GHS Classification Result

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GENERAL INFORMATION
Item Information
CAS RN 593-74-8
Chemical Name Dimethyl mercury
Substance ID H27-B-035/C-071B_P
Classification year (FY) FY2015
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 FY2008  
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 (Ver. 1.1))
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 present in the molecule associated with explosive properties.
2 Flammable gases (including chemically unstable gases) Not applicable
-
-
- - "Liquids" according to GHS definition.
3 Aerosols Not applicable
-
-
- - Not an aerosol product.
4 Oxidizing gases Not applicable
-
-
- - "Liquids" according to GHS definition.
5 Gases under pressure Not applicable
-
-
- - "Liquids" according to GHS definition.
6 Flammable liquids Category 2


Danger
H225 P303+P361+P353
P370+P378
P403+P235
P210
P233
P240
P241
P242
P243
P280
P501
From data of a flash point of 5 degrees C (methods; unknown), and a boiling point of 93-94 degrees C (ICSC (2003)), it is estimated that it corresponds to Category 2 in a prescribed test method.
7 Flammable solids Not applicable
-
-
- - "Liquids" according to 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 Classification not possible
-
-
- - Due to no data, the classification is not possible.
10 Pyrophoric solids Not applicable
-
-
- - "Liquids" according to GHS definition.
11 Self-heating substances and mixtures Classification not possible
-
-
- - No established test method suitable for liquid substances.
12 Substances and mixtures which, in contact with water, emit flammable gases Not classified
-
-
- - From the observation result of insoluble in water (IARC58 (1993)), it is estimated that it does not react vigorously with water.
13 Oxidizing liquids Not applicable
-
-
- - It is an organic compound that does not contain oxygen, fluorine, or chlorine.
14 Oxidizing solids Not applicable
-
-
- - "Liquids" according to GHS definition.
15 Organic peroxides Not applicable
-
-
- - It is an organic compound that does not contain bivalent -O-O- structure in the molecule.
16 Corrosive to metals Classification not possible
-
-
- - Due to no data, the classification is not possible.

HEALTH HAZARDS
Hazard class Classification Pictogram
Signal word
Hazard statement
(code)
Precautionary statement
(code)
Rationale for the classification
1 Acute toxicity (Oral) Classification not possible
-
-
- - Due to lack of data, the classification is not possible.
1 Acute toxicity (Dermal) Classification not possible
-
-
- - Due to lack of data, the classification is not possible.
1 Acute toxicity (Inhalation: Gases) Not applicable
-
-
- - "Liquids" according to GHS definition.
1 Acute toxicity (Inhalation: Vapours) Classification not possible
-
-
- - Due to lack of data, the classification is not possible.
1 Acute toxicity (Inhalation: Dusts and mists) Classification not possible
-
-
- - Due to lack of data, the classification is not possible.
2 Skin corrosion/irritation Classification not possible
-
-
- - The classification is not possible due to lack of data. Besides, it is written that alkyl mercury compounds are severely irritating to skin (HSDB (Access on August 2015)).
3 Serious eye damage/eye irritation Classification not possible
-
-
- - Due to lack of data, the classification is not possible.
4 Respiratory sensitization Classification not possible
-
-
- - Due to lack of data, the classification is not possible.
4 Skin sensitization Classification not possible
-
-
- - Due to lack of data, the classification is not possible.
5 Germ cell mutagenicity Classification not possible
-
-
- - The classification is not possible due to lack of data. As for in vivo, a chromosomal aberration test in mouse oocytes after intravenous administration was negative (IARC 58 (1993)). As for in vitro, a chromosomal aberration test in cultured human lymphocytes was positive (IARC 58 (1993)), and a chromosomal aberration test in cultured Chinese hamster cells was negative (ATSDR (1999)). It is written that a positive result in a chromosomal aberration test using Chinese hamster cells mentioned in the previous classification is that on only one dose (ATSDR (1999)).
6 Carcinogenicity Category 2


