:
effects observed, non-treatment-related
Description (incidence and severity):
Examination of foetal skeletons indicated mainly delayed development of the skeleton at all dose levels of a.i. as well as in the control group. According to the OECD 414 the litter as the unit for data analysis should be used for statistical evaluation. The statistical evaluation was performed for the number of foetuses with skeletal findings and also for number of litters with skeletal findings in this study. Statistically significant differences without toxicological significance were recorded during the statistical evaluation of the number of foetuses. No statistically significant differences were recorded in the number of the litters with the skeletal findings.
Visceral malformations:
no effects observed
Description (incidence and severity):
Treatment with the test item was not associated with the occurrence of visceral variations and malformations.

Effect levels (fetuses)

Dose descriptor:
NOAEL
Effect level:
> 1 000 mg/kg bw/day (nominal)
Based on:
act. ingr.
Sex:
male/female
Basis for effect level:
reduction in number of live offspring
changes in sex ratio
fetal/pup body weight changes
changes in litter size and weights
changes in postnatal survival
external malformations
skeletal malformations
visceral malformations
other:
Remarks on result:
other: none

Fetal abnormalities

Abnormalities:
no effects observed

Overall developmental toxicity

Developmental effects observed:
no

Applicant's summary and conclusion

Conclusions:
The NOAEL (No Observed Adverse Effect Level) for TOXICITY in pregnant females is 1000 mg of a.i./kg bw/day.
The NOAEL (No Observed Adverse Effect Level) for PRENATAL DEVELOPMENT is 1000 mg of a.i./kg bw/day.
Executive summary:

The test item, 4 -hydroxybenzenesulphonic acid,was tested for prenatal developmental toxicity following OECD 414.

There were no deaths of females during the study at any dose of a.i. No adverse changes in health condition and no clinical symptoms of intoxication were observed in maternal animals following administration of the test item at any dose. Nor were there any toxicologically significant treatment-related effects on body weight or food consumption in maternal animals.

Macroscopic structure of examined organsof pregnant females and reproduction parameters (number of females with live foetuses, number of live and dead foetuses, early and late resorptions),were unaffected by treatment with the test item.

Examination of the thyroid glands (absolute and relative weight of thyroid gland, histological examination of thyroid gland)did not reveal any changes associated with the application of the test item.

Test item-related foetal mortality was not evident at any dose level. Detailed necropsy of foetuses did not reveal an increase of external and visceral variations and malformationsat any dose of a.i..

Based on statistical evaluation of mean values of foetal body weight, no significant growth retardation was detected in treated groups.

Dead foetuses were observed during necropsy. One dead foetus was observed at the lowest dose level (250 mg of a.i./kg bw/day) and one dead foetus was observed at the highest dose level (1000 mg of a.i./kg bw/day). It is sporadical finding and dead foetuses can be found also in historical control group. 

Based on statistical evaluation of mean values of foetal body weight, no significant growth retardation was detected in treated groups

The mean AGD and corrected AGD of male and female foetuses in treated groups was not statistically significantly different from the control group.

No statistically significant differences with toxicological significance were recorded in number of foetuses and litters during the statistical evaluation of skeletal findings.