NITE - Chemical Management Field

GHS Classification Result

GENERAL INFORMATION

Item	Information
CAS RN	999-97-3
Chemical Name	Hexamethyldisilazane
Substance ID	24A6122
Classification year (FY)	FY2012
Ministry who conducted the classification	Ministry of Health, Labour and Welfare (MHLW)/Ministry of the Environment (MOE)
New/Revised	New
Classification result in other fiscal year
Download of Excel format	Excel file

REFERENCE INFORMATION

Item	Information
Guidance used for the classification (External link)	Physical Hazards and Health Hazards: GHS Classification Guidance by the Japanese Government (July, 2010) Environmental Hazards: UN GHS Document (4th 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	- -	-	-	There are no chemical groups associated with explosive properties present in the molecule.
2	Flammable gases (including chemically unstable gases)	Not applicable	- -	-	-	Liquid (GHS definition)
3	Aerosols	Not applicable	- -	-	-	Not aerosol products.
4	Oxidizing gases	Not applicable	- -	-	-	Liquid (GHS definition)
5	Gases under pressure	Not applicable	- -	-	-	Liquid (GHS definition)
6	Flammable liquids	Category 2	Danger	H225	P303+P361+P353 P370+P378 P403+P235 P210 P233 P240 P241 P242 P243 P280 P501	It corresponds to Category 2 from a flash point of 9 deg C [closed-cup] (NFPA (14th, 2010)) < 23 deg C and an initial boiling point of 126 deg C (Merck (14th, 2006)) > 35 deg C.
7	Flammable solids	Not applicable	- -	-	-	Liquid (GHS definition)
8	Self-reactive substances and mixtures	Not applicable	- -	-	-	There are no chemical groups present in the molecule associated with explosive or self-reactive properties.
9	Pyrophoric liquids	Not classified	- -	-	-	It is estimated that it does not ignite at normal temperatures from an autoignition temperature of 325 deg C (HSDB (2004)).
10	Pyrophoric solids	Not applicable	- -	-	-	Liquid (GHS definition)
11	Self-heating substances and mixtures	Classification not possible	- -	-	-	Test methods applicable to liquid substances are not available.
12	Substances and mixtures which, in contact with water, emit flammable gases	Classification not possible	- -	-	-	It contains a metalloid (Si), and there is the information that ammonia is formed upon contact with water or humid air (MSDS (Sigma-Aldrich, 2012)), but the classification is not possible due to no data on gases produced and the rate of evolution of gases.
13	Oxidizing liquids	Not applicable	- -	-	-	Organic compounds containing no oxygen, fluorine or chlorine.
14	Oxidizing solids	Not applicable	- -	-	-	Liquid (GHS definition)
15	Organic peroxides	Not applicable	- -	-	-	Organic compounds containing no bivalent -O-O- structure.
16	Corrosive to metals	Classification not possible	- -	-	-	No data available.