Warning
H351 P308+P313
P201
P202
P280
P405
P501
There is no carcinogenicity information in humans. As for experimental animals, it is written that in carcinogenicity tests in rats or mice in diet administration of methylmercury chloride, no tumors were observed in rats, but an increased incidence of adenoma or adenocarcinoma of renal tubules was found in males in all of the three mouse test results (IARC 58 (1993)). Namely, it is written that in the other test in mice in diet administration of methylmercury chloride, a significantly increased number of kidney tumors was observed in male mice, and that (a few) kidney tumors were found in male and female mice treated with testosterone propionate after gonadectomy (increased kidney tumors did not occur in male and female mice not dosed of testosterone after gonadectomy) (IARC 58 (1993)). Based on these results, IARC classified it in Group 2B (IARC 58 (1993)). After this, there are no classification results in carcinogenicity by other organizations, and no information supporting evidence of carcinogenicity in humans was obtained. Therefore, the substance was classified in Category 2. in this hazard class.
7 Reproductive toxicity Category 1A, Additional category: Effects on or via lactation


Danger
H360
H362
P308+P313
P201
P202
P280
P405
P501
There are no data on reproductive toxicity effects limited to this substance (dimethylmercury). However, it is written in Handbook on the Toxicology of Metals (4th, ed., 2015) that this substance is effectively absorbed by an inhalation or dermal route and is converted to "methylmercury (MeHg)" in vivo, and from a symptomatologic and toxicokinetic point of view, dimethylmercury poisoning is equivalent to the symptoms occurred after exposure to methylmercury compounds, based on the signs described in a few fatal poisoning exposure cases. It is written that by estimating from the case of person who developed delayed neurological symptoms 5 months after single exposure to this substance, absorbed dimethylmercury is distributed and accumulated in fat tissue, and demethylated form may be gradually generated (Handbook on the Toxicology of Metals. 4th. ed., Volume II. pp. 1061 (2015)). Therefore, it was judged that reproductive toxicity information of "methylmercury" is usable for the classification in this hazard class, hereafter, it will be classified by referring to the information described in JECFA FAS (2007), ATSDR (2013), and ACGIH (7th, 2001) on reproductive/developmental toxicity effects of methyl mercury as well as the information mentioned in the official position of the country on "fetal Minamata disease" in Japan.

In assessment of health effects by methylmercury in humans at a joint WHO/FAO expert committee, an investigation research on pregnant women and children exposed to this substance in the Faroe Islands, and from the investigation research on children who were prenatally and postnatally, or only postnatally exposed in Japan and Iraq, as sensitivity to neurobehavioral toxic effects such as slight decrease in motor control function and visual disorder that occur after birth, there is no difference in vulnerability between prenatal exposure from a stage of fetuses in maternal uterus and postnatal exposure from a stage of infants, and the committee concluded that exposure to methylmercury by ingestion of contaminated fish and so on should be strictly curbed in pregnant women and infants, especially as a high-risk group (JECFA FAS 58 (2007)). Moreover, as for humans, it is written that in a population of women exposed to methylmercury during pregnancy in Michigan in the US, a women subgroup having preterm delivery with a gestation period of less than 35 weeks tended to have hair mercury levels above the 90th percentile (0.55 to 2.5 micro g/g) of those in a subgroup of women who delivered after a full gestation period of 37 weeks or longer (ATSDR addendum (2013)). On the other hand, for methylmercury, a causality of diaplacental methylmercury poisoning called as fetal Minamata disease and newborn Minamata disease was clarified. Namely, neurological symptoms are observed in pregnant women who are exposed to methylmercury by ingesting fish and seafood contaminated with organic mercury and progressed from sensory disturbance gradually to ataxia and constriction of the visual field, and children born show cerebral-paralysis-like signs such as intelligence impairment, disturbance of development, speech difficulty, gait disorder, and posture change, which tend to be severer than those of adults. It is written that even at levels of methylmercury which do not always cause clinical signs in mothers, fetuses are more likely to have effects of Minamata disease because they are more sensitive due to low excretion of methylmercury (Summary of Minamata disease problem (2015), edited by Environmental Research Office, Research Bureau, the House of Representatives, June (2015)). Besides these, it is written that a major target organ of methylmercury is the central nervous system in experimental animals, and methylmercury is a teratogen in experimental animals and humans (ACGIH (7th, 2001)).
As above, because the toxicity information of "methylmercury" is thought to be applicable for the classification in this hazard class as mentioned at the front, the substance was classified in "Category 1A" in this hazard class, and "effects on or via lactation" was added.
8 Specific target organ toxicity - Single exposure Category 1 (nervous system)


