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GHS Classification Result

GENERAL INFORMATION

Item	Information
CAS RN	74-93-1
Chemical Name	Methyl mercaptan (Methanethiol)
Substance ID	H26-B-104, R-047
Classification year (FY)	FY2014
Ministry who conducted the classification	Ministry of Health, Labour and Welfare (MHLW)/Ministry of the Environment (MOE)
New/Revised	Revised
Classification result in other fiscal year	FY2006
Download of Excel format	Excel file

REFERENCE INFORMATION

Item	Information
Guidance used for the classification (External link)	GHS Classification Guidance for the Japanese Government (FY2013 revised edition)
UN GHS document (External link)	UN GHS document
Definitions/Abbreviations (Excel file)	Definitions/Abbreviations
Model Label by MHLW (External link)	MHLW Website (in Japanese Only)
Model SDS by MHLW (External link)	MHLW Website (in Japanese Only)
OECD/eChemPortal (External link)	eChemPortal

PHYSICAL HAZARDS

Hazard class		Classification	Pictogram Signal word	Hazard statement (code)	Precautionary statement (code)	Rationale for the classification
1	Explosives	Not applicable	- -	-	-	Gas (GHS definition)
2	Flammable gases (including chemically unstable gases)	Category 1	Danger	H220	P210 P377 P381 P403	It was classified in Category 1 from an explosion limit (3.9-21.8% (ICSC (2003))). Besides, it is classified in Division 2.3, Subsidiary Risk 2.1 (UN1064) in UNRTDG.
3	Aerosols	Not applicable	- -	-	-	Not aerosol products.
4	Oxidizing gases	Not classified	- -	-	-	Flammable gas classified in Division 2.3, Subsidiary Risk 2.1 (UN1064) in UNRTDG.
5	Gases under pressure	Liquefied gas	Warning	H280	P410+P403	From a critical temperature (196.8 deg C (HSDB (Access on September 2014))) above +65 deg C, it was classified as liquefied gas (low pressure liquefied gas).
6	Flammable liquids	Not applicable	- -	-	-	Gas (GHS definition)
7	Flammable solids	Not applicable	- -	-	-	Gas (GHS definition)
8	Self-reactive substances and mixtures	Not applicable	- -	-	-	Gas (GHS definition)
9	Pyrophoric liquids	Not applicable	- -	-	-	Gas (GHS definition)
10	Pyrophoric solids	Not applicable	- -	-	-	Gas (GHS definition)
11	Self-heating substances and mixtures	Not applicable	- -	-	-	Gas (GHS definition)
12	Substances and mixtures which, in contact with water, emit flammable gases	Not applicable	- -	-	-	Gas (GHS definition)
13	Oxidizing liquids	Not applicable	- -	-	-	Gas (GHS definition)
14	Oxidizing solids	Not applicable	- -	-	-	Gas (GHS definition)
15	Organic peroxides	Not applicable	- -	-	-	Gas (GHS definition)
16	Corrosive to metals	Classification not possible	- -	-	-	Test methods applicable to gas substances are not available.

