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Toxicity to reproduction

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Administrative data

Endpoint:
extended one-generation reproductive toxicity - with developmental neurotoxicity (Cohorts 1A, 1B without extension, 2A and 2B)
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Justification for type of information:
Carbon disulphide has been demonstrated to form during hydrolysis in gastric fluid.
Any oral toxicity on the xanthate needs to consider oral effects of carbon disulphide and the corresponding alcohol
Data access has been requested, but this summary is extracted from disseminated information published by ECHA
Further animal testing on the xanthate cannot be justified
Cross-referenceopen allclose all
Reason / purpose for cross-reference:
read-across: supporting information
Reason / purpose for cross-reference:
read-across: supporting information
Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Justification for type of information:
Special study performed to confirm rapid hydrolysis of potassium and sodium xanthates in simulated gastric fluid with identification of key metabolites.
This study is used to justify the use of surrogate data in animal testing on the basis that if ingested, the substance will rapidly degrade.
Qualifier:
no guideline followed
Principles of method if other than guideline:
study of the decomposition of four samples of xanthates in simulated gastric fluid; sodium soamyl xanthate, sodium isobutyl xanthate, sodium ethyl xanthate and potassium isoamyl xanthate.
The chemical reaction for this decomposition is:

Xanthate Salt + Hydrochloric acid Alcohol + Sodium Chloride + Carbon Disulphide

The reaction between simulated gastric fluid and the xanthate salts was carried out at 0oC for reasons of safety, as the reaction was expected to occur very quickly. The reaction mixture was then allowed to warm to room temperature over 1 hour, the final temperature being 25oC. A high degree of degradation at this temperature would lead to the inference that degradation would be at least as complete, if not more so, in actual gastric conditions.

Following the reaction solvent was added to produce a biphasic mixture, and the resulting organic
phases were analysed by GC-MS to confirm the presence of the corresponding alcohols. These
alcohols were quantified by comparison to known standards in order to confirm the completeness of the reaction, and to show that these salts behave in the same way under these reaction conditions.
Radiolabelling:
no
Analytical monitoring:
yes
Buffers:
Performed at pH 1.5 in synthetic gastric fluid
Details on test conditions:
Performed at 5 g/l to simulate possible concentration following ingestion
Performed at low temperatures for safety reasons due to exothermic nature of reaction
Duration:
1 h
pH:
1.5
Temp.:
0 °C
Initial conc. measured:
ca. 5 000 mg/L
Remarks:
Performed at initial temperature of 0 C, but in view of exothermic reaction, temperature will have risen by the end of the reaction.
Number of replicates:
One replicate per substance
A number of xanthates were evaluated as part of this study; all showed the same outcome
Positive controls:
no
Negative controls:
no
Statistical methods:
Not required
Preliminary study:
No
Transformation products:
yes
No.:
#1
No.:
#2
No.:
#3
No.:
#4
Details on hydrolysis and appearance of transformation product(s):
Exothermic reaction. No direct measurement of carbon disulphide possible, but elemental sulphur noted (estimated to be as dissolved sulphur dioxide or sulphates
% Recovery:
0
pH:
1.5
Temp.:
0 °C
Duration:
1 h
Remarks on result:
other: No parent material detected
Remarks on result:
not determinable because of methodological limitations
Remarks:
Too rapid to determine a rate constant
Details on results:
Rapid exothermic reaction in simulated gastric fluid at a loading of 5g/l

Sodium isoamyl xanthate, sodium isobutyl xanthate and sodium ethyl xanthate were added to separate solutions of simulated gastric fluid at 0 C over 1 hour. The low starting temperature was to prevent reaction occurring too quickly, for reasons of safety.


Following the reaction, a liquid-liquid extraction was performed with ethyl acetate and the organic solvent analysed using GCMS. The extracts were compared to a standard curve of ethanol, isoamyl alcohol and isobutyl alcohol were quantified.



