Hydrogen sulphide

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

01.10.1986 - 23.10.1989

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Guideline study, reliable with acceptable restrictions. Minor deviations: - Purity and stability are missing - Note: In the study, a higher mortality rate was found for a lower dose (68.1 mg/kg) than for the next higher dose (100.0 mg/kg). This was not explained in the study neither could an explanation be derived. - The calculation of the LD50 was not clear. In the study only approx. values were stated and not exact values. For this reason, ranges were stated for the LD50 in this IUCLID entry. One problem with the results provided as ranges was that the classification according the Regulation (EC) No 1272/2008 caused the test item to fall into two different categories (category 2 and 3). - According to the guideline, the 95 per cent confidence interval for the LD50 should be stated. This was missing in this report. - According to the guideline, the number of animals displaying signs of toxicity should be stated. In this study report it was stated that clinical signs were observed, but not how many animals showed these signs. - According to the guideline, the body weight should be determined weekly and at death. In this study the body weight was determined on day 7 and 13, and not weekly and on the day of sacrifice (day 14). - Individual weights and weight changes were not stated, which according to the guideline should be determined. - According to the guideline, healthy young adults should be used. The age of the rats were missing in this report.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1986

Report date:

1986

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Version / remarks:

, 1981

Deviations:

yes

Remarks:

see rational for reliability

GLP compliance:

no

Test type:

standard acute method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Sodium hydrogensulphide

EC Number:

240-778-0

EC Name:

Sodium hydrogensulphide

Cas Number:

16721-80-5

Molecular formula:

NaHS

IUPAC Name:

sodium hydrogensulfide

Constituent 2

Reference substance name:

sodium hydrogensulfide (70 - 72 %)

IUPAC Name:

sodium hydrogensulfide (70 - 72 %)

Test material form:

solid: crystalline

Details on test material:

- Name of test material (as cited in study report): Sodium sulfhydrate scales 70%
No further information on the test material was stated.

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Dr. K. Thomae GmbH, D-7950 Biberach, FRG
- Weight at study initiation: The different groups of males had mean weights between 180 g and 188 g; The different groups of females had mean weights between 173 g and 188 g
- Fasting period before study: The animals were given no feed 16 hours before administration, but water was available ad libitum.
- Housing: Stainless steel wire mesh cages, Type DK-III (Becker & Co., Castrop-Rauxel, FRG); 5 animals per cage; animals were housed in fully air-conditioned rooms
- Diet (ad libitum): Kliba- Labordiaet 343, Klingentalmuehle AG, CH-4303 Kaiseraugst. Switzerland
- Water (ad libitum): tap water
- Acclimation period: acclimatization for at least 1 week

ENVIRONMENTAL CONDITIONS
- Temperature: 20 - 24 °C
- Relative humidity: 30 - 70 %
- Photoperiod (hrs dark / hrs light): 12/12
No further information on the test animals was stated.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Details on oral exposure:

VEHICLE
- Concentration in vehicle: 2.150 (w/v), 1.000 (w/v), 0.681 (w/v), 0.464 (w/v)
- Justification for choice of vehicle:

MAXIMUM DOSE VOLUME APPLIED: 10 ml/kg
No further information on details on oral wxposure was stated.

Doses:

215.0 mg/kg, 100.0 mg/kg, 68.1 mg/kg, 46.4 mg/kg

No. of animals per sex per dose:

5 male / 5 female

Control animals:

not specified

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Recording of signs and symptoms several times on the day of administration, at least once each workday. Check for moribund and dead animals twice each workday and once on holidays.
- Necropsy of survivors performed: Yes. Withdrawal of food 16 hours before sacrifice with CO2; then necropsy with gross-pathological examination. Necropsy of all animals that die as early as possible.
- Other examinations performed: Body weight was measured at the beginning of the test, on day 7 and on day 13.
No further information on details on study design was stated.

Results and discussion

Effect levels

Effect levels 1

Sex:

male

Dose descriptor:

LD50

Effect level:

> 46.4 - < 68.1 mg/kg bw

Based on:

test mat.

Remarks:

NaHS, 70 %

Remarks on result:

other: Mortality per dose: 46.4 mg/kg: 0.0 %; 68.1 mg/kg: 60 %

Effect levels 2

Sex:

female

Dose descriptor:

LD50

Effect level:

> 100 - < 215

Based on:

test mat.

