Proxan-sodium

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

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-reference

Cross-reference 1

Reason / purpose for cross-reference:

exposure-related information

Remarks:

Due to rapid hydrolysis in gastric fluid, oral ingestion of xanthates will result in formation of carbon disulphide

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 eight samples of xanthates in simulated gastric fluid; sodium isoamyl xanthate, sodium isobutyl xanthate, sodium ethyl xanthateр potassium isoamyl xanthate, potassium ethyl xanthate (PEX). sodium isopropyl xanthate (SIPX), Potassium amyl xanthate and potassium isobutyl 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, sodium ethyl xanthateр  potassium isoamyl xanthate, potassium ethyl xanthate (PEX), sodium isopropyl xanthate (SIPX), Potassium amyl xanthate and potassium isobutyl 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 isopropyl xanthate (SIPX), was found to be  100% under the experimental conditions and degradation of potassium amyl xanthate was found to give 93% under the experimental conditions , potassium isobutyl xanthate was found to give 94%, sodium isobutyl xanthate was found to give 96% under the experimental conditions .  However, no xanthates could be found at the end of the exposure period.

To confirm that potassium salts will behave in a similar manner, potassium xanthates 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 Xanthates, 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 isopropyl xanthate (SIPX), was found to be  100% under the experimental conditions and degradation of potassium amyl xanthate was found to give 93% under the experimental conditions , potassium isobutyl xanthate was found to give 94%, sodium isobutyl xanthate was found to give 96% under the experimental conditions .  However, no xanthates could be found at the end of the exposure period.

 

To confirm that potassium salts will behave in a similar manner, potassium xanthates 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. The corresponding 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 Xanthates, 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.

 

Cross-reference 2

Reason / purpose for cross-reference:

read-across: supporting information

Cross-reference 3

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:

Report prepared for the Norwegian Government regarding degradation of xanthates in seawater
Peer reviewed publication.
Confirms degradation pathways and attempts to quantify formation of CS2

Qualifier:

no guideline followed

Principles of method if other than guideline:

Experiments were performed to evaluate the kinetics of degradation of Sodium Isopropyl Xanthate (SIPX) in marine water.
Both, the decay of the target compound SIPX and the production of carbon disulphide (CS2) have been tracked in time-course experiments during 28 days.
In order to distinguish between two anticipated degradation pathways, hydrolysis and biological degradation, the decay of SIPX in marine water has been tracked through experiments in sterile and non-sterile water. Apart from CS2 other potential transformation products were investigated

GLP compliance:

not specified

Radiolabelling:

no

Analytical monitoring:

yes

Buffers:

Performed with sea water under natural pH 7.5

Details on test conditions:

28 days duration at 9.5 C

Duration:

28 d

pH:

7.5

Temp.:

9.5 °C

Initial conc. measured:

ca. 10 mg/L

Number of replicates:

Not specified

Positive controls:

no

Negative controls:

yes

Remarks:

Pure water. No test material

Transformation products:

yes

No.:

#1

No.:

#2

% Recovery:

0

pH:

7.5

Temp.:

95

Duration:

28 d

pH:

7.5

Temp.:

9.5

DT50:

ca. 7 d

Type:

not specified

Details on results:

Degradation of SIPX was observed at investigated conditions.
The concentrations of CS2 found are below the theatrical concentration (around 1.8 mg/L) expected for the degradation observed in the solution with initial concentration of 10 mg/L of SIPX.
The evolution observed in the concentration of SIPX and the CS2 during the 28 days period might be explained as intermediates generated would be unnoticed since the analysis was only focusing in the CS2 measurements.
After several days of SIPX exposure, the microbial community naturally present in marine water might adapt to the media and lead to reducing conditions in the sample with biodegradation of the carbon disulphide to sulphates and CO2

Conclusions:

Degradation of SIPX was observed at investigated conditions.

Executive summary:

The concentrations of CS2 found are below the theatrical concentration (around 1.8 mg/L) expected for the degradation observed in the solution with initial concentration of 10 mg/L of SIPX.
The evolution observed in the concentration of SIPX and the CS2 during the 28 days period might be explained as intermediates generated would be unnoticed since the analysis was only focusing in the CS2 measurements.
After several days of SIPX exposure, the microbial community naturally present in marine water might adapt to the media and lead to reducing conditions in the sample with biodegradation of the carbon disulphide to sulphates and CO2. This is in with other studies, including the microbial biodegradation of the Zahn Wellens showing 98% evolution of carbon as CO2.