Based on analysis of the alcohols. degradation of sodium isobutyl xanthate was found to be > 96% under the experimental conditions and degradation of sodium isoamyl xanthate was found to be > 75% under the experimental conditions.  However, no xanthates could be found at the end of the exposure period


The degradation of sodium ethyl xanthate could not be quantified under the experimental conditions and assumed 100%


To confirm that potassium salts will behave in a similar manner, potassium isoamyl xanthate was added to simulated gastric fluid under the same conditions as the sodium salts above. A liquid-liquid extraction was performed with ethyl acetate and the organic solvent analysed using GCMS. Isoamyl alcohol was observed in the resulting gas chromatogram, as expected.


NMR spectroscopy did not provide any further evidence of the presence of xanthate post addition to gastric fluid. 


To confirm that the sodium or potassium remains in solution as the chloride salt, ICP-OES analysis was carried out on the aqueous phase of the reaction mixture, as well as on the simulated gastric fluid with the difference between the two measurements being an indication of how much sodium or potassium has been added as a result of the xanthate degradation. The analysis showed increased levels of potassium and sodium in the gastric fluid phase upon addition of potassium and sodium xanthates respectively. This provides further evidence that the potassium salts behave in a similar manner to the sodium salts under the experimental conditions.



The increase in sodium could not be quantified owing to the high levels of Na observed, and the addition of Na from processing.


For Potassium Isoamyl Xanthate, a significant increase in potassium was observed and the potassium and sodium salts can be considered as behaving in identical manner.


Carbon disulphide was not detected and due to limitations of the methods detection of carbon dioxide or sulphur dioxide was not possible.  There was no reported odour of carbon dislulphide.

Executive summary:

Based on analysis of the alcohols. degradation of sodium isobutyl xanthate was found to be > 96% under the experimental conditions a


To confirm that potassium salts will behave in a similar manner, potassium isoamyl xanthate was added to simulated gastric fluid under the same conditions as the sodium salts above. A liquid-liquid extraction was performed with ethyl acetate and the organic solvent analysed using GCMS. Isoamyl alcohol was observed in the resulting gas chromatogram, as expected.


NMR spectroscopy did not provide any further evidence of the presence of xanthate post addition to gastric fluid. 


To confirm that the sodium or potassium remains in solution as the chloride salt, ICP-OES analysis was carried out on the aqueous phase of the reaction mixture, as well as on the simulated gastric fluid with the difference between the two measurements being an indication of how much sodium or potassium has been added as a result of the xanthate degradation. The analysis showed increased levels of potassium and sodium in the gastric fluid phase upon addition of potassium and sodium xanthates respectively. This provides further evidence that the potassium salts behave in a similar manner to the sodium salts under the experimental conditions.



The increase in sodium could not be quantified owing to the high levels of Na observed, and the addition of Na from processing.


For Potassium Isoamyl Xanthate, a significant increase in potassium was observed and the potassium and sodium salts can be considered as behaving in identical manner.


Carbon disulphide was not detected and due to limitations of the methods detection of carbon dioxide or sulphur dioxide was not possible.  There was no reported odour of carbon dislulphide.

Data source

Reference
Reference Type:
review article or handbook
Title:
Unnamed
Year:
2022

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 443 (Extended One-Generation Reproductive Toxicity Study)
GLP compliance:
yes
Limit test:
no
Justification for study design:
The summary document indicates that the study design was agreed with ECHA prior to performing the laboratory work. This included a toxicokinetic assessment indicating that oral route of administration was appropriate

Test material

Constituent 1
Chemical structure
Reference substance name:
Carbon disulphide
EC Number:
200-843-6
EC Name:
Carbon disulphide
Cas Number:
75-15-0
Molecular formula:
CS2
IUPAC Name:
carbon disulfide

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
corn oil
Details on exposure:
Once daily 7 days a week.
Details on mating procedure:
Cohabitation 1:1
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Concentrations of 91%, 95% and 89% were determined
Results are therefore expressed as nominal
Duration of treatment / exposure:
F0-males minimum of 11 weeks, including 10 weeks prior to mating and during the mating period,
F0-females minimum of 16 weeks, including 10 weeks prior to mating, and at least 21 days after delivery, Females were not dosed during littering.