HEALTH HAZARDS

Hazard class		Classification	Pictogram Signal word	Hazard statement (code)	Precautionary statement (code)	Rationale for the classification
1	Acute toxicity (Oral)	Not applicable	- -	-	-	Gas (GHS definition)
1	Acute toxicity (Dermal)	Not applicable	- -	-	-	Gas (GHS definition)
1	Acute toxicity (Inhalation: Gases)	Category 3	Danger	H331	P304+P340 P403+P233 P261 P271 P311 P321 P405 P501	Based on a report of an LC50 value of 675 ppm for rats (PATTY (6th, 2012), SIDS (2009), ACGIH (7th, 2004), DFGOT Vol. 20 (2003), ATSDR (1992)), it was classified in Category 3. Besides, according to the GHS Classification Guidance for the Japanese Government, by giving priority to an LC50 value (4 hours), the reference value in units of ppm was applied.
1	Acute toxicity (Inhalation: Vapours)	Not applicable	- -	-	-	Gas (GHS definition)
1	Acute toxicity (Inhalation: Dusts and mists)	Not applicable	- -	-	-	Gas (GHS definition)
2	Skin corrosion/irritation	Category 2	Warning	H315	P302+P352 P332+P313 P362+P364 P264 P280 P321	Although there were no concrete data, based on a description that this substance was irritating to the skin (HSDB (Access on September 2014)), it was classified in Category 2. New information, HSDB (Access on September 2014) was added, and the category was changed.
3	Serious eye damage/eye irritation	Category 2	Warning	H319	P305+P351+P338 P337+P313 P264 P280	There are reports that mucosa irritation was observed by exposure of rats to this substance (ACGIH (7th, 2004)), and that mucosa irritation was observed as the effect by exposure of humans (ACGIH (7th, 2004)). In addition, there is a description that this substance was irritating to the eyes (HSDB (Access on September 2014)). From the above results, it was classified in Category 2.
4	Respiratory sensitization	Classification not possible	- -	-	-	Classification not possible due to lack of data.
4	Skin sensitization	Classification not possible	- -	-	-	Classification not possible due to lack of data.
5	Germ cell mutagenicity	Classification not possible	- -	-	-	The substance was classified as "Classification not possible" because it was not possible to classify a substance as "Not classified" according to the revised GHS classification guidance for the Japanese government. As for in vivo, it was negative in mouse bone marrow micronucleus tests (SIDS (2009), ACGIH (2004), DFGOT Vol. 20 (2003)). As for in vitro, it was negative in a bacterial reverse mutation test (IUCLID (2000)).
6	Carcinogenicity	Classification not possible	- -	-	-	Classification not possible due to lack of data.
7	Reproductive toxicity	Classification not possible	- -	-	-	There is a report that, in a combined repeated dose toxicity study with the reproduction/developmental toxicity screening test (TG 422) in which rats were exposed to the sodium salt of this substance (methyl mercaptan sodium salt) through the oral route (gavage), neither reproductive toxicity nor developmental toxicity was observed (SIDS (2009)). However, since it was a screening test, it was classified as "Classification not possible."
8	Specific target organ toxicity - Single exposure	Category 1 (central nervous system, respiratory organs, haemal system), Category 3 (narcotic effects)	Danger Warning	H370 H336	P308+P311 P260 P264 P270 P321 P405 P501 P304+P340 P403+P233 P261 P271 P312	This substance was irritating to the respiratory tract (DFGOT Vol. 20 (2003), PATTY (6th, 2012), HSDB (Access on September 2014)). In humans, in cases such as inhalation exposure of workers, cough, headache, dizziness, staggering gait, nausea, vomiting, chest tightness, wheezing, tachypnea, respiratory insufficiency, coma, inflammation in the nasal mucosa and lung, pulmonary edema, methemoglobinemia, cyanosis, acute hemolytic anemia, muscular weakness, convulsions, diplopia, central nervous system depression, paralysis of skeletal and respiratory muscles were observed (DFGOT Vol. 20 (2003), PATTY (6th, 2012), ATSDR (1992), HSDB (Access on September 2014)). As for experimental animals, there were reports of narcotic effects, lethargy, gait difficulty, tremors, loss of righting reflex, tachypnea, respiratory depression, dyspnea, coma, muscular weakness, convulsions, paralysis of skeletal and respiratory muscles, cyanosis, inflammation in the nasal mucosa and lung, pulmonary edema within the range of 1.33-3.31 mg/L by inhalation exposure (SIDS (2009), ACGIH (7th, 2004), DFGOT Vol. 20 (2003), PATTY (6th, 2012), ATSDR (1992), HSDB (Access on September 2014)). Effects on the central nervous system, respiratory organs and blood system were observed in human findings, and effects on the respiratory organs and central nervous system were observed in experimental animals at doses within the guidance value range of Category 1. From the above, it was classified in Category 1 (central nervous system, respiratory organs, blood system), Category 3 (narcotic effects).
9	Specific target organ toxicity - Repeated exposure	Category 1 (central nervous system, respiratory organs)	Danger	H372	P260 P264 P270 P314 P501	In humans, there is a description that irritation of the eye and nasal mucosa, headache, nausea, vomiting, breathing difficulties, and impaired heme synthesis were observed as effects not by the effect of a sole exposure of this substance, but by long-term combined exposure with other sulfuric compounds such as dimethyl sulfide (DFGOT vol. 20 (2003)). In addition, there is a description that this substance was a central nervous system depressant and acted like hydrogen sulfide on the respiratory center producing death by respiratory paralysis (PATTY (6th, 2012)). As for experimental animals, in a test in which rats were exposed to this substance (estimated as the gas) at concentrations up to 57 ppm by inhalation for 3 months, although a change in behavior during exposures (crowding together with upturned noses) was observed at or above 2 ppm, and it was notably observed with decreased body weight gain in the 57 ppm group, no toxicities indicative of target organs were detected (SIDS (2009), ACGIH (2004), DFGOT vol. 20 (2003), PATTY (6th, 2012)). Although this study did not cover the concentrations within the guidance value range of Category 2 to be possible to determine the overall toxicity of this substance through the inhalation route, it is considered that the change in behavior with the upturned noses, observed during exposures, was due to nasal irritation (DFGOT vol. 20 (2003)). As above, based on the findings in humans, it was classified in Category 1 (central nervous system, respiratory organs). Besides, although there is a description that, in a combined repeated dose toxicity study with the reproduction/developmental toxicity screening test in which rats were dosed the sodium salt of this substance (CAS RN: 5188-07-8) by gavage for 8-9 weeks, at 45 mg/kg/day (converted guidance value: ca. 29.4 mg/kg/day (Category 2)) of the maximum dose, clinical symptoms considered due to central nerve depression (hypotonia, ataxia) and effects on the hemal system (decreased erythrocyte counts, reduced hemoglobin concentration and hematocrit value, etc.) were observed, and secondary effects associated with anemia (extramedullary hematopoiesis, hemosiderin deposition) were observed in the spleen or the liver (SIDS (2009)), this substance is gaseous, and there was lack of findings to support effects on the blood system in the hazardous information through the inhalation route. Therefore, "the blood system" was not adopted as the target organ.
10	Aspiration hazard	Not applicable	- -	-	-	Gas (GHS definition)