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1984

Reference 2

Reference Type:

review article or handbook

Title:

Unnamed

Year:

2022

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

GLP compliance:

not specified

Remarks:

Pre-dates widespread introduction of GLP Data set considered valid

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Carbon disulphide

EC Number:

200-843-6

EC Name:

Carbon disulphide

Cas Number:

75-15-0

Molecular formula:

CS2

IUPAC Name:

dithioxomethane

Test animals

Species:

rat

Strain:

other: CD

Details on test animals or test system and environmental conditions:

Age 8 - 12 weeks at start of study
TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc. (Kingston, NY)
- Age at study initiation: 8-12 weeks
- Housing: solid bottoom polypropylene or polycarbonate cages with stainless steel wire lids
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 14 days quarantine period

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18-20
- Humidity (%): 52-77
- Air changes (per hr): 12-14
- Photoperiod (hrs dark / hrs light): 12

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Analytical verification of doses or concentrations:

yes

Details on mating procedure:

- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: 1/1
- Length of cohabitation: overnight
- Proof of pregnancy: sperm in vaginal smear referred to as day 0 of pregnancy

Duration of treatment / exposure:

Gestation day 6 to 15

Frequency of treatment:

Daily

Duration of test:

From gestation day 6 to 15

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 mg/kg bw/day (nominal)

Doses / concentrations 2

Dose / conc.:

100 mg/kg bw/day (nominal)

Doses / concentrations 3

Dose / conc.:

200 mg/kg bw/day (nominal)

Doses / concentrations 4

Dose / conc.:

400 mg/kg bw/day (nominal)

Doses / concentrations 5

Dose / conc.:

600 mg/kg bw/day (nominal)

No. of animals per sex per dose:

22-27 (in total; two replicates)

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: based on a preliminary toxicity study performed. The doses applied were: 0, 10, 50, 100 and 200 mg/kg bw/day

Examinations

Maternal examinations:

CLINICAL OBSERVATIONS: Yes
- Time schedule: before exposure, 0 and 4 h after exposure

BODY WEIGHT: Yes
- Time schedule for examinations: gestation day 0, 6 through 15 (prior to daily dosing) and 20 (immediately after sacrifice)

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 20
- Organ weights measured: liver, gravide uterine
- Status of uterine implantation sites were examined (i.e. number of implants, resorptions, dead fetuses and live fetuses)

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

Blood sampling:

Not specified

Fetal examinations:

Yes; external, visceral, skeletal and head

The following observations were recorded: live litter size, individual body weight, sex and gross morphological abnormalities
- External examinations: Yes
- Visceral examinations: Yes, all live fetuses
- Skeletal examinations: Yes, all per litter
- Head examinations: Yes, half per litter

Statistics:

Non-parametric statistics, Kruskal-Wallis test, ANOVA, Mann-Whitney U test, Jonckheere's test, one-tailed Fischer's exact test, two-way ANOVA design, William's test, Dunnett's test

Historical control data:

Not specified

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Lethargy, ataxia, abnormal posture and rough coat

Mortality:

mortality observed, non-treatment-related

Description (incidence):

One female, mid dose

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Decrease in body weight for highest doses

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

not specified

Clinical biochemistry findings:

not specified

Endocrine findings:

not examined

Urinalysis findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Increased liver weights in higher dose groups

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

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

Dead fetuses:

no effects observed

Changes in pregnancy duration:

not examined

Other effects:

no effects observed

Details on maternal toxic effects:

Maternal toxic effects:yes
Details on maternal toxic effects:
Substance-treated animals exerted clinical signs of toxicity: lehtargy, ataxia, abnormal posture, rigidity and/or paralysis of the hindlimbs, and rough or erect coat. No deaths were observed, except for 1 (1/25, 4%) animal at the 400 mg/kg bw dose level. After sacrifice pregnacy was confirmed in 92%, 82.8%, 81.5%, 92.3, and 100% of females in the control, 100, 200, 400 and 600 mg/kg bw/ day groups, respectively. Maternal body weights were depressed significantly on gestation days 11, 15 and 20 for the groups exposed to the last two doses, when compared to the controls. For the dose groups of 200, 400 and 600 mg/kg bw/day, a significant decrease in absolute body weight gain was observed during treatment. Gravid uterine weights showed a dose-consistent decreasing trend; still, not significant. Larger relative liver weights were measured in the two high dose groups.