Danger
H370 P308+P311
P260
P264
P270
P321
P405
P501
In acute inhalation exposure to alkyl mercury compounds in humans, neurological effects such as numbness and tingling of limbs, unsteady gait, and walking difficulty were observed (ATSDR (1999)). Also for this substance, as effects in humans, there is a case of a female chemist who inadvertently spilled several drops (estimated as 0.44 mL) of dimethylmercury onto the disposable gloves she wore and showed disturbance in balance, gait, and speech by exposure via penetrating gloves (in addition to dermal exposure, inhalation exposure is suggested from the property of this substance). Even after hospitalization and treatment, she became comatose 175 days after exposure and died after 298 days (ATSDR (1999)). Therefore, the substance was classified in Category 1 (nervous system).
9 Specific target organ toxicity - Repeated exposure Category 1 (nervous system, kidney)


Danger
H372 P260
P264
P270
P314
P501
As effects in humans, it is reported that after 2-week dermal exposure, a 23-year-old laboratory worker showed gingival pain, salivation, numbness of hands/feet/tongue, deafness, weak sight, slow answers to questions with an inarticulate voice, throat pain in swallowing, unable to speak, and a death from pneumonia (at least 12 months after exposure), and a 30-year-old chemist who synthesized 6 kg dimethylmercury within 3 months developed constriction of the visual field and symptoms of related to disturbance to the cerebellum and cerebral cortex (paralysis and deafness) (GESTIS (Access on August 2015)). Furthermore, it is not this substance, but it is written in ACGIH that major target organs of alkyl mercury compounds are the central and peripheral nervous systems and the kidney (ACGIH (7th, 2001)), and it is reported in ATSDR that irreversible disturbance in the brain and kidney occurred in a part of people who ate fish contaminated with a large amount of methylmercury and in a part of people who ate seeds treated with methylmercury or other organic mercury compounds (ATSDR (1999)).
From the above, it is thought that the nervous system is the main target organ, and the kidney is also a target organ.
Therefore, the substance was classified in Category 1 (nervous system, kidney).
10 Aspiration hazard Classification not possible
-
-
- - Due to lack of data, the classification is not possible.

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
-
-
- - No data.
11 Hazardous to the aquatic environment (Long-term) Classification not possible
-
-
- - No data.
12 Hazardous to the ozone layer Classification not possible
-
-
- - No data.


NOTE:
* A blank or "-" in a cell of classification denotes that the classification of the hazard class was not conducted.
* Hazard_statement_and/or_Precautionary_statement will show when hovering the mouse over a code of Hazard_statement_and/or_Precautionary_statement.
Hazard_statement_and/or_Precautionary_statement are also provided in the Excel file.
* Classification was conducted by relevant Japanese Ministries in accordance with GHS Classification Guidance for the Japanese Government,
and is intended to provide a reference for preparing GHS labelling and SDS for users.
* This is a provisional English translation of classification results and is subject to revision without notice.
* The responsibility for any resulting GHS labelling and SDS referenced from this site is with users.
* Codes assigned to each of the hazard statements and codes for each of the precautionary statement are
based on the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) in United Nations.

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