ENVIRONMENTAL HAZARDS

Hazard class		Classification	Pictogram Signal word	Hazard statement (code)	Precautionary statement (code)	Rationale for the classification
11	Hazardous to the aquatic environment (Acute)	Classification not possible	- -	-	-	Classification not possible due to lack of data.
11	Hazardous to the aquatic environment (Long-term)	Classification not possible	- -	-	-	Classification not possible due to lack of data.
12	Hazardous to the ozone layer	Classification not possible	- -	-	-	This substance is not listed in the Annexes to the Montreal Protocol.

NOTE:

GHS Classification Result by the Japanese Government is intended to provide a reference for preparing a GHS label or SDS for users. To include the same classification result in a label or SDS for Japan is NOT mandatory.
Users can cite or copy this classification result when preparing a GHS label or SDS. Please be aware, however, that the responsibility for a label or SDS prepared by citing or copying this classification result lies with users.
This GHS classification was conducted based on the information sources and the guidance for classification and judgement which are described in the GHS Classification Guidance for the Japanese Government etc. Using other literature, test results etc. as evidence and including different content from this classification result in a label or SDS are allowed.
Hazard statement and precautionary statement will show by hovering the mouse cursor over a code in the column of "Hazard statement" and "Precautionary statement," respectively. In the excel file, both the codes and statements are provided.
A blank or "-" in the column of "Classification" denotes that a classification for the hazard class was not conducted in the year.

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