Effect levels (maternal animals)

Dose descriptor:

NOAEL

Effect level:

100 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

body weight and weight gain

organ weights and organ / body weight ratios

Remarks on result:

other: Toxicological significance of maternal effects not specified

Maternal abnormalities

Abnormalities:

not specified

Results (fetuses)

Fetal body weight changes:

effects observed, treatment-related

Description (incidence and severity):

Weight decrease in highest dose groups

Reduction in number of live offspring:

no effects observed

Changes in sex ratio:

no effects observed

Changes in litter size and weights:

effects observed, treatment-related

Description (incidence and severity):

Reduced weights of litters at higher doses, mirroring maternal effect

Changes in postnatal survival:

no effects observed

External malformations:

effects observed, non-treatment-related

Description (incidence and severity):

Across various dose levels and within historical control

Skeletal malformations:

effects observed, non-treatment-related

Description (incidence and severity):

Across various dose levels and within historical control

Visceral malformations:

effects observed, non-treatment-related

Description (incidence and severity):

Across various dose levels and within historical control

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:yes. Remark: fetal toxicity, but no teratogenic effects
Details on embryotoxic / teratogenic effects:
No statistically signifcant changes were observed in: implantation sites/litter, proportion of litters with resorbed, dead, nonlive or affected fettuses, number of live fetuses/live litter, % of males/live litter. Average fetal body weight/litter was decreased significantly in both sexes for the dose groups of 200, 400, and 600 mg/kg bw. The percent of fetuses malformed per litter (but not the proportion of litters with one or more malformed fetuses) and the percent of females malformed per litter was significantly different across the groups. However, a clear dose-related trend was not observed. The percent of of malformed fetuses declined at the high dose group (0.53%) in comparison to the control (~5%) and no individual group showed a significant difference when compared to the control. What follows is stated in the report, with some modifications: Four fetuses exhibited malformations which had not been previously observed in historical control fetuses. These anomalies included (1) branched rib observed in one fetus with multiple skeletal defects, edema and low body weight (2.32 g) in the 100 mg/kg/day CS2 group; (2) micromelia observed in one fetus (200 mg/kg/day CS2 group), with low body weight (2.58 g), edema and bilateral anophthalmia, (3) constricted tail in one fetus (200 mg/kg/day CS group) with low body weight (2.95 g), and (4) displaced ovaries, fused kidneys and missing adrenals in one fetus with low body weight (2.32 g) and multiple skeletal malformations in the 400 mg/kg/day CS2 group.

Effect levels (fetuses)

Dose descriptor:

NOAEL

Effect level:

100 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

fetal/pup body weight changes

Fetal abnormalities

Abnormalities:

effects observed, non-treatment-related

Localisation:

other: Various changes - no obvious significance

Description (incidence and severity):

Various effects observed but within historical levels.

Overall developmental toxicity

Developmental effects observed:

yes

Lowest effective dose / conc.:

200 mg/kg bw/day

Treatment related:

yes

Relation to maternal toxicity:

developmental effects as a secondary non-specific consequence of maternal toxicity effects

Dose response relationship:

yes

Relevant for humans:

not specified

Applicant's summary and conclusion

Conclusions:

Oral treatment produced dose-related maternal and foetal toxicity at 200 mg/kg bw/day or higher.
There was no increase in the incidence of malformed foetuses.
Carbon disulfide oral gavage treatment produced dose-related maternal and fetal toxicity when administered in CD rats at doses including and above 200 mg/kg bw/daily, but did not increase the incidence of malformed fetuses.

Executive summary:

Carbon disulfide (CS2), was evaluated for teratogenic effects in timed-pregnant CD rats. The following doses were administered: 0, 100, 200, 400 and 600 mg/kg/day in corn oil by gavage, in a volume of 5 ml/kg bw, on gestational days (gd) 6 to 15. All animals were sacrificed on gestation day 20. The gravid uterus for each dam was weighed and the number of implantation sites, and live, dead or resorbed fetuses were recorded. All live fetuses were weighed and examined for external, visceral and skeletal malformations. For the dose groups of 200, 400 and 600 mg/kg bw/day, a significant decrease in absolute maternal body weight gain was observed during treatment. Gravid uterine weights showed a dose-consistent decreasing trend; still, not significant. Larger relative liver weights were measured in the two high dose groups. Fetal body weights were decreased in rats exposed to 200 mg/kg bw/day and above.

There was no compound-related increase in malformations of the offspring.