Remarks:

NaHS, 70 %

Remarks on result:

other: Mortality per dose: 100.0 mg/kg: 40.0 %; 215 mg/kg: 100.0%

Effect levels 3

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 100 - < 215 mg/kg bw

Based on:

test mat.

Remarks:

NaHS, 70 %

Remarks on result:

other: Mortality per dose: 68.1 mg/kg: 30%; 100.0 mg/kg: 30 %; 215 mg/kg: 100.0 %. The results indicate that the LD50 (male and female) calculated for the most concentrated commercial form, NaHS, 77 %, would be 105 mg/kg bw.

Mortality:

Number of dead males per dose:
46.4 mg/kg: 0/5
68.1 mg/kg: 3/5 (dead after 1 hour)
100.0 mg/kg: 1/5 (dead after 1 hour)
215.0 mg/kg: 5/5 (dead after 1 hour)
Number of dead females per dose:
46.4 mg/kg: 0/5
68.1 mg/kg: 0/5
100.0 mg/kg: 2/5 (dead after 1 hour)
215.0 mg/kg: 5/5 (dead after 1 hour)
Number of dead females and males per dose:
46.4 mg/kg: 0/10
68.1 mg/kg: 3/10
100.0 mg/kg: 3/10
215.0 mg/kg: 10/10

Clinical signs:

other: Clinical signs of males per dose: 215.0 mg/kg: Dyspnea: < 15 minutes Apathy: < 15 minutes Abnormal position: < 15 minutes Atonia: < 15 minutes Paresis: < 15 minutes Poor general state: < 15 minutes 100.0 mg/kg: Dyspnea: < 15 minutes - 1 hour Imbalance:

Gross pathology:

Animals that died (male + female):
General congestion
Sacrificed animals (male + female):
Organs: no abnormalities detected

Applicant's summary and conclusion

Interpretation of results:

Toxicity Category II

Remarks:

Migrated information according to GHS Criteria used for interpretation of results: EU

Conclusions:

H2S dissolves in water up to a limit concentration. At 20 °C the limit is 3.98 g H2S/l.
In aqueous environment H2S and its salt NaHS dissolves easily and are immediately hydrolyzed and an pH-dependent equilibrium is established between S2-, HS- and H2S. As there is no acute oral toxicity study available with H2S the result of the study with NaHS is taken to derive a LD50.
An LD50 range >46.4 and <215 mg/kg bw can be derived for sodium hydrogensulfide (70 %) from this study. An estimated LD50 value has been calculated as 115 mg/kg for males and females.
The LD50 of 100% NaHS can be calculated: 80.5 mg/kg bw. and from this an LD50 value for H2S can be caldulated:
molecular weight of NaHS: 56.06;
molecular weight of H2S: 34.08;
LD50 of H2S: 49 mg/kg bw.
According to the criteria specified by Directive 67/548/EC, Regulation (EC) No 1272/2008 and subsequent regulations the test item is toxic and requires classification (toxic category II according to GHS).

Executive summary:

Up to a limit concentration H2S dissolves in water in a temperature dependent way. At 20 °C the limit is 3,98 g/l. H2S can stay present in water for several hours. In aqueous environments, H2S and the corresponding salt Na2S, are immediately hydrolyzed and, as a function of pH, an equilibrium is established between S2-, HS-, and H2S, with increasing H2S formation at decreasing pH. Temperature and salinity also affect this equilibrium but to a much lesser extent than pH.

As there is no acute oral toxicity study with H2S available the present acute oral toxicity study with 70% NaHS ist taken to evaluate the toxicity of H2S.

A LD50 range >46.4 and >215 mg/kg bw. was seen with sodium hydrogensulphide (70%) in this study. An estimated LD50 value can be calculated as 115 mg/kg bw.. Lethal effects started with dosages of 68.1 mg/kg bw and reached 100% after dosages of 215 mg/kg bw.

The lethal effects emerged within one hour, at later timepoints no further fatalities were observed..

From these data the LD50 of 100% NaHS can be calculated: 80.5 mg/kg bw.; further on a LD50 value for H2S can be derived:

molecular weight of NaHS: 56.06;

molecular weight of H2S: 34.08;

oral LD50 of H2S with rats: 49 mg/kg bw.