HEALTH HAZARDS

Hazard class		Classification	Pictogram Signal word	Hazard statement (code)	Precautionary statement (code)	Rationale for the classification
1	Acute toxicity (Oral)	Category 4	Warning	H302	P301+P312 P264 P270 P330 P501	There is a report on four LD50 values for rats (1,416 mg/kg (males), 1,904 mg/kg (females), 774 mg/kg, 851 mg/kg) (all SIAP (2009)), and all correspond to Category 4. Besides, as for health hazards, also refer to ammonia (CAS RN 7664-41-7) and trimethylsilanol (CAS RN 1066-40-6), the hydrolysates of this substance.
1	Acute toxicity (Dermal)	Category 3	Danger	H311	P302+P352 P361+P364 P280 P312 P321 P405 P501	There is a report on three LD50 values for rabbits (547 mg/kg (females), 589 mg/kg (males), 1,350 mg/kg (males and females combined)) (all SIAP (2009)), two (data in males and data in females in one test) correspond to Category 3, and the other one (combined data for males and females) corresponds to Category 4. A more hazardous category was adopted, and it was classified in Category 3.
1	Acute toxicity (Inhalation: Gases)	Not applicable	- -	-	-	Liquid (GHS definition)
1	Acute toxicity (Inhalation: Vapours)	Category 3	Danger	H331	P304+P340 P403+P233 P261 P271 P311 P321 P405 P501	It was classified in Category 3 based on an LC50 value for rats of 10 mg/L/6 hours (1,516 ppm, converted 4-hour equivalent value = 1,857 ppm/4 hours) (SIAP (2009)). Besides, because the LC50 value (1,516 ppm) was lower than 90% of the saturated vapour pressure concentration (18,158 ppm), a reference value of gas was applied.
1	Acute toxicity (Inhalation: Dusts and mists)	Classification not possible	- -	-	-	No data available.
2	Skin corrosion/irritation	Category 1	Danger	H314	P301+P330+P331 P303+P361+P353 P305+P351+P338 P304+P340 P260 P264 P280 P310 P321 P363 P405 P501	It is reported that in a Draize test by a 4-hour application to six rabbits, severe erythema, moderate to severe edema, and necrosis were observed in all six animals (IUCLID (2000)), and it is reported that this substance caused necrosis in a test by exposure under 4-hour occlusive conditions (U.S. Department of Transportation regulations) (SIAP (2009)). Therefore, it was classified in Category 1. Besides, it is also described that it was not irritating to the skin in a test with rabbits (OECD TG 404), and the use of the occlusive cover is likely to have increased the severity of the effect, although the details are unknown (SIAP (2009)).
3	Serious eye damage/eye irritation	Category 2B	- Warning	H320	P305+P351+P338 P337+P313 P264	It was classified in Category 2B because it was slightly irritating in an eye irritation test with rabbits (IUCLID (2000)), and it is described that it was slightly or not irritating in standard animal tests (OECD TG405 or similar test methods) (SIAP (2009)).
4	Respiratory sensitization	Classification not possible	- -	-	-	No data available.
4	Skin sensitization	Classification not possible	- -	-	-	No data available.
5	Germ cell mutagenicity	Classification not possible	- -	-	-	The classification is not possible due to no in vivo test data. Besides, as for in vitro tests, it is reported that it was negative in all of an Ames test (SIAP (2009), NTP DB (1995)), a mouse lymphoma test (SIAP (2009)), and a chromosomal aberration test with CHO cells (NTP DB (Access on Sep. 2012)).
6	Carcinogenicity	Classification not possible	- -	-	-	No data available.
7	Reproductive toxicity	Classification not possible	- -	-	-	In a combined repeated dose toxicity study with the reproduction/developmental toxicity screening test with rats by inhalation exposure (OECD TG422), no evidence of adverse reproductive and developmental effects was observed at the highest dose (2.66 mg/L/6 hours/day) where parent animals showed general toxicity such as effects on the nervous system and decreases in body weights and food consumption (SIAP (2009)). However, because data are lacking on effects on the development of offspring including teratogenicity, it was classified as "Classification not possible."
8	Specific target organ toxicity - Single exposure	Category 1 (nervous system), Category 3 (narcotic effects, respiratory tract irritation)	Danger Warning	H370 H336 H335	P308+P311 P260 P264 P270 P321 P405 P501 P304+P340 P403+P233 P261 P271 P312	Clinical signs consistent with nervous system effects were observed in a single administration test in each route (oral or inhalation in rats, or dermal in rabbits) (SIAP (2009)). Effects were found after inhalation in rats at or above 5.9 mg/L/6 hours (7.2 mg/L/4 hours) corresponding to the guidance values for Category 1, and LD50 values by dermal administration to rabbits (547 and 589 mg/kg) correspond to the guidance value range for Category 1 for a single exposure. Therefore, it was classified in Category 1 (nervous system). And it was classified in Category 3 (narcotic effects) from the information that sedation was seen after oral administration of 300 or 450 mg/kg to mice, and at doses above, there were dyspnea, ataxia, and excessive excitement, followed by long-term narcotic effects with loss of righting reflex (IUCLID (2000)). Furthermore, it was classified in Category 3 (respiratory tract irritation) because it is described that slow/noisy respiration and respiratory difficulties were observed in an inhalation exposure test with rats, and respiratory tract irritation was suggested (SIAP (2009)).
9	Specific target organ toxicity - Repeated exposure	Classification not possible	- -	-	-	As for nervous system signs observed immediately after exposure at 2.66 mg/L/6 hours in a combined repeated dose toxicity study with the reproduction/developmental toxicity screening test with rats by inhalation exposure (OECD TG 422) (SIAP (2009)), those were not adopted for the rationale for classification in this hazard class because they were acute effects. As for the other effects, decreases in body weights and food consumption and effects on hematology and blood biochemistry parameters were found in the 2.66 mg/L/6 hours group (converted guidance value: males 0.82 mg/L/6 hours, females 1.27 mg/L/6 hours), and there were weight changes of the epididymis, lung, kidney, and liver, and the only microscopic finding of centrilobular hypertrophy in the liver in females (SIAP (2009)). No findings to show apparent adverse effects were seen in the dose range in the above report. However, because the details are unknown, and there are no data on the other routes, it was classified as "Classification not possible" due to lack of data.
10	Aspiration hazard	Classification not possible	- -	-	-	No data available.

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)	Category 3	- -	H402	P273 P501	It was classified in Category 3 from 72-hour ErC50 = 50 mg/L for algae (Desmodesmus subspicatus) (measured as TOC; SIDS, 2010). Besides, the aquatic toxicity test result was shown as TOC because this substance quickly hydrolyzes (the half-life for hydrolysis at 22 deg C, pH 5.5: < 0.1 minute) to form ammonia and trimethylsilanol.
11	Hazardous to the aquatic environment (Long-term)	Category 3	- -	H412	P273 P501	If chronic toxicity data are used, then it is classified as "Not classified" due to 72-hour NOEC = 2.7 mg/L for algae (Desmodesmus subspicatus) (measured as TOC; SIDS, 2010), although it is not rapidly degradable (not readily degradable, a degradation rate by BOD: 0% (Biodegradation and Bioconcentration Results of Existing Chemical Substances under the Chemical Substances Control Law, 1998)). If acute toxicity data are used for a trophic level for which chronic toxicity data are not obtained, then it is classified in Category 3 due to being not rapidly degradable (not readily degradable, a degradation rate by BOD: 0% (Biodegradation and Bioconcentration Results of Existing Chemical Substances under the Chemical Substances Control Law, 1998)), and 48-hour EC50 = 80 mg/L for crustacea (Daphnia magna) (measured as TOC; SIDS, 2010). By drawing a comparison between the above results, it was classified in Category 3.
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.

To GHS Information