During lactation (up to PND 21), pups were not treated directly
From weaning onwards (PND 21), F1-animals of Cohorts 1A, 1B, 1C and 2A dosed
Frequency of treatment:
Daily
Doses / concentrationsopen allclose all
Dose / conc.:
0 mg/kg bw/day (nominal)
Dose / conc.:
1.2 mg/kg bw/day (nominal)
Dose / conc.:
12 mg/kg bw/day (nominal)
Dose / conc.:
120 mg/kg bw/day (nominal)
No. of animals per sex per dose:
25
Control animals:
yes, concurrent vehicle

Examinations

Parental animals: Observations and examinations:
At least daily observations
Weekly weight assessment
Food consumption assessed for each group
Blood chemistry assessed in parental animals
Oestrous cyclicity (parental animals):
Yes
Sperm parameters (parental animals):
Checked on necropsy as part of post-mortum examinations
Litter observations:
Number and vigour
Postmortem examinations (parental animals):
Full necropsy and gross examination of organs at scheduled termination
Postmortem examinations (offspring):
Pups found dead and at scheduled termination
Statistics:
Statistical analysis was applied as needed

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
Slight salivation in response to treatment, predominantly at highest dose.
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
120 mg/kg/day, body weights / body weight gain of males and females were slightly decreased
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
not specified
Water consumption and compound intake (if drinking water study):
no effects observed
Ophthalmological findings:
not examined
Haematological findings:
effects observed, non-treatment-related
Description (incidence and severity):
Minor changes in white blood cell count and reticulocyte count (males) but not considered significant
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
Minor but statistically significant effects seen in the top dose.
The changes were not considered to be of toxicological significance.
Endocrine findings:
not examined
Urinalysis findings:
no effects observed
Behaviour (functional findings):
not specified
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
Effects seen at top dose, confirming maximum tolerated dose was used
Minor changes in spleen, thymus and eyes, with the effect on eyes considered adverse
Histopathological findings: neoplastic:
no effects observed

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:
no effects observed
Reproductive function: sperm measures:
no effects observed
Reproductive performance:
effects observed, non-treatment-related
Description (incidence and severity):
A small number of pairs in all treatment and control groups failed to reproduce.
This was in line with background observations and not treatment related

Effect levels (P0)

open allclose all
Dose descriptor:
NOAEL
Effect level:
ca. 12 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
ophthalmological examination
Dose descriptor:
LOAEL
Effect level:
ca. 120 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
ophthalmological examination

Target system / organ toxicity (P0)

Critical effects observed:
yes
Lowest effective dose / conc.:
120 mg/kg bw/day (nominal)
System:
eye
Organ:
retina
Treatment related:
yes
Dose response relationship:
yes
Relevant for humans:
not specified

Results: F1 generation

General toxicity (F1)

Clinical signs:
no effects observed
Mortality / viability:
mortality observed, non-treatment-related
Description (incidence and severity):
Mortality across groups not considered to be significantly different to historical levels
No treatment related effects
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Statistically significantly decreased in males at 120 mg/kg/day from Day 8
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
no effects observed
Water consumption and compound intake (if drinking water study):
no effects observed
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
no effects observed
Sexual maturation:
no effects observed
Anogenital distance (AGD):
effects observed, non-treatment-related
Description (incidence and severity):
Minimal changes, perhaps based on actual size of pups in highest dose group
Nipple retention in male pups:
no effects observed
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
Decrease in brain weight and spleen, male and female at higher dose level
Gross pathological findings:
no effects observed
Histopathological findings:
effects observed, treatment-related
Description (incidence and severity):
Effects seen in top dose group, including significant effect on eyes
Other findings not considered adverse

Developmental neurotoxicity (F1)

Behaviour (functional findings):
no effects observed

Details on results (F1)

Effects on F1 similar to those seen in parental animals

Effect levels (F1)

open allclose all
Dose descriptor:
NOAEL
Generation:
F1
Effect level:
ca. 12 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
organ weights and organ / body weight ratios
Dose descriptor:
LOAEL
Generation:
F1
Effect level:
ca. 120 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
organ weights and organ / body weight ratios

Target system / organ toxicity (F1)

Critical effects observed:
yes
System:
central nervous system
Organ:
brain

Overall reproductive toxicity

Reproductive effects observed:
no

Applicant's summary and conclusion

Conclusions:
Animals were treated at up to the maximum tolerated dose with some parental toxicity observed.
No reproductive or developmental effects were seen, other than a slight reduction in size of the young in the highest